Java importOrder support for sorting wildcards last

Adds support for sorting wildcards after non-wildcards in the import list. Gradle config like so:

```
importOrder('java', 'javax', 'com.acme', '').wildcardsLast()
```

Not implemented here: Maven plugin support

Fixes diffplug#879.

lib/src/main/java/com/diffplug/spotless/java/ImportOrderStep.java

@@ -51,20 +51,28 @@ private ImportOrderStep(String lineFormat) {
 	}
 
 	public FormatterStep createFrom(String... importOrder) {
+		return createFrom(false, importOrder);
+	}
+
+	public FormatterStep createFrom(boolean wildcardsLast, String... importOrder) {
 		// defensive copying and null checking
 		List<String> importOrderList = requireElementsNonNull(Arrays.asList(importOrder));
-		return createFrom(() -> importOrderList);
+		return createFrom(wildcardsLast, () -> importOrderList);
 	}
 
 	public FormatterStep createFrom(File importsFile) {
+		return createFrom(false, importsFile);
+	}
+
+	public FormatterStep createFrom(boolean wildcardsLast, File importsFile) {
 		Objects.requireNonNull(importsFile);
-		return createFrom(() -> getImportOrder(importsFile));
+		return createFrom(wildcardsLast, () -> getImportOrder(importsFile));
 	}
 
-	private FormatterStep createFrom(Supplier<List<String>> importOrder) {
+	private FormatterStep createFrom(boolean wildcardsLast, Supplier<List<String>> importOrder) {
 		return FormatterStep.createLazy("importOrder",
-				() -> new State(importOrder.get(), lineFormat),
-				State::toFormatter);
+			() -> new State(importOrder.get(), lineFormat, wildcardsLast),
+			State::toFormatter);
 	}
 
 	private static List<String> getImportOrder(File importsFile) {
@@ -92,14 +100,16 @@ private static final class State implements Serializable {
 
 		private final List<String> importOrder;
 		private final String lineFormat;
+		private final boolean wildcardsLast;
 
-		State(List<String> importOrder, String lineFormat) {
+		State(List<String> importOrder, String lineFormat, boolean wildcardsLast) {
 			this.importOrder = importOrder;
 			this.lineFormat = lineFormat;
+			this.wildcardsLast = wildcardsLast;
 		}
 
 		FormatterFunc toFormatter() {
-			return raw -> new ImportSorter(importOrder).format(raw, lineFormat);
+			return raw -> new ImportSorter(importOrder, wildcardsLast).format(raw, lineFormat);
 		}
 	}
 }

lib/src/main/java/com/diffplug/spotless/java/ImportSorter.java

@@ -29,9 +29,11 @@ final class ImportSorter {
 	static final String N = "\n";
 
 	private final List<String> importsOrder;
+	private final boolean wildcardsLast;
 
-	ImportSorter(List<String> importsOrder) {
+	ImportSorter(List<String> importsOrder, boolean wildcardsLast) {
 		this.importsOrder = new ArrayList<>(importsOrder);
+		this.wildcardsLast = wildcardsLast;
 	}
 
 	String format(String raw, String lineFormat) {
@@ -79,7 +81,7 @@ String format(String raw, String lineFormat) {
 		}
 		scanner.close();
 
-		List<String> sortedImports = ImportSorterImpl.sort(imports, importsOrder, lineFormat);
+		List<String> sortedImports = ImportSorterImpl.sort(imports, importsOrder, wildcardsLast, lineFormat);
 		return applyImportsToDocument(raw, firstImportLine, lastImportLine, sortedImports);
 	}
 

lib/src/main/java/com/diffplug/spotless/java/ImportSorterImpl.java

@@ -15,13 +15,7 @@
  */
 package com.diffplug.spotless.java;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 import javax.annotation.Nullable;
 
@@ -34,9 +28,10 @@ final class ImportSorterImpl {
 	private final Map<String, List<String>> matchingImports = new HashMap<>();
 	private final List<String> notMatching = new ArrayList<>();
 	private final Set<String> allImportOrderItems = new HashSet<>();
+	private final Comparator<String> ordering;
 
-	static List<String> sort(List<String> imports, List<String> importsOrder, String lineFormat) {
-		ImportSorterImpl importsSorter = new ImportSorterImpl(importsOrder);
+	static List<String> sort(List<String> imports, List<String> importsOrder, boolean wildcardsLast, String lineFormat) {
+		ImportSorterImpl importsSorter = new ImportSorterImpl(importsOrder, wildcardsLast);
 		return importsSorter.sort(imports, lineFormat);
 	}
 
