content: Handle clusters of images in parseImplicitParagraphBlockContentList

Fixes: #193

Author: sirpengi

lib/model/content.dart

@@ -1016,6 +1016,7 @@ class _ZulipContentParser {
     assert(_debugParserContext == _ParserContext.block);
     final List<BlockContentNode> result = [];
     final List<dom.Node> currentParagraph = [];
+    List<ImageNode> imageNodes = [];
     void consumeParagraph() {
       final parsed = parseBlockInline(currentParagraph);
       result.add(ParagraphNode(
@@ -1029,13 +1030,31 @@ class _ZulipContentParser {
       if (node is dom.Text && (node.text == '\n')) continue;
 
       if (_isPossibleInlineNode(node)) {
+        if (imageNodes.isNotEmpty) {
+          result.add(ImageNodeList(imageNodes));
+          imageNodes = [];
+          // In a context where paragraphs are implicit it should be impossible
+          // to have more paragraph content after image previews.
+          result.add(UnimplementedBlockContentNode(htmlNode: node));
+          continue;
+        }
         currentParagraph.add(node);
         continue;
       }
       if (currentParagraph.isNotEmpty) consumeParagraph();
-      result.add(parseBlockContent(node));
+      final block = parseBlockContent(node);
+      if (block is ImageNode) {
+        imageNodes.add(block);
+        continue;
+      }
+      if (imageNodes.isNotEmpty) {
+        result.add(ImageNodeList(imageNodes));
+        imageNodes = [];
+      }
+      result.add(block);
     }
     if (currentParagraph.isNotEmpty) consumeParagraph();
+    if (imageNodes.isNotEmpty) result.add(ImageNodeList(imageNodes));
 
     return result;
   }

lib/widgets/content.dart

@@ -87,6 +87,10 @@ class BlockContentList extends StatelessWidget {
         } else if (node is ImageNodeList) {
           return MessageImageList(node: node);
         } else if (node is ImageNode) {
+          assert(false,
+            "[ImageNode] not allowed in [BlockContentList]. "
+            "It should be wrapped in [ImageNodeList]."
+          );
           return MessageImage(node: node);
         } else if (node is UnimplementedBlockContentNode) {
           return Text.rich(_errorUnimplemented(node));

test/model/content_test.dart

@@ -365,6 +365,71 @@ class ContentExample {
       ImageNode(srcUrl: 'https://uploads.zulipusercontent.net/51b70540cf6a5b3c8a0b919c893b8abddd447e88/68747470733a2f2f656e2e77696b6970656469612e6f72672f7374617469632f696d616765732f69636f6e732f77696b6970656469612e706e673f763d33'),
     ]),
   ]);
+
+  static const imageInImplicitParagraph = ContentExample(
+    'image as immediate child in implicit paragraph',
+    "* https://chat.zulip.org/user_avatars/2/realm/icon.png",
+    '<ul>\n'
+      '<li>'
+        '<div class="message_inline_image">'
+          '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png">'
+            '<img src="https://chat.zulip.org/user_avatars/2/realm/icon.png"></a></div></li>\n</ul>', [
+    ListNode(ListStyle.unordered, [[
+      ImageNodeList([
+        ImageNode(srcUrl: 'https://chat.zulip.org/user_avatars/2/realm/icon.png'),
+      ]),
+    ]]),
+  ]);
+
+  static const imageClusterInImplicitParagraph = ContentExample(
+    'image cluster in implicit paragraph',
+    "* [icon.png](https://chat.zulip.org/user_avatars/2/realm/icon.png) [icon.png](https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2)",
+    '<ul>\n'
+      '<li>'
+        '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png">icon.png</a> '
+        '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2">icon.png</a>'
+        '<div class="message_inline_image">'
+          '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png" title="icon.png">'
+            '<img src="https://chat.zulip.org/user_avatars/2/realm/icon.png"></a></div>'
+        '<div class="message_inline_image">'
+          '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2" title="icon.png">'
+            '<img src="https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2"></a></div></li>\n</ul>', [
+    ListNode(ListStyle.unordered, [[
+      ParagraphNode(wasImplicit: true, links: null, nodes: [
+        LinkNode(url: 'https://chat.zulip.org/user_avatars/2/realm/icon.png', nodes: [TextNode('icon.png')]),
+        TextNode(' '),
+        LinkNode(url: 'https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2', nodes: [TextNode('icon.png')]),
+      ]),
+      ImageNodeList([
+        ImageNode(srcUrl: 'https://chat.zulip.org/user_avatars/2/realm/icon.png'),
+        ImageNode(srcUrl: 'https://chat.zulip.org/user_avatars/2/realm/icon.png?version=2'),
+      ]),
+    ]]),
+  ]);
+
+  static final imageClusterInImplicitParagraphThenContent = ContentExample(
+    'impossible content after image cluster in implicit paragraph',
+    // Image previews are always inserted at the end of the paragraph
+    //  so it would be impossible to have content after.
+    null,
+    '<ul>\n'
+      '<li>'
+        '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png">icon.png</a> '
+        '<div class="message_inline_image">'
+          '<a href="https://chat.zulip.org/user_avatars/2/realm/icon.png" title="icon.png">'
+            '<img src="https://chat.zulip.org/user_avatars/2/realm/icon.png"></a></div>'
+        'more text</li>\n</ul>', [
+    ListNode(ListStyle.unordered, [[
+      const ParagraphNode(wasImplicit: true, links: null, nodes: [
+        LinkNode(url: 'https://chat.zulip.org/user_avatars/2/realm/icon.png', nodes: [TextNode('icon.png')]),
+        TextNode(' '),
+      ]),
+      const ImageNodeList([
+        ImageNode(srcUrl: 'https://chat.zulip.org/user_avatars/2/realm/icon.png'),
+      ]),
+      blockUnimplemented('more text'),
+    ]]),
+  ]);
 }
 
 UnimplementedBlockContentNode blockUnimplemented(String html) {
@@ -689,6 +754,9 @@ void main() {
   testParseExample(ContentExample.imageCluster);
   testParseExample(ContentExample.imageClusterThenContent);
   testParseExample(ContentExample.imageMultipleClusters);
+  testParseExample(ContentExample.imageInImplicitParagraph);
+  testParseExample(ContentExample.imageClusterInImplicitParagraph);
+  testParseExample(ContentExample.imageClusterInImplicitParagraphThenContent);
 
   testParse('parse nested lists, quotes, headings, code blocks',
     // "1. > ###### two\n   > * three\n\n      four"

test/widgets/content_test.dart

@@ -321,6 +321,28 @@ void main() {
       check(images.map((i) => i.src.toString()).toList())
         .deepEquals(expectedImages.map((n) => n.srcUrl));
     });
+
+    testWidgets('image as immediate child in implicit paragraph', (tester) async {
+      const example = ContentExample.imageInImplicitParagraph;
+      await prepareContent(tester, example.html);
+      final expectedImages = ((example.expectedNodes[0] as ListNode)
+        .items[0][0] as ImageNodeList).images;
+      final images = tester.widgetList<RealmContentNetworkImage>(
+        find.byType(RealmContentNetworkImage));
+      check(images.map((i) => i.src.toString()).toList())
+        .deepEquals(expectedImages.map((n) => n.srcUrl));
+    });
+
+    testWidgets('image cluster in implicit paragraph', (tester) async {
+      const example = ContentExample.imageClusterInImplicitParagraph;
+      await prepareContent(tester, example.html);
+      final expectedImages = ