feat: check references between Media Overlays and Content documents

Add the following new errors:
- Error MED-010 when an item is missing a media-overlay attribute
- Error MED-011 when the media-overlay attribute references the wrong
  overlay
- Error MED-012 when the media-overlay attribute references an overlay
  that does not reference the underlying content document
- Error MED-013 when a content doc is referenced from multiple overlays

Also Add tests for the new errors.

Implementation note:
- pull the unique references from the text elements while parsing
  the overlay documents
- then run checks on the affected content documents in the post-processing
  function.

Author: mattgarrish

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

@@ -146,6 +146,10 @@ private void initialize()
     severities.put(MessageId.MED_007, Severity.ERROR);
     severities.put(MessageId.MED_008, Severity.ERROR);
     severities.put(MessageId.MED_009, Severity.ERROR);
+    severities.put(MessageId.MED_010, Severity.ERROR);
+    severities.put(MessageId.MED_011, Severity.ERROR);
+    severities.put(MessageId.MED_012, Severity.ERROR);
+    severities.put(MessageId.MED_013, Severity.ERROR);
 
     // NAV
     severities.put(MessageId.NAV_001, Severity.ERROR);

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

@@ -140,6 +140,10 @@ public enum MessageId implements Comparable<MessageId>
   MED_007("MED_007"),
   MED_008("MED-008"),
   MED_009("MED-009"),
+  MED_010("MED_010"),
+  MED_011("MED_011"),
+  MED_012("MED_012"),
+  MED_013("MED_013"),
 
   // Epub3 based table of content errors
   NAV_001("NAV-001"),

src/main/java/com/adobe/epubcheck/opf/OPFChecker.java

@@ -43,6 +43,7 @@
 import com.adobe.epubcheck.ocf.OCFPackage;
 import com.adobe.epubcheck.opf.ValidationContext.ValidationContextBuilder;
 import com.adobe.epubcheck.ops.OPSCheckerFactory;
+import com.adobe.epubcheck.overlay.OverlayTextChecker;
 import com.adobe.epubcheck.util.EPUBVersion;
 import com.adobe.epubcheck.util.FeatureEnum;
 import com.adobe.epubcheck.util.PathUtil;
@@ -114,6 +115,7 @@ public OPFChecker(ValidationContext context)
       newContext.pubTypes(opfData != null ? opfData.getTypes() : null);
       newContext.xrefChecker(new XRefChecker(context.ocf.get(), context.report, context.version));
       newContext.profile(EPUBProfile.makeOPFCompatible(context.profile, opfData, path, report));
+      newContext.overlayTextChecker(new OverlayTextChecker());
     }
     this.context = newContext.build();
 

src/main/java/com/adobe/epubcheck/opf/OPFChecker30.java

@@ -40,6 +40,7 @@
 import com.adobe.epubcheck.opf.ResourceCollection.Roles;
 import com.adobe.epubcheck.ops.OPSCheckerFactory;
 import com.adobe.epubcheck.overlay.OverlayCheckerFactory;
+import com.adobe.epubcheck.overlay.OverlayTextChecker;
 import com.adobe.epubcheck.util.EPUBVersion;
 import com.adobe.epubcheck.util.FeatureEnum;
 import com.adobe.epubcheck.util.PathUtil;
@@ -182,6 +183,29 @@ else if (xrefChecker.getTypes(item.getPath()).isEmpty())
         }
       }
     }
+    
+    if (isBlessedItemType(mediatype, version)) {
+      // check whether media-overlay attribute needs to be specified
+      OverlayTextChecker overlayTextChecker = context.overlayTextChecker.get();
+      String mo = item.getMediaOverlay();
+      String docpath = item.getPath();
+      if (overlayTextChecker.isReferencedByOverlay(docpath)) {
+        if (Strings.isNullOrEmpty(mo)) {
+          // missing media-overlay attribute
+          report.message(MessageId.MED_010, EPUBLocation.create(path, item.getLineNumber(), item.getColumnNumber(), item.getPath()));
+        }
+        else if (!overlayTextChecker.isCorrectOverlay(docpath,mo)) {
+          // media-overlay attribute references the wrong media overlay
+          report.message(MessageId.MED_012, EPUBLocation.create(path, item.getLineNumber(), item.getColumnNumber(), item.getPath()));
+        }
+      }
+      else {
+        if (!Strings.isNullOrEmpty(mo)) {
+          // referenced overlay does not reference this content document
+          report.message(MessageId.MED_013, EPUBLocation.create(path, item.getLineNumber(), item.getColumnNumber(), item.getPath()));
+        }
+      }
+    }
   }
 