@@ -49,11 +44,12 @@ private List<String> sort(List<String> imports, String lineFormat) {
 		return getResult(lineFormat);
 	}
 
-	private ImportSorterImpl(List<String> importOrder) {
+	private ImportSorterImpl(List<String> importOrder, boolean wildcardsLast) {
 		List<String> importOrderCopy = new ArrayList<>(importOrder);
 		normalizeStaticOrderItems(importOrderCopy);
 		putStaticItemIfNotExists(importOrderCopy);
 		template.addAll(importOrderCopy);
+		ordering = new OrderingComparator(wildcardsLast);
 		this.allImportOrderItems.addAll(importOrderCopy);
 	}
 
@@ -119,7 +115,7 @@ private void filterMatchingImports(List<String> imports) {
 	 * not matching means it does not match any order item, so it will be appended before or after order items
 	 */
 	private void mergeNotMatchingItems(boolean staticItems) {
-		Collections.sort(notMatching);
+		sort(notMatching);
 
 		int firstIndexOfOrderItem = getFirstIndexOfOrderItem(notMatching, staticItems);
 		int indexOfOrderItem = 0;
@@ -192,7 +188,7 @@ private void mergeMatchingItems() {
 					continue;
 				}
 				List<String> matchingItems = new ArrayList<>(strings);
-				Collections.sort(matchingItems);
+				sort(matchingItems);
 
 				// replace order item by matching import statements
 				// this is a mess and it is only a luck that it works :-]
@@ -218,6 +214,10 @@ private void mergeMatchingItems() {
 		}
 	}
 
+	private void sort(List<String> items) {
+		items.sort(ordering);
+	}
+
 	private List<String> getResult(String lineFormat) {
 		List<String> strings = new ArrayList<>();
 
@@ -256,4 +256,28 @@ private List<String> getResult(String lineFormat) {
 		return null;
 	}
 
+	private static class OrderingComparator implements Comparator<String> {
+		private final boolean wildcardsLast;
+
+		private OrderingComparator(boolean wildcardsLast) {
+			this.wildcardsLast = wildcardsLast;
+		}
+
+		@Override
+		public int compare(String string1, String string2) {
+			int string1WildcardIndex = string1.indexOf('*');
+			int string2WildcardIndex = string2.indexOf('*');
+			boolean string1IsWildcard = string1WildcardIndex >= 0;
+			boolean string2IsWildcard = string2WildcardIndex >= 0;
+			if (string1IsWildcard == string2IsWildcard) {
+				return string1.compareTo(string2);
+			}
+			int prefixLength = string1IsWildcard ? string1WildcardIndex : string2WildcardIndex;
+			boolean samePrefix = string1.regionMatches(0, string2, 0, prefixLength);
+			if (!samePrefix) {
+				return string1.compareTo(string2);
+			}
+			return (string1IsWildcard == wildcardsLast) ? 1 : -1;
+		}
+	}
 }

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/JavaExtension.java

@@ -17,6 +17,7 @@
 
 import static com.diffplug.gradle.spotless.PluginGradlePreconditions.requireElementsNonNull;
 
+import java.io.File;
 import java.util.Objects;
 
 import javax.inject.Inject;
@@ -57,13 +58,47 @@ public LicenseHeaderConfig licenseHeaderFile(Object licenseHeaderFile) {
 		return licenseHeaderFile(licenseHeaderFile, LICENSE_HEADER_DELIMITER);
 	}
 
-	public void importOrder(String... importOrder) {
-		addStep(ImportOrderStep.forJava().createFrom(importOrder));
+	public ImportOrderConfig importOrder(String... importOrder) {
+		return new ImportOrderConfig(importOrder);
 	}
 
