From 7fa909ea97275f5b8d513ed4fc8de9df25998e54 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Sun, 16 Jun 2019 23:10:02 +0200
Subject: [PATCH 01/22] Added previewTab

---
 .../gui/preferences/PreferencesDialog.css     |  43 ++-
 .../PreferencesDialogViewModel.java           |   2 +-
 .../preferences/PreviewPreferencesTab.java    | 231 ----------------
 .../jabref/gui/preferences/PreviewTab.fxml    |  55 ++++
 .../gui/preferences/PreviewTabView.java       | 250 ++++++++++++++++++
 .../gui/preferences/PreviewTabViewModel.java  | 188 +++++++++++++
 src/main/resources/l10n/JabRef_en.properties  |   3 +
 7 files changed, 539 insertions(+), 233 deletions(-)
 delete mode 100644 src/main/java/org/jabref/gui/preferences/PreviewPreferencesTab.java
 create mode 100644 src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
 create mode 100644 src/main/java/org/jabref/gui/preferences/PreviewTabView.java
 create mode 100644 src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java

diff --git a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
index f1b7bfdd5e1..bc62ccf1e00 100644
--- a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
+++ b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
@@ -14,7 +14,7 @@
     -fx-background: -fx-control-inner-background;
 }
 
-.split-pane-divider {
+.split-pane > .split-pane-divider {
     -fx-padding: 0 4 0 4;
     -fx-background-color: transparent;
 }
@@ -26,3 +26,44 @@
 *:search-highlight {
 	-fx-background-color: -jr-light-red;
 }
+
+.code-area {
+    -fx-padding: 0;
+    -fx-border-width: 1;
+    -fx-background-color: transparent;
+    -fx-border-color: -fx-outer-border;
+}
+
+.code-area .tagmark .{
+    -fx-fill: gray;
+}
+
+.code-area .anytag {
+    -fx-fill: crimson;
+}
+
+.code-area .paren {
+    -fx-fill: firebrick;
+    -fx-font-weight: bold;
+}
+
+.code-area .attribute {
+    -fx-fill: darkviolet;
+}
+
+.code-area .avalue {
+    -fx-fill: black;
+}
+
+.code-area .comment {
+    -fx-fill: teal;
+}
+
+.code-area .highlight-keyword {
+    -fx-text-fill: -jr-purple;
+}
+
+.code-area .context-menu {
+    -fx-font-family: sans-serif;
+    -fx-padding: 0;
+}
diff --git a/src/main/java/org/jabref/gui/preferences/PreferencesDialogViewModel.java b/src/main/java/org/jabref/gui/preferences/PreferencesDialogViewModel.java
index 85647268743..0347e948824 100644
--- a/src/main/java/org/jabref/gui/preferences/PreferencesDialogViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreferencesDialogViewModel.java
@@ -49,7 +49,7 @@ public PreferencesDialogViewModel(DialogService dialogService, TaskExecutor task
         preferenceTabs.add(new FileTabView(prefs));
         preferenceTabs.add(new TablePrefsTab(prefs));
         preferenceTabs.add(new TableColumnsTab(prefs, frame));
-        preferenceTabs.add(new PreviewPreferencesTab(dialogService, this.taskExecutor));
+        preferenceTabs.add(new PreviewTabView(prefs));
         preferenceTabs.add(new ExternalTabView(prefs, frame));
         preferenceTabs.add(new GroupsPrefsTab(prefs));
         preferenceTabs.add(new EntryEditorPrefsTab(prefs));
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewPreferencesTab.java b/src/main/java/org/jabref/gui/preferences/PreviewPreferencesTab.java
deleted file mode 100644
index ec4c6348a23..00000000000
--- a/src/main/java/org/jabref/gui/preferences/PreviewPreferencesTab.java
+++ /dev/null
@@ -1,231 +0,0 @@
-package org.jabref.gui.preferences;
-
-import java.util.ArrayList;
-import java.util.Comparator;
-import java.util.List;
-
-import javafx.beans.binding.Bindings;
-import javafx.beans.binding.BooleanBinding;
-import javafx.collections.FXCollections;
-import javafx.collections.ObservableList;
-import javafx.scene.Node;
-import javafx.scene.control.Button;
-import javafx.scene.control.ButtonType;
-import javafx.scene.control.DialogPane;
-import javafx.scene.control.Label;
-import javafx.scene.control.ListView;
-import javafx.scene.control.ScrollPane;
-import javafx.scene.control.TextArea;
-import javafx.scene.layout.GridPane;
-import javafx.scene.layout.VBox;
-
-import org.jabref.Globals;
-import org.jabref.JabRefGUI;
-import org.jabref.gui.BasePanel;
-import org.jabref.gui.DialogService;
-import org.jabref.gui.preview.PreviewViewer;
-import org.jabref.gui.util.BackgroundTask;
-import org.jabref.gui.util.TaskExecutor;
-import org.jabref.gui.util.ViewModelListCellFactory;
-import org.jabref.logic.citationstyle.CitationStyle;
-import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
-import org.jabref.logic.citationstyle.PreviewLayout;
-import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
-import org.jabref.logic.l10n.Localization;
-import org.jabref.logic.util.TestEntry;
-import org.jabref.model.database.BibDatabaseContext;
-import org.jabref.preferences.PreviewPreferences;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-public class PreviewPreferencesTab implements PrefsTab {
-
-    private static final Logger LOGGER = LoggerFactory.getLogger(PreviewPreferencesTab.class);
-
-    private final ObservableList<PreviewLayout> availableModel = FXCollections.observableArrayList();
-    private final ObservableList<PreviewLayout> chosenModel = FXCollections.observableArrayList();
-
-    private final ListView<PreviewLayout> available = new ListView<>(availableModel);
-    private final ListView<PreviewLayout> chosen = new ListView<>(chosenModel);
-
-    private final Button btnRight = new Button("»");
-    private final Button btnLeft = new Button("«");
-    private final Button btnUp = new Button(Localization.lang("Up"));
-    private final Button btnDown = new Button(Localization.lang("Down"));
-    private final GridPane gridPane = new GridPane();
-    private final TextArea previewTextArea = new TextArea();
-    private final Button btnTest = new Button(Localization.lang("Test"));
-    private final Button btnDefault = new Button(Localization.lang("Default"));
-    private final ScrollPane scrollPane = new ScrollPane(previewTextArea);
-    private final DialogService dialogService;
-    private final TaskExecutor taskExecutor;
-
-    public PreviewPreferencesTab(DialogService dialogService, TaskExecutor taskExecutor) {
-        this.dialogService = dialogService;
-        this.taskExecutor = taskExecutor;
-        setupLogic();
-        setupGui();
-    }
-
-    private void setupLogic() {
-        BooleanBinding nothingSelectedFromChosen = Bindings.isEmpty(chosen.getSelectionModel().getSelectedItems());
-
-        btnLeft.disableProperty().bind(nothingSelectedFromChosen);
-        btnDown.disableProperty().bind(nothingSelectedFromChosen);
-        btnUp.disableProperty().bind(nothingSelectedFromChosen);
-        btnRight.disableProperty().bind(Bindings.isEmpty(available.getSelectionModel().getSelectedItems()));
-
-        btnRight.setOnAction(event -> {
-            for (PreviewLayout layout : available.getSelectionModel().getSelectedItems()) {
-                availableModel.remove(layout);
-                chosenModel.add(layout);
-            }
-        });
-
-        btnLeft.setOnAction(event -> {
-            for (PreviewLayout layout : chosen.getSelectionModel().getSelectedItems()) {
-                availableModel.add(layout);
-                chosenModel.remove(layout);
-            }
-        });
-
-        btnUp.setOnAction(event -> {
-            List<Integer> newSelectedIndices = new ArrayList<>();
-            for (int oldIndex : chosen.getSelectionModel().getSelectedIndices()) {
-                boolean alreadyTaken = newSelectedIndices.contains(oldIndex - 1);
-                int newIndex = ((oldIndex > 0) && !alreadyTaken) ? oldIndex - 1 : oldIndex;
-                chosenModel.add(newIndex, chosenModel.remove(oldIndex));
-                chosen.getSelectionModel().select(newIndex);
-            }
-        });
-
-        btnDown.setOnAction(event -> {
-            List<Integer> newSelectedIndices = new ArrayList<>();
-            ObservableList<Integer> selectedIndices = chosen.getSelectionModel().getSelectedIndices();
-            for (int i = selectedIndices.size() - 1; i >= 0; i--) {
-                int oldIndex = selectedIndices.get(i);
-                boolean alreadyTaken = newSelectedIndices.contains(oldIndex + 1);
-                int newIndex = ((oldIndex < (chosenModel.size() - 1)) && !alreadyTaken) ? oldIndex + 1 : oldIndex;
-                chosenModel.add(newIndex, chosenModel.remove(oldIndex));
-                chosen.getSelectionModel().select(newIndex);
-            }
-        });
-
-        btnDefault.setOnAction(event -> previewTextArea.setText(Globals.prefs.getPreviewPreferences()
-                                                                             .getDefaultPreviewStyle()
-                                                                             .replace("__NEWLINE__", "\n")));
-
-        btnTest.setOnAction(event -> {
-            try {
-                PreviewViewer testPane = new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager);
-                testPane.setEntry(TestEntry.getTestEntry());
-
-                PreviewLayout layout = chosen.getSelectionModel().getSelectedItem();
-                testPane.setLayout(layout);
-
-                DialogPane pane = new DialogPane();
-                pane.setContent(testPane);
-                dialogService.showCustomDialogAndWait(Localization.lang("Preview"), pane, ButtonType.OK);
-
-            } catch (StringIndexOutOfBoundsException exception) {
-                LOGGER.warn("Parsing error.", exception);
-                dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
-            }
-        });
-    }
-
-    private void setupGui() {
-        VBox vBox = new VBox();
-        btnRight.setPrefSize(80, 20);
-        btnLeft.setPrefSize(80, 20);
-        btnUp.setPrefSize(80, 20);
-        btnDown.setPrefSize(80, 20);
-        vBox.getChildren().addAll(new Label(""), new Label(""), new Label(""), new Label(""), new Label(""),
-                new Label(""), new Label(""), btnRight, btnLeft, new Label(""), new Label(""), new Label(""),
-                btnUp, btnDown);
-        Label currentPreview = new Label(Localization.lang("Current Preview"));
-        currentPreview.getStyleClass().add("sectionHeader");
-        gridPane.add(currentPreview, 1, 1);
-        gridPane.add(available, 1, 2);
-        gridPane.add(vBox, 2, 2);
-        gridPane.add(chosen, 3, 2);
-        gridPane.add(btnTest, 2, 6);
-        gridPane.add(btnDefault, 3, 6);
-        previewTextArea.setPrefSize(600, 300);
-        gridPane.add(scrollPane, 1, 9);
-
-        btnTest.disableProperty().bind(Bindings.isEmpty(chosen.getSelectionModel().getSelectedItems()));
-
-        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosen);
-        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(available);
-    }
-
-    @Override
-    public Node getBuilder() {
-        return gridPane;
-    }
-
-    @Override
-    public void setValues() {
-        PreviewPreferences previewPreferences = Globals.prefs.getPreviewPreferences();
-
-        chosenModel.clear();
-        chosenModel.addAll(previewPreferences.getPreviewCycle());
-
-        availableModel.clear();
-        if (chosenModel.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
-            availableModel.add(previewPreferences.getTextBasedPreviewLayout());
-        }
-
-        BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
-                      .onSuccess(value -> value.stream()
-                                               .map(CitationStylePreviewLayout::new)
-                                               .filter(style -> !chosenModel.contains(style))
-                                               .sorted(Comparator.comparing(PreviewLayout::getName))
-                                               .forEach(availableModel::add))
-                      .onFailure(ex -> {
-                          LOGGER.error("something went wrong while adding the discovered CitationStyles to the list ", ex);
-                          dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
-                      })
-                      .executeWith(taskExecutor);
-
-        previewTextArea.setText(previewPreferences.getPreviewStyle().replace("__NEWLINE__", "\n"));
-    }
-
-    @Override
-    public void storeSettings() {
-        PreviewPreferences previewPreferences = Globals.prefs.getPreviewPreferences();
-
-        if (chosenModel.isEmpty()) {
-            chosenModel.add(previewPreferences.getTextBasedPreviewLayout());
-        }
-
-        PreviewPreferences newPreviewPreferences = Globals.prefs.getPreviewPreferences()
-                                                                .getBuilder()
-                                                                .withPreviewCycle(chosenModel)
-                                                                .withPreviewStyle(previewTextArea.getText().replace("\n", "__NEWLINE__"))
-                                                                .build();
-        if (!chosen.getSelectionModel().isEmpty()) {
-            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosen.getSelectionModel().getSelectedIndex()).build();
-        }
-        Globals.prefs.storePreviewPreferences(newPreviewPreferences);
-
-        for (BasePanel basePanel : JabRefGUI.getMainFrame().getBasePanelList()) {
-            // TODO: Find a better way to update preview
-            basePanel.closeBottomPane();
-            //basePanel.getPreviewPanel().updateLayout(Globals.prefs.getPreviewPreferences());
-        }
-    }
-
-    @Override
-    public boolean validateSettings() {
-        return !chosenModel.isEmpty();
-    }
-
-    @Override
-    public String getTabName() {
-        return Localization.lang("Entry preview");
-    }
-
-}
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
new file mode 100644
index 00000000000..324b6e69d9b
--- /dev/null
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.ListView?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.VBox?>
+
+<?import org.fxmisc.richtext.CodeArea?>
+
+<?import org.fxmisc.flowless.VirtualizedScrollPane?>
+<fx:root prefWidth="650.0" spacing="4.0" type="VBox" xmlns="http://javafx.com/javafx/8.0.212"
+         xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.jabref.gui.preferences.PreviewTabView">
+    <children>
+        <Label text="%Current Preview" styleClass="titleHeader"/>
+        <HBox prefHeight="100.0" prefWidth="200.0" spacing="4.0">
+            <children>
+                <VBox spacing="4.0" HBox.hgrow="ALWAYS">
+                    <children>
+                        <Label text="%Available" styleClass="sectionHeader" />
+                        <ListView fx:id="availableListView" maxHeight="250.0" minHeight="250.0"/>
+                    </children>
+                </VBox>
+                <VBox alignment="CENTER" spacing="4.0">
+                    <children>
+                        <Label styleClass="sectionHeader" />
+                        <Button fx:id="toRightButton"  prefWidth="60.0" text="&gt;&gt;" onAction="#toRightButtonAction" />
+                        <Button fx:id="toLeftButton" prefWidth="60.0" text="&lt;&lt;" onAction="#toLeftButtonAction" />
+                        <VBox prefHeight="40.0"/>
+                        <Button fx:id="sortUpButton" prefWidth="60.0" text="%Up" onAction="#sortUpButtonAction" />
+                        <Button fx:id="sortDownButton" prefWidth="60.0" text="%Down" onAction="#sortDownButtonAction" />
+                    </children>
+                </VBox>
+                <VBox spacing="4.0" HBox.hgrow="ALWAYS">
+                    <children>
+                        <Label text="%Selected" styleClass="sectionHeader" />
+                        <ListView fx:id="chosenListView" maxHeight="250.0" minHeight="250.0"/>
+                        <HBox alignment="CENTER" spacing="4.0">
+                            <children>
+                                <Button fx:id="testButton" prefWidth="80" text="%Test" onAction="#testButtonAction"/>
+                                <Button fx:id="defaultButton" prefWidth="80" text="%Default" onAction="#defaultButtonAction" />
+                            </children>
+                        </HBox>
+                    </children>
+                </VBox>
+            </children>
+        </HBox>
+        <Label text="%Selected style source" styleClass="sectionHeader" />
+        <VirtualizedScrollPane>
+            <content>
+                <CodeArea fx:id="previewTextArea" prefHeight="200.0" />
+            </content>
+        </VirtualizedScrollPane>
+    </children>
+</fx:root>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
new file mode 100644
index 00000000000..414f3f574d6
--- /dev/null
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -0,0 +1,250 @@
+package org.jabref.gui.preferences;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.inject.Inject;
+
+import javafx.beans.binding.BooleanBinding;
+import javafx.beans.property.ReadOnlyListWrapper;
+import javafx.fxml.FXML;
+import javafx.scene.Node;
+import javafx.scene.control.Button;
+import javafx.scene.control.ContextMenu;
+import javafx.scene.control.ListView;
+import javafx.scene.layout.VBox;
+
+import org.jabref.Globals;
+import org.jabref.gui.DialogService;
+import org.jabref.gui.actions.ActionFactory;
+import org.jabref.gui.actions.SimpleCommand;
+import org.jabref.gui.actions.StandardActions;
+import org.jabref.gui.util.BindingsHelper;
+import org.jabref.gui.util.TaskExecutor;
+import org.jabref.gui.util.ViewModelListCellFactory;
+import org.jabref.logic.citationstyle.PreviewLayout;
+import org.jabref.logic.l10n.Localization;
+import org.jabref.preferences.JabRefPreferences;
+
+import com.airhacks.afterburner.views.ViewLoader;
+import org.fxmisc.richtext.CodeArea;
+import org.fxmisc.richtext.LineNumberFactory;
+import org.fxmisc.richtext.model.StyleSpans;
+import org.fxmisc.richtext.model.StyleSpansBuilder;
+
+public class PreviewTabView extends VBox implements PrefsTab {
+
+    @FXML private ListView<PreviewLayout> availableListView;
+    @FXML private ListView<PreviewLayout> chosenListView;
+
+    @FXML private Button toRightButton;
+    @FXML private Button toLeftButton;
+    @FXML private Button sortUpButton;
+    @FXML private Button sortDownButton;
+
+    @FXML private Button testButton;
+    @FXML private Button defaultButton;
+
+    @FXML private CodeArea previewTextArea;
+
+    @Inject private TaskExecutor taskExecutor;
+    @Inject private DialogService dialogService;
+    private final JabRefPreferences preferences;
+
+    private PreviewTabViewModel viewModel;
+
+    private class EditAction extends SimpleCommand {
+
+        private final StandardActions command;
+
+        public EditAction(StandardActions command) { this.command = command; }
+
+        @Override
+        public void execute() {
+            if (previewTextArea != null) {
+                switch (command) {
+                    case COPY:
+                        previewTextArea.copy();
+                        break;
+                    case CUT:
+                        previewTextArea.cut();
+                        break;
+                    case PASTE:
+                        previewTextArea.paste();
+                        break;
+                    case SELECT_ALL:
+                        previewTextArea.selectAll();
+                        break;
+                }
+                previewTextArea.requestFocus();
+            }
+        }
+    }
+
+    public PreviewTabView(JabRefPreferences preferences) {
+        this.preferences = preferences;
+
+        ViewLoader.view(this)
+                  .root(this)
+                  .load();
+    }
+
+    public void initialize() {
+        viewModel = new PreviewTabViewModel(dialogService, preferences, taskExecutor);
+
+        availableListView.itemsProperty().bind(viewModel.availableListProperty());
+        viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper(availableListView.getSelectionModel().getSelectedItems()));
+        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
+
+        chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
+        viewModel.selectedChosenItemsProperty().bind(new ReadOnlyListWrapper(chosenListView.getSelectionModel().getSelectedItems()));
+        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosenListView);
+
+        toRightButton.disableProperty().bind(availableListView.selectionModelProperty().getValue().selectedItemProperty().isNull());
+
+        BooleanBinding nothingSelectedFromChosen = chosenListView.selectionModelProperty().getValue().selectedItemProperty().isNull();
+        toLeftButton.disableProperty().bind(nothingSelectedFromChosen);
+        sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
+        sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
+        testButton.disableProperty().bind(nothingSelectedFromChosen);
+        defaultButton.disableProperty().bind(nothingSelectedFromChosen);
+
+        previewTextArea.setParagraphGraphicFactory(LineNumberFactory.get(previewTextArea));
+        previewTextArea.textProperty().addListener((obs, oldText, newText) -> {
+            previewTextArea.setStyleSpans(0, computeHighlighting(newText));
+        });
+
+        BindingsHelper.bindBidirectional(previewTextArea.textProperty(), viewModel.previewTextProperty(),
+                text -> previewTextArea.replaceText(viewModel.previewTextProperty().getValue()),
+                text -> viewModel.previewTextProperty().setValue(previewTextArea.getText()));
+
+        ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
+        ContextMenu contextMenu = new ContextMenu();
+        contextMenu.getItems().addAll(
+                factory.createMenuItem(StandardActions.CUT, new PreviewTabView.EditAction(StandardActions.CUT)),
+                factory.createMenuItem(StandardActions.COPY, new PreviewTabView.EditAction(StandardActions.COPY)),
+                factory.createMenuItem(StandardActions.PASTE, new PreviewTabView.EditAction(StandardActions.PASTE)),
+                factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
+        );
+
+        contextMenu.getStyleClass().add("context-menu");
+        previewTextArea.setContextMenu(contextMenu);
+    }
+
+    /**
+     * This was originally created by Carlos Martins (github: @cemarins )
+     * Can this be used here? (BSD-2clause License)
+     * See here: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/XMLEditorDemo.java
+     * and also here: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#automatic-highlighting-of-java-keywords
+     *
+     * @author: Carlos Martins
+     * @param text to highlight
+     * @return highlighted span for codeArea
+     */
+    private StyleSpans<Collection<String>> computeHighlighting(String text) {
+
+        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
+                + "|(?<COMMENT><!--[^<>]+-->)");
+        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
+
+        final int GROUP_OPEN_BRACKET = 2;
+        final int GROUP_ELEMENT_NAME = 3;
+        final int GROUP_ATTRIBUTES_SECTION = 4;
+        final int GROUP_CLOSE_BRACKET = 5;
+        final int GROUP_ATTRIBUTE_NAME = 1;
+        final int GROUP_EQUAL_SYMBOL = 2;
+        final int GROUP_ATTRIBUTE_VALUE = 3;
+
+        Matcher matcher = XML_TAG.matcher(text);
+        int lastKwEnd = 0;
+        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
+        while (matcher.find()) {
+
+            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
+            if (matcher.group("COMMENT") != null) {
+                spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
+            } else {
+                if (matcher.group("ELEMENT") != null) {
+                    String attributesText = matcher.group(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_OPEN_BRACKET) - matcher.start(GROUP_OPEN_BRACKET));
+                    spansBuilder.add(Collections.singleton("anytag"), matcher.end(GROUP_ELEMENT_NAME) - matcher.end(GROUP_OPEN_BRACKET));
+
+                    if (!attributesText.isEmpty()) {
+
+                        lastKwEnd = 0;
+
+                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
+                        while (amatcher.find()) {
+                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
+                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
+                            lastKwEnd = amatcher.end();
+                        }
+                        if (attributesText.length() > lastKwEnd) {
+                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
+                        }
+                    }
+
+                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
+                }
+            }
+            lastKwEnd = matcher.end();
+        }
+        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
+        return spansBuilder.create();
+    }
+
+    @Override
+    public Node getBuilder() {
+        return this;
+    }
+
+    @Override
+    public void setValues() {
+        // Done by bindings
+    }
+
+    @Override
+    public void storeSettings() {
+        viewModel.storeSettings();
+    }
+
+    @Override
+    public boolean validateSettings() {
+        return viewModel.validateSettings();
+    }
+
+    @Override
+    public String getTabName() {
+        return Localization.lang("Entry preview");
+    }
+
+    public void toRightButtonAction() { viewModel.addToChosen(); }
+
+    public void toLeftButtonAction() { viewModel.removeFromChosen(); }
+
+    public void sortUpButtonAction() {
+        List<Integer> newIndices = viewModel.selectedInChosenUp(chosenListView.getSelectionModel().getSelectedIndices());
+        for (int index : newIndices) {
+            chosenListView.getSelectionModel().select(index);
+        }
+    }
+
+    public void sortDownButtonAction() {
+        List<Integer> newIndices = viewModel.selectedInChosenDown(chosenListView.getSelectionModel().getSelectedIndices());
+        for (int index : newIndices) {
+            chosenListView.getSelectionModel().select(index);
+        }
+    }
+
+    public void testButtonAction() { viewModel.testChosen(); }
+
+    public void defaultButtonAction() { viewModel.setChosenDefault(); }
+}
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
new file mode 100644
index 00000000000..b4f59eb08b8
--- /dev/null
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -0,0 +1,188 @@
+package org.jabref.gui.preferences;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+import javafx.beans.property.ListProperty;
+import javafx.beans.property.SimpleListProperty;
+import javafx.beans.property.SimpleStringProperty;
+import javafx.beans.property.StringProperty;
+import javafx.collections.FXCollections;
+import javafx.collections.ObservableList;
+import javafx.scene.control.ButtonType;
+import javafx.scene.control.DialogPane;
+
+import org.jabref.Globals;
+import org.jabref.JabRefGUI;
+import org.jabref.gui.BasePanel;
+import org.jabref.gui.DialogService;
+import org.jabref.gui.preview.PreviewViewer;
+import org.jabref.gui.util.BackgroundTask;
+import org.jabref.gui.util.TaskExecutor;
+import org.jabref.logic.citationstyle.CitationStyle;
+import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
+import org.jabref.logic.citationstyle.PreviewLayout;
+import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
+import org.jabref.logic.l10n.Localization;
+import org.jabref.logic.util.TestEntry;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.preferences.JabRefPreferences;
+import org.jabref.preferences.PreviewPreferences;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class PreviewTabViewModel implements PreferenceTabViewModel {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabViewModel.class);
+
+    private final ListProperty<PreviewLayout> availableListProperty = new SimpleListProperty<>();
+    private final ListProperty<PreviewLayout> selectedAvailableItemsProperty = new SimpleListProperty<>();
+    private final ListProperty<PreviewLayout> chosenListProperty = new SimpleListProperty<>();
+    private final ListProperty<PreviewLayout> selectedChosenItemsProperty = new SimpleListProperty<>();
+
+    private final StringProperty previewTextProperty = new SimpleStringProperty("");
+
+    private final DialogService dialogService;
+    private final JabRefPreferences preferences;
+    private final TaskExecutor taskExecutor;
+
+    public PreviewTabViewModel(DialogService dialogService, JabRefPreferences preferences, TaskExecutor taskExecutor) {
+        this.dialogService = dialogService;
+        this.preferences = preferences;
+        this.taskExecutor = taskExecutor;
+
+        setValues();
+    }
+
+    public void setValues() {
+        PreviewPreferences previewPreferences = preferences.getPreviewPreferences();
+        ObservableList<PreviewLayout> availableLayouts = FXCollections.observableArrayList();
+
+        chosenListProperty.setValue(FXCollections.observableArrayList(previewPreferences.getPreviewCycle()));
+
+        availableLayouts.clear();
+        if (chosenListProperty.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
+            availableLayouts.add(previewPreferences.getTextBasedPreviewLayout());
+        }
+
+        BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
+                      .onSuccess(value -> value.stream()
+                                               .map(CitationStylePreviewLayout::new)
+                                               .filter(style -> !chosenListProperty.contains(style))
+                                               .sorted(Comparator.comparing(PreviewLayout::getName))
+                                               .forEach(availableLayouts::add))
+                      .onFailure(ex -> {
+                          LOGGER.error("something went wrong while adding the discovered CitationStyles to the list ", ex);
+                          dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
+                      })
+                      .executeWith(taskExecutor);
+
+        availableListProperty.setValue(availableLayouts);
+
+        previewTextProperty.setValue(previewPreferences.getPreviewStyle().replace("__NEWLINE__", "\n"));
+    }
+
+    @Override
+    public void storeSettings() {
+        PreviewPreferences previewPreferences = Globals.prefs.getPreviewPreferences();
+
+        if (chosenListProperty.isEmpty()) {
+            chosenListProperty.add(previewPreferences.getTextBasedPreviewLayout());
+        }
+
+        PreviewPreferences newPreviewPreferences = Globals.prefs.getPreviewPreferences()
+                                                                .getBuilder()
+                                                                .withPreviewCycle(chosenListProperty)
+                                                                .withPreviewStyle(previewTextProperty.getValue().replace("\n", "__NEWLINE__"))
+                                                                .build();
+        if (!selectedChosenItemsProperty.getValue().isEmpty()) {
+            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(selectedChosenItemsProperty.get(0))).build();
+        }
+        Globals.prefs.storePreviewPreferences(newPreviewPreferences);
+
+        for (BasePanel basePanel : JabRefGUI.getMainFrame().getBasePanelList()) {
+            // TODO: Find a better way to update preview
+            basePanel.closeBottomPane();
+            //basePanel.getPreviewPanel().updateLayout(Globals.prefs.getPreviewPreferences());
+        }
+    }
+
+    @Override
+    public boolean validateSettings() {
+        return true;
+    }
+
+    public void addToChosen() {
+        for (PreviewLayout layout : selectedAvailableItemsProperty.getValue()) {
+            availableListProperty.remove(layout);
+            chosenListProperty.add(layout);
+        }
+    }
+
+    public void removeFromChosen() {
+        for (PreviewLayout layout : selectedChosenItemsProperty.getValue()) {
+            availableListProperty.add(layout);
+            availableListProperty.sort((a,b) -> { return a.getName().compareToIgnoreCase(b.getName()); } );
+            chosenListProperty.remove(layout);
+        }
+    }
+
+    public List<Integer> selectedInChosenUp(List<Integer> oldindices) {
+        List<Integer> newIndices = new ArrayList<>();
+        for (int oldIndex : oldindices) {
+            boolean alreadyTaken = newIndices.contains(oldIndex - 1);
+            int newIndex = ((oldIndex > 0) && !alreadyTaken) ? oldIndex - 1 : oldIndex;
+            chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
+            newIndices.add(newIndex);
+        }
+        return newIndices;
+    }
+
+    public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
+        List<Integer> newSelectedIndices = new ArrayList<>();
+        for (int i = oldIndices.size() - 1; i >= 0; i--) {
+            int oldIndex = oldIndices.get(i);
+            boolean alreadyTaken = newSelectedIndices.contains(oldIndex + 1);
+            int newIndex = ((oldIndex < (chosenListProperty.size() - 1)) && !alreadyTaken) ? oldIndex + 1 : oldIndex;
+            chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
+            newSelectedIndices.add(newIndex);
+        }
+        return newSelectedIndices;
+    }
+
+    public void testChosen() {
+        try {
+            PreviewViewer testPane = new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager);
+            testPane.setEntry(TestEntry.getTestEntry());
+
+            PreviewLayout layout = chosenListProperty.getValue().get(0);
+            testPane.setLayout(layout);
+
+            DialogPane pane = new DialogPane();
+            pane.setContent(testPane);
+            dialogService.showCustomDialogAndWait(Localization.lang("Preview"), pane, ButtonType.OK);
+
+        } catch (StringIndexOutOfBoundsException exception) {
+            LOGGER.warn("Parsing error.", exception);
+            dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
+        }
+    }
+
+    public void setChosenDefault() {
+        previewTextProperty.setValue(Globals.prefs.getPreviewPreferences()
+                                                  .getDefaultPreviewStyle()
+                                                  .replace("__NEWLINE__", "\n"));
+    }
+
+    public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
+
+    public ListProperty<PreviewLayout> selectedAvailableItemsProperty() { return selectedAvailableItemsProperty; }
+
+    public ListProperty<PreviewLayout> chosenListProperty() { return chosenListProperty; }
+
+    public ListProperty<PreviewLayout> selectedChosenItemsProperty() { return selectedChosenItemsProperty; }
+
+    public StringProperty previewTextProperty() { return previewTextProperty; }
+}
diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index bae2e82011d..3dce40d427b 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -694,6 +694,9 @@ Error\ while\ generating\ citation\ style=Error while generating citation style
 Preview\ style\ changed\ to\:\ %0=Preview style changed to: %0
 Next\ preview\ layout=Next preview layout
 Previous\ preview\ layout=Previous preview layout
+Available=Available
+Selected=Selected
+Selected\ style\ source=Selected style source
 