   @Override

src/main/java/com/adobe/epubcheck/opf/OPFHandler.java

@@ -314,6 +314,9 @@ else if (name.equals("item"))
           itemBuilders.put(id.trim(), itemBuilder);
           itemBuildersByPath.put(href, itemBuilder);
 
+          String mediaOverlay = e.getAttribute("media-overlay");
+          itemBuilder.mediaOverlay(mediaOverlay);
+
           report.info(href, FeatureEnum.UNIQUE_IDENT, id);
         }
       }

src/main/java/com/adobe/epubcheck/opf/OPFItem.java

@@ -54,10 +54,11 @@ public class OPFItem
   private final boolean scripted;
   private final boolean linear;
   private final boolean fixedLayout;
+  private final String mediaOverlay;
 
   private OPFItem(String id, String path, String mimetype, int lineNumber, int columnNumber,
       Optional<String> fallback, Optional<String> fallbackStyle, Set<Property> properties,
-      boolean ncx, int spinePosition, boolean nav, boolean scripted, boolean linear, boolean fxl)
+      boolean ncx, int spinePosition, boolean nav, boolean scripted, boolean linear, boolean fxl, String mediaOverlay)
   {
     this.id = id;
     this.path = path;
@@ -74,6 +75,7 @@ private OPFItem(String id, String path, String mimetype, int lineNumber, int col
     this.scripted = scripted;
     this.linear = linear;
     this.fixedLayout = fxl;
+    this.mediaOverlay = mediaOverlay;
   }
 
   /**
@@ -240,6 +242,11 @@ public boolean isFixedLayout()
     return fixedLayout;
   }
 
+  public String getMediaOverlay()
+  {
+    return mediaOverlay;
+  }
+
   @Override
   public String toString()
   {
@@ -293,6 +300,7 @@ public static final class Builder
     private boolean linear = true;
     private int spinePosition = -1;
     private boolean fxl = false;
+    private String mediaOverlay;
     private ImmutableSet.Builder<Property> propertiesBuilder = new ImmutableSet.Builder<Property>();
 
     /**
@@ -339,6 +347,12 @@ public Builder fixedLayout()
 
     }
 
+    public Builder mediaOverlay(String path)
+    {
+      this.mediaOverlay = path;
+      return this;
+    }
+
     public Builder ncx()
     {
       this.ncx = true;
@@ -388,7 +402,7 @@ public OPFItem build()
           properties, ncx, spinePosition,
           properties.contains(PackageVocabs.ITEM_VOCAB.get(PackageVocabs.ITEM_PROPERTIES.NAV)),
           properties.contains(PackageVocabs.ITEM_VOCAB.get(PackageVocabs.ITEM_PROPERTIES.SCRIPTED)),
-          linear, fxl);
+          linear, fxl, mediaOverlay);
     }
   }
 }

