feat: update viewport meta element requirements

This commit implements the post-CR changes on the requirements for the
viewport meta element used to define the ICB in fixed-layout documents.

Viewport syntax:
- properties can now have several values
- the `ViewportMeta` object now return a list of string values when
  looking up values for a name.

ICB definition checks:
- only the first `viewport` `meta` element of fixed-layout documents
  is checked
- new `HTM-059` error is reported when `height` or `width` dimensions
  are specified more than once
- new `HTM-060a` usage is reported for any subsequent `viewport` `meta`
  element found in fixed-layout documents
- new `HTM-060b` usage is reported fo any `viewport` `meta` element
  found in reflowable documents

Fix #1401, Fix #1449

src/main/java/com/adobe/epubcheck/messages/DefaultSeverities.java

@@ -142,6 +142,9 @@ private void initialize()
     severities.put(MessageId.HTM_056, Severity.ERROR);
     severities.put(MessageId.HTM_057, Severity.ERROR);
     severities.put(MessageId.HTM_058, Severity.ERROR);
+    severities.put(MessageId.HTM_059, Severity.ERROR);
+    severities.put(MessageId.HTM_060a, Severity.USAGE);
+    severities.put(MessageId.HTM_060b, Severity.USAGE);
 
     // Media
     severities.put(MessageId.MED_001, Severity.SUPPRESSED);

src/main/java/com/adobe/epubcheck/messages/MessageId.java

@@ -136,6 +136,9 @@ public enum MessageId implements Comparable<MessageId>
   HTM_056("HTM_056"),
   HTM_057("HTM_057"),
   HTM_058("HTM_058"),
+  HTM_059("HTM_059"),
+  HTM_060a("HTM_060a"),
+  HTM_060b("HTM_060b"),
 
   // Messages associated with media (images, audio and video)
   MED_001("MED-001"),

src/main/java/com/adobe/epubcheck/ops/OPSHandler30.java

@@ -1,5 +1,6 @@
 package com.adobe.epubcheck.ops;
 
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashMap;
@@ -10,6 +11,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.stream.Collectors;
 
 import org.w3c.epubcheck.constants.MIMEType;
 import org.w3c.epubcheck.core.references.Reference;
@@ -763,17 +765,14 @@ protected void processMeta()
       String name = e.getAttribute("name");
       if ("viewport".equals(Strings.nullToEmpty(name).trim()))
       {
-        // Mark the viewport as seen
-        // (used when checking the existence of viewport metadata)
-        hasViewport = true;
-        // For a fixed-layout documents:
-        if (context.opfItem.isPresent() && context.opfItem.get().isFixedLayout())
+        String content = e.getAttribute("content");
+        // For fixed-layout documents, check the first viewport meta element
+        if (!hasViewport && context.opfItem.isPresent() && context.opfItem.get().isFixedLayout())
         {
-          String contentAttribute = e.getAttribute("content");
-
+          hasViewport = true;
           // parse viewport metadata
           List<ViewportMeta.ParseError> syntaxErrors = new LinkedList<>();
-          ViewportMeta viewport = ViewportMeta.parse(contentAttribute,
+          ViewportMeta viewport = ViewportMeta.parse(content,
               new ViewportMeta.ErrorHandler()
               {
                 @Override
@@ -785,31 +784,46 @@ public void error(ParseError error, int position)
           if (!syntaxErrors.isEmpty())
           {
             // report any syntax error
-            report.message(MessageId.HTM_047, location(), contentAttribute);
+            report.message(MessageId.HTM_047, location(), content);
           }
           else
           {
-            // check that viewport metadata has a valid width value
-            if (!viewport.hasProperty("width"))
-            {
-              report.message(MessageId.HTM_056, location(), "width");
-            }
-            else if (!ViewportMeta.isValidWidth(viewport.getValue("width")))
+            for (String property : Arrays.asList("width", "height"))
             {
-              report.message(MessageId.HTM_057, location(), "width");
+              // check that viewport metadata has a valid width value
+              if (!viewport.hasProperty(property))
+              {
+                report.message(MessageId.HTM_056, location(), property);
+              }
+              else
+              {
+                List<String> values = viewport.getValues(property);
+                if (values.size() > 1)
+                {
+                  report.message(MessageId.HTM_059, location(), property,
+                      values.stream().map(v -> '"' + v + '"').collect(Collectors.joining(", ")));
+                }
+                if (!ViewportMeta.isValidProperty(property, values.get(0)))
+                {
+                  report.message(MessageId.HTM_057, location(), property);
+                }
+              }
             }
 