 Previous\ entry=Previous entry
 

From b64d49a994637ce16fea194d672180e839e4ca4b Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 17 Jun 2019 10:24:34 +0200
Subject: [PATCH 02/22] Refactor minor issues

---
 .../jabref/gui/preferences/PreviewTab.fxml    |  8 ++---
 .../gui/preferences/PreviewTabView.java       | 17 +++++-----
 .../gui/preferences/PreviewTabViewModel.java  | 31 ++++++++++---------
 src/main/resources/l10n/JabRef_en.properties  |  4 ++-
 4 files changed, 32 insertions(+), 28 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 324b6e69d9b..1f167a04905 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -35,21 +35,21 @@
                     <children>
                         <Label text="%Selected" styleClass="sectionHeader" />
                         <ListView fx:id="chosenListView" maxHeight="250.0" minHeight="250.0"/>
-                        <HBox alignment="CENTER" spacing="4.0">
+                        <HBox alignment="CENTER">
                             <children>
-                                <Button fx:id="testButton" prefWidth="80" text="%Test" onAction="#testButtonAction"/>
-                                <Button fx:id="defaultButton" prefWidth="80" text="%Default" onAction="#defaultButtonAction" />
+                                <Button fx:id="testButton" text="%Test selected style" onAction="#testButtonAction"/>
                             </children>
                         </HBox>
                     </children>
                 </VBox>
             </children>
         </HBox>
-        <Label text="%Selected style source" styleClass="sectionHeader" />
+        <Label text="%Default preview style" styleClass="sectionHeader" />
         <VirtualizedScrollPane>
             <content>
                 <CodeArea fx:id="previewTextArea" prefHeight="200.0" />
             </content>
         </VirtualizedScrollPane>
+        <Button fx:id="resetDefaultButton" text="%Reset default preview style" onAction="#resetDefaultButtonAction" />
     </children>
 </fx:root>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 414f3f574d6..8000b0aa266 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -46,7 +46,7 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @FXML private Button sortDownButton;
 
     @FXML private Button testButton;
-    @FXML private Button defaultButton;
+    @FXML private Button resetDefaultButton;
 
     @FXML private CodeArea previewTextArea;
 
@@ -110,7 +110,6 @@ public void initialize() {
         sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
         sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
         testButton.disableProperty().bind(nothingSelectedFromChosen);
-        defaultButton.disableProperty().bind(nothingSelectedFromChosen);
 
         previewTextArea.setParagraphGraphicFactory(LineNumberFactory.get(previewTextArea));
         previewTextArea.textProperty().addListener((obs, oldText, newText) -> {
@@ -135,13 +134,13 @@ public void initialize() {
     }
 
     /**
-     * This was originally created by Carlos Martins (github: @cemarins )
-     * Can this be used here? (BSD-2clause License)
-     * See here: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/XMLEditorDemo.java
-     * and also here: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#automatic-highlighting-of-java-keywords
+     * XML-Syntax-Highlighting for RichTextFX-Codearea
+     * created by (c) Carlos Martins (github: @cemartins)
+     * distributed under the BSD 2-Clause "Simplified" License
+     * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE
+     * and: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
      *
-     * @author: Carlos Martins
-     * @param text to highlight
+     * @param text to parse and highlight
      * @return highlighted span for codeArea
      */
     private StyleSpans<Collection<String>> computeHighlighting(String text) {
@@ -246,5 +245,5 @@ public void sortDownButtonAction() {
 
     public void testButtonAction() { viewModel.testChosen(); }
 
-    public void defaultButtonAction() { viewModel.setChosenDefault(); }
+    public void resetDefaultButtonAction() { viewModel.resetDefaultStyle(); }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index b4f59eb08b8..a14752120af 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -86,32 +86,32 @@ public void setValues() {
 
     @Override
     public void storeSettings() {
-        PreviewPreferences previewPreferences = Globals.prefs.getPreviewPreferences();
+        PreviewPreferences previewPreferences = preferences.getPreviewPreferences();
 
         if (chosenListProperty.isEmpty()) {
             chosenListProperty.add(previewPreferences.getTextBasedPreviewLayout());
         }
 
-        PreviewPreferences newPreviewPreferences = Globals.prefs.getPreviewPreferences()
-                                                                .getBuilder()
-                                                                .withPreviewCycle(chosenListProperty)
-                                                                .withPreviewStyle(previewTextProperty.getValue().replace("\n", "__NEWLINE__"))
-                                                                .build();
+        PreviewPreferences newPreviewPreferences = preferences.getPreviewPreferences()
+                                                              .getBuilder()
+                                                              .withPreviewCycle(chosenListProperty)
+                                                              .withPreviewStyle(previewTextProperty.getValue().replace("\n", "__NEWLINE__"))
+                                                              .build();
         if (!selectedChosenItemsProperty.getValue().isEmpty()) {
             newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(selectedChosenItemsProperty.get(0))).build();
         }
-        Globals.prefs.storePreviewPreferences(newPreviewPreferences);
+        preferences.storePreviewPreferences(newPreviewPreferences);
 
         for (BasePanel basePanel : JabRefGUI.getMainFrame().getBasePanelList()) {
             // TODO: Find a better way to update preview
             basePanel.closeBottomPane();
-            //basePanel.getPreviewPanel().updateLayout(Globals.prefs.getPreviewPreferences());
+            //basePanel.getPreviewPanel().updateLayout(preferences.getPreviewPreferences());
         }
     }
 
     @Override
     public boolean validateSettings() {
-        return true;
+        return !chosenListProperty.getValue().isEmpty();
     }
 
     public void addToChosen() {
@@ -157,7 +157,10 @@ public void testChosen() {
             PreviewViewer testPane = new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager);
             testPane.setEntry(TestEntry.getTestEntry());
 
-            PreviewLayout layout = chosenListProperty.getValue().get(0);
+            PreviewLayout layout = (selectedChosenItemsProperty.getValue().isEmpty()) ?
+                    chosenListProperty.getValue().get(0) :
+                    selectedChosenItemsProperty.getValue().get(0);
+
             testPane.setLayout(layout);
 
             DialogPane pane = new DialogPane();
@@ -170,10 +173,10 @@ public void testChosen() {
         }
     }
 
-    public void setChosenDefault() {
-        previewTextProperty.setValue(Globals.prefs.getPreviewPreferences()
-                                                  .getDefaultPreviewStyle()
-                                                  .replace("__NEWLINE__", "\n"));
+    public void resetDefaultStyle() {
+        previewTextProperty.setValue(preferences.getPreviewPreferences()
+                                                .getDefaultPreviewStyle()
+                                                .replace("__NEWLINE__", "\n"));
     }
 
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index 3dce40d427b..176a068d3dc 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -696,7 +696,9 @@ Next\ preview\ layout=Next preview layout
 Previous\ preview\ layout=Previous preview layout
 Available=Available
 Selected=Selected
-Selected\ style\ source=Selected style source
+Default\ preview\ style=Default preview style
+Test\ selected\ style=Test selected style
+Reset\ default\ preview\ style=Reset default preview style
 
 Previous\ entry=Previous entry
 

From 0f989cc0482d2fb788926c275714170d39db64b1 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 17 Jun 2019 10:26:10 +0200
Subject: [PATCH 03/22] Added scrolling to letter pressed

---
 .../jabref/gui/preferences/PreviewTabView.java   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 8000b0aa266..73c5dec4975 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -15,6 +15,7 @@
 import javafx.scene.control.Button;
 import javafx.scene.control.ContextMenu;
 import javafx.scene.control.ListView;
+import javafx.scene.input.KeyEvent;
 import javafx.scene.layout.VBox;
 
 import org.jabref.Globals;
@@ -98,10 +99,12 @@ public void initialize() {
         availableListView.itemsProperty().bind(viewModel.availableListProperty());
         viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper(availableListView.getSelectionModel().getSelectedItems()));
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
+        availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
 
         chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
         viewModel.selectedChosenItemsProperty().bind(new ReadOnlyListWrapper(chosenListView.getSelectionModel().getSelectedItems()));
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosenListView);
+        chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
 
         toRightButton.disableProperty().bind(availableListView.selectionModelProperty().getValue().selectedItemProperty().isNull());
 
@@ -200,6 +203,19 @@ private StyleSpans<Collection<String>> computeHighlighting(String text) {
         return spansBuilder.create();
     }
 
+    public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
+        if (keypressed.getCharacter() == null) {
+            return;
+        }
+
+        for (PreviewLayout item : list.getItems()) {
+            if (item.getName().toLowerCase().startsWith(keypressed.getCharacter().toLowerCase())) {
+                list.scrollTo(item);
+                return;
+            }
+        }
+    }
+
     @Override
     public Node getBuilder() {
         return this;

From decd90370dd21af71e0af5a778f291a81353aed3 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 19 Jun 2019 15:57:59 +0200
Subject: [PATCH 04/22] Refactored layout, TextBasedPreviewStyle editable

---
 .../jabref/gui/preferences/PreviewTab.fxml    | 50 +++++++++-------
 .../gui/preferences/PreviewTabView.java       | 49 +++++++++++++---
 .../gui/preferences/PreviewTabViewModel.java  | 57 +++++++++----------
 .../citationstyle/TextBasedPreviewLayout.java | 21 +++++--
 src/main/resources/l10n/JabRef_en.properties  |  1 +
 5 files changed, 115 insertions(+), 63 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 1f167a04905..45a613c1636 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -9,6 +9,10 @@
 <?import org.fxmisc.richtext.CodeArea?>
 
 <?import org.fxmisc.flowless.VirtualizedScrollPane?>
+<?import javafx.scene.control.TabPane?>
+<?import javafx.scene.control.Tab?>
+<?import javafx.scene.control.ScrollPane?>
+
 <fx:root prefWidth="650.0" spacing="4.0" type="VBox" xmlns="http://javafx.com/javafx/8.0.212"
          xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.jabref.gui.preferences.PreviewTabView">
     <children>
@@ -17,39 +21,47 @@
             <children>
                 <VBox spacing="4.0" HBox.hgrow="ALWAYS">
                     <children>
-                        <Label text="%Available" styleClass="sectionHeader" />
+                        <Label text="%Available" styleClass="sectionHeader"/>
                         <ListView fx:id="availableListView" maxHeight="250.0" minHeight="250.0"/>
                     </children>
                 </VBox>
                 <VBox alignment="CENTER" spacing="4.0">
                     <children>
-                        <Label styleClass="sectionHeader" />
-                        <Button fx:id="toRightButton"  prefWidth="60.0" text="&gt;&gt;" onAction="#toRightButtonAction" />
-                        <Button fx:id="toLeftButton" prefWidth="60.0" text="&lt;&lt;" onAction="#toLeftButtonAction" />
+                        <Label styleClass="sectionHeader"/>
+                        <Button fx:id="toRightButton" prefWidth="60.0" text="&gt;&gt;" onAction="#toRightButtonAction"/>
+                        <Button fx:id="toLeftButton" prefWidth="60.0" text="&lt;&lt;" onAction="#toLeftButtonAction"/>
                         <VBox prefHeight="40.0"/>
-                        <Button fx:id="sortUpButton" prefWidth="60.0" text="%Up" onAction="#sortUpButtonAction" />
-                        <Button fx:id="sortDownButton" prefWidth="60.0" text="%Down" onAction="#sortDownButtonAction" />
+                        <Button fx:id="sortUpButton" prefWidth="60.0" text="%Up" onAction="#sortUpButtonAction"/>
+                        <Button fx:id="sortDownButton" prefWidth="60.0" text="%Down" onAction="#sortDownButtonAction"/>
                     </children>
                 </VBox>
                 <VBox spacing="4.0" HBox.hgrow="ALWAYS">
                     <children>
-                        <Label text="%Selected" styleClass="sectionHeader" />
+                        <Label text="%Selected" styleClass="sectionHeader"/>
                         <ListView fx:id="chosenListView" maxHeight="250.0" minHeight="250.0"/>
-                        <HBox alignment="CENTER">
-                            <children>
-                                <Button fx:id="testButton" text="%Test selected style" onAction="#testButtonAction"/>
-                            </children>
-                        </HBox>
                     </children>
                 </VBox>
             </children>
         </HBox>
-        <Label text="%Default preview style" styleClass="sectionHeader" />
-        <VirtualizedScrollPane>
-            <content>
-                <CodeArea fx:id="previewTextArea" prefHeight="200.0" />
-            </content>
-        </VirtualizedScrollPane>
-        <Button fx:id="resetDefaultButton" text="%Reset default preview style" onAction="#resetDefaultButtonAction" />
+        <TabPane prefHeight="250.0" prefWidth="650.0" tabClosingPolicy="UNAVAILABLE">
+            <tabs>
+                <Tab text="%Preview">
+                    <content>
+                        <ScrollPane fx:id="previewPreviewArea" />
+                    </content>
+                </Tab>
+                <Tab text="%Edit">
+                    <content>
+                        <VirtualizedScrollPane>
+                            <content>
+                                <CodeArea fx:id="previewTextArea" prefHeight="300.0"/>
+                                <Button fx:id="resetDefaultButton" text="%Reset default preview style"
+                                        onAction="#resetDefaultButtonAction"/>
+                            </content>
+                        </VirtualizedScrollPane>
+                    </content>
+                </Tab>
+            </tabs>
+        </TabPane>
     </children>
 </fx:root>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 73c5dec4975..c1aab4014f8 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -10,11 +10,13 @@
 
 import javafx.beans.binding.BooleanBinding;
 import javafx.beans.property.ReadOnlyListWrapper;
+import javafx.collections.ListChangeListener;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
 import javafx.scene.control.Button;
 import javafx.scene.control.ContextMenu;
 import javafx.scene.control.ListView;
+import javafx.scene.control.ScrollPane;
 import javafx.scene.input.KeyEvent;
 import javafx.scene.layout.VBox;
 
@@ -27,6 +29,7 @@
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.gui.util.ViewModelListCellFactory;
 import org.jabref.logic.citationstyle.PreviewLayout;
+import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.preferences.JabRefPreferences;
 
@@ -46,9 +49,9 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @FXML private Button sortUpButton;
     @FXML private Button sortDownButton;
 
-    @FXML private Button testButton;
     @FXML private Button resetDefaultButton;
 
+    @FXML private ScrollPane previewPreviewArea;
     @FXML private CodeArea previewTextArea;
 
     @Inject private TaskExecutor taskExecutor;
@@ -112,16 +115,42 @@ public void initialize() {
         toLeftButton.disableProperty().bind(nothingSelectedFromChosen);
         sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
         sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
-        testButton.disableProperty().bind(nothingSelectedFromChosen);
 
         previewTextArea.setParagraphGraphicFactory(LineNumberFactory.get(previewTextArea));
         previewTextArea.textProperty().addListener((obs, oldText, newText) -> {
             previewTextArea.setStyleSpans(0, computeHighlighting(newText));
         });
 
-        BindingsHelper.bindBidirectional(previewTextArea.textProperty(), viewModel.previewTextProperty(),
-                text -> previewTextArea.replaceText(viewModel.previewTextProperty().getValue()),
-                text -> viewModel.previewTextProperty().setValue(previewTextArea.getText()));
+        BindingsHelper.bindBidirectional(previewTextArea.textProperty(), viewModel.selectedChosenItemsProperty(),
+                layoutList -> {
+                    if (layoutList.isEmpty()) {
+                        previewTextArea.clear();
+                    } else {
+                        if (layoutList.get(0) instanceof TextBasedPreviewLayout) {
+                            String previewText = ((TextBasedPreviewLayout)layoutList.get(0)).getLayoutText().replace("__NEWLINE__", "\n");
+                            previewTextArea.replaceText(previewText);
+                            previewTextArea.setStyleSpans(0, computeHighlighting(previewText));
+                            previewTextArea.disableProperty().setValue(false);
+                        } else {
+                            previewTextArea.replaceText(Localization.lang("CitationStyleLayout cannot be edited."));
+                            previewTextArea.disableProperty().setValue(true);
+                        }
+                    }
+                },
+                text -> {
+                    if (!viewModel.selectedChosenItemsProperty().getValue().isEmpty()) {
+                        PreviewLayout item = viewModel.selectedChosenItemsProperty().get(0);
+                        if (item instanceof TextBasedPreviewLayout) {
+                            ((TextBasedPreviewLayout)item).setLayoutText(previewTextArea.getText().replace("\n", "__NEWLINE__"));
+                        }
+                    }
+                }
+        );
+
+        //previewPreviewArea.contentProperty().bind(viewModel.previewPaneProperty());
+        chosenListView.getSelectionModel().getSelectedItems()
+                      .addListener((ListChangeListener<? super PreviewLayout>) c ->
+                              previewPreviewArea.setContent(viewModel.getPreviewViewer()));
 
         ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
         ContextMenu contextMenu = new ContextMenu();
@@ -131,7 +160,6 @@ public void initialize() {
                 factory.createMenuItem(StandardActions.PASTE, new PreviewTabView.EditAction(StandardActions.PASTE)),
                 factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
         );
-
         contextMenu.getStyleClass().add("context-menu");
         previewTextArea.setContextMenu(contextMenu);
     }
@@ -259,7 +287,10 @@ public void sortDownButtonAction() {
         }
     }
 