src/main/java/com/adobe/epubcheck/opf/ValidationContext.java

@@ -10,6 +10,7 @@
 import com.adobe.epubcheck.api.LocalizableReport;
 import com.adobe.epubcheck.api.Report;
 import com.adobe.epubcheck.ocf.OCFPackage;
+import com.adobe.epubcheck.overlay.OverlayTextChecker;
 import com.adobe.epubcheck.util.EPUBVersion;
 import com.adobe.epubcheck.util.GenericResourceProvider;
 import com.adobe.epubcheck.vocab.Property;
@@ -77,6 +78,10 @@ public final class ValidationContext
    * The cross-reference checker, absent for single-file validation.
    */
   public final Optional<XRefChecker> xrefChecker;
+  /**
+   * The src checker for media overlay text elements, absent for single-file validation
+   */
+  public final Optional<OverlayTextChecker> overlayTextChecker;
   /**
    * The set of 'dc:type' values declared at the OPF level. Guaranteed non-null,
    * can be empty.
@@ -90,7 +95,7 @@ public final class ValidationContext
   private ValidationContext(String path, String mimeType, EPUBVersion version, EPUBProfile profile,
       Report report, Locale locale, FeatureReport featureReport,
       GenericResourceProvider resourceProvider, Optional<OPFItem> opfItem, Optional<OCFPackage> ocf,
-      Optional<XRefChecker> xrefChecker, Set<String> pubTypes, Set<Property> properties)
+      Optional<XRefChecker> xrefChecker, Optional<OverlayTextChecker> overlayTextChecker, Set<String> pubTypes, Set<Property> properties)
   {
     super();
     this.path = path;
@@ -104,6 +109,7 @@ private ValidationContext(String path, String mimeType, EPUBVersion version, EPU
     this.opfItem = opfItem;
     this.ocf = ocf;
     this.xrefChecker = xrefChecker;
+    this.overlayTextChecker = overlayTextChecker;
     this.pubTypes = pubTypes;
     this.properties = properties;
   }
@@ -125,6 +131,7 @@ public static final class ValidationContextBuilder
     private GenericResourceProvider resourceProvider = null;
     private OCFPackage ocf = null;
     private XRefChecker xrefChecker = null;
+    private OverlayTextChecker overlayTextChecker = null;
     private Set<String> pubTypes = null;
     private ImmutableSet.Builder<Property> properties = ImmutableSet.<Property> builder();
 
@@ -148,6 +155,7 @@ public ValidationContextBuilder copy(ValidationContext context)
       resourceProvider = context.resourceProvider;
       ocf = context.ocf.orNull();
       xrefChecker = context.xrefChecker.orNull();
+      overlayTextChecker = context.overlayTextChecker.orNull();
       pubTypes = context.pubTypes;
       properties = ImmutableSet.<Property> builder().addAll(context.properties);
       return this;
@@ -207,6 +215,12 @@ public ValidationContextBuilder xrefChecker(XRefChecker xrefChecker)
       return this;
     }
 
+    public ValidationContextBuilder overlayTextChecker(OverlayTextChecker overlayTextChecker)
+    {
+      this.overlayTextChecker = overlayTextChecker;
+      return this;
+    }
+
     public ValidationContextBuilder pubTypes(Set<String> pubTypes)
     {
       this.pubTypes = pubTypes;
@@ -243,7 +257,7 @@ public ValidationContext build()
           profile != null ? profile : EPUBProfile.DEFAULT, report, locale,
           featureReport != null ? featureReport : new FeatureReport(), resourceProvider,
           (xrefChecker != null) ? xrefChecker.getResource(path) : Optional.<OPFItem> absent(),
-          Optional.fromNullable(ocf), Optional.fromNullable(xrefChecker),
+          Optional.fromNullable(ocf), Optional.fromNullable(xrefChecker), Optional.fromNullable(overlayTextChecker),
           pubTypes != null ? ImmutableSet.copyOf(pubTypes) : ImmutableSet.<String> of(),
           properties.build());
     }

src/main/java/com/adobe/epubcheck/overlay/OverlayHandler.java

@@ -1,5 +1,6 @@
 package com.adobe.epubcheck.overlay;
 
