Merge pull request #1 from SofieTorch/feature/metadata-shortcuts

add getters for epub title, authors and cover

lib/epub.dart

@@ -43,6 +43,33 @@ class Epub extends Equatable {
   late final Lazy<List<Item>> _items;
   late final Lazy<List<Section>> _sections;
 
+  String get title =>
+      metadata
+          .firstWhere(
+              (element) =>
+                  element is DublinCoreMetadata && element.key == 'title',
+              orElse: () => Metadata.empty)
+          .value ??
+      '';
+
+  List<String> get authors => metadata
+      .where((element) =>
+          element is DublinCoreMetadata && element.key == 'creator')
+      .map((element) => element.value ?? '')
+      .toList();
+
+  Item? get cover {
+    Item? result;
+    try {
+      result = items.firstWhere(
+        (element) => element.properties.contains(ItemProperty.coverImage),
+      );
+    } on StateError {
+      result = null;
+    }
+    return result;
+  }
+
   /// Path to the root file (usually 'content.opf') in the EPUB.
   ///
   /// Throws a [FormatException] if the container file or the root file path
@@ -128,7 +155,7 @@ class Epub extends Equatable {
         final mediaOverlay = itemsxml.descendantElements.firstWhere(
           (itemxml) => itemxml.getAttribute('id') == mediaOverlayId,
           orElse: () => throw UnimplementedError(
-              'Referenced media overlay not found or not declared.'),
+              'Media overlay with id $mediaOverlayId not found or not declared.'),
         );
         item = Item.fromXmlElement(
           element,

lib/models/item.dart

@@ -51,7 +51,9 @@ class Item extends Equatable {
   /// Media type of the represented file.
   final ItemMediaType mediaType;
 
-  /// Special uses for this item.
+  /// Indicators that this item has some special use case, such as cover image, svg, etc.
+  ///
+  /// See [ItemProperty] for all the available use cases.
   final List<ItemProperty> properties;
 
   /// Additional information for this item.

test/epub_test.dart

@@ -10,7 +10,8 @@ void main() {
   setUp(() {
     epub = Epub.fromFile(File('test/resources/demo.epub'));
 
-    final badFormattedEpubFile = File('test/resources/bad_formatted_demo.epub');
+    final badFormattedEpubFile =
+        File('test/resources/bad_formatted_demo01.epub');
     badFormattedEpub = Epub.fromBytes(badFormattedEpubFile.readAsBytesSync());
   });
 
@@ -89,4 +90,34 @@ void main() {
     epub.sections;
     expect(epub, isNot(equals(epub2)));
   });
+
+  test('''Epub.title returns EPUB title correctly''', () {
+    expect(epub.title, '[DEMO002] How To Create EPUB 3 Read Aloud eBooks');
+  });
+
+  test('''Epub.title returns empty when <dc:title> does not exist''', () {
+    expect(badFormattedEpub.title, '');
+  });
+
+  test('''Epub.authors returns EPUB authors correctly''', () {
+    expect(epub.authors, ['Alberto Pettarin']);
+  });
+
+  test('''Epub.cover returns expected Item''', () {
+    final cover = epub.cover;
+    expect(cover, isNotNull);
+    expect(cover!.id, 'cover.png');
+    expect(cover.href, 'Images/cover.png');
+    expect(cover.mediaType, ItemMediaType.png);
+    expect(cover.properties, [ItemProperty.coverImage]);
+  });
+
+  test('''Epub.cover returns null when no
+      Item with "cover-image" in its properties exist''', () {
+    final epubWithoutCover = Epub.fromFile(
+      File('test/resources/bad_formatted_demo02_no_cover.epub'),
+    );
+
+    expect(epubWithoutCover.cover, isNull);
+  });
 }

test/models/section_test.dart

@@ -93,7 +93,7 @@ void main() {
   test('''Section.audio throws exception
       when the referenced audio file is not found''', () {
     final badFormattedEpub = Epub.fromFile(
-      File('test/resources/bad_formatted_demo.epub'),
+      File('test/resources/bad_formatted_demo01.epub'),
     );
 
     final section = Section(