-    public void testButtonAction() { viewModel.testChosen(); }
-
-    public void resetDefaultButtonAction() { viewModel.resetDefaultStyle(); }
+    public void resetDefaultButtonAction() {
+        viewModel.resetDefaultStyle();
+        if (!chosenListView.getSelectionModel().isEmpty()) {
+// not yet working
+        }
+    }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index a14752120af..0e323ad4d61 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -6,12 +6,9 @@
 
 import javafx.beans.property.ListProperty;
 import javafx.beans.property.SimpleListProperty;
-import javafx.beans.property.SimpleStringProperty;
-import javafx.beans.property.StringProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
-import javafx.scene.control.ButtonType;
-import javafx.scene.control.DialogPane;
+import javafx.scene.control.ScrollPane;
 
 import org.jabref.Globals;
 import org.jabref.JabRefGUI;
@@ -42,29 +39,29 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
     private final ListProperty<PreviewLayout> chosenListProperty = new SimpleListProperty<>();
     private final ListProperty<PreviewLayout> selectedChosenItemsProperty = new SimpleListProperty<>();
 
-    private final StringProperty previewTextProperty = new SimpleStringProperty("");
-
     private final DialogService dialogService;
     private final JabRefPreferences preferences;
+    private final PreviewPreferences previewPreferences;
     private final TaskExecutor taskExecutor;
 
+    private final ObservableList<PreviewLayout> allLayouts;
+
     public PreviewTabViewModel(DialogService dialogService, JabRefPreferences preferences, TaskExecutor taskExecutor) {
         this.dialogService = dialogService;
         this.preferences = preferences;
         this.taskExecutor = taskExecutor;
+        allLayouts = FXCollections.observableArrayList();
+        previewPreferences = preferences.getPreviewPreferences();
 
         setValues();
     }
 
     public void setValues() {
-        PreviewPreferences previewPreferences = preferences.getPreviewPreferences();
-        ObservableList<PreviewLayout> availableLayouts = FXCollections.observableArrayList();
-
         chosenListProperty.setValue(FXCollections.observableArrayList(previewPreferences.getPreviewCycle()));
 
-        availableLayouts.clear();
+        allLayouts.clear();
         if (chosenListProperty.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
-            availableLayouts.add(previewPreferences.getTextBasedPreviewLayout());
+            allLayouts.add(previewPreferences.getTextBasedPreviewLayout());
         }
 
         BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
@@ -72,16 +69,20 @@ public void setValues() {
                                                .map(CitationStylePreviewLayout::new)
                                                .filter(style -> !chosenListProperty.contains(style))
                                                .sorted(Comparator.comparing(PreviewLayout::getName))
-                                               .forEach(availableLayouts::add))
+                                               .forEach(allLayouts::add))
                       .onFailure(ex -> {
                           LOGGER.error("something went wrong while adding the discovered CitationStyles to the list ", ex);
                           dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
                       })
                       .executeWith(taskExecutor);
 
-        availableListProperty.setValue(availableLayouts);
+        availableListProperty.setValue(allLayouts);
+    }
 
-        previewTextProperty.setValue(previewPreferences.getPreviewStyle().replace("__NEWLINE__", "\n"));
+    private PreviewLayout findLayoutByNameOrDefault(String name) {
+        return allLayouts.stream().filter(layout -> layout.getName().equals(name))
+                          .findAny()
+                          .orElse(previewPreferences.getTextBasedPreviewLayout());
     }
 
     @Override
@@ -95,8 +96,9 @@ public void storeSettings() {
         PreviewPreferences newPreviewPreferences = preferences.getPreviewPreferences()
                                                               .getBuilder()
                                                               .withPreviewCycle(chosenListProperty)
-                                                              .withPreviewStyle(previewTextProperty.getValue().replace("\n", "__NEWLINE__"))
+                                                              .withPreviewStyle(((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")).getLayoutText())
                                                               .build();
+
         if (!selectedChosenItemsProperty.getValue().isEmpty()) {
             newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(selectedChosenItemsProperty.get(0))).build();
         }
@@ -152,31 +154,26 @@ public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
         return newSelectedIndices;
     }
 
-    public void testChosen() {
+    public PreviewViewer getPreviewViewer() {
+        PreviewLayout layout = (selectedChosenItemsProperty.getValue().isEmpty()) ?
+                chosenListProperty.getValue().get(0) :
+                selectedChosenItemsProperty.getValue().get(0);
+
         try {
             PreviewViewer testPane = new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager);
             testPane.setEntry(TestEntry.getTestEntry());
-
-            PreviewLayout layout = (selectedChosenItemsProperty.getValue().isEmpty()) ?
-                    chosenListProperty.getValue().get(0) :
-                    selectedChosenItemsProperty.getValue().get(0);
-
             testPane.setLayout(layout);
-
-            DialogPane pane = new DialogPane();
-            pane.setContent(testPane);
-            dialogService.showCustomDialogAndWait(Localization.lang("Preview"), pane, ButtonType.OK);
-
+            return testPane;
         } catch (StringIndexOutOfBoundsException exception) {
             LOGGER.warn("Parsing error.", exception);
             dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
+            return ((PreviewViewer) new ScrollPane());
         }
     }
 
     public void resetDefaultStyle() {
-        previewTextProperty.setValue(preferences.getPreviewPreferences()
-                                                .getDefaultPreviewStyle()
-                                                .replace("__NEWLINE__", "\n"));
+        ((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")) // There are issues with caching the testentries
+                .setLayoutText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
     }
 
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
@@ -186,6 +183,4 @@ public void resetDefaultStyle() {
     public ListProperty<PreviewLayout> chosenListProperty() { return chosenListProperty; }
 
     public ListProperty<PreviewLayout> selectedChosenItemsProperty() { return selectedChosenItemsProperty; }
-
-    public StringProperty previewTextProperty() { return previewTextProperty; }
 }
diff --git a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
index dced3da5b89..f86459f8a9f 100644
--- a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
+++ b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
@@ -17,8 +17,21 @@ public class TextBasedPreviewLayout implements PreviewLayout {
     private static final Logger LOGGER = LoggerFactory.getLogger(TextBasedPreviewLayout.class);
 
     private Layout layout;
+    private String layoutText;
+    private LayoutFormatterPreferences layoutFormatterPreferences;
 
     public TextBasedPreviewLayout(String layoutText, LayoutFormatterPreferences layoutFormatterPreferences) {
+        this.layoutFormatterPreferences = layoutFormatterPreferences;
+        setLayoutText(layoutText);
+    }
+
+    public TextBasedPreviewLayout(Layout layout) {
+        this.layout = layout;
+        this.layoutText = layout.toString();
+    }
+
+    public void setLayoutText(String layoutText) {
+        this.layoutText = layoutText;
         StringReader sr = new StringReader(layoutText.replace("__NEWLINE__", "\n"));
         try {
             layout = new LayoutHelper(sr, layoutFormatterPreferences).getLayoutFromText();
@@ -27,10 +40,6 @@ public TextBasedPreviewLayout(String layoutText, LayoutFormatterPreferences layo
         }
     }
 
-    public TextBasedPreviewLayout(Layout layout) {
-        this.layout = layout;
-    }
-
     @Override
     public String generatePreview(BibEntry entry, BibDatabase database) {
         if (layout != null) {
@@ -40,6 +49,10 @@ public String generatePreview(BibEntry entry, BibDatabase database) {
         }
     }
 
+    public String getLayoutText() {
+        return layoutText;
+    }
+
     @Override
     public String getName() {
         return Localization.lang("Preview");
diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index 176a068d3dc..2536a11e386 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -1145,6 +1145,7 @@ Extra\ information\ (e.g.\ page\ number)=Extra information (e.g. page number)
 Manage\ citations=Manage citations
 Problem\ modifying\ citation=Problem modifying citation
 Citation=Citation
+CitationStyleLayout\ cannot\ be\ edited.=CitationStyleLayout cannot be edited.
 Connecting...=Connecting...
 Could\ not\ resolve\ BibTeX\ entry\ for\ citation\ marker\ '%0'.=Could not resolve BibTeX entry for citation marker '%0'.
 Select\ style=Select style

From 7814c225acde38ace96f77b4051769dd74cefdec Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 19 Jun 2019 16:16:07 +0200
Subject: [PATCH 05/22] Fix languages for travis

---
 src/main/resources/l10n/JabRef_en.properties | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index 2536a11e386..4739e1f5dfe 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -696,8 +696,7 @@ Next\ preview\ layout=Next preview layout
 Previous\ preview\ layout=Previous preview layout
 Available=Available
 Selected=Selected
-Default\ preview\ style=Default preview style
-Test\ selected\ style=Test selected style
+
 Reset\ default\ preview\ style=Reset default preview style
 
 Previous\ entry=Previous entry
@@ -900,8 +899,6 @@ Switches\ between\ full\ and\ abbreviated\ journal\ name\ if\ the\ journal\ name
 Tabname=Tabname
 Tertiary\ sort\ criterion=Tertiary sort criterion
 
-Test=Test
-
 The\ chosen\ encoding\ '%0'\ could\ not\ encode\ the\ following\ characters\:=The chosen encoding '%0' could not encode the following characters:
 
 

From 4201ba33b5088b587efa244e40187b5cd173a7e4 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Thu, 20 Jun 2019 22:15:10 +0200
Subject: [PATCH 06/22] Fixed updating PreviewPane, refactoring

---
 .../jabref/gui/preferences/PreviewTab.fxml    |  4 +-
 .../gui/preferences/PreviewTabView.java       | 51 ++++++++++---------
 .../gui/preferences/PreviewTabViewModel.java  | 41 ++++++++-------
 3 files changed, 50 insertions(+), 46 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 45a613c1636..347287fe893 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -47,14 +47,14 @@
             <tabs>
                 <Tab text="%Preview">
                     <content>
-                        <ScrollPane fx:id="previewPreviewArea" />
+                        <ScrollPane fx:id="previewPane" />
                     </content>
                 </Tab>
                 <Tab text="%Edit">
                     <content>
                         <VirtualizedScrollPane>
                             <content>
-                                <CodeArea fx:id="previewTextArea" prefHeight="300.0"/>
+                                <CodeArea fx:id="editArea" prefHeight="300.0"/>
                                 <Button fx:id="resetDefaultButton" text="%Reset default preview style"
                                         onAction="#resetDefaultButtonAction"/>
                             </content>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index c1aab4014f8..66717b75037 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -25,6 +25,7 @@
 import org.jabref.gui.actions.ActionFactory;
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.actions.StandardActions;
+import org.jabref.gui.preview.PreviewViewer;
 import org.jabref.gui.util.BindingsHelper;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.gui.util.ViewModelListCellFactory;
@@ -38,9 +39,13 @@
 import org.fxmisc.richtext.LineNumberFactory;
 import org.fxmisc.richtext.model.StyleSpans;
 import org.fxmisc.richtext.model.StyleSpansBuilder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class PreviewTabView extends VBox implements PrefsTab {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabView.class);
+
     @FXML private ListView<PreviewLayout> availableListView;
     @FXML private ListView<PreviewLayout> chosenListView;
 
@@ -51,8 +56,8 @@ public class PreviewTabView extends VBox implements PrefsTab {
 
     @FXML private Button resetDefaultButton;
 
-    @FXML private ScrollPane previewPreviewArea;
-    @FXML private CodeArea previewTextArea;
+    @FXML private ScrollPane previewPane;
+    @FXML private CodeArea editArea;
 
     @Inject private TaskExecutor taskExecutor;
     @Inject private DialogService dialogService;
@@ -68,22 +73,22 @@ private class EditAction extends SimpleCommand {
 
         @Override
         public void execute() {
-            if (previewTextArea != null) {
+            if (editArea != null) {
                 switch (command) {
                     case COPY:
-                        previewTextArea.copy();
+                        editArea.copy();
                         break;
                     case CUT:
-                        previewTextArea.cut();
+                        editArea.cut();
                         break;
                     case PASTE:
-                        previewTextArea.paste();
+                        editArea.paste();
                         break;
                     case SELECT_ALL:
-                        previewTextArea.selectAll();
+                        editArea.selectAll();
                         break;
                 }
-                previewTextArea.requestFocus();
+                editArea.requestFocus();
             }
         }
     }
@@ -116,24 +121,24 @@ public void initialize() {
         sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
         sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
 
-        previewTextArea.setParagraphGraphicFactory(LineNumberFactory.get(previewTextArea));
-        previewTextArea.textProperty().addListener((obs, oldText, newText) -> {
-            previewTextArea.setStyleSpans(0, computeHighlighting(newText));
+        editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));
+        editArea.textProperty().addListener((obs, oldText, newText) -> {
+            editArea.setStyleSpans(0, computeHighlighting(newText));
         });
 
-        BindingsHelper.bindBidirectional(previewTextArea.textProperty(), viewModel.selectedChosenItemsProperty(),
+        BindingsHelper.bindBidirectional(editArea.textProperty(), viewModel.selectedChosenItemsProperty(),
                 layoutList -> {
                     if (layoutList.isEmpty()) {
-                        previewTextArea.clear();
+                        editArea.clear();
                     } else {
                         if (layoutList.get(0) instanceof TextBasedPreviewLayout) {
                             String previewText = ((TextBasedPreviewLayout)layoutList.get(0)).getLayoutText().replace("__NEWLINE__", "\n");
-                            previewTextArea.replaceText(previewText);
-                            previewTextArea.setStyleSpans(0, computeHighlighting(previewText));
-                            previewTextArea.disableProperty().setValue(false);
+                            editArea.replaceText(previewText);
+                            editArea.setStyleSpans(0, computeHighlighting(previewText));
+                            editArea.disableProperty().setValue(false);
                         } else {
-                            previewTextArea.replaceText(Localization.lang("CitationStyleLayout cannot be edited."));
-                            previewTextArea.disableProperty().setValue(true);
+                            editArea.replaceText(Localization.lang("CitationStyleLayout cannot be edited."));
+                            editArea.disableProperty().setValue(true);
                         }
                     }
                 },
@@ -141,16 +146,16 @@ public void initialize() {
                     if (!viewModel.selectedChosenItemsProperty().getValue().isEmpty()) {
                         PreviewLayout item = viewModel.selectedChosenItemsProperty().get(0);
                         if (item instanceof TextBasedPreviewLayout) {
-                            ((TextBasedPreviewLayout)item).setLayoutText(previewTextArea.getText().replace("\n", "__NEWLINE__"));
+                            ((TextBasedPreviewLayout)item).setLayoutText(editArea.getText().replace("\n", "__NEWLINE__"));
+                            ((PreviewViewer) previewPane.getContent()).setLayout(item);
                         }
                     }
                 }
         );
 
-        //previewPreviewArea.contentProperty().bind(viewModel.previewPaneProperty());
         chosenListView.getSelectionModel().getSelectedItems()
                       .addListener((ListChangeListener<? super PreviewLayout>) c ->
-                              previewPreviewArea.setContent(viewModel.getPreviewViewer()));
+                              previewPane.setContent(viewModel.getPreviewViewer()));
 
         ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
         ContextMenu contextMenu = new ContextMenu();
@@ -161,13 +166,13 @@ public void initialize() {
                 factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
         );
         contextMenu.getStyleClass().add("context-menu");
-        previewTextArea.setContextMenu(contextMenu);
+        editArea.setContextMenu(contextMenu);
     }
 
     /**
      * XML-Syntax-Highlighting for RichTextFX-Codearea
      * created by (c) Carlos Martins (github: @cemartins)
-     * distributed under the BSD 2-Clause "Simplified" License
+     * License: BSD-2-Clause
      * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE
      * and: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
      *
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 0e323ad4d61..20312f568a1 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -44,45 +44,44 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
     private final PreviewPreferences previewPreferences;
     private final TaskExecutor taskExecutor;
 
-    private final ObservableList<PreviewLayout> allLayouts;
-
     public PreviewTabViewModel(DialogService dialogService, JabRefPreferences preferences, TaskExecutor taskExecutor) {
         this.dialogService = dialogService;
         this.preferences = preferences;
         this.taskExecutor = taskExecutor;
-        allLayouts = FXCollections.observableArrayList();
         previewPreferences = preferences.getPreviewPreferences();
 
         setValues();
     }
 
     public void setValues() {
-        chosenListProperty.setValue(FXCollections.observableArrayList(previewPreferences.getPreviewCycle()));
+        final ObservableList<PreviewLayout> availableLayouts = FXCollections.observableArrayList();
 
-        allLayouts.clear();
+        chosenListProperty.setValue(FXCollections.observableArrayList(previewPreferences.getPreviewCycle()));
         if (chosenListProperty.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
-            allLayouts.add(previewPreferences.getTextBasedPreviewLayout());
+            chosenListProperty.add(previewPreferences.getTextBasedPreviewLayout());
         }
 
         BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
-                      .onSuccess(value -> value.stream()
-                                               .map(CitationStylePreviewLayout::new)
-                                               .filter(style -> !chosenListProperty.contains(style))
-                                               .sorted(Comparator.comparing(PreviewLayout::getName))
-                                               .forEach(allLayouts::add))
-                      .onFailure(ex -> {
-                          LOGGER.error("something went wrong while adding the discovered CitationStyles to the list ", ex);
-                          dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
-                      })
-                      .executeWith(taskExecutor);
-
-        availableListProperty.setValue(allLayouts);
+                .onSuccess(value -> value.stream()
+                        .map(CitationStylePreviewLayout::new)
+                        .sorted(Comparator.comparing(PreviewLayout::getName))
+                        .filter(style -> !chosenListProperty.contains(style))
+                        .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
+                .onFailure(ex -> {
+                    LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
+                    dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
+                })
+                .executeWith(taskExecutor);
+
+        availableListProperty.setValue(availableLayouts);
     }
 
     private PreviewLayout findLayoutByNameOrDefault(String name) {
-        return allLayouts.stream().filter(layout -> layout.getName().equals(name))
-                          .findAny()
-                          .orElse(previewPreferences.getTextBasedPreviewLayout());
+        return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                .findAny()
+                .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                        .findAny()
+                        .orElse(previewPreferences.getTextBasedPreviewLayout()));
     }
 
     @Override

From 2984cada8d91d63866bb8a1192dd18d2848b156b Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Fri, 21 Jun 2019 14:17:41 +0200
Subject: [PATCH 07/22] Added advanced searching in ListView

---
 .../gui/preferences/PreviewTabView.java       | 20 ++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 66717b75037..48484e487b1 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -63,6 +63,9 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @Inject private DialogService dialogService;
     private final JabRefPreferences preferences;
 
+    private long lastKeyPressTime;
+    private String listSearchTerm;
+
     private PreviewTabViewModel viewModel;
 
     private class EditAction extends SimpleCommand {
@@ -104,6 +107,9 @@ public PreviewTabView(JabRefPreferences preferences) {
     public void initialize() {
         viewModel = new PreviewTabViewModel(dialogService, preferences, taskExecutor);
 
+        lastKeyPressTime = System.currentTimeMillis();
+        listSearchTerm = "";
+
         availableListView.itemsProperty().bind(viewModel.availableListProperty());
         viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper(availableListView.getSelectionModel().getSelectedItems()));
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
@@ -241,12 +247,16 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
             return;
         }
 
-        for (PreviewLayout item : list.getItems()) {
-            if (item.getName().toLowerCase().startsWith(keypressed.getCharacter().toLowerCase())) {
-                list.scrollTo(item);
-                return;
-            }
+        if (System.currentTimeMillis() - lastKeyPressTime < 1000) {
+            listSearchTerm += keypressed.getCharacter().toLowerCase();
+        } else {
+            listSearchTerm = keypressed.getCharacter().toLowerCase();
         }
+
+        lastKeyPressTime = System.currentTimeMillis();
+
+        list.getItems().stream().filter(item -> item.getName().toLowerCase().startsWith(listSearchTerm))
+                .findFirst().ifPresent(item -> list.scrollTo(item));
     }
 
     @Override

From 343045fa255d518ead8e9e71c8da748bd43fb1eb Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Fri, 21 Jun 2019 23:11:55 +0200
Subject: [PATCH 08/22] Fixed default button and refactoring

---
 .../gui/preferences/PreferencesDialog.css     |   7 +-
 .../jabref/gui/preferences/PreviewTab.fxml    |  47 +++---
 .../gui/preferences/PreviewTabView.java       | 139 +++++++++++-------
 .../gui/preferences/PreviewTabViewModel.java  |  34 ++---
 .../citationstyle/TextBasedPreviewLayout.java |  18 +--
 src/main/resources/l10n/JabRef_en.properties  |   3 +-
 6 files changed, 144 insertions(+), 104 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
index bc62ccf1e00..51bd8f6d4dc 100644
--- a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
+++ b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
@@ -34,7 +34,7 @@
     -fx-border-color: -fx-outer-border;
 }
 
-.code-area .tagmark .{
+.code-area .tagmark {
     -fx-fill: gray;
 }
 
@@ -65,5 +65,8 @@
 
 .code-area .context-menu {
     -fx-font-family: sans-serif;
-    -fx-padding: 0;
+}
+
+.code-area .context-menu .menu-item {
+    -fx-padding: 2;
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 347287fe893..3384dfcf4b8 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -12,6 +12,7 @@
 <?import javafx.scene.control.TabPane?>
 <?import javafx.scene.control.Tab?>
 <?import javafx.scene.control.ScrollPane?>
+<?import javafx.scene.layout.AnchorPane?>
 
 <fx:root prefWidth="650.0" spacing="4.0" type="VBox" xmlns="http://javafx.com/javafx/8.0.212"
          xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.jabref.gui.preferences.PreviewTabView">
@@ -43,25 +44,35 @@
                 </VBox>
             </children>
         </HBox>
-        <TabPane prefHeight="250.0" prefWidth="650.0" tabClosingPolicy="UNAVAILABLE">
-            <tabs>
-                <Tab text="%Preview">
-                    <content>
-                        <ScrollPane fx:id="previewPane" />
-                    </content>
-                </Tab>
-                <Tab text="%Edit">
-                    <content>
-                        <VirtualizedScrollPane>
+        <AnchorPane>
+            <children>
+                <TabPane prefHeight="250.0" prefWidth="650.0" tabClosingPolicy="UNAVAILABLE">
+                    <tabs>
+                        <Tab text="%Preview">
+                            <content>
+                                <ScrollPane fx:id="previewPane"/>
+                            </content>
+                        </Tab>
+                        <Tab text="%Edit">
                             <content>
-                                <CodeArea fx:id="editArea" prefHeight="300.0"/>
-                                <Button fx:id="resetDefaultButton" text="%Reset default preview style"
-                                        onAction="#resetDefaultButtonAction"/>
+                                <VirtualizedScrollPane>
+                                    <content>
+                                        <CodeArea fx:id="editArea" prefHeight="300.0"/>
+                                    </content>
+                                </VirtualizedScrollPane>
                             </content>
-                        </VirtualizedScrollPane>
-                    </content>
-                </Tab>
-            </tabs>
-        </TabPane>
+                        </Tab>
+                    </tabs>
+                </TabPane>
+                <HBox alignment="CENTER_RIGHT" AnchorPane.rightAnchor="5.0" AnchorPane.topAnchor="2.0" spacing="5.0" >
+                    <children>
+                        <Label fx:id="readOnlyLabel" text="%Read only" />
+                        <Button
+                                fx:id="resetDefaultButton" text="%Reset default preview style"
+                                onAction="#resetDefaultButtonAction"/>
+                    </children>
+                </HBox>
+            </children>
+        </AnchorPane>
     </children>
 </fx:root>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 48484e487b1..e77e260739f 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -10,11 +10,12 @@
 
 import javafx.beans.binding.BooleanBinding;
 import javafx.beans.property.ReadOnlyListWrapper;
-import javafx.collections.ListChangeListener;
+import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
 import javafx.scene.control.Button;
 import javafx.scene.control.ContextMenu;
+import javafx.scene.control.Label;
 import javafx.scene.control.ListView;
 import javafx.scene.control.ScrollPane;
 import javafx.scene.input.KeyEvent;
@@ -29,9 +30,12 @@
 import org.jabref.gui.util.BindingsHelper;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.gui.util.ViewModelListCellFactory;
+import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
 import org.jabref.logic.citationstyle.PreviewLayout;
 import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
 import org.jabref.logic.l10n.Localization;
+import org.jabref.logic.util.TestEntry;
+import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.preferences.JabRefPreferences;
 
 import com.airhacks.afterburner.views.ViewLoader;
@@ -54,11 +58,14 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @FXML private Button sortUpButton;
     @FXML private Button sortDownButton;
 
+    @FXML private Label readOnlyLabel;
     @FXML private Button resetDefaultButton;
 