-            // check that viewport metadata has a valid height value
-            if (!viewport.hasProperty("height"))
-            {
-              report.message(MessageId.HTM_056, location(), "height");
-            }
-            else if (!ViewportMeta.isValidHeight(viewport.getValue("height")))
-            {
-              report.message(MessageId.HTM_057, location(), "height");
-            }
           }
-
+        }
+        else
+        {
+          // Report ignored secondary viewport meta in fixed-layout documents
+          if (context.opfItem.isPresent() && context.opfItem.get().isFixedLayout())
+          {
+            report.message(MessageId.HTM_060a, location(), content);
+          }
+          // Report ignored viewport meta in reflowable documents
+          else
+          {
+            report.message(MessageId.HTM_060b, location(), content);
+          }
         }
       }
     }

src/main/java/org/w3c/epubcheck/util/microsyntax/ViewportMeta.java

@@ -3,11 +3,12 @@
 import static org.w3c.epubcheck.util.infra.InfraUtil.isASCIIWhitespace;
 
 import java.nio.CharBuffer;
-import java.util.Map;
+import java.util.List;
 import java.util.regex.Pattern;
 
 import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ListMultimap;
 
 public class ViewportMeta
 {
@@ -19,16 +20,18 @@ public static ViewportMeta parse(String string, ErrorHandler errorHandler)
     return new Parser(errorHandler).parse(string);
   }
 
-  public static boolean isValidHeight(String height)
+  public static boolean isValidProperty(String name, String value)
   {
-    Preconditions.checkArgument(height != null);
-    return VIEWPORT_HEIGHT_REGEX.matcher(height).matches();
-  }
-
-  public static boolean isValidWidth(String width)
-  {
-    Preconditions.checkArgument(width != null);
-    return VIEWPORT_WIDTH_REGEX.matcher(width).matches();
+    Preconditions.checkNotNull(value);
+    switch (Preconditions.checkNotNull(name))
+    {
+    case "width":
+      return VIEWPORT_WIDTH_REGEX.matcher(value).matches();
+    case "height":
+      return VIEWPORT_HEIGHT_REGEX.matcher(value).matches();
+    default:
+      return true;
+    }
   }
 
   public static enum ParseError
@@ -51,7 +54,8 @@ public interface ErrorHandler
 
   private final static class Builder
   {
-    public ImmutableMap.Builder<String, String> properties = ImmutableMap.builder();
+    public ImmutableListMultimap.Builder<String, String> properties = ImmutableListMultimap
+        .builder();
 
     public ViewportMeta build()
     {
@@ -123,40 +127,38 @@ public ViewportMeta parse(CharSequence string)
           }
           else if (c == '=' || isASCIIWhitespace(c))
           {
-            if (name.length() == 0)
-            {
-              error(ParseError.NAME_EMPTY, input.position());
-              return builder.build();
-            }
             state = State.ASSIGN;
             consume = false;
           }
           else if (c == ',' || c == ';')
           {
-            if (name.length() == 0)
-            {
-              error(ParseError.LEADING_SEPARATOR, input.position());
-            }
-            else
-            {
-              error(ParseError.VALUE_EMPTY, input.position());
-            }
-            return builder.build();
+            state = State.SEPARATOR;
+            consume = false;
           }
           else
           {
             name.append(c);
           }
           break;
         case ASSIGN:
-          if (isASCIIWhitespace(c))
+          if (name.length()==0) {
+            // assign state but no name was found
+            error(ParseError.NAME_EMPTY, input.position());
+            return builder.build();
+          }
+          else if (isASCIIWhitespace(c))
           {
             // skip whitespace
           }
           else if (c == '=')
           {
             state = State.VALUE;
           }
+          else if (c == ',' || c == ';')
+          {
+            state = State.SEPARATOR;
+            consume = false;
+          }
           else
           {
             // no '=' was matched (i.e. no value is set)
@@ -200,6 +202,11 @@ else if (c == '=')
             consume = false;
           }
         case SEPARATOR:
+          if (name.length() == 0)
+          {
+            error(ParseError.LEADING_SEPARATOR, input.position());
+            return builder.build();
+          }
           if (c == ',' || c == ';' || isASCIIWhitespace(c))
           {
             // skip repeating separators
@@ -215,13 +222,12 @@ else if (c == '=')
           break;
         }
       }
-      if (value.length() != 0)
-      {
-        builder.withProperty(name.toString(), value.toString());
-      }
-      else if (name.length() != 0)
+      // finalize, report if unexpected final state
+      if (state == State.VALUE && value.length() == 0)
       {
         error(ParseError.VALUE_EMPTY, input.position());
+      } else {
+        builder.withProperty(name.toString(), value.toString());
       }
       if (state == State.SEPARATOR)
       {
@@ -231,7 +237,7 @@ else if (name.length() != 0)
     }
   }
 
-  private final Map<String, String> properties;
+  private final ImmutableListMultimap<String, String> properties;
 
   private ViewportMeta(Builder builder)
   {
@@ -243,9 +249,14 @@ public boolean hasProperty(String name)
     return properties.containsKey(name);
   }
 