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
@@ -20,6 +21,7 @@
 import com.adobe.epubcheck.xml.XMLElement;
 import com.adobe.epubcheck.xml.XMLHandler;
 import com.adobe.epubcheck.xml.XMLParser;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 
@@ -40,6 +42,8 @@ public class OverlayHandler implements XMLHandler
 
   private Map<String, Vocab> vocabs = RESERVED_VOCABS;
 
+  private Set<String> resourceRefs = new HashSet<String>();
+
   public OverlayHandler(ValidationContext context, XMLParser parser)
   {
     this.context = context;
@@ -158,6 +162,14 @@ private void processRef(String ref, XRefChecker.Type type)
           report.message(MessageId.MED_005, EPUBLocation.create(path, parser.getLineNumber(), parser.getColumnNumber()), ref, mimeType);
         }
       }
+      else {
+        String uniqueResource = PathUtil.removeFragment(ref);
+        if (!Strings.isNullOrEmpty(uniqueResource)) {
+          if (!context.overlayTextChecker.get().add(uniqueResource, context.opfItem.get().getId())) {
+              report.message(MessageId.MED_011, EPUBLocation.create(path, parser.getLineNumber(), parser.getColumnNumber()), ref);
+          }
+        }
+      }
       context.xrefChecker.get().registerReference(path, parser.getLineNumber(),
           parser.getColumnNumber(), ref, type);
     }
@@ -176,6 +188,12 @@ public void characters(char[] chars, int arg1, int arg2)
 
   public void endElement()
   {
+	XMLElement e = parser.getCurrentElement();
+	String name = e.getName();
+    if (name.equals("smil"))
+    {
+      checkItemReferences();
+    }
   }
 
   public void ignorableWhitespace(char[] chars, int arg1, int arg2)
@@ -185,4 +203,13 @@ public void ignorableWhitespace(char[] chars, int arg1, int arg2)
   public void processingInstruction(String arg0, String arg1)
   {
   }
+  
+  private void checkItemReferences() {
+
+    if(this.resourceRefs.isEmpty()) {
+    	return;
+    }
+    
+  }
+
 }

src/main/java/com/adobe/epubcheck/overlay/OverlayTextChecker.java

@@ -0,0 +1,35 @@
+package com.adobe.epubcheck.overlay;
+
+import java.util.Map;
+import java.util.HashMap;
+
+public class OverlayTextChecker {
+
+	private Map<String,String> refs;
+	
+    public OverlayTextChecker() {
+    	refs = new HashMap<String,String>();
+    }
+
+    public boolean add(String ref, String overlay) {
+      if (!refs.containsKey(ref)) {
+        refs.put(ref, overlay);
+        return true;
+      }
+      else if (!refs.get(ref).equalsIgnoreCase(overlay)) {
+        return false;
+      }
+      return true;
+    }
+	
+	public boolean isReferencedByOverlay(String path) {
+      if (path == null || path.equals("")) {
+        return false;
+      }
+      return refs.containsKey(path) ? true : false;
+    }
+	
+	public boolean isCorrectOverlay(String path, String overlay) {
+      return overlay.equalsIgnoreCase(refs.get(path)) ? true : false;
+    }
+}

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

@@ -133,6 +133,10 @@ MED_006=Some browsers do not support rendering SVG images which use a filename i
 MED_007=Foreign resources can only be referenced from "source" elements with an explicit "type" attribute; found resource "%1$s" of foreign type "%2$s".
 MED_008=The time specified in the clipBegin attribute must not be after clipEnd.
 MED_009=The time specified in the clipBegin attribute must not be the same as clipEnd.
+MED_010=EPUB Content Documents referenced from a Media Overlay must specify the "media-overlay" attribute.
+MED_011=EPUB Content Document referenced from multiple Media Overlay Documents.
+MED_012=The "media-overlay" attribute does not match the ID of the Media Overlay that refers to this document.
+MED_013=Media Overlay Document referenced from the "media-overlay" attribute does not contain a reference to this Content Document.
 
 #NAV EPUB v3 Table of contents
 NAV_001=The nav file is not supported for EPUB v2.