     @FXML private ScrollPane previewPane;
     @FXML private CodeArea editArea;
 
+    private final ContextMenu contextMenu;
+
     @Inject private TaskExecutor taskExecutor;
     @Inject private DialogService dialogService;
     private final JabRefPreferences preferences;
@@ -98,7 +105,7 @@ public void execute() {
 
     public PreviewTabView(JabRefPreferences preferences) {
         this.preferences = preferences;
-
+        contextMenu = new ContextMenu();
         ViewLoader.view(this)
                   .root(this)
                   .load();
@@ -107,16 +114,26 @@ public PreviewTabView(JabRefPreferences preferences) {
     public void initialize() {
         viewModel = new PreviewTabViewModel(dialogService, preferences, taskExecutor);
 
+        ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
+        contextMenu.getItems().addAll(
+                factory.createMenuItem(StandardActions.CUT, new PreviewTabView.EditAction(StandardActions.CUT)),
+                factory.createMenuItem(StandardActions.COPY, new PreviewTabView.EditAction(StandardActions.COPY)),
+                factory.createMenuItem(StandardActions.PASTE, new PreviewTabView.EditAction(StandardActions.PASTE)),
+                factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
+        );
+        contextMenu.getStyleClass().add("context-menu");
+        editArea.setContextMenu(contextMenu);
+
         lastKeyPressTime = System.currentTimeMillis();
         listSearchTerm = "";
 
         availableListView.itemsProperty().bind(viewModel.availableListProperty());
-        viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper(availableListView.getSelectionModel().getSelectedItems()));
+        viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper<>(availableListView.getSelectionModel().getSelectedItems()));
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
         availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
 
         chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
-        viewModel.selectedChosenItemsProperty().bind(new ReadOnlyListWrapper(chosenListView.getSelectionModel().getSelectedItems()));
+        viewModel.selectedChosenItemsProperty().bind(new ReadOnlyListWrapper<>(chosenListView.getSelectionModel().getSelectedItems()));
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosenListView);
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
 
@@ -126,53 +143,71 @@ public void initialize() {
         toLeftButton.disableProperty().bind(nothingSelectedFromChosen);
         sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
         sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
+        contextMenu.getItems().get(0).disableProperty().bind(nothingSelectedFromChosen); // ToDo: should not if readonly
+        contextMenu.getItems().get(2).disableProperty().bind(nothingSelectedFromChosen);
+
+        previewPane.setContent(new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager));
+        ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
+        ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getTestLayout());
 
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));
-        editArea.textProperty().addListener((obs, oldText, newText) -> {
-            editArea.setStyleSpans(0, computeHighlighting(newText));
-        });
-
-        BindingsHelper.bindBidirectional(editArea.textProperty(), viewModel.selectedChosenItemsProperty(),
-                layoutList -> {
-                    if (layoutList.isEmpty()) {
-                        editArea.clear();
-                    } else {
-                        if (layoutList.get(0) instanceof TextBasedPreviewLayout) {
-                            String previewText = ((TextBasedPreviewLayout)layoutList.get(0)).getLayoutText().replace("__NEWLINE__", "\n");
-                            editArea.replaceText(previewText);
-                            editArea.setStyleSpans(0, computeHighlighting(previewText));
-                            editArea.disableProperty().setValue(false);
-                        } else {
-                            editArea.replaceText(Localization.lang("CitationStyleLayout cannot be edited."));
-                            editArea.disableProperty().setValue(true);
-                        }
-                    }
-                },
-                text -> {
-                    if (!viewModel.selectedChosenItemsProperty().getValue().isEmpty()) {
-                        PreviewLayout item = viewModel.selectedChosenItemsProperty().get(0);
-                        if (item instanceof TextBasedPreviewLayout) {
-                            ((TextBasedPreviewLayout)item).setLayoutText(editArea.getText().replace("\n", "__NEWLINE__"));
-                            ((PreviewViewer) previewPane.getContent()).setLayout(item);
-                        }
-                    }
-                }
-        );
+        editArea.textProperty().addListener((obs, oldText, newText) ->
+                editArea.setStyleSpans(0, computeHighlighting(newText)));
+
+        BindingsHelper.bindBidirectional(editArea.textProperty(), new ReadOnlyListWrapper<>(chosenListView.selectionModelProperty().getValue().getSelectedItems()),
+                layoutList -> update(),
+                            text -> {
+                                if (!viewModel.selectedChosenItemsProperty().getValue().isEmpty()) {
+                                    PreviewLayout item = viewModel.selectedChosenItemsProperty().get(0);
+                                    if (item instanceof TextBasedPreviewLayout) {
+                                        ((TextBasedPreviewLayout)item).setText(editArea.getText().replace("\n", "__NEWLINE__"));
+                                    }
+                                }
+                                update();
+                            }
+                );
+
+        update();
+    }
 
-        chosenListView.getSelectionModel().getSelectedItems()
-                      .addListener((ListChangeListener<? super PreviewLayout>) c ->
-                              previewPane.setContent(viewModel.getPreviewViewer()));
+    private void update() { // ToDo: convert to bindings
+        ObservableList<PreviewLayout> layoutList = chosenListView.getSelectionModel().getSelectedItems();
+        if (layoutList.isEmpty()) {
+            ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getTestLayout());
+            previewPane.visibleProperty().setValue(false);
 
-        ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
-        ContextMenu contextMenu = new ContextMenu();
-        contextMenu.getItems().addAll(
-                factory.createMenuItem(StandardActions.CUT, new PreviewTabView.EditAction(StandardActions.CUT)),
-                factory.createMenuItem(StandardActions.COPY, new PreviewTabView.EditAction(StandardActions.COPY)),
-                factory.createMenuItem(StandardActions.PASTE, new PreviewTabView.EditAction(StandardActions.PASTE)),
-                factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
-        );
-        contextMenu.getStyleClass().add("context-menu");
-        editArea.setContextMenu(contextMenu);
+            editArea.clear();
+           // editArea.editableProperty().setValue(false);
+            readOnlyLabel.visibleProperty().setValue(false);
+            resetDefaultButton.disableProperty().setValue(true);
+        } else {
+            String previewText;
+            PreviewLayout item = layoutList.get(0);
+
+            try {
+                ((PreviewViewer) previewPane.getContent()).setLayout(item);
+            } catch (StringIndexOutOfBoundsException exception) {
+                LOGGER.warn("Parsing error.", exception);
+                dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
+            }
+            previewPane.visibleProperty().setValue(true);
+
+            if (item instanceof TextBasedPreviewLayout) {
+                previewText = ((TextBasedPreviewLayout) item).getText().replace("__NEWLINE__", "\n");
+                //editArea.editableProperty().setValue(false);
+                readOnlyLabel.visibleProperty().setValue(false);
+                resetDefaultButton.disableProperty().setValue(false);
+            } else {
+                previewText = ((CitationStylePreviewLayout) item).getSource();
+                //editArea.editableProperty().setValue(true); // ToDo: Cursor caret disappears
+                readOnlyLabel.visibleProperty().setValue(true);
+                resetDefaultButton.disableProperty().setValue(true);
+            }
+
+            editArea.replaceText(previewText);
+            editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea)); // ToDo: throws NPE on CitationStylePreviewLayout
+            editArea.setStyleSpans(0, computeHighlighting(previewText));
+        }
     }
 
     /**
@@ -288,11 +323,12 @@ public String getTabName() {
 
     public void toLeftButtonAction() { viewModel.removeFromChosen(); }
 
-    public void sortUpButtonAction() {
+    public void sortUpButtonAction() { // ToDo: previewPane loads first in chosenList if Preview is moved
         List<Integer> newIndices = viewModel.selectedInChosenUp(chosenListView.getSelectionModel().getSelectedIndices());
         for (int index : newIndices) {
             chosenListView.getSelectionModel().select(index);
         }
+        update();
     }
 
     public void sortDownButtonAction() {
@@ -300,12 +336,11 @@ public void sortDownButtonAction() {
         for (int index : newIndices) {
             chosenListView.getSelectionModel().select(index);
         }
+        update();
     }
 
-    public void resetDefaultButtonAction() {
+    public void resetDefaultButtonAction() { // not yet working
         viewModel.resetDefaultStyle();
-        if (!chosenListView.getSelectionModel().isEmpty()) {
-// not yet working
-        }
+        update();
     }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 20312f568a1..83f6fed825f 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -8,13 +8,10 @@
 import javafx.beans.property.SimpleListProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
-import javafx.scene.control.ScrollPane;
 
-import org.jabref.Globals;
 import org.jabref.JabRefGUI;
 import org.jabref.gui.BasePanel;
 import org.jabref.gui.DialogService;
-import org.jabref.gui.preview.PreviewViewer;
 import org.jabref.gui.util.BackgroundTask;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.logic.citationstyle.CitationStyle;
@@ -22,8 +19,6 @@
 import org.jabref.logic.citationstyle.PreviewLayout;
 import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
 import org.jabref.logic.l10n.Localization;
-import org.jabref.logic.util.TestEntry;
-import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.preferences.JabRefPreferences;
 import org.jabref.preferences.PreviewPreferences;
 
@@ -95,7 +90,7 @@ public void storeSettings() {
         PreviewPreferences newPreviewPreferences = preferences.getPreviewPreferences()
                                                               .getBuilder()
                                                               .withPreviewCycle(chosenListProperty)
-                                                              .withPreviewStyle(((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")).getLayoutText())
+                                                              .withPreviewStyle(((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")).getText())
                                                               .build();
 
         if (!selectedChosenItemsProperty.getValue().isEmpty()) {
@@ -153,26 +148,21 @@ public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
         return newSelectedIndices;
     }
 
-    public PreviewViewer getPreviewViewer() {
-        PreviewLayout layout = (selectedChosenItemsProperty.getValue().isEmpty()) ?
-                chosenListProperty.getValue().get(0) :
-                selectedChosenItemsProperty.getValue().get(0);
-
-        try {
-            PreviewViewer testPane = new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager);
-            testPane.setEntry(TestEntry.getTestEntry());
-            testPane.setLayout(layout);
-            return testPane;
-        } catch (StringIndexOutOfBoundsException exception) {
-            LOGGER.warn("Parsing error.", exception);
-            dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
-            return ((PreviewViewer) new ScrollPane());
+    public PreviewLayout getTestLayout() {
+        if (!selectedChosenItemsProperty.getValue().isEmpty()) {
+            return selectedAvailableItemsProperty.getValue().get(0);
+        }
+
+        if (!chosenListProperty.getValue().isEmpty()) {
+            return chosenListProperty.getValue().get(0);
         }
+
+        return findLayoutByNameOrDefault("Preview");
     }
 
     public void resetDefaultStyle() {
-        ((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")) // There are issues with caching the testentries
-                .setLayoutText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
+        ((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview"))
+                .setText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
     }
 
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
diff --git a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
index f86459f8a9f..cdc38127ba0 100644
--- a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
+++ b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
@@ -17,22 +17,22 @@ public class TextBasedPreviewLayout implements PreviewLayout {
     private static final Logger LOGGER = LoggerFactory.getLogger(TextBasedPreviewLayout.class);
 
     private Layout layout;
-    private String layoutText;
+    private String text;
     private LayoutFormatterPreferences layoutFormatterPreferences;
 
-    public TextBasedPreviewLayout(String layoutText, LayoutFormatterPreferences layoutFormatterPreferences) {
+    public TextBasedPreviewLayout(String text, LayoutFormatterPreferences layoutFormatterPreferences) {
         this.layoutFormatterPreferences = layoutFormatterPreferences;
-        setLayoutText(layoutText);
+        setText(text);
     }
 
     public TextBasedPreviewLayout(Layout layout) {
         this.layout = layout;
-        this.layoutText = layout.toString();
+        this.text = layout.toString();
     }
 
-    public void setLayoutText(String layoutText) {
-        this.layoutText = layoutText;
-        StringReader sr = new StringReader(layoutText.replace("__NEWLINE__", "\n"));
+    public void setText(String text) {
+        this.text = text;
+        StringReader sr = new StringReader(text.replace("__NEWLINE__", "\n"));
         try {
             layout = new LayoutHelper(sr, layoutFormatterPreferences).getLayoutFromText();
         } catch (IOException e) {
@@ -49,8 +49,8 @@ public String generatePreview(BibEntry entry, BibDatabase database) {
         }
     }
 
-    public String getLayoutText() {
-        return layoutText;
+    public String getText() {
+        return text;
     }
 
     @Override
diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index 4739e1f5dfe..00a310b3035 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -712,6 +712,8 @@ Push\ applications=Push applications
 
 Quit\ JabRef=Quit JabRef
 
+Read\ only=Read only
+
 Redo=Redo
 
 Refine\ supergroup\:\ When\ selected,\ view\ entries\ contained\ in\ both\ this\ group\ and\ its\ supergroup=Refine supergroup: When selected, view entries contained in both this group and its supergroup
@@ -1142,7 +1144,6 @@ Extra\ information\ (e.g.\ page\ number)=Extra information (e.g. page number)
 Manage\ citations=Manage citations
 Problem\ modifying\ citation=Problem modifying citation
 Citation=Citation
-CitationStyleLayout\ cannot\ be\ edited.=CitationStyleLayout cannot be edited.
 Connecting...=Connecting...
 Could\ not\ resolve\ BibTeX\ entry\ for\ citation\ marker\ '%0'.=Could not resolve BibTeX entry for citation marker '%0'.
 Select\ style=Select style

From ba375ba3ba51ca18d881c05c77956ee13386f75a Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 24 Jun 2019 12:16:32 +0200
Subject: [PATCH 09/22] Fixes and refactoring

---
 .../gui/preferences/PreviewTabView.java       | 140 ++++--------------
 .../gui/preferences/PreviewTabViewModel.java  | 107 +++++++++++--
 2 files changed, 127 insertions(+), 120 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index e77e260739f..84fec52e2b2 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -1,14 +1,9 @@
 package org.jabref.gui.preferences;
 
-import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import javax.inject.Inject;
 
-import javafx.beans.binding.BooleanBinding;
 import javafx.beans.property.ReadOnlyListWrapper;
 import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
@@ -18,6 +13,7 @@
 import javafx.scene.control.Label;
 import javafx.scene.control.ListView;
 import javafx.scene.control.ScrollPane;
+import javafx.scene.control.SelectionMode;
 import javafx.scene.input.KeyEvent;
 import javafx.scene.layout.VBox;
 
@@ -41,8 +37,6 @@
 import com.airhacks.afterburner.views.ViewLoader;
 import org.fxmisc.richtext.CodeArea;
 import org.fxmisc.richtext.LineNumberFactory;
-import org.fxmisc.richtext.model.StyleSpans;
-import org.fxmisc.richtext.model.StyleSpansBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -114,6 +108,8 @@ public PreviewTabView(JabRefPreferences preferences) {
     public void initialize() {
         viewModel = new PreviewTabViewModel(dialogService, preferences, taskExecutor);
 
+        lastKeyPressTime = System.currentTimeMillis();
+
         ActionFactory factory = new ActionFactory(Globals.getKeyPrefs());
         contextMenu.getItems().addAll(
                 factory.createMenuItem(StandardActions.CUT, new PreviewTabView.EditAction(StandardActions.CUT)),
@@ -122,43 +118,43 @@ public void initialize() {
                 factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
         );
         contextMenu.getStyleClass().add("context-menu");
-        editArea.setContextMenu(contextMenu);
-
-        lastKeyPressTime = System.currentTimeMillis();
-        listSearchTerm = "";
 
         availableListView.itemsProperty().bind(viewModel.availableListProperty());
-        viewModel.selectedAvailableItemsProperty().bind(new ReadOnlyListWrapper<>(availableListView.getSelectionModel().getSelectedItems()));
+        viewModel.availableSelectionModelProperty().setValue(availableListView.getSelectionModel());
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
         availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
+        availableListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
         chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
-        viewModel.selectedChosenItemsProperty().bind(new ReadOnlyListWrapper<>(chosenListView.getSelectionModel().getSelectedItems()));
+        viewModel.chosenSelectionModelProperty().setValue(chosenListView.getSelectionModel());
         new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosenListView);
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
+        chosenListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
-        toRightButton.disableProperty().bind(availableListView.selectionModelProperty().getValue().selectedItemProperty().isNull());
+        toRightButton.disableProperty().bind(viewModel.availableSelectionModelProperty().getValue().selectedItemProperty().isNull());
 
-        BooleanBinding nothingSelectedFromChosen = chosenListView.selectionModelProperty().getValue().selectedItemProperty().isNull();
-        toLeftButton.disableProperty().bind(nothingSelectedFromChosen);
-        sortUpButton.disableProperty().bind(nothingSelectedFromChosen);
-        sortDownButton.disableProperty().bind(nothingSelectedFromChosen);
-        contextMenu.getItems().get(0).disableProperty().bind(nothingSelectedFromChosen); // ToDo: should not if readonly
-        contextMenu.getItems().get(2).disableProperty().bind(nothingSelectedFromChosen);
+        toLeftButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
+        sortUpButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
+        sortDownButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
 
         previewPane.setContent(new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager));
+        // previewPane.setMaxWidth(650); // FixMe: PreviewViewer is too large
+        // previewPane.getContent().maxWidth(650);
         ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
-        ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getTestLayout());
+        ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getCurrentLayout());
+        previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));
-        editArea.textProperty().addListener((obs, oldText, newText) ->
-                editArea.setStyleSpans(0, computeHighlighting(newText)));
+        editArea.textProperty().addListener((obs, oldText, newText) -> editArea.setStyleSpans(0, viewModel.computeHighlighting(newText)));
+        editArea.setContextMenu(contextMenu);
+        editArea.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
+        // ToDo: Convert to bindings
         BindingsHelper.bindBidirectional(editArea.textProperty(), new ReadOnlyListWrapper<>(chosenListView.selectionModelProperty().getValue().getSelectedItems()),
                 layoutList -> update(),
                             text -> {
-                                if (!viewModel.selectedChosenItemsProperty().getValue().isEmpty()) {
-                                    PreviewLayout item = viewModel.selectedChosenItemsProperty().get(0);
+                                if (!viewModel.chosenSelectionModelProperty().getValue().getSelectedItems().isEmpty()) {
+                                    PreviewLayout item = viewModel.chosenSelectionModelProperty().getValue().getSelectedItems().get(0);
                                     if (item instanceof TextBasedPreviewLayout) {
                                         ((TextBasedPreviewLayout)item).setText(editArea.getText().replace("\n", "__NEWLINE__"));
                                     }
@@ -167,19 +163,22 @@ public void initialize() {
                             }
                 );
 
+        // ToDo: Implement selectedIsEditableProperty-Logic in ViewModel
+        readOnlyLabel.visibleProperty().bind(viewModel.selectedIsEditableProperty().not());
+        resetDefaultButton.disableProperty().bind(viewModel.selectedIsEditableProperty().not());
+        contextMenu.getItems().get(0).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
+        contextMenu.getItems().get(2).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
+
+        //editArea.editableProperty().bind(true); // FixMe: Cursor caret disappears
+
         update();
     }
 
     private void update() { // ToDo: convert to bindings
         ObservableList<PreviewLayout> layoutList = chosenListView.getSelectionModel().getSelectedItems();
         if (layoutList.isEmpty()) {
-            ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getTestLayout());
-            previewPane.visibleProperty().setValue(false);
-
+            ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getCurrentLayout());
             editArea.clear();
-           // editArea.editableProperty().setValue(false);
-            readOnlyLabel.visibleProperty().setValue(false);
-            resetDefaultButton.disableProperty().setValue(true);
         } else {
             String previewText;
             PreviewLayout item = layoutList.get(0);
@@ -190,91 +189,15 @@ private void update() { // ToDo: convert to bindings
                 LOGGER.warn("Parsing error.", exception);
                 dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
             }
-            previewPane.visibleProperty().setValue(true);
 
             if (item instanceof TextBasedPreviewLayout) {
                 previewText = ((TextBasedPreviewLayout) item).getText().replace("__NEWLINE__", "\n");
-                //editArea.editableProperty().setValue(false);
-                readOnlyLabel.visibleProperty().setValue(false);
-                resetDefaultButton.disableProperty().setValue(false);
             } else {
                 previewText = ((CitationStylePreviewLayout) item).getSource();
-                //editArea.editableProperty().setValue(true); // ToDo: Cursor caret disappears
-                readOnlyLabel.visibleProperty().setValue(true);
-                resetDefaultButton.disableProperty().setValue(true);
             }
 
             editArea.replaceText(previewText);
-            editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea)); // ToDo: throws NPE on CitationStylePreviewLayout
-            editArea.setStyleSpans(0, computeHighlighting(previewText));
-        }
-    }
-
-    /**
-     * XML-Syntax-Highlighting for RichTextFX-Codearea
-     * created by (c) Carlos Martins (github: @cemartins)
-     * License: BSD-2-Clause
-     * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE
-     * and: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
-     *
-     * @param text to parse and highlight
-     * @return highlighted span for codeArea
-     */
-    private StyleSpans<Collection<String>> computeHighlighting(String text) {
-
-        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
-                + "|(?<COMMENT><!--[^<>]+-->)");
-        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
-
-        final int GROUP_OPEN_BRACKET = 2;
-        final int GROUP_ELEMENT_NAME = 3;
-        final int GROUP_ATTRIBUTES_SECTION = 4;
-        final int GROUP_CLOSE_BRACKET = 5;
-        final int GROUP_ATTRIBUTE_NAME = 1;
-        final int GROUP_EQUAL_SYMBOL = 2;
-        final int GROUP_ATTRIBUTE_VALUE = 3;
-
-        Matcher matcher = XML_TAG.matcher(text);
-        int lastKwEnd = 0;
-        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
-        while (matcher.find()) {
-
-            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
-            if (matcher.group("COMMENT") != null) {
-                spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
-            } else {
-                if (matcher.group("ELEMENT") != null) {
-                    String attributesText = matcher.group(GROUP_ATTRIBUTES_SECTION);
-
-                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_OPEN_BRACKET) - matcher.start(GROUP_OPEN_BRACKET));
-                    spansBuilder.add(Collections.singleton("anytag"), matcher.end(GROUP_ELEMENT_NAME) - matcher.end(GROUP_OPEN_BRACKET));
-
-                    if (!attributesText.isEmpty()) {
-
-                        lastKwEnd = 0;
-
-                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
-                        while (amatcher.find()) {
-                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
-                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
-                            lastKwEnd = amatcher.end();
-                        }
-                        if (attributesText.length() > lastKwEnd) {
-                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
-                        }
-                    }
-
-                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
-
-                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
-                }
-            }
-            lastKwEnd = matcher.end();
         }
-        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
-        return spansBuilder.create();
     }
 
     public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
@@ -323,7 +246,8 @@ public String getTabName() {
 
     public void toLeftButtonAction() { viewModel.removeFromChosen(); }
 
-    public void sortUpButtonAction() { // ToDo: previewPane loads first in chosenList if Preview is moved
+    // ToDo: Move selectionstuff to ViewModel
+    public void sortUpButtonAction() { // FixMe: previewPane loads first in chosenList if Preview is moved
         List<Integer> newIndices = viewModel.selectedInChosenUp(chosenListView.getSelectionModel().getSelectedIndices());
         for (int index : newIndices) {
             chosenListView.getSelectionModel().select(index);
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 83f6fed825f..ae2b0a65206 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -1,13 +1,22 @@
 package org.jabref.gui.preferences;
 
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
+import javafx.beans.property.BooleanProperty;
 import javafx.beans.property.ListProperty;
+import javafx.beans.property.ObjectProperty;
+import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleListProperty;
+import javafx.beans.property.SimpleObjectProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
+import javafx.scene.control.MultipleSelectionModel;
 
 import org.jabref.JabRefGUI;
 import org.jabref.gui.BasePanel;
@@ -22,6 +31,8 @@
 import org.jabref.preferences.JabRefPreferences;
 import org.jabref.preferences.PreviewPreferences;
 
+import org.fxmisc.richtext.model.StyleSpans;
+import org.fxmisc.richtext.model.StyleSpansBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -30,9 +41,11 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
     private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabViewModel.class);
 
     private final ListProperty<PreviewLayout> availableListProperty = new SimpleListProperty<>();
-    private final ListProperty<PreviewLayout> selectedAvailableItemsProperty = new SimpleListProperty<>();
+    private final ObjectProperty<MultipleSelectionModel<PreviewLayout>> availableSelectionModelProperty = new SimpleObjectProperty<>();
     private final ListProperty<PreviewLayout> chosenListProperty = new SimpleListProperty<>();
-    private final ListProperty<PreviewLayout> selectedChosenItemsProperty = new SimpleListProperty<>();
+    private final ObjectProperty<MultipleSelectionModel<PreviewLayout>> chosenSelectionModelProperty = new SimpleObjectProperty<>();
+
+    private final BooleanProperty selectedIsEditableProperty = new SimpleBooleanProperty(false);
 
     private final DialogService dialogService;
     private final JabRefPreferences preferences;
@@ -71,6 +84,7 @@ public void setValues() {
         availableListProperty.setValue(availableLayouts);
     }
 