-  public String getValue(String name)
+  public List<String> getValues(String name)
   {
     return properties.get(name);
   }
 
+  public ListMultimap<String, String> asMultimap()
+  {
+    return properties;
+  }
+
 }

src/main/resources/com/adobe/epubcheck/messages/MessageBundle.properties

@@ -60,7 +60,10 @@ HTM_054=Custom attribute namespace ("%1$s") must not include the string "%2$s" i
 HTM_055=The "%1$s" element should not be used (discouraged construct)
 HTM_056=Viewport metadata has no "%1$s" dimension (both "width" and "height" properties are required)
 HTM_057=Viewport "%1$s" value must be a positive number or the keyword "device-%1$s"
-HTM_058=HTML documents must be encoded in UTF-8, but UTF-16 was detected. 
+HTM_058=HTML documents must be encoded in UTF-8, but UTF-16 was detected.
+HTM_059=Viewport "%1$s" property must not be defined more than once, but found values [%2$s].
+HTM_060a=EPUB reading systems must ignore secondary viewport meta elements in fixed-layout documents; viewport declaration "%1$s" will be ignored. 
+HTM_060b=EPUB reading systems must ignore viewport meta elements in reflowable documents; viewport declaration "%1$s" will be ignored.
 
 #media
 MED_003=Picture "img" elements must reference core media type resources, but found resource "%1$s" of type "%2$s".

src/test/java/org/w3c/epubcheck/util/microsyntax/ViewportSteps.java

@@ -2,6 +2,7 @@
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.is;
 
@@ -12,6 +13,7 @@
 import org.w3c.epubcheck.util.microsyntax.ViewportMeta.ParseError;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
 
 import io.cucumber.java.ParameterType;
 import io.cucumber.java.en.Then;
@@ -20,6 +22,8 @@
 public class ViewportSteps
 {
 
+  private ViewportMeta viewport;
+
   public static final class TestErrorHandler implements ErrorHandler
   {
     public final List<ParseError> errors = new LinkedList<>();
@@ -58,7 +62,7 @@ public ParseError error(String error)
   @When("parsing viewport {string}")
   public void parseViewport(String content)
   {
-    ViewportMeta.parse(content, handler);
+    viewport = ViewportMeta.parse(content, handler);
   }
 
   @Then("no error is returned")
@@ -67,6 +71,12 @@ public void assertValid()
     assertThat("Unexpected errors", handler.errors(), is(empty()));
   }
 
+  @Then("the parsed viewport equals {multimap}")
+  public void assertResult(ImmutableListMultimap<String, String> multimap)
+  {
+    assertThat(viewport.asMultimap(), is(equalTo(multimap)));
+  }
+
   @Then("error {error} is returned")
   public void assertError(ParseError error)
   {

src/test/resources/epub3/08-layout/files/content-fxl-xhtml-viewport-multiple-valid/EPUB/content_001.xhtml → src/test/resources/epub3/08-layout/files/content-fxl-xhtml-viewport-duplicate-width-height-error/EPUB/content_001.xhtml

@@ -2,8 +2,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 	<head>
 		<meta charset="utf-8"/>
-		<meta name="viewport" content="width=600,height=1200" />
-		<meta name="viewport" content="width=600,height=1200" />
+		<meta name="viewport" content="width=600,height=1200,width=device-width,height=device-height" />
 		<title>Minimal EPUB</title>
 	</head>
 	<body>

src/test/resources/epub3/08-layout/files/content-fxl-xhtml-viewport-height-empty-error/EPUB/content_001.xhtml

@@ -2,7 +2,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
 	<head>
 		<meta charset="utf-8" />
-		<meta name="viewport" content="width=600,height=" />
+		<meta name="viewport" content="width=600,height" />
 		<title>Minimal EPUB</title>
 	</head>
 	<body>

src/test/resources/epub3/08-layout/files/content-fxl-xhtml-viewport-icb-missing-in-first-meta-error/EPUB/content_001.xhtml

@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<meta name="viewport" content="inital-scale=1.0" />
+		<!-- ICB dimensions must be defined in the first viewport meta element -->
+		<meta name="viewport" content="width=600,height=600" />
+		<title>Minimal EPUB</title>
+	</head>
+	<body>
+		<h1>Loomings</h1>
+		<p>Call me Ishmael.</p>
+	</body>
+</html>

src/test/resources/epub3/08-layout/files/content-fxl-xhtml-viewport-icb-missing-in-first-meta-error/EPUB/nav.xhtml

@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xml:lang="en" lang="en">
+	<head>
+		<meta charset="utf-8"/>
+		<title>Minimal Nav</title>
+	</head>
+	<body>
+		<nav epub:type="toc">
+			<ol>
+				<li><a href="content_001.xhtml">content 001</a></li>
+			</ol>
+		</nav>
+	</body>
+</html>