-	public void importOrderFile(Object importOrderFile) {
+	public ImportOrderConfig importOrderFile(Object importOrderFile) {
 		Objects.requireNonNull(importOrderFile);
-		addStep(ImportOrderStep.forJava().createFrom(getProject().file(importOrderFile)));
+		return new ImportOrderConfig(getProject().file(importOrderFile));
+	}
+
+	public class ImportOrderConfig {
+		final String[] importOrder;
+		final File importOrderFile;
+
+		boolean wildcardsLast = false;
+
+		ImportOrderConfig(String[] importOrder) {
+			this.importOrder = importOrder;
+			importOrderFile = null;
+			addStep(createStep());
+		}
+
+		ImportOrderConfig(File importOrderFile) {
+			importOrder = null;
+			this.importOrderFile = importOrderFile;
+			addStep(createStep());
+		}
+
+		/** Sorts wildcard imports after non-wildcard imports, instead of before. */
+		public ImportOrderConfig wildcardsLast() {
+			wildcardsLast = true;
+			replaceStep(createStep());
+			return this;
+		}
+
+		private FormatterStep createStep() {
+			ImportOrderStep importOrderStep = ImportOrderStep.forJava();
+
+			return importOrderFile != null
+				? importOrderStep.createFrom(wildcardsLast, getProject().file(importOrderFile))
+				: importOrderStep.createFrom(wildcardsLast, importOrder);
+		}
 	}
 
 	/** Removes any unused imports. */

testlib/src/main/resources/java/importsorter/JavaCodeImportComments.test

@@ -7,8 +7,14 @@ import java.lang.Runnable;
 import org.comments.be
 import org.comments.removed
 */
-import static java.lang.Runnable.*; 
+import static java.lang.Runnable.*;
 /*
 import other.multiline.comments
-import will.be.removed.too */ 
+import will.be.removed.too */
 import static com.foo.Bar
+import java.awt.*;
+import java.util.*;
+import java.util.List;
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
+import static org.hamcrest.Matchers.*;

testlib/src/main/resources/java/importsorter/JavaCodeSortedImports.test

@@ -1,9 +1,15 @@
+import java.awt.*;
 import java.lang.Runnable;
 import java.lang.Thread;
+import java.util.*;
+import java.util.List;
 
 import org.dooda.Didoo;
 
 import static java.lang.Exception.*;
 import static java.lang.Runnable.*;
+import static org.hamcrest.Matchers.*;
 
 import static com.foo.Bar;
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;

testlib/src/main/resources/java/importsorter/JavaCodeSortedImportsDefault.test

@@ -1,7 +1,13 @@
 import static com.foo.Bar;
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
 import static java.lang.Exception.*;
 import static java.lang.Runnable.*;
+import static org.hamcrest.Matchers.*;
 
+import java.awt.*;
 import java.lang.Runnable;
 import java.lang.Thread;
+import java.util.*;
+import java.util.List;
 import org.dooda.Didoo;

testlib/src/main/resources/java/importsorter/JavaCodeSortedImportsWildcardsLast.test

@@ -0,0 +1,13 @@
+import static com.foo.Bar;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
+import static java.lang.Exception.*;
+import static java.lang.Runnable.*;
+import static org.hamcrest.Matchers.*;
+
+import java.awt.*;
+import java.lang.Runnable;
+import java.lang.Thread;
+import java.util.List;
+import java.util.*;
+import org.dooda.Didoo;

testlib/src/main/resources/java/importsorter/JavaCodeUnsortedImports.test

@@ -1,7 +1,13 @@
 import static java.lang.Exception.*;
+import static com.github.tomakehurst.wiremock.client.WireMock.*;
 import org.dooda.Didoo;
+import java.util.List;
 import java.lang.Thread;
+import java.util.*;
 import java.lang.Runnable;
+import static org.hamcrest.Matchers.*;
 
 import static java.lang.Runnable.*;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
 import static com.foo.Bar
+import java.awt.*;

testlib/src/test/java/com/diffplug/spotless/java/ImportOrderStepTest.java

@@ -46,6 +46,12 @@ void sortImportsUnmatched() throws Throwable {
 		assertOnResources(step, "java/importsorter/JavaCodeUnsortedImportsUnmatched.test", "java/importsorter/JavaCodeSortedImportsUnmatched.test");
 	}
 
+	@Test
+	void sortImportsWildcardsLast() throws Throwable {
+		FormatterStep step = ImportOrderStep.forJava().createFrom(true);
+		assertOnResources(step, "java/importsorter/JavaCodeUnsortedImports.test", "java/importsorter/JavaCodeSortedImportsWildcardsLast.test");
+	}
+
 	@Test
 	void removeDuplicates() throws Throwable {
 		FormatterStep step = ImportOrderStep.forJava().createFrom(createTestFile("java/importsorter/import_unmatched.properties"));