+    // ToDo: Does this really work as intended? Test!
     private PreviewLayout findLayoutByNameOrDefault(String name) {
         return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
                 .findAny()
@@ -79,6 +93,73 @@ private PreviewLayout findLayoutByNameOrDefault(String name) {
                         .orElse(previewPreferences.getTextBasedPreviewLayout()));
     }
 
+    /**
+     * XML-Syntax-Highlighting for RichTextFX-Codearea
+     * created by (c) Carlos Martins (github: @cemartins)
+     * License: BSD-2-Clause
+     * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE
+     * and: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
+     *
+     * @param text to parse and highlight
+     * @return highlighted span for codeArea
+     */
+    public StyleSpans<Collection<String>> computeHighlighting(String text) {
+
+        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
+                + "|(?<COMMENT><!--[^<>]+-->)");
+        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
+
+        final int GROUP_OPEN_BRACKET = 2;
+        final int GROUP_ELEMENT_NAME = 3;
+        final int GROUP_ATTRIBUTES_SECTION = 4;
+        final int GROUP_CLOSE_BRACKET = 5;
+        final int GROUP_ATTRIBUTE_NAME = 1;
+        final int GROUP_EQUAL_SYMBOL = 2;
+        final int GROUP_ATTRIBUTE_VALUE = 3;
+
+        Matcher matcher = XML_TAG.matcher(text);
+        int lastKwEnd = 0;
+        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
+        while (matcher.find()) {
+
+            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
+            if (matcher.group("COMMENT") != null) {
+                spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
+            } else {
+                if (matcher.group("ELEMENT") != null) {
+                    String attributesText = matcher.group(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_OPEN_BRACKET) - matcher.start(GROUP_OPEN_BRACKET));
+                    spansBuilder.add(Collections.singleton("anytag"), matcher.end(GROUP_ELEMENT_NAME) - matcher.end(GROUP_OPEN_BRACKET));
+
+                    if (!attributesText.isEmpty()) {
+
+                        lastKwEnd = 0;
+
+                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
+                        while (amatcher.find()) {
+                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
+                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
+                            lastKwEnd = amatcher.end();
+                        }
+                        if (attributesText.length() > lastKwEnd) {
+                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
+                        }
+                    }
+
+                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
+                }
+            }
+            lastKwEnd = matcher.end();
+        }
+        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
+        return spansBuilder.create();
+    }
+
     @Override
     public void storeSettings() {
         PreviewPreferences previewPreferences = preferences.getPreviewPreferences();
@@ -93,8 +174,8 @@ public void storeSettings() {
                                                               .withPreviewStyle(((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")).getText())
                                                               .build();
 
-        if (!selectedChosenItemsProperty.getValue().isEmpty()) {
-            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(selectedChosenItemsProperty.get(0))).build();
+        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(chosenSelectionModelProperty.getValue().getSelectedItems().get(0))).build();
         }
         preferences.storePreviewPreferences(newPreviewPreferences);
 
@@ -111,18 +192,18 @@ public boolean validateSettings() {
     }
 
     public void addToChosen() {
-        for (PreviewLayout layout : selectedAvailableItemsProperty.getValue()) {
+        for (PreviewLayout layout : availableSelectionModelProperty.getValue().getSelectedItems()) {
             availableListProperty.remove(layout);
             chosenListProperty.add(layout);
         }
     }
 
     public void removeFromChosen() {
-        for (PreviewLayout layout : selectedChosenItemsProperty.getValue()) {
+        for (PreviewLayout layout : chosenSelectionModelProperty.getValue().getSelectedItems()) {
             availableListProperty.add(layout);
-            availableListProperty.sort((a,b) -> { return a.getName().compareToIgnoreCase(b.getName()); } );
             chosenListProperty.remove(layout);
         }
+        availableListProperty.sort((a,b) -> a.getName().compareToIgnoreCase(b.getName()));
     }
 
     public List<Integer> selectedInChosenUp(List<Integer> oldindices) {
@@ -148,9 +229,9 @@ public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
         return newSelectedIndices;
     }
 
-    public PreviewLayout getTestLayout() {
-        if (!selectedChosenItemsProperty.getValue().isEmpty()) {
-            return selectedAvailableItemsProperty.getValue().get(0);
+    public PreviewLayout getCurrentLayout() {
+        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+            return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
         }
 
         if (!chosenListProperty.getValue().isEmpty()) {
@@ -167,9 +248,11 @@ public void resetDefaultStyle() {
 
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
 
-    public ListProperty<PreviewLayout> selectedAvailableItemsProperty() { return selectedAvailableItemsProperty; }
+    public ObjectProperty<MultipleSelectionModel<PreviewLayout>> availableSelectionModelProperty() { return availableSelectionModelProperty; }
 
     public ListProperty<PreviewLayout> chosenListProperty() { return chosenListProperty; }
 
-    public ListProperty<PreviewLayout> selectedChosenItemsProperty() { return selectedChosenItemsProperty; }
+    public ObjectProperty<MultipleSelectionModel<PreviewLayout>> chosenSelectionModelProperty() { return chosenSelectionModelProperty; }
+
+    public BooleanProperty selectedIsEditableProperty() { return selectedIsEditableProperty; }
 }

From 5df18fa55c237dfbe7016d980516a50fb589e8b3 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 24 Jun 2019 13:04:02 +0200
Subject: [PATCH 10/22] Fix getText in Layout

---
 .../jabref/logic/citationstyle/TextBasedPreviewLayout.java   | 2 +-
 src/main/java/org/jabref/logic/layout/Layout.java            | 5 +++++
 src/main/java/org/jabref/logic/layout/LayoutEntry.java       | 2 ++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
index cdc38127ba0..193a0fd6949 100644
--- a/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
+++ b/src/main/java/org/jabref/logic/citationstyle/TextBasedPreviewLayout.java
@@ -27,7 +27,7 @@ public TextBasedPreviewLayout(String text, LayoutFormatterPreferences layoutForm
 
     public TextBasedPreviewLayout(Layout layout) {
         this.layout = layout;
-        this.text = layout.toString();
+        this.text = layout.getText();
     }
 
     public void setText(String text) {
diff --git a/src/main/java/org/jabref/logic/layout/Layout.java b/src/main/java/org/jabref/logic/layout/Layout.java
index a0615af1a2f..873fb396de4 100644
--- a/src/main/java/org/jabref/logic/layout/Layout.java
+++ b/src/main/java/org/jabref/logic/layout/Layout.java
@@ -3,6 +3,7 @@
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.jabref.model.database.BibDatabase;
 import org.jabref.model.database.BibDatabaseContext;
@@ -82,6 +83,10 @@ public void setPostFormatter(LayoutFormatter formatter) {
         }
     }
 
+    public String getText() {
+        return layoutEntries.stream().map(LayoutEntry::getText).collect(Collectors.joining("\n"));
+    }
+
     /**
      * Returns the processed bibtex entry. If the database argument is
      * null, no string references will be resolved. Otherwise all valid
diff --git a/src/main/java/org/jabref/logic/layout/LayoutEntry.java b/src/main/java/org/jabref/logic/layout/LayoutEntry.java
index cae756e3a22..bd611bc80f5 100644
--- a/src/main/java/org/jabref/logic/layout/LayoutEntry.java
+++ b/src/main/java/org/jabref/logic/layout/LayoutEntry.java
@@ -669,4 +669,6 @@ public static List<List<String>> parseMethodsCalls(String calls) {
 
         return result;
     }
+
+    public String getText() { return text; }
 }

From 9db93db43b9248ff02433a29b071862add774522 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Tue, 25 Jun 2019 19:21:47 +0200
Subject: [PATCH 11/22] Added dragndrop between lists, multiple selection,
 fixes and refactoring

---
 .../jabref/gui/DragAndDropDataFormats.java    |   1 +
 .../gui/preferences/PreviewTabView.java       | 132 +++++++++++++-----
 .../gui/preferences/PreviewTabViewModel.java  |  47 ++++---
 3 files changed, 126 insertions(+), 54 deletions(-)

diff --git a/src/main/java/org/jabref/gui/DragAndDropDataFormats.java b/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
index 8776ecaca3f..b74aa8dbb97 100644
--- a/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
+++ b/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
@@ -14,6 +14,7 @@ public class DragAndDropDataFormats {
     public static final DataFormat GROUP = new DataFormat("dnd/org.jabref.model.groups.GroupTreeNode");
     public static final DataFormat LINKED_FILE = new DataFormat("dnd/org.jabref.model.entry.LinkedFile");
     public static final DataFormat ENTRIES = new DataFormat("dnd/org.jabref.model.entry.BibEntries");
+    public static final DataFormat PREVIEWLAYOUT = new DataFormat("dnd/org.jabref.logic.citationstyle.PreviewLayout");
     @SuppressWarnings("unchecked") public static final Class<List<BibEntry>> BIBENTRY_LIST_CLASS = (Class<List<BibEntry>>) (Class<?>) List.class;
 
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 84fec52e2b2..88441eb56e3 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -4,8 +4,6 @@
 
 import javax.inject.Inject;
 
-import javafx.beans.property.ReadOnlyListWrapper;
-import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
 import javafx.scene.control.Button;
@@ -14,11 +12,17 @@
 import javafx.scene.control.ListView;
 import javafx.scene.control.ScrollPane;
 import javafx.scene.control.SelectionMode;
+import javafx.scene.input.ClipboardContent;
+import javafx.scene.input.DragEvent;
+import javafx.scene.input.Dragboard;
 import javafx.scene.input.KeyEvent;
+import javafx.scene.input.MouseEvent;
+import javafx.scene.input.TransferMode;
 import javafx.scene.layout.VBox;
 
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
+import org.jabref.gui.DragAndDropDataFormats;
 import org.jabref.gui.actions.ActionFactory;
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.actions.StandardActions;
@@ -64,6 +68,8 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @Inject private DialogService dialogService;
     private final JabRefPreferences preferences;
 
+    private ListView<PreviewLayout> dragSourceList = null;
+
     private long lastKeyPressTime;
     private String listSearchTerm;
 
@@ -121,13 +127,23 @@ public void initialize() {
 
         availableListView.itemsProperty().bind(viewModel.availableListProperty());
         viewModel.availableSelectionModelProperty().setValue(availableListView.getSelectionModel());
-        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(availableListView);
+        new ViewModelListCellFactory<PreviewLayout>()
+                .withText(PreviewLayout::getName)
+                .setOnDragOver(this::dragOverAvailable)
+                .install(availableListView);
+        availableListView.setOnDragDetected(event -> dragDetected(availableListView, event));
+        availableListView.setOnDragDropped(event -> dragDropped(availableListView, event));
         availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
         availableListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
         chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
         viewModel.chosenSelectionModelProperty().setValue(chosenListView.getSelectionModel());
-        new ViewModelListCellFactory<PreviewLayout>().withText(PreviewLayout::getName).install(chosenListView);
+        new ViewModelListCellFactory<PreviewLayout>()
+                .withText(PreviewLayout::getName)
+                .install(chosenListView);
+        chosenListView.setOnDragOver(this::dragOverChosen);
+        chosenListView.setOnDragDetected(event -> dragDetected(chosenListView, event));
+        chosenListView.setOnDragDropped(event -> dragDropped(chosenListView, event));
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
         chosenListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
@@ -144,58 +160,52 @@ public void initialize() {
         ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getCurrentLayout());
         previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
+        editArea.clear();
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));
-        editArea.textProperty().addListener((obs, oldText, newText) -> editArea.setStyleSpans(0, viewModel.computeHighlighting(newText)));
+        editArea.textProperty().addListener((observable, oldText, newText) -> editArea.setStyleSpans(0, viewModel.computeHighlighting(newText)));
         editArea.setContextMenu(contextMenu);
         editArea.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
-        // ToDo: Convert to bindings
-        BindingsHelper.bindBidirectional(editArea.textProperty(), new ReadOnlyListWrapper<>(chosenListView.selectionModelProperty().getValue().getSelectedItems()),
-                layoutList -> update(),
-                            text -> {
-                                if (!viewModel.chosenSelectionModelProperty().getValue().getSelectedItems().isEmpty()) {
-                                    PreviewLayout item = viewModel.chosenSelectionModelProperty().getValue().getSelectedItems().get(0);
-                                    if (item instanceof TextBasedPreviewLayout) {
-                                        ((TextBasedPreviewLayout)item).setText(editArea.getText().replace("\n", "__NEWLINE__"));
-                                    }
-                                }
-                                update();
-                            }
-                );
-
-        // ToDo: Implement selectedIsEditableProperty-Logic in ViewModel
+        BindingsHelper.bindBidirectional(
+                editArea.textProperty(),
+                viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty(),
+                selectedItem -> update(),
+                text -> {
+                    PreviewLayout selectedItem = viewModel.chosenSelectionModelProperty().getValue().getSelectedItem();
+                    if (selectedItem instanceof TextBasedPreviewLayout) {
+                        ((TextBasedPreviewLayout) selectedItem).setText(editArea.getText().replace("\n", "__NEWLINE__"));
+                    }
+                    update();
+                }
+        );
+
+       // ToDo: Implement selectedIsEditableProperty-Logic in ViewModel
         readOnlyLabel.visibleProperty().bind(viewModel.selectedIsEditableProperty().not());
         resetDefaultButton.disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         contextMenu.getItems().get(0).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         contextMenu.getItems().get(2).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
 
-        //editArea.editableProperty().bind(true); // FixMe: Cursor caret disappears
+        // editArea.editableProperty().bind(true); // FixMe: Cursor caret disappears
 
         update();
     }
 
-    private void update() { // ToDo: convert to bindings
-        ObservableList<PreviewLayout> layoutList = chosenListView.getSelectionModel().getSelectedItems();
-        if (layoutList.isEmpty()) {
-            ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getCurrentLayout());
-            editArea.clear();
-        } else {
+    private void update() {
+        PreviewLayout selectedLayout = viewModel.chosenSelectionModelProperty().getValue().getSelectedItem();
+        if (selectedLayout != null) {
             String previewText;
-            PreviewLayout item = layoutList.get(0);
-
             try {
-                ((PreviewViewer) previewPane.getContent()).setLayout(item);
+                ((PreviewViewer) previewPane.getContent()).setLayout(selectedLayout);
             } catch (StringIndexOutOfBoundsException exception) {
                 LOGGER.warn("Parsing error.", exception);
                 dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
             }
 
-            if (item instanceof TextBasedPreviewLayout) {
-                previewText = ((TextBasedPreviewLayout) item).getText().replace("__NEWLINE__", "\n");
+            if (selectedLayout instanceof TextBasedPreviewLayout) {
+                previewText = ((TextBasedPreviewLayout) selectedLayout).getText().replace("__NEWLINE__", "\n");
             } else {
-                previewText = ((CitationStylePreviewLayout) item).getSource();
+                previewText = ((CitationStylePreviewLayout) selectedLayout).getSource();
             }
-
             editArea.replaceText(previewText);
         }
     }
@@ -214,7 +224,56 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
         lastKeyPressTime = System.currentTimeMillis();
 
         list.getItems().stream().filter(item -> item.getName().toLowerCase().startsWith(listSearchTerm))
-                .findFirst().ifPresent(item -> list.scrollTo(item));
+                .findFirst().ifPresent(list::scrollTo);
+    }
+
+    public void dragOverAvailable(@SuppressWarnings("unused") PreviewLayout layout, DragEvent event) {
+        if ((event.getGestureSource() != layout) && event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
+            event.acceptTransferModes(TransferMode.MOVE);
+        }
+    }
+
+    public void dragOverChosen(DragEvent event) {
+        if (event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
+            event.acceptTransferModes(TransferMode.MOVE);
+        }
+    }
+
+    public void dragDetected(ListView<PreviewLayout> sourceListView, MouseEvent event) {
+        PreviewLayout layout = sourceListView.getSelectionModel().getSelectedItem();
+        if (layout != null) {
+            ClipboardContent content = new ClipboardContent();
+            Dragboard dragboard = sourceListView.startDragAndDrop(TransferMode.MOVE);
+            content.put(DragAndDropDataFormats.PREVIEWLAYOUT, layout.getName());
+            dragboard.setContent(content);
+            dragSourceList = sourceListView;
+        }
+        event.consume();
+    }
+
+    public void dragDropped(ListView<PreviewLayout> targetListView, DragEvent event) {
+        Dragboard dragboard = event.getDragboard();
+        boolean success = false;
+
+        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
+            PreviewLayout draggedLayout = viewModel.findLayoutByNameOrNull((String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT));
+            if (draggedLayout != null) {
+                if (dragSourceList != null) {
+                    dragSourceList.getItems().remove(draggedLayout);
+                }
+
+                targetListView.getItems().add(draggedLayout);
+
+                success = true;
+
+                if (targetListView == availableListView) {
+                    targetListView.getItems().sort((a, b) -> a.getName().compareToIgnoreCase(b.getName()));
+                }
+            }
+        }
+
+        event.setDropCompleted(success);
+        event.consume();
     }
 
     @Override
@@ -246,7 +305,6 @@ public String getTabName() {
 
     public void toLeftButtonAction() { viewModel.removeFromChosen(); }
 
-    // ToDo: Move selectionstuff to ViewModel
     public void sortUpButtonAction() { // FixMe: previewPane loads first in chosenList if Preview is moved
         List<Integer> newIndices = viewModel.selectedInChosenUp(chosenListView.getSelectionModel().getSelectedIndices());
         for (int index : newIndices) {
@@ -263,7 +321,7 @@ public void sortDownButtonAction() {
         update();
     }
 
-    public void resetDefaultButtonAction() { // not yet working
+    public void resetDefaultButtonAction() {
         viewModel.resetDefaultStyle();
         update();
     }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index ae2b0a65206..d09f60a6ec9 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -84,7 +84,6 @@ public void setValues() {
         availableListProperty.setValue(availableLayouts);
     }
 
-    // ToDo: Does this really work as intended? Test!
     private PreviewLayout findLayoutByNameOrDefault(String name) {
         return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
                 .findAny()
@@ -93,6 +92,14 @@ private PreviewLayout findLayoutByNameOrDefault(String name) {
                         .orElse(previewPreferences.getTextBasedPreviewLayout()));
     }
 
+    public PreviewLayout findLayoutByNameOrNull(String name) {
+        return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                .findAny()
+                .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                        .findAny()
+                        .orElse(null));
+    }
+
     /**
      * XML-Syntax-Highlighting for RichTextFX-Codearea
      * created by (c) Carlos Martins (github: @cemartins)
@@ -192,23 +199,26 @@ public boolean validateSettings() {
     }
 
     public void addToChosen() {
-        for (PreviewLayout layout : availableSelectionModelProperty.getValue().getSelectedItems()) {
-            availableListProperty.remove(layout);
-            chosenListProperty.add(layout);
-        }
+        List<PreviewLayout> selected = new ArrayList<>();
+        selected.addAll(availableSelectionModelProperty.getValue().getSelectedItems());
+        availableListProperty.removeAll(selected);
+        chosenListProperty.addAll(selected);
     }
 
     public void removeFromChosen() {
-        for (PreviewLayout layout : chosenSelectionModelProperty.getValue().getSelectedItems()) {
-            availableListProperty.add(layout);
-            chosenListProperty.remove(layout);
-        }
+        List<PreviewLayout> selected = new ArrayList<>();
+        selected.addAll(chosenSelectionModelProperty.getValue().getSelectedItems());
+        chosenListProperty.removeAll(selected);
+        availableListProperty.addAll(selected);
         availableListProperty.sort((a,b) -> a.getName().compareToIgnoreCase(b.getName()));
     }
 
-    public List<Integer> selectedInChosenUp(List<Integer> oldindices) {
+    public List<Integer> selectedInChosenUp(List<Integer> oldIndices) {
+        List<Integer> selected = new ArrayList<>();
         List<Integer> newIndices = new ArrayList<>();
-        for (int oldIndex : oldindices) {
+        selected.addAll(oldIndices); // oldIndices needs to be copied, because remove(oldIndex) alters oldIndices
+
+        for (int oldIndex : selected) {
             boolean alreadyTaken = newIndices.contains(oldIndex - 1);
             int newIndex = ((oldIndex > 0) && !alreadyTaken) ? oldIndex - 1 : oldIndex;
             chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
@@ -218,15 +228,18 @@ public List<Integer> selectedInChosenUp(List<Integer> oldindices) {
     }
 
     public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
-        List<Integer> newSelectedIndices = new ArrayList<>();
-        for (int i = oldIndices.size() - 1; i >= 0; i--) {
-            int oldIndex = oldIndices.get(i);
-            boolean alreadyTaken = newSelectedIndices.contains(oldIndex + 1);
+        List<Integer> selected = new ArrayList<>();
+        List<Integer> newIndices = new ArrayList<>();
+        selected.addAll(oldIndices);
+
+        for (int i = selected.size() - 1; i >= 0; i--) {
+            int oldIndex = selected.get(i);
+            boolean alreadyTaken = newIndices.contains(oldIndex + 1);
             int newIndex = ((oldIndex < (chosenListProperty.size() - 1)) && !alreadyTaken) ? oldIndex + 1 : oldIndex;
             chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
-            newSelectedIndices.add(newIndex);
+            newIndices.add(newIndex);
         }
-        return newSelectedIndices;
+        return newIndices;
     }
 
     public PreviewLayout getCurrentLayout() {

From 488ef2e2369f8d08cd25e9bad0a817e6f3f6522a Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Tue, 2 Jul 2019 15:45:23 +0200
Subject: [PATCH 12/22] Refactor, cleanup and fixes

---
 .../jabref/gui/preferences/PreviewTab.fxml    |   6 +-
 .../gui/preferences/PreviewTabView.java       | 126 +++------
 .../gui/preferences/PreviewTabViewModel.java  | 267 +++++++++++-------
 3 files changed, 200 insertions(+), 199 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 3384dfcf4b8..21f2a4bcf17 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -57,16 +57,16 @@
                             <content>
                                 <VirtualizedScrollPane>
                                     <content>
-                                        <CodeArea fx:id="editArea" prefHeight="300.0"/>
+                                        <CodeArea fx:id="editArea"/>
                                     </content>
                                 </VirtualizedScrollPane>
                             </content>
                         </Tab>
                     </tabs>
                 </TabPane>
-                <HBox alignment="CENTER_RIGHT" AnchorPane.rightAnchor="5.0" AnchorPane.topAnchor="2.0" spacing="5.0" >
+                <HBox alignment="CENTER_RIGHT" AnchorPane.rightAnchor="5.0" AnchorPane.topAnchor="2.0" spacing="5.0">
                     <children>
-                        <Label fx:id="readOnlyLabel" text="%Read only" />
+                        <Label fx:id="readOnlyLabel" text="%Read only"/>
                         <Button
                                 fx:id="resetDefaultButton" text="%Reset default preview style"
                                 onAction="#resetDefaultButtonAction"/>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 88441eb56e3..77ac7262d68 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -1,7 +1,5 @@
 package org.jabref.gui.preferences;
 
-import java.util.List;
-
 import javax.inject.Inject;
 
 import javafx.fxml.FXML;
@@ -27,27 +25,21 @@
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.actions.StandardActions;
 import org.jabref.gui.preview.PreviewViewer;
-import org.jabref.gui.util.BindingsHelper;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.gui.util.ViewModelListCellFactory;
-import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
 import org.jabref.logic.citationstyle.PreviewLayout;
-import org.jabref.logic.citationstyle.TextBasedPreviewLayout;
 import org.jabref.logic.l10n.Localization;
 import org.jabref.logic.util.TestEntry;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.preferences.JabRefPreferences;
 
 import com.airhacks.afterburner.views.ViewLoader;
+import org.fxmisc.easybind.EasyBind;
 import org.fxmisc.richtext.CodeArea;
 import org.fxmisc.richtext.LineNumberFactory;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 public class PreviewTabView extends VBox implements PrefsTab {
 
-    private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabView.class);
-
     @FXML private ListView<PreviewLayout> availableListView;
     @FXML private ListView<PreviewLayout> chosenListView;
 
@@ -79,7 +71,9 @@ private class EditAction extends SimpleCommand {
 
         private final StandardActions command;
 
-        public EditAction(StandardActions command) { this.command = command; }
+        public EditAction(StandardActions command) {
+            this.command = command;
+        }
 
         @Override
         public void execute() {
@@ -146,6 +140,7 @@ public void initialize() {
         chosenListView.setOnDragDropped(event -> dragDropped(chosenListView, event));
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
         chosenListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
+        chosenListView.selectionModelProperty().getValue().selectedItemProperty().addListener((observable, oldValue, newValue) -> viewModel.setPreviewLayout(newValue));
 
         toRightButton.disableProperty().bind(viewModel.availableSelectionModelProperty().getValue().selectedItemProperty().isNull());
 
@@ -157,57 +152,29 @@ public void initialize() {
         // previewPane.setMaxWidth(650); // FixMe: PreviewViewer is too large
         // previewPane.getContent().maxWidth(650);
         ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
-        ((PreviewViewer) previewPane.getContent()).setLayout(viewModel.getCurrentLayout());
+        EasyBind.subscribe(viewModel.layoutProperty(), value -> ((PreviewViewer) previewPane.getContent()).setLayout(value));
         previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
         editArea.clear();
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));
-        editArea.textProperty().addListener((observable, oldText, newText) -> editArea.setStyleSpans(0, viewModel.computeHighlighting(newText)));
         editArea.setContextMenu(contextMenu);
         editArea.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
+        viewModel.sourceTextProperty().addListener((observable, oldValue, newValue) -> editArea.replaceText(newValue));
+        editArea.textProperty().addListener((observable, oldValue, newValue) -> {
+            viewModel.sourceTextProperty().setValue(newValue);
+            editArea.setStyleSpans(0, viewModel.computeHighlighting(newValue));
+        });
+        editArea.focusedProperty().addListener((observable, oldValue, newValue) -> {
+            if (!newValue) {
+                viewModel.refreshPreview();
+            }
+        });
 
-        BindingsHelper.bindBidirectional(
-                editArea.textProperty(),
-                viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty(),
-                selectedItem -> update(),
-                text -> {
-                    PreviewLayout selectedItem = viewModel.chosenSelectionModelProperty().getValue().getSelectedItem();
-                    if (selectedItem instanceof TextBasedPreviewLayout) {
-                        ((TextBasedPreviewLayout) selectedItem).setText(editArea.getText().replace("\n", "__NEWLINE__"));
-                    }
-                    update();
-                }
-        );
-
-       // ToDo: Implement selectedIsEditableProperty-Logic in ViewModel
         readOnlyLabel.visibleProperty().bind(viewModel.selectedIsEditableProperty().not());
         resetDefaultButton.disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         contextMenu.getItems().get(0).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         contextMenu.getItems().get(2).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
-
-        // editArea.editableProperty().bind(true); // FixMe: Cursor caret disappears
-
-        update();
-    }
-
-    private void update() {
-        PreviewLayout selectedLayout = viewModel.chosenSelectionModelProperty().getValue().getSelectedItem();
-        if (selectedLayout != null) {
-            String previewText;
-            try {
-                ((PreviewViewer) previewPane.getContent()).setLayout(selectedLayout);
-            } catch (StringIndexOutOfBoundsException exception) {
-                LOGGER.warn("Parsing error.", exception);
-                dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
-            }
-
-            if (selectedLayout instanceof TextBasedPreviewLayout) {
-                previewText = ((TextBasedPreviewLayout) selectedLayout).getText().replace("__NEWLINE__", "\n");
-            } else {
-                previewText = ((CitationStylePreviewLayout) selectedLayout).getSource();
-            }
-            editArea.replaceText(previewText);
-        }
+        editArea.editableProperty().bind(viewModel.selectedIsEditableProperty());
     }
 
     public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
@@ -224,7 +191,7 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
         lastKeyPressTime = System.currentTimeMillis();
 
         list.getItems().stream().filter(item -> item.getName().toLowerCase().startsWith(listSearchTerm))
-                .findFirst().ifPresent(list::scrollTo);
+            .findFirst().ifPresent(list::scrollTo);
     }
 
     public void dragOverAvailable(@SuppressWarnings("unused") PreviewLayout layout, DragEvent event) {
@@ -256,7 +223,7 @@ public void dragDropped(ListView<PreviewLayout> targetListView, DragEvent event)
         boolean success = false;
 
         if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
-            PreviewLayout draggedLayout = viewModel.findLayoutByNameOrNull((String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT));
+            PreviewLayout draggedLayout = viewModel.findLayoutByName((String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT));
             if (draggedLayout != null) {
                 if (dragSourceList != null) {
                     dragSourceList.getItems().remove(draggedLayout);
@@ -276,53 +243,28 @@ public void dragDropped(ListView<PreviewLayout> targetListView, DragEvent event)
         event.consume();
     }
 
-    @Override
-    public Node getBuilder() {
-        return this;
-    }
+    public void toRightButtonAction() { viewModel.addToChosen(); }
 
-    @Override
-    public void setValues() {
-        // Done by bindings
-    }
+    public void toLeftButtonAction() { viewModel.removeFromChosen(); }
 
-    @Override
-    public void storeSettings() {
-        viewModel.storeSettings();
-    }
+    public void sortUpButtonAction() { viewModel.selectedInChosenUp(); }
 
-    @Override
-    public boolean validateSettings() {
-        return viewModel.validateSettings();
-    }
+    public void sortDownButtonAction() { viewModel.selectedInChosenDown(); }
 
-    @Override
-    public String getTabName() {
-        return Localization.lang("Entry preview");
-    }
+    public void resetDefaultButtonAction() { viewModel.resetDefaultLayout(); }
 
-    public void toRightButtonAction() { viewModel.addToChosen(); }
+    @Override
+    public Node getBuilder() { return this; }
 
-    public void toLeftButtonAction() { viewModel.removeFromChosen(); }
+    @Override
+    public void setValues() { } // Done by bindings
 
-    public void sortUpButtonAction() { // FixMe: previewPane loads first in chosenList if Preview is moved
-        List<Integer> newIndices = viewModel.selectedInChosenUp(chosenListView.getSelectionModel().getSelectedIndices());
-        for (int index : newIndices) {
-            chosenListView.getSelectionModel().select(index);
-        }
-        update();
-    }
+    @Override
+    public void storeSettings() { viewModel.storeSettings(); }
 
-    public void sortDownButtonAction() {
-        List<Integer> newIndices = viewModel.selectedInChosenDown(chosenListView.getSelectionModel().getSelectedIndices());
-        for (int index : newIndices) {
-            chosenListView.getSelectionModel().select(index);
-        }
-        update();
-    }
+    @Override
+    public boolean validateSettings() { return viewModel.validateSettings(); }
 
-    public void resetDefaultButtonAction() {
-        viewModel.resetDefaultStyle();
-        update();
-    }
+    @Override
+    public String getTabName() { return Localization.lang("Entry preview"); }
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index d09f60a6ec9..2fe834cd89c 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -14,6 +14,8 @@
 import javafx.beans.property.SimpleBooleanProperty;
 import javafx.beans.property.SimpleListProperty;
 import javafx.beans.property.SimpleObjectProperty;
+import javafx.beans.property.SimpleStringProperty;
+import javafx.beans.property.StringProperty;
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 import javafx.scene.control.MultipleSelectionModel;
@@ -47,6 +49,9 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
 
     private final BooleanProperty selectedIsEditableProperty = new SimpleBooleanProperty(false);
 
+    private final ObjectProperty<PreviewLayout> layoutProperty = new SimpleObjectProperty<>();
+    private final StringProperty sourceTextProperty = new SimpleStringProperty("");
+
     private final DialogService dialogService;
     private final JabRefPreferences preferences;
     private final PreviewPreferences previewPreferences;
@@ -59,6 +64,12 @@ public PreviewTabViewModel(DialogService dialogService, JabRefPreferences prefer
         previewPreferences = preferences.getPreviewPreferences();
 
         setValues();
+
+        sourceTextProperty.addListener((observable, oldValue, newValue) -> {
+            if (getCurrentLayout() instanceof TextBasedPreviewLayout) {
+                ((TextBasedPreviewLayout) getCurrentLayout()).setText(sourceTextProperty.getValue().replace("\n", "__NEWLINE__"));
+            }
+        });
     }
 
     public void setValues() {
@@ -70,101 +81,70 @@ public void setValues() {
         }
 
         BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
-                .onSuccess(value -> value.stream()
-                        .map(CitationStylePreviewLayout::new)
-                        .sorted(Comparator.comparing(PreviewLayout::getName))
-                        .filter(style -> !chosenListProperty.contains(style))
-                        .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
-                .onFailure(ex -> {
-                    LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
-                    dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
-                })
-                .executeWith(taskExecutor);
+                      .onSuccess(value -> value.stream()
+                                               .map(CitationStylePreviewLayout::new)
+                                               .sorted(Comparator.comparing(PreviewLayout::getName))
+                                               .filter(style -> !chosenListProperty.contains(style))
+                                               .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
+                      .onFailure(ex -> {
+                          LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
+                          dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
+                      })
+                      .executeWith(taskExecutor);
 
         availableListProperty.setValue(availableLayouts);
     }
 
-    private PreviewLayout findLayoutByNameOrDefault(String name) {
-        return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
-                .findAny()
-                .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
-                        .findAny()
-                        .orElse(previewPreferences.getTextBasedPreviewLayout()));
-    }
-
-    public PreviewLayout findLayoutByNameOrNull(String name) {
-        return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
-                .findAny()
-                .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
-                        .findAny()
-                        .orElse(null));
-    }
-
-    /**
-     * XML-Syntax-Highlighting for RichTextFX-Codearea
-     * created by (c) Carlos Martins (github: @cemartins)
-     * License: BSD-2-Clause
-     * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE
-     * and: https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
-     *
-     * @param text to parse and highlight
-     * @return highlighted span for codeArea
-     */
-    public StyleSpans<Collection<String>> computeHighlighting(String text) {
-
-        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
-                + "|(?<COMMENT><!--[^<>]+-->)");
-        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
-
-        final int GROUP_OPEN_BRACKET = 2;
-        final int GROUP_ELEMENT_NAME = 3;
-        final int GROUP_ATTRIBUTES_SECTION = 4;
-        final int GROUP_CLOSE_BRACKET = 5;
-        final int GROUP_ATTRIBUTE_NAME = 1;
-        final int GROUP_EQUAL_SYMBOL = 2;
-        final int GROUP_ATTRIBUTE_VALUE = 3;
-
-        Matcher matcher = XML_TAG.matcher(text);
-        int lastKwEnd = 0;
-        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
-        while (matcher.find()) {
+    public void setPreviewLayout(PreviewLayout selectedLayout) {
+        if (selectedLayout == null) {
+            selectedIsEditableProperty.setValue(false);
+            return;
+        }
 
-            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
-            if (matcher.group("COMMENT") != null) {
-                spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
-            } else {
-                if (matcher.group("ELEMENT") != null) {
-                    String attributesText = matcher.group(GROUP_ATTRIBUTES_SECTION);
+        try {
+            layoutProperty.setValue(selectedLayout);
+        } catch (StringIndexOutOfBoundsException exception) {
+            LOGGER.warn("Parsing error.", exception);
+            dialogService.showErrorDialogAndWait(Localization.lang("Parsing error"), Localization.lang("Parsing error") + ": " + Localization.lang("illegal backslash expression"), exception);
+        }
 
-                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_OPEN_BRACKET) - matcher.start(GROUP_OPEN_BRACKET));
-                    spansBuilder.add(Collections.singleton("anytag"), matcher.end(GROUP_ELEMENT_NAME) - matcher.end(GROUP_OPEN_BRACKET));
+        if (selectedLayout instanceof TextBasedPreviewLayout) {
+            sourceTextProperty.setValue(((TextBasedPreviewLayout) selectedLayout).getText().replace("__NEWLINE__", "\n"));
+            selectedIsEditableProperty.setValue(true);
+        } else {
+            sourceTextProperty.setValue(((CitationStylePreviewLayout) selectedLayout).getSource());
+            selectedIsEditableProperty.setValue(false);
+        }
+    }
 
-                    if (!attributesText.isEmpty()) {
+    public void refreshPreview() {
+        layoutProperty.setValue(null);
+        setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
+    }
 
-                        lastKwEnd = 0;
+    public PreviewLayout findLayoutByName(String name) {
+        return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                                    .findAny()
+                                    .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
+                                                              .findAny()
+                                                              .orElse(null));
+    }
 
-                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
-                        while (amatcher.find()) {
-                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
-                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
-                            lastKwEnd = amatcher.end();
-                        }
-                        if (attributesText.length() > lastKwEnd) {
-                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
-                        }
-                    }
+    public PreviewLayout getCurrentLayout() {
+        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+            return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
+        }
 
-                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
+        if (!chosenListProperty.getValue().isEmpty()) {
+            return chosenListProperty.getValue().get(0);
+        }
 
-                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
-                }
-            }
-            lastKwEnd = matcher.end();
+        PreviewLayout layout = findLayoutByName("Preview");
+        if (layout == null) {
+            layout = previewPreferences.getTextBasedPreviewLayout();
         }
-        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
-        return spansBuilder.create();
+
+        return layout;
     }
 
     @Override
@@ -175,10 +155,15 @@ public void storeSettings() {
             chosenListProperty.add(previewPreferences.getTextBasedPreviewLayout());
         }
 
+        PreviewLayout previewStyle = findLayoutByName("Preview");
+        if (previewStyle == null) {
+            previewStyle = previewPreferences.getTextBasedPreviewLayout();
+        }
+
         PreviewPreferences newPreviewPreferences = preferences.getPreviewPreferences()
                                                               .getBuilder()
                                                               .withPreviewCycle(chosenListProperty)
-                                                              .withPreviewStyle(((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview")).getText())
+                                                              .withPreviewStyle(((TextBasedPreviewLayout) previewStyle).getText())
                                                               .build();
 
         if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
@@ -210,13 +195,16 @@ public void removeFromChosen() {
         selected.addAll(chosenSelectionModelProperty.getValue().getSelectedItems());
         chosenListProperty.removeAll(selected);
         availableListProperty.addAll(selected);
-        availableListProperty.sort((a,b) -> a.getName().compareToIgnoreCase(b.getName()));
+        availableListProperty.sort((a, b) -> a.getName().compareToIgnoreCase(b.getName()));
     }
 
-    public List<Integer> selectedInChosenUp(List<Integer> oldIndices) {
-        List<Integer> selected = new ArrayList<>();
+    public void selectedInChosenUp() {
+        if (chosenSelectionModelProperty.getValue().isEmpty()) {
+            return;
+        }
+
+        List<Integer> selected = new ArrayList<>(chosenSelectionModelProperty.getValue().getSelectedIndices());
         List<Integer> newIndices = new ArrayList<>();
-        selected.addAll(oldIndices); // oldIndices needs to be copied, because remove(oldIndex) alters oldIndices
 
         for (int oldIndex : selected) {
             boolean alreadyTaken = newIndices.contains(oldIndex - 1);
@@ -224,13 +212,20 @@ public List<Integer> selectedInChosenUp(List<Integer> oldIndices) {
             chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
             newIndices.add(newIndex);
         }
-        return newIndices;
+
+        chosenSelectionModelProperty.getValue().clearSelection();
+        newIndices.forEach(index -> chosenSelectionModelProperty.getValue().select(index));
+        chosenSelectionModelProperty.getValue().select(newIndices.get(0));
+        refreshPreview();
     }
 
-    public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
-        List<Integer> selected = new ArrayList<>();
+    public void selectedInChosenDown() {
+        if (chosenSelectionModelProperty.getValue().isEmpty()) {
+            return;
+        }
+
+        List<Integer> selected = new ArrayList<>(chosenSelectionModelProperty.getValue().getSelectedIndices());
         List<Integer> newIndices = new ArrayList<>();
-        selected.addAll(oldIndices);
 
         for (int i = selected.size() - 1; i >= 0; i--) {
             int oldIndex = selected.get(i);
@@ -239,24 +234,84 @@ public List<Integer> selectedInChosenDown(List<Integer> oldIndices) {
             chosenListProperty.add(newIndex, chosenListProperty.remove(oldIndex));
             newIndices.add(newIndex);
         }
-        return newIndices;
+
+        chosenSelectionModelProperty.getValue().clearSelection();
+        newIndices.forEach(index -> chosenSelectionModelProperty.getValue().select(index));
+        chosenSelectionModelProperty.getValue().select(newIndices.get(0));
+        refreshPreview();
     }
 
-    public PreviewLayout getCurrentLayout() {
-        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
-            return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
+    public void resetDefaultLayout() {
+        PreviewLayout defaultLayout = findLayoutByName("Preview");
+        if ((defaultLayout != null) && (defaultLayout instanceof TextBasedPreviewLayout)) {
+            ((TextBasedPreviewLayout) defaultLayout).setText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
         }
+        refreshPreview();
+    }
 
-        if (!chosenListProperty.getValue().isEmpty()) {
-            return chosenListProperty.getValue().get(0);
-        }
+    /**
+     * XML-Syntax-Highlighting for RichTextFX-Codearea created by (c) Carlos Martins (github: @cemartins) License:
+     * BSD-2-Clause see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE and:
+     * https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
+     *
+     * @param text to parse and highlight
+     * @return highlighted span for codeArea
+     */
+    public StyleSpans<Collection<String>> computeHighlighting(String text) {
 
-        return findLayoutByNameOrDefault("Preview");
-    }
+        final Pattern XML_TAG = Pattern.compile("(?<ELEMENT>(</?\\h*)(\\w+)([^<>]*)(\\h*/?>))"
+                + "|(?<COMMENT><!--[^<>]+-->)");
+        final Pattern ATTRIBUTES = Pattern.compile("(\\w+\\h*)(=)(\\h*\"[^\"]+\")");
+
+        final int GROUP_OPEN_BRACKET = 2;
+        final int GROUP_ELEMENT_NAME = 3;
+        final int GROUP_ATTRIBUTES_SECTION = 4;
+        final int GROUP_CLOSE_BRACKET = 5;
+        final int GROUP_ATTRIBUTE_NAME = 1;
+        final int GROUP_EQUAL_SYMBOL = 2;
+        final int GROUP_ATTRIBUTE_VALUE = 3;
+
+        Matcher matcher = XML_TAG.matcher(text);
+        int lastKwEnd = 0;
+        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
+        while (matcher.find()) {
 
-    public void resetDefaultStyle() {
-        ((TextBasedPreviewLayout) findLayoutByNameOrDefault("Preview"))
-                .setText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
+            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
+            if (matcher.group("COMMENT") != null) {
+                spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
+            } else {
+                if (matcher.group("ELEMENT") != null) {
+                    String attributesText = matcher.group(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_OPEN_BRACKET) - matcher.start(GROUP_OPEN_BRACKET));
+                    spansBuilder.add(Collections.singleton("anytag"), matcher.end(GROUP_ELEMENT_NAME) - matcher.end(GROUP_OPEN_BRACKET));
+
+                    if (!attributesText.isEmpty()) {
+
+                        lastKwEnd = 0;
+
+                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
+                        while (amatcher.find()) {
+                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
+                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
+                            lastKwEnd = amatcher.end();
+                        }
+                        if (attributesText.length() > lastKwEnd) {
+                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
+                        }
+                    }
+
+                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
+
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
+                }
+            }
+            lastKwEnd = matcher.end();
+        }
+        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
+        return spansBuilder.create();
     }
 
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
@@ -268,4 +323,8 @@ public void resetDefaultStyle() {
     public ObjectProperty<MultipleSelectionModel<PreviewLayout>> chosenSelectionModelProperty() { return chosenSelectionModelProperty; }
 
     public BooleanProperty selectedIsEditableProperty() { return selectedIsEditableProperty; }
+
+    public ObjectProperty<PreviewLayout> layoutProperty() { return layoutProperty; }
+
+    public StringProperty sourceTextProperty() { return sourceTextProperty; }
 }

From cdd4988dd5e9d91296da792b270c9016385cad36 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Tue, 2 Jul 2019 20:38:43 +0200
Subject: [PATCH 13/22] Refactor, drag'n'drop sorting in chosen with single
 selection

---
 .../gui/preferences/PreviewTabView.java       | 48 ++++++++++++++-----
 .../gui/preferences/PreviewTabViewModel.java  | 17 +++----
 2 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 77ac7262d68..cea2468b14b 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -2,6 +2,7 @@
 
 import javax.inject.Inject;
 
+import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
 import javafx.scene.control.Button;
@@ -119,23 +120,24 @@ public void initialize() {
         );
         contextMenu.getStyleClass().add("context-menu");
 
-        availableListView.itemsProperty().bind(viewModel.availableListProperty());
+        availableListView.itemsProperty().bindBidirectional(viewModel.availableListProperty());
         viewModel.availableSelectionModelProperty().setValue(availableListView.getSelectionModel());
         new ViewModelListCellFactory<PreviewLayout>()
                 .withText(PreviewLayout::getName)
-                .setOnDragOver(this::dragOverAvailable)
                 .install(availableListView);
+        availableListView.setOnDragOver(this::dragOver);
         availableListView.setOnDragDetected(event -> dragDetected(availableListView, event));
         availableListView.setOnDragDropped(event -> dragDropped(availableListView, event));
         availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
         availableListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
-        chosenListView.itemsProperty().bind(viewModel.chosenListProperty());
+        chosenListView.itemsProperty().bindBidirectional(viewModel.chosenListProperty());
         viewModel.chosenSelectionModelProperty().setValue(chosenListView.getSelectionModel());
         new ViewModelListCellFactory<PreviewLayout>()
                 .withText(PreviewLayout::getName)
+                .setOnDragDropped(this::dragDroppedInChosenCell)
                 .install(chosenListView);
-        chosenListView.setOnDragOver(this::dragOverChosen);
+        chosenListView.setOnDragOver(this::dragOver);
         chosenListView.setOnDragDetected(event -> dragDetected(chosenListView, event));
         chosenListView.setOnDragDropped(event -> dragDropped(chosenListView, event));
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
@@ -194,13 +196,7 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
             .findFirst().ifPresent(list::scrollTo);
     }
 
-    public void dragOverAvailable(@SuppressWarnings("unused") PreviewLayout layout, DragEvent event) {
-        if ((event.getGestureSource() != layout) && event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
-            event.acceptTransferModes(TransferMode.MOVE);
-        }
-    }
-
-    public void dragOverChosen(DragEvent event) {
+    public void dragOver(DragEvent event) {
         if (event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
             event.acceptTransferModes(TransferMode.MOVE);
         }
@@ -243,6 +239,36 @@ public void dragDropped(ListView<PreviewLayout> targetListView, DragEvent event)
         event.consume();
     }
 
+    public void dragDroppedInChosenCell(PreviewLayout targetLayout, DragEvent event) {
+        Dragboard dragboard = event.getDragboard();
+        ObservableList<PreviewLayout> items = dragSourceList.itemsProperty().get();
+        boolean success = false;
+
+        int targetId = chosenListView.getItems().indexOf(targetLayout);;
+
+        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
+            String draggedLayoutName = (String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT);
+            if (!draggedLayoutName.isEmpty()) {
+                PreviewLayout draggedLayout = null;
+                for (int i = 0; i < items.size(); i++) {
+                    if (items.get(i).getName().equals(draggedLayoutName)) {
+                        draggedLayout = dragSourceList.getItems().remove(i);
+                        break;
+                    }
+                }
+
+                if (draggedLayout != null) {
+                    chosenListView.getItems().add(targetId, draggedLayout);
+                    chosenListView.getSelectionModel().clearAndSelect(targetId);
+                    success = true;
+                }
+            }
+        }
+
+        event.setDropCompleted(success);
+        event.consume();
+    }
+
     public void toRightButtonAction() { viewModel.addToChosen(); }
 
     public void toLeftButtonAction() { viewModel.removeFromChosen(); }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 2fe834cd89c..b6d44649aa7 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -42,9 +42,9 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(PreviewTabViewModel.class);
 
-    private final ListProperty<PreviewLayout> availableListProperty = new SimpleListProperty<>();
+    private final ListProperty<PreviewLayout> availableListProperty = new SimpleListProperty<>(FXCollections.observableArrayList());
     private final ObjectProperty<MultipleSelectionModel<PreviewLayout>> availableSelectionModelProperty = new SimpleObjectProperty<>();
-    private final ListProperty<PreviewLayout> chosenListProperty = new SimpleListProperty<>();
+    private final ListProperty<PreviewLayout> chosenListProperty = new SimpleListProperty<>(FXCollections.observableArrayList());
     private final ObjectProperty<MultipleSelectionModel<PreviewLayout>> chosenSelectionModelProperty = new SimpleObjectProperty<>();
 
     private final BooleanProperty selectedIsEditableProperty = new SimpleBooleanProperty(false);
@@ -73,26 +73,27 @@ public PreviewTabViewModel(DialogService dialogService, JabRefPreferences prefer
     }
 
     public void setValues() {
-        final ObservableList<PreviewLayout> availableLayouts = FXCollections.observableArrayList();
+        ObservableList<PreviewLayout> availableLayouts = availableListProperty.getValue();
 
-        chosenListProperty.setValue(FXCollections.observableArrayList(previewPreferences.getPreviewCycle()));
+        chosenListProperty().getValue().clear();
+        chosenListProperty.getValue().addAll(previewPreferences.getPreviewCycle());
+
+        availableLayouts.clear();
         if (chosenListProperty.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
-            chosenListProperty.add(previewPreferences.getTextBasedPreviewLayout());
+            availableListProperty.getValue().add(previewPreferences.getTextBasedPreviewLayout());
         }
 
         BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
                       .onSuccess(value -> value.stream()
                                                .map(CitationStylePreviewLayout::new)
+                                               .filter(style -> !chosenListProperty.getValue().contains(style))
                                                .sorted(Comparator.comparing(PreviewLayout::getName))
-                                               .filter(style -> !chosenListProperty.contains(style))
                                                .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
                       .onFailure(ex -> {
                           LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
                           dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
                       })
                       .executeWith(taskExecutor);
-
-        availableListProperty.setValue(availableLayouts);
     }
 
     public void setPreviewLayout(PreviewLayout selectedLayout) {

From 9c69bdaa43e92652d28c097591c3d5083172afff Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 8 Jul 2019 00:53:51 +0200
Subject: [PATCH 14/22] Fixes, added drag'n'drop sorting with multiple
 selection

---
 .../jabref/gui/DragAndDropDataFormats.java    |   5 +-
 .../gui/preferences/PreviewTabView.java       |  97 +++++-----------
 .../gui/preferences/PreviewTabViewModel.java  | 107 +++++++++++++++++-
 .../jabref/gui/util/CustomLocalDragboard.java |  23 +++-
 4 files changed, 158 insertions(+), 74 deletions(-)

diff --git a/src/main/java/org/jabref/gui/DragAndDropDataFormats.java b/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
index b74aa8dbb97..82f3e8606ac 100644
--- a/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
+++ b/src/main/java/org/jabref/gui/DragAndDropDataFormats.java
@@ -4,6 +4,7 @@
 
 import javafx.scene.input.DataFormat;
 
+import org.jabref.logic.citationstyle.PreviewLayout;
 import org.jabref.model.entry.BibEntry;
 
 /**
@@ -14,7 +15,7 @@ public class DragAndDropDataFormats {
     public static final DataFormat GROUP = new DataFormat("dnd/org.jabref.model.groups.GroupTreeNode");
     public static final DataFormat LINKED_FILE = new DataFormat("dnd/org.jabref.model.entry.LinkedFile");
     public static final DataFormat ENTRIES = new DataFormat("dnd/org.jabref.model.entry.BibEntries");
-    public static final DataFormat PREVIEWLAYOUT = new DataFormat("dnd/org.jabref.logic.citationstyle.PreviewLayout");
     @SuppressWarnings("unchecked") public static final Class<List<BibEntry>> BIBENTRY_LIST_CLASS = (Class<List<BibEntry>>) (Class<?>) List.class;
-
+    public static final DataFormat PREVIEWLAYOUTS = new DataFormat("dnd/org.jabref.logic.citationstyle.PreviewLayouts");
+    @SuppressWarnings("unchecked") public static final Class<List<PreviewLayout>> PREVIEWLAYOUT_LIST_CLASS = (Class<List<PreviewLayout>>) (Class<?>) List.class;
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index cea2468b14b..a25bca1ba6e 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -1,8 +1,11 @@
 package org.jabref.gui.preferences;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import javax.inject.Inject;
 
-import javafx.collections.ObservableList;
+import javafx.beans.property.ListProperty;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
 import javafx.scene.control.Button;
@@ -11,7 +14,6 @@
 import javafx.scene.control.ListView;
 import javafx.scene.control.ScrollPane;
 import javafx.scene.control.SelectionMode;
-import javafx.scene.input.ClipboardContent;
 import javafx.scene.input.DragEvent;
 import javafx.scene.input.Dragboard;
 import javafx.scene.input.KeyEvent;
@@ -21,7 +23,6 @@
 
 import org.jabref.Globals;
 import org.jabref.gui.DialogService;
-import org.jabref.gui.DragAndDropDataFormats;
 import org.jabref.gui.actions.ActionFactory;
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.actions.StandardActions;
@@ -61,8 +62,6 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @Inject private DialogService dialogService;
     private final JabRefPreferences preferences;
 
-    private ListView<PreviewLayout> dragSourceList = null;
-
     private long lastKeyPressTime;
     private String listSearchTerm;
 
@@ -126,8 +125,8 @@ public void initialize() {
                 .withText(PreviewLayout::getName)
                 .install(availableListView);
         availableListView.setOnDragOver(this::dragOver);
-        availableListView.setOnDragDetected(event -> dragDetected(availableListView, event));
-        availableListView.setOnDragDropped(event -> dragDropped(availableListView, event));
+        availableListView.setOnDragDetected(this::dragDetectedInAvailable);
+        availableListView.setOnDragDropped(event -> dragDropped(viewModel.availableListProperty(), event));
         availableListView.setOnKeyTyped(event -> jumpToSearchKey(availableListView, event));
         availableListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
 
@@ -138,8 +137,8 @@ public void initialize() {
                 .setOnDragDropped(this::dragDroppedInChosenCell)
                 .install(chosenListView);
         chosenListView.setOnDragOver(this::dragOver);
-        chosenListView.setOnDragDetected(event -> dragDetected(chosenListView, event));
-        chosenListView.setOnDragDropped(event -> dragDropped(chosenListView, event));
+        chosenListView.setOnDragDetected(this::dragDetectedInChosen);
+        chosenListView.setOnDragDropped(event -> dragDropped(viewModel.chosenListProperty(), event));
         chosenListView.setOnKeyTyped(event -> jumpToSearchKey(chosenListView, event));
         chosenListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
         chosenListView.selectionModelProperty().getValue().selectedItemProperty().addListener((observable, oldValue, newValue) -> viewModel.setPreviewLayout(newValue));
@@ -151,8 +150,6 @@ public void initialize() {
         sortDownButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
 
         previewPane.setContent(new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager));
-        // previewPane.setMaxWidth(650); // FixMe: PreviewViewer is too large
-        // previewPane.getContent().maxWidth(650);
         ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
         EasyBind.subscribe(viewModel.layoutProperty(), value -> ((PreviewViewer) previewPane.getContent()).setLayout(value));
         previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
@@ -179,6 +176,13 @@ public void initialize() {
         editArea.editableProperty().bind(viewModel.selectedIsEditableProperty());
     }
 
+    /**
+     * This is called, if a user starts typing some characters into the keyboard with focus on one ListView.
+     * The ListView will scroll to the next cell with the name of the PreviewLayout fitting those characters.
+     * @param list The ListView currently focused
+     * @param keypressed The pressed character
+     */
+
     public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
         if (keypressed.getCharacter() == null) {
             return;
@@ -197,74 +201,35 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
     }
 
     public void dragOver(DragEvent event) {
-        if (event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
-            event.acceptTransferModes(TransferMode.MOVE);
-        }
+        viewModel.dragOver(event);
     }
 
-    public void dragDetected(ListView<PreviewLayout> sourceListView, MouseEvent event) {
-        PreviewLayout layout = sourceListView.getSelectionModel().getSelectedItem();
-        if (layout != null) {
-            ClipboardContent content = new ClipboardContent();
-            Dragboard dragboard = sourceListView.startDragAndDrop(TransferMode.MOVE);
-            content.put(DragAndDropDataFormats.PREVIEWLAYOUT, layout.getName());
-            dragboard.setContent(content);
-            dragSourceList = sourceListView;
+    public void dragDetectedInAvailable(MouseEvent event) {
+        List<PreviewLayout> selectedLayouts = new ArrayList<>(viewModel.availableSelectionModelProperty().getValue().getSelectedItems());
+        if (!selectedLayouts.isEmpty()) {
+            Dragboard dragboard = startDragAndDrop(TransferMode.MOVE);
+            viewModel.dragDetected(viewModel.availableListProperty(), selectedLayouts, dragboard);
         }
         event.consume();
     }
 
-    public void dragDropped(ListView<PreviewLayout> targetListView, DragEvent event) {
-        Dragboard dragboard = event.getDragboard();
-        boolean success = false;
-
-        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
-            PreviewLayout draggedLayout = viewModel.findLayoutByName((String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT));
-            if (draggedLayout != null) {
-                if (dragSourceList != null) {
-                    dragSourceList.getItems().remove(draggedLayout);
-                }
-
-                targetListView.getItems().add(draggedLayout);
-
-                success = true;
-
-                if (targetListView == availableListView) {
-                    targetListView.getItems().sort((a, b) -> a.getName().compareToIgnoreCase(b.getName()));
-                }
-            }
+    public void dragDetectedInChosen(MouseEvent event) {
+        List<PreviewLayout> selectedLayouts = new ArrayList<>(viewModel.chosenSelectionModelProperty().getValue().getSelectedItems());
+        if (!selectedLayouts.isEmpty()) {
+            Dragboard dragboard = startDragAndDrop(TransferMode.MOVE);
+            viewModel.dragDetected(viewModel.chosenListProperty(), selectedLayouts, dragboard);
         }
+        event.consume();
+    }
 
+    public void dragDropped(ListProperty<PreviewLayout> targetList, DragEvent event) {
+        boolean success = viewModel.dragDropped(targetList, event.getDragboard());
         event.setDropCompleted(success);
         event.consume();
     }
 
     public void dragDroppedInChosenCell(PreviewLayout targetLayout, DragEvent event) {
-        Dragboard dragboard = event.getDragboard();
-        ObservableList<PreviewLayout> items = dragSourceList.itemsProperty().get();
-        boolean success = false;
-
-        int targetId = chosenListView.getItems().indexOf(targetLayout);;
-
-        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUT)) {
-            String draggedLayoutName = (String) dragboard.getContent(DragAndDropDataFormats.PREVIEWLAYOUT);
-            if (!draggedLayoutName.isEmpty()) {
-                PreviewLayout draggedLayout = null;
-                for (int i = 0; i < items.size(); i++) {
-                    if (items.get(i).getName().equals(draggedLayoutName)) {
-                        draggedLayout = dragSourceList.getItems().remove(i);
-                        break;
-                    }
-                }
-
-                if (draggedLayout != null) {
-                    chosenListView.getItems().add(targetId, draggedLayout);
-                    chosenListView.getSelectionModel().clearAndSelect(targetId);
-                    success = true;
-                }
-            }
-        }
-
+        boolean success = viewModel.dragDroppedInChosenCell(targetLayout, event.getDragboard());
         event.setDropCompleted(success);
         event.consume();
     }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index b6d44649aa7..fc7228dd3ba 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -19,11 +19,18 @@
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
 import javafx.scene.control.MultipleSelectionModel;
+import javafx.scene.input.ClipboardContent;
+import javafx.scene.input.DragEvent;
+import javafx.scene.input.Dragboard;
+import javafx.scene.input.TransferMode;
 
 import org.jabref.JabRefGUI;
 import org.jabref.gui.BasePanel;
 import org.jabref.gui.DialogService;
+import org.jabref.gui.DragAndDropDataFormats;
+import org.jabref.gui.GUIGlobals;
 import org.jabref.gui.util.BackgroundTask;
+import org.jabref.gui.util.CustomLocalDragboard;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.logic.citationstyle.CitationStyle;
 import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
@@ -57,6 +64,9 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
     private final PreviewPreferences previewPreferences;
     private final TaskExecutor taskExecutor;
 
+    private ListProperty<PreviewLayout> dragSourceList = null;
+    private final CustomLocalDragboard localDragboard = GUIGlobals.localDragboard;
+
     public PreviewTabViewModel(DialogService dialogService, JabRefPreferences preferences, TaskExecutor taskExecutor) {
         this.dialogService = dialogService;
         this.preferences = preferences;
@@ -84,11 +94,12 @@ public void setValues() {
         }
 
         BackgroundTask.wrap(CitationStyle::discoverCitationStyles)
-                      .onSuccess(value -> value.stream()
-                                               .map(CitationStylePreviewLayout::new)
-                                               .filter(style -> !chosenListProperty.getValue().contains(style))
-                                               .sorted(Comparator.comparing(PreviewLayout::getName))
-                                               .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
+                      .onSuccess(styles -> styles.stream()
+                                                 .map(CitationStylePreviewLayout::new)
+                                                 .filter(style -> chosenListProperty.getValue().filtered(item ->
+                                                         item.getName().equals(style.getName())).isEmpty())
+                                                 .sorted(Comparator.comparing(PreviewLayout::getName))
+                                                 .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
                       .onFailure(ex -> {
                           LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
                           dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
@@ -315,6 +326,92 @@ public StyleSpans<Collection<String>> computeHighlighting(String text) {
         return spansBuilder.create();
     }
 
+    public void dragOver(DragEvent event) {
+        if (event.getDragboard().hasContent(DragAndDropDataFormats.PREVIEWLAYOUTS)) {
+            event.acceptTransferModes(TransferMode.MOVE);
+        }
+    }
+
+    public void dragDetected(ListProperty<PreviewLayout> sourceList, List<PreviewLayout> selectedLayouts, Dragboard dragboard) {
+        ClipboardContent content = new ClipboardContent();
+        content.put(DragAndDropDataFormats.PREVIEWLAYOUTS, "");
+        dragboard.setContent(content);
+        localDragboard.putPreviewLayouts(selectedLayouts);
+        dragSourceList = sourceList;
+    }
+
+    /**
+     * Is called, when the user drops some PreviewLayouts either in the availableListView or in the empty space of
+     * chosenListView
+     *
+     * @param targetList either availableListView or chosenListView
+     */
+
+    public boolean dragDropped(ListProperty<PreviewLayout> targetList, Dragboard dragboard) {
+        boolean success = false;
+
+        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUTS)) {
+            List<PreviewLayout> draggedLayouts = localDragboard.getPreviewLayouts();
+            if (!draggedLayouts.isEmpty()) {
+                dragSourceList.getValue().removeAll(draggedLayouts);
+                targetList.getValue().addAll(draggedLayouts);
+                success = true;
+
+                if (targetList == availableListProperty) {
+                    targetList.getValue().sort((a, b) -> a.getName().compareToIgnoreCase(b.getName()));
+                }
+            }
+        }
+
+        return success;
+    }
+
+    /**
+     * This is called, when the user drops some PreviewLayouts on another cell to sort them
+     *
+     * @param targetLayout the Layout, the user drops a layout on
+     */
+
+    public boolean dragDroppedInChosenCell(PreviewLayout targetLayout, Dragboard dragboard) {
+        boolean success = false;
+
+        if (dragboard.hasContent(DragAndDropDataFormats.PREVIEWLAYOUTS)) {
+            List<PreviewLayout> draggedSelectedLayouts = new ArrayList<>(localDragboard.getPreviewLayouts());
+            if (!draggedSelectedLayouts.isEmpty()) {
+
+                int targetId = chosenListProperty.getValue().indexOf(targetLayout);
+
+                // see https://stackoverflow.com/questions/28603224/sort-tableview-with-drag-and-drop-rows
+                int onSelectedDelta = 0;
+                while (draggedSelectedLayouts.contains(targetLayout)) {
+                    onSelectedDelta = 1;
+                    targetId--;
+                    if (targetId < 0) {
+                        targetId = 0;
+                        targetLayout = null;
+                        break;
+                    }
+                    targetLayout = chosenListProperty.getValue().get(targetId);
+                }
+
+                dragSourceList.getValue().removeAll(draggedSelectedLayouts);
+
+                if (targetLayout != null) {
+                    targetId = chosenListProperty.getValue().indexOf(targetLayout) + onSelectedDelta;
+                } else if (targetId != 0) {
+                    targetId = chosenListProperty.getValue().size();
+                }
+
+                chosenListProperty.getValue().addAll(targetId, draggedSelectedLayouts);
+                chosenSelectionModelProperty.getValue().clearSelection();
+                draggedSelectedLayouts.forEach(layout -> chosenSelectionModelProperty.getValue().select(layout));
+                success = true;
+            }
+        }
+
+        return success;
+    }
+
     public ListProperty<PreviewLayout> availableListProperty() { return availableListProperty; }
 
     public ObjectProperty<MultipleSelectionModel<PreviewLayout>> availableSelectionModelProperty() { return availableSelectionModelProperty; }
diff --git a/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java b/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
index d8af9e34948..7fbf1f5feed 100644
--- a/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
+++ b/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
@@ -7,6 +7,7 @@
 
 import org.jabref.gui.DragAndDropDataFormats;
 import org.jabref.gui.GUIGlobals;
+import org.jabref.logic.citationstyle.PreviewLayout;
 import org.jabref.model.entry.BibEntry;
 
 /**
@@ -63,4 +64,24 @@ public List<BibEntry> getBibEntries() {
         return Collections.emptyList();
     }
 
-}
\ No newline at end of file
+    /**
+     * Puts A List of {@link PreviewLayout} in the map All previous content is cleared
+     *
+     * @param previewLayouts The list to put
+     */
+    public void putPreviewLayouts(List<PreviewLayout> previewLayouts) {
+        putValue(DragAndDropDataFormats.PREVIEWLAYOUT_LIST_CLASS, previewLayouts);
+    }
+
+    /**
+     * Get a List of {@link PreviewLayout} from the dragboard
+     *
+     * @return List of BibEntry or empty list if no entries are avaiable
+     */
+    public List<PreviewLayout> getPreviewLayouts() {
+        if (hasType(DragAndDropDataFormats.PREVIEWLAYOUT_LIST_CLASS)) {
+            return getValue(DragAndDropDataFormats.PREVIEWLAYOUT_LIST_CLASS);
+        }
+        return Collections.emptyList();
+    }
+}

From e1dc129c167e4990f7cb4101c1e0d4eaac0f2fdc Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 8 Jul 2019 09:00:56 +0200
Subject: [PATCH 15/22] Added Validator and some minor optimizations

---
 .../gui/preferences/PreviewTabView.java       | 20 +++++++---
 .../gui/preferences/PreviewTabViewModel.java  | 40 +++++++++++++++----
 2 files changed, 46 insertions(+), 14 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index a25bca1ba6e..48def0fb44f 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -5,6 +5,7 @@
 
 import javax.inject.Inject;
 
+import javafx.application.Platform;
 import javafx.beans.property.ListProperty;
 import javafx.fxml.FXML;
 import javafx.scene.Node;
@@ -27,6 +28,7 @@
 import org.jabref.gui.actions.SimpleCommand;
 import org.jabref.gui.actions.StandardActions;
 import org.jabref.gui.preview.PreviewViewer;
+import org.jabref.gui.util.IconValidationDecorator;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.gui.util.ViewModelListCellFactory;
 import org.jabref.logic.citationstyle.PreviewLayout;
@@ -36,6 +38,7 @@
 import org.jabref.preferences.JabRefPreferences;
 
 import com.airhacks.afterburner.views.ViewLoader;
+import de.saxsys.mvvmfx.utils.validation.visualization.ControlsFxVisualizer;
 import org.fxmisc.easybind.EasyBind;
 import org.fxmisc.richtext.CodeArea;
 import org.fxmisc.richtext.LineNumberFactory;
@@ -67,6 +70,8 @@ public class PreviewTabView extends VBox implements PrefsTab {
 
     private PreviewTabViewModel viewModel;
 
+    private ControlsFxVisualizer validationVisualizer = new ControlsFxVisualizer();
+
     private class EditAction extends SimpleCommand {
 
         private final StandardActions command;
@@ -174,6 +179,9 @@ public void initialize() {
         contextMenu.getItems().get(0).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         contextMenu.getItems().get(2).disableProperty().bind(viewModel.selectedIsEditableProperty().not());
         editArea.editableProperty().bind(viewModel.selectedIsEditableProperty());
+
+        validationVisualizer.setDecoration(new IconValidationDecorator());
+        Platform.runLater(() -> validationVisualizer.initVisualization(viewModel.chosenListValidationStatus(), chosenListView));
     }
 
     /**
@@ -183,7 +191,7 @@ public void initialize() {
      * @param keypressed The pressed character
      */
 
-    public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
+    private void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
         if (keypressed.getCharacter() == null) {
             return;
         }
@@ -200,11 +208,11 @@ public void jumpToSearchKey(ListView<PreviewLayout> list, KeyEvent keypressed) {
             .findFirst().ifPresent(list::scrollTo);
     }
 
-    public void dragOver(DragEvent event) {
+    private void dragOver(DragEvent event) {
         viewModel.dragOver(event);
     }
 
-    public void dragDetectedInAvailable(MouseEvent event) {
+    private void dragDetectedInAvailable(MouseEvent event) {
         List<PreviewLayout> selectedLayouts = new ArrayList<>(viewModel.availableSelectionModelProperty().getValue().getSelectedItems());
         if (!selectedLayouts.isEmpty()) {
             Dragboard dragboard = startDragAndDrop(TransferMode.MOVE);
@@ -213,7 +221,7 @@ public void dragDetectedInAvailable(MouseEvent event) {
         event.consume();
     }
 
-    public void dragDetectedInChosen(MouseEvent event) {
+    private void dragDetectedInChosen(MouseEvent event) {
         List<PreviewLayout> selectedLayouts = new ArrayList<>(viewModel.chosenSelectionModelProperty().getValue().getSelectedItems());
         if (!selectedLayouts.isEmpty()) {
             Dragboard dragboard = startDragAndDrop(TransferMode.MOVE);
@@ -222,13 +230,13 @@ public void dragDetectedInChosen(MouseEvent event) {
         event.consume();
     }
 
-    public void dragDropped(ListProperty<PreviewLayout> targetList, DragEvent event) {
+    private void dragDropped(ListProperty<PreviewLayout> targetList, DragEvent event) {
         boolean success = viewModel.dragDropped(targetList, event.getDragboard());
         event.setDropCompleted(success);
         event.consume();
     }
 
-    public void dragDroppedInChosenCell(PreviewLayout targetLayout, DragEvent event) {
+    private void dragDroppedInChosenCell(PreviewLayout targetLayout, DragEvent event) {
         boolean success = viewModel.dragDroppedInChosenCell(targetLayout, event.getDragboard());
         event.setDropCompleted(success);
         event.consume();
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index fc7228dd3ba..8a3e463dddf 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -17,7 +17,6 @@
 import javafx.beans.property.SimpleStringProperty;
 import javafx.beans.property.StringProperty;
 import javafx.collections.FXCollections;
-import javafx.collections.ObservableList;
 import javafx.scene.control.MultipleSelectionModel;
 import javafx.scene.input.ClipboardContent;
 import javafx.scene.input.DragEvent;
@@ -40,6 +39,9 @@
 import org.jabref.preferences.JabRefPreferences;
 import org.jabref.preferences.PreviewPreferences;
 
+import de.saxsys.mvvmfx.utils.validation.FunctionBasedValidator;
+import de.saxsys.mvvmfx.utils.validation.ValidationMessage;
+import de.saxsys.mvvmfx.utils.validation.ValidationStatus;
 import org.fxmisc.richtext.model.StyleSpans;
 import org.fxmisc.richtext.model.StyleSpansBuilder;
 import org.slf4j.Logger;
@@ -59,6 +61,8 @@ public class PreviewTabViewModel implements PreferenceTabViewModel {
     private final ObjectProperty<PreviewLayout> layoutProperty = new SimpleObjectProperty<>();
     private final StringProperty sourceTextProperty = new SimpleStringProperty("");
 
+    private FunctionBasedValidator chosenListValidator;
+
     private final DialogService dialogService;
     private final JabRefPreferences preferences;
     private final PreviewPreferences previewPreferences;
@@ -80,15 +84,24 @@ public PreviewTabViewModel(DialogService dialogService, JabRefPreferences prefer
                 ((TextBasedPreviewLayout) getCurrentLayout()).setText(sourceTextProperty.getValue().replace("\n", "__NEWLINE__"));
             }
         });
+
+        chosenListValidator = new FunctionBasedValidator<>(
+                chosenListProperty,
+                input -> !chosenListProperty.getValue().isEmpty(),
+                ValidationMessage.error(String.format("%s > %s %n %n %s",
+                        Localization.lang("Entry preview"),
+                        Localization.lang("Selected"),
+                        Localization.lang("Selected Layouts can not be empty")
+                        )
+                )
+        );
     }
 
     public void setValues() {
-        ObservableList<PreviewLayout> availableLayouts = availableListProperty.getValue();
-
         chosenListProperty().getValue().clear();
         chosenListProperty.getValue().addAll(previewPreferences.getPreviewCycle());
 
-        availableLayouts.clear();
+        availableListProperty.clear();
         if (chosenListProperty.stream().noneMatch(layout -> layout instanceof TextBasedPreviewLayout)) {
             availableListProperty.getValue().add(previewPreferences.getTextBasedPreviewLayout());
         }
@@ -99,7 +112,7 @@ public void setValues() {
                                                  .filter(style -> chosenListProperty.getValue().filtered(item ->
                                                          item.getName().equals(style.getName())).isEmpty())
                                                  .sorted(Comparator.comparing(PreviewLayout::getName))
-                                                 .forEach(availableLayouts::add)) // does not accept a property, so this is using availableLayouts
+                                                 .forEach(availableListProperty::add))
                       .onFailure(ex -> {
                           LOGGER.error("Something went wrong while adding the discovered CitationStyles to the list. ", ex);
                           dialogService.showErrorDialogAndWait(Localization.lang("Error adding discovered CitationStyles"), ex);
@@ -134,7 +147,7 @@ public void refreshPreview() {
         setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
     }
 
-    public PreviewLayout findLayoutByName(String name) {
+    private PreviewLayout findLayoutByName(String name) {
         return availableListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
                                     .findAny()
                                     .orElse(chosenListProperty.getValue().stream().filter(layout -> layout.getName().equals(name))
@@ -142,7 +155,7 @@ public PreviewLayout findLayoutByName(String name) {
                                                               .orElse(null));
     }
 
-    public PreviewLayout getCurrentLayout() {
+    private PreviewLayout getCurrentLayout() {
         if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
             return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
         }
@@ -190,9 +203,20 @@ public void storeSettings() {
         }
     }
 
+    public ValidationStatus chosenListValidationStatus() {
+        return chosenListValidator.getValidationStatus();
+    }
+
     @Override
     public boolean validateSettings() {
-        return !chosenListProperty.getValue().isEmpty();
+        ValidationStatus status = chosenListValidationStatus();
+        if (!status.isValid()) {
+            if (status.getHighestMessage().isPresent()) {
+                dialogService.showErrorDialogAndWait(status.getHighestMessage().get().getMessage());
+            }
+            return false;
+        }
+        return true;
     }
 
     public void addToChosen() {

From eb05d019d45681ed9d08554e208d17a13b47f15d Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 8 Jul 2019 09:16:00 +0200
Subject: [PATCH 16/22] Added l10n

---
 src/main/resources/l10n/JabRef_en.properties | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main/resources/l10n/JabRef_en.properties b/src/main/resources/l10n/JabRef_en.properties
index 41518555356..8b67b70eaa3 100644
--- a/src/main/resources/l10n/JabRef_en.properties
+++ b/src/main/resources/l10n/JabRef_en.properties
@@ -696,6 +696,7 @@ Next\ preview\ layout=Next preview layout
 Previous\ preview\ layout=Previous preview layout
 Available=Available
 Selected=Selected
+Selected\ Layouts\ can\ not\ be\ empty=Selected Layouts can not be empty
 
 Reset\ default\ preview\ style=Reset default preview style
 

From 70cebaf59c3934e69d11611722067d96c8a8da93 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Mon, 8 Jul 2019 10:09:18 +0200
Subject: [PATCH 17/22] Comments

---
 .../jabref/gui/preferences/PreviewTabViewModel.java  | 12 +++++++-----
 .../org/jabref/gui/util/CustomLocalDragboard.java    |  2 +-
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 8a3e463dddf..32cefa7dea3 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -286,8 +286,9 @@ public void resetDefaultLayout() {
     }
 
     /**
-     * XML-Syntax-Highlighting for RichTextFX-Codearea created by (c) Carlos Martins (github: @cemartins) License:
-     * BSD-2-Clause see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE and:
+     * XML-Syntax-Highlighting for RichTextFX-Codearea created by (c) Carlos Martins (github: @cemartins)
+     * License: BSD-2-Clause
+     * see https://github.com/FXMisc/RichTextFX/blob/master/LICENSE and:
      * https://github.com/FXMisc/RichTextFX/blob/master/richtextfx-demos/README.md#xml-editor
      *
      * @param text to parse and highlight
@@ -365,8 +366,8 @@ public void dragDetected(ListProperty<PreviewLayout> sourceList, List<PreviewLay
     }
 
     /**
-     * Is called, when the user drops some PreviewLayouts either in the availableListView or in the empty space of
-     * chosenListView
+     * This is called, when the user drops some PreviewLayouts either in the availableListView
+     * or in the empty space of chosenListView
      *
      * @param targetList either availableListView or chosenListView
      */
@@ -391,7 +392,8 @@ public boolean dragDropped(ListProperty<PreviewLayout> targetList, Dragboard dra
     }
 
     /**
-     * This is called, when the user drops some PreviewLayouts on another cell to sort them
+     * This is called, when the user drops some PreviewLayouts on another cell in
+     * chosenListView to sort them
      *
      * @param targetLayout the Layout, the user drops a layout on
      */
diff --git a/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java b/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
index 7fbf1f5feed..a80e3522d49 100644
--- a/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
+++ b/src/main/java/org/jabref/gui/util/CustomLocalDragboard.java
@@ -76,7 +76,7 @@ public void putPreviewLayouts(List<PreviewLayout> previewLayouts) {
     /**
      * Get a List of {@link PreviewLayout} from the dragboard
      *
-     * @return List of BibEntry or empty list if no entries are avaiable
+     * @return List of PreviewLayout or empty list if no entries are avaiable
      */
     public List<PreviewLayout> getPreviewLayouts() {
         if (hasType(DragAndDropDataFormats.PREVIEWLAYOUT_LIST_CLASS)) {

From 72d93d59e5cbdd47020e0162a78a6b6f61100e21 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 10 Jul 2019 10:36:13 +0200
Subject: [PATCH 18/22] Refactor minor things and some rewording

---
 .../gui/preferences/PreviewTabViewModel.java  | 77 ++++++++++++-------
 1 file changed, 48 insertions(+), 29 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 32cefa7dea3..25fdf4de178 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -144,7 +144,11 @@ public void setPreviewLayout(PreviewLayout selectedLayout) {
 
     public void refreshPreview() {
         layoutProperty.setValue(null);
-        setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
+        if (chosenSelectionModelProperty.isNotNull().getValue()) {
+            setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
+        } else {
+            setPreviewLayout(null);
+        }
     }
 
     private PreviewLayout findLayoutByName(String name) {
@@ -156,7 +160,7 @@ private PreviewLayout findLayoutByName(String name) {
     }
 
     private PreviewLayout getCurrentLayout() {
-        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+        if (chosenSelectionModelProperty.isNotNull().getValue() && !chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
             return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
         }
 
@@ -191,9 +195,13 @@ public void storeSettings() {
                                                               .withPreviewStyle(((TextBasedPreviewLayout) previewStyle).getText())
                                                               .build();
 
-        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
-            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(chosenListProperty.getValue().indexOf(chosenSelectionModelProperty.getValue().getSelectedItems().get(0))).build();
+        if (chosenSelectionModelProperty.isNotNull().getValue()
+                && !chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+            newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(
+                    chosenListProperty.getValue().indexOf(
+                            chosenSelectionModelProperty.getValue().getSelectedItems().get(0))).build();
         }
+
         preferences.storePreviewPreferences(newPreviewPreferences);
 
         for (BasePanel basePanel : JabRefGUI.getMainFrame().getBasePanelList()) {
@@ -220,22 +228,29 @@ public boolean validateSettings() {
     }
 
     public void addToChosen() {
-        List<PreviewLayout> selected = new ArrayList<>();
-        selected.addAll(availableSelectionModelProperty.getValue().getSelectedItems());
+        if (chosenSelectionModelProperty.isNull().getValue()) {
+            return;
+        }
+
+        List<PreviewLayout> selected = new ArrayList<>(availableSelectionModelProperty.getValue().getSelectedItems());
         availableListProperty.removeAll(selected);
         chosenListProperty.addAll(selected);
     }
 
     public void removeFromChosen() {
-        List<PreviewLayout> selected = new ArrayList<>();
-        selected.addAll(chosenSelectionModelProperty.getValue().getSelectedItems());
+        if (chosenSelectionModelProperty.isNull().getValue()) {
+            return;
+        }
+
+        List<PreviewLayout> selected = new ArrayList<>(chosenSelectionModelProperty.getValue().getSelectedItems());
         chosenListProperty.removeAll(selected);
         availableListProperty.addAll(selected);
         availableListProperty.sort((a, b) -> a.getName().compareToIgnoreCase(b.getName()));
     }
 
     public void selectedInChosenUp() {
-        if (chosenSelectionModelProperty.getValue().isEmpty()) {
+        if (chosenSelectionModelProperty.isNull().getValue()
+                || chosenSelectionModelProperty.getValue().isEmpty()) {
             return;
         }
 
@@ -256,7 +271,8 @@ public void selectedInChosenUp() {
     }
 
     public void selectedInChosenDown() {
-        if (chosenSelectionModelProperty.getValue().isEmpty()) {
+        if (chosenSelectionModelProperty.isNull().getValue()
+                || chosenSelectionModelProperty.getValue().isEmpty()) {
             return;
         }
 
@@ -279,7 +295,7 @@ public void selectedInChosenDown() {
 
     public void resetDefaultLayout() {
         PreviewLayout defaultLayout = findLayoutByName("Preview");
-        if ((defaultLayout != null) && (defaultLayout instanceof TextBasedPreviewLayout)) {
+        if (defaultLayout instanceof TextBasedPreviewLayout) {
             ((TextBasedPreviewLayout) defaultLayout).setText(preferences.getPreviewPreferences().getDefaultPreviewStyle());
         }
         refreshPreview();
@@ -309,11 +325,11 @@ public StyleSpans<Collection<String>> computeHighlighting(String text) {
         final int GROUP_ATTRIBUTE_VALUE = 3;
 
         Matcher matcher = XML_TAG.matcher(text);
-        int lastKwEnd = 0;
+        int lastKeywordEnd = 0;
         StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
         while (matcher.find()) {
 
-            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
+            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKeywordEnd);
             if (matcher.group("COMMENT") != null) {
                 spansBuilder.add(Collections.singleton("comment"), matcher.end() - matcher.start());
             } else {
@@ -325,29 +341,29 @@ public StyleSpans<Collection<String>> computeHighlighting(String text) {
 
                     if (!attributesText.isEmpty()) {
 
-                        lastKwEnd = 0;
+                        lastKeywordEnd = 0;
 
-                        Matcher amatcher = ATTRIBUTES.matcher(attributesText);
-                        while (amatcher.find()) {
-                            spansBuilder.add(Collections.emptyList(), amatcher.start() - lastKwEnd);
-                            spansBuilder.add(Collections.singleton("attribute"), amatcher.end(GROUP_ATTRIBUTE_NAME) - amatcher.start(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("tagmark"), amatcher.end(GROUP_EQUAL_SYMBOL) - amatcher.end(GROUP_ATTRIBUTE_NAME));
-                            spansBuilder.add(Collections.singleton("avalue"), amatcher.end(GROUP_ATTRIBUTE_VALUE) - amatcher.end(GROUP_EQUAL_SYMBOL));
-                            lastKwEnd = amatcher.end();
+                        Matcher attributesMatcher = ATTRIBUTES.matcher(attributesText);
+                        while (attributesMatcher.find()) {
+                            spansBuilder.add(Collections.emptyList(), attributesMatcher.start() - lastKeywordEnd);
+                            spansBuilder.add(Collections.singleton("attribute"), attributesMatcher.end(GROUP_ATTRIBUTE_NAME) - attributesMatcher.start(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("tagmark"), attributesMatcher.end(GROUP_EQUAL_SYMBOL) - attributesMatcher.end(GROUP_ATTRIBUTE_NAME));
+                            spansBuilder.add(Collections.singleton("avalue"), attributesMatcher.end(GROUP_ATTRIBUTE_VALUE) - attributesMatcher.end(GROUP_EQUAL_SYMBOL));
+                            lastKeywordEnd = attributesMatcher.end();
                         }
-                        if (attributesText.length() > lastKwEnd) {
-                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKwEnd);
+                        if (attributesText.length() > lastKeywordEnd) {
+                            spansBuilder.add(Collections.emptyList(), attributesText.length() - lastKeywordEnd);
                         }
                     }
 
-                    lastKwEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
+                    lastKeywordEnd = matcher.end(GROUP_ATTRIBUTES_SECTION);
 
-                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKwEnd);
+                    spansBuilder.add(Collections.singleton("tagmark"), matcher.end(GROUP_CLOSE_BRACKET) - lastKeywordEnd);
                 }
             }
-            lastKwEnd = matcher.end();
+            lastKeywordEnd = matcher.end();
         }
-        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
+        spansBuilder.add(Collections.emptyList(), text.length() - lastKeywordEnd);
         return spansBuilder.create();
     }
 
@@ -429,8 +445,11 @@ public boolean dragDroppedInChosenCell(PreviewLayout targetLayout, Dragboard dra
                 }
 
                 chosenListProperty.getValue().addAll(targetId, draggedSelectedLayouts);
-                chosenSelectionModelProperty.getValue().clearSelection();
-                draggedSelectedLayouts.forEach(layout -> chosenSelectionModelProperty.getValue().select(layout));
+
+                if (chosenSelectionModelProperty.isNotNull().getValue()) {
+                    chosenSelectionModelProperty.getValue().clearSelection();
+                    draggedSelectedLayouts.forEach(layout -> chosenSelectionModelProperty.getValue().select(layout));
+                }
                 success = true;
             }
         }

From c3773cd3d3d25b1866a79c5edafe4d4c993ffafe Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 10 Jul 2019 10:40:21 +0200
Subject: [PATCH 19/22] Refactor mistake

---
 .../java/org/jabref/gui/preferences/PreviewTabViewModel.java    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index 25fdf4de178..a4e83cd1a63 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -228,7 +228,7 @@ public boolean validateSettings() {
     }
 
     public void addToChosen() {
-        if (chosenSelectionModelProperty.isNull().getValue()) {
+        if (availableSelectionModelProperty.isNull().getValue()) {
             return;
         }
 

From 4b275a640598b014ba5a7a8595e6d7cdab363750 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 17 Jul 2019 15:02:07 +0200
Subject: [PATCH 20/22] Removed icon in context-menu and fixed
 PreviewViewer-width

---
 src/main/java/org/jabref/gui/preferences/PreferencesDialog.css | 2 +-
 src/main/java/org/jabref/gui/preferences/PreviewTabView.java   | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
index 51bd8f6d4dc..be2f9cec4be 100644
--- a/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
+++ b/src/main/java/org/jabref/gui/preferences/PreferencesDialog.css
@@ -67,6 +67,6 @@
     -fx-font-family: sans-serif;
 }
 
-.code-area .context-menu .menu-item {
+.code-area .context-menu .menu-item .label {
     -fx-padding: 2;
 }
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 48def0fb44f..40a850647c1 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -122,6 +122,7 @@ public void initialize() {
                 factory.createMenuItem(StandardActions.PASTE, new PreviewTabView.EditAction(StandardActions.PASTE)),
                 factory.createMenuItem(StandardActions.SELECT_ALL, new PreviewTabView.EditAction(StandardActions.SELECT_ALL))
         );
+        contextMenu.getItems().forEach(item -> item.setGraphic(null));
         contextMenu.getStyleClass().add("context-menu");
 
         availableListView.itemsProperty().bindBidirectional(viewModel.availableListProperty());
@@ -158,6 +159,7 @@ public void initialize() {
         ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
         EasyBind.subscribe(viewModel.layoutProperty(), value -> ((PreviewViewer) previewPane.getContent()).setLayout(value));
         previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
+        ((PreviewViewer) previewPane.getContent()).setMaxWidth(640.0);
 
         editArea.clear();
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));

From 61e4e8cf31a62ab672c78c5743bb74613e3047aa Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 17 Jul 2019 15:07:25 +0200
Subject: [PATCH 21/22] Added default NoSelectionModel in ViewModel

---
 .../gui/preferences/PreviewTabViewModel.java  | 36 +++++++------------
 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
index a4e83cd1a63..cc40248258d 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabViewModel.java
@@ -30,6 +30,7 @@
 import org.jabref.gui.GUIGlobals;
 import org.jabref.gui.util.BackgroundTask;
 import org.jabref.gui.util.CustomLocalDragboard;
+import org.jabref.gui.util.NoSelectionModel;
 import org.jabref.gui.util.TaskExecutor;
 import org.jabref.logic.citationstyle.CitationStyle;
 import org.jabref.logic.citationstyle.CitationStylePreviewLayout;
@@ -98,6 +99,9 @@ public PreviewTabViewModel(DialogService dialogService, JabRefPreferences prefer
     }
 
     public void setValues() {
+        availableSelectionModelProperty.setValue(new NoSelectionModel<>());
+        chosenSelectionModelProperty.setValue(new NoSelectionModel<>());
+
         chosenListProperty().getValue().clear();
         chosenListProperty.getValue().addAll(previewPreferences.getPreviewCycle());
 
@@ -144,11 +148,7 @@ public void setPreviewLayout(PreviewLayout selectedLayout) {
 
     public void refreshPreview() {
         layoutProperty.setValue(null);
-        if (chosenSelectionModelProperty.isNotNull().getValue()) {
-            setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
-        } else {
-            setPreviewLayout(null);
-        }
+        setPreviewLayout(chosenSelectionModelProperty.getValue().getSelectedItem());
     }
 
     private PreviewLayout findLayoutByName(String name) {
@@ -160,7 +160,7 @@ private PreviewLayout findLayoutByName(String name) {
     }
 
     private PreviewLayout getCurrentLayout() {
-        if (chosenSelectionModelProperty.isNotNull().getValue() && !chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
             return chosenSelectionModelProperty.getValue().getSelectedItems().get(0);
         }
 
@@ -195,8 +195,7 @@ public void storeSettings() {
                                                               .withPreviewStyle(((TextBasedPreviewLayout) previewStyle).getText())
                                                               .build();
 
-        if (chosenSelectionModelProperty.isNotNull().getValue()
-                && !chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
+        if (!chosenSelectionModelProperty.getValue().getSelectedItems().isEmpty()) {
             newPreviewPreferences = newPreviewPreferences.getBuilder().withPreviewCyclePosition(
                     chosenListProperty.getValue().indexOf(
                             chosenSelectionModelProperty.getValue().getSelectedItems().get(0))).build();
@@ -228,20 +227,12 @@ public boolean validateSettings() {
     }
 
     public void addToChosen() {
-        if (availableSelectionModelProperty.isNull().getValue()) {
-            return;
-        }
-
         List<PreviewLayout> selected = new ArrayList<>(availableSelectionModelProperty.getValue().getSelectedItems());
         availableListProperty.removeAll(selected);
         chosenListProperty.addAll(selected);
     }
 
     public void removeFromChosen() {
-        if (chosenSelectionModelProperty.isNull().getValue()) {
-            return;
-        }
-
         List<PreviewLayout> selected = new ArrayList<>(chosenSelectionModelProperty.getValue().getSelectedItems());
         chosenListProperty.removeAll(selected);
         availableListProperty.addAll(selected);
@@ -249,8 +240,7 @@ public void removeFromChosen() {
     }
 
     public void selectedInChosenUp() {
-        if (chosenSelectionModelProperty.isNull().getValue()
-                || chosenSelectionModelProperty.getValue().isEmpty()) {
+        if (chosenSelectionModelProperty.getValue().isEmpty()) {
             return;
         }
 
@@ -271,8 +261,7 @@ public void selectedInChosenUp() {
     }
 
     public void selectedInChosenDown() {
-        if (chosenSelectionModelProperty.isNull().getValue()
-                || chosenSelectionModelProperty.getValue().isEmpty()) {
+        if (chosenSelectionModelProperty.getValue().isEmpty()) {
             return;
         }
 
@@ -446,10 +435,9 @@ public boolean dragDroppedInChosenCell(PreviewLayout targetLayout, Dragboard dra
 
                 chosenListProperty.getValue().addAll(targetId, draggedSelectedLayouts);
 
-                if (chosenSelectionModelProperty.isNotNull().getValue()) {
-                    chosenSelectionModelProperty.getValue().clearSelection();
-                    draggedSelectedLayouts.forEach(layout -> chosenSelectionModelProperty.getValue().select(layout));
-                }
+                chosenSelectionModelProperty.getValue().clearSelection();
+                draggedSelectedLayouts.forEach(layout -> chosenSelectionModelProperty.getValue().select(layout));
+
                 success = true;
             }
         }

From 5b3f98398fc29c2ec60795a441f7012032371348 Mon Sep 17 00:00:00 2001
From: Carl Christian Snethlage <cc.snethlage@gmail.com>
Date: Wed, 17 Jul 2019 15:55:03 +0200
Subject: [PATCH 22/22] Refactor fxml and view

---
 .../java/org/jabref/gui/preferences/PreviewTab.fxml |  7 +------
 .../org/jabref/gui/preferences/PreviewTabView.java  | 13 ++++++-------
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
index 21f2a4bcf17..2a0477e9349 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTab.fxml
@@ -11,7 +11,6 @@
 <?import org.fxmisc.flowless.VirtualizedScrollPane?>
 <?import javafx.scene.control.TabPane?>
 <?import javafx.scene.control.Tab?>
-<?import javafx.scene.control.ScrollPane?>
 <?import javafx.scene.layout.AnchorPane?>
 
 <fx:root prefWidth="650.0" spacing="4.0" type="VBox" xmlns="http://javafx.com/javafx/8.0.212"
@@ -48,11 +47,7 @@
             <children>
                 <TabPane prefHeight="250.0" prefWidth="650.0" tabClosingPolicy="UNAVAILABLE">
                     <tabs>
-                        <Tab text="%Preview">
-                            <content>
-                                <ScrollPane fx:id="previewPane"/>
-                            </content>
-                        </Tab>
+                        <Tab text="%Preview" fx:id="previewTab" />
                         <Tab text="%Edit">
                             <content>
                                 <VirtualizedScrollPane>
diff --git a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
index 40a850647c1..c4b229187ce 100644
--- a/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
+++ b/src/main/java/org/jabref/gui/preferences/PreviewTabView.java
@@ -13,8 +13,8 @@
 import javafx.scene.control.ContextMenu;
 import javafx.scene.control.Label;
 import javafx.scene.control.ListView;
-import javafx.scene.control.ScrollPane;
 import javafx.scene.control.SelectionMode;
+import javafx.scene.control.Tab;
 import javafx.scene.input.DragEvent;
 import javafx.scene.input.Dragboard;
 import javafx.scene.input.KeyEvent;
@@ -56,7 +56,7 @@ public class PreviewTabView extends VBox implements PrefsTab {
     @FXML private Label readOnlyLabel;
     @FXML private Button resetDefaultButton;
 
-    @FXML private ScrollPane previewPane;
+    @FXML private Tab previewTab;
     @FXML private CodeArea editArea;
 
     private final ContextMenu contextMenu;
@@ -155,11 +155,10 @@ public void initialize() {
         sortUpButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
         sortDownButton.disableProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNull());
 
-        previewPane.setContent(new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager));
-        ((PreviewViewer) previewPane.getContent()).setEntry(TestEntry.getTestEntry());
-        EasyBind.subscribe(viewModel.layoutProperty(), value -> ((PreviewViewer) previewPane.getContent()).setLayout(value));
-        previewPane.visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
-        ((PreviewViewer) previewPane.getContent()).setMaxWidth(640.0);
+        previewTab.setContent(new PreviewViewer(new BibDatabaseContext(), dialogService, Globals.stateManager));
+        ((PreviewViewer) previewTab.getContent()).setEntry(TestEntry.getTestEntry());
+        EasyBind.subscribe(viewModel.layoutProperty(), value -> ((PreviewViewer) previewTab.getContent()).setLayout(value));
+        previewTab.getContent().visibleProperty().bind(viewModel.chosenSelectionModelProperty().getValue().selectedItemProperty().isNotNull());
 
         editArea.clear();
         editArea.setParagraphGraphicFactory(LineNumberFactory.get(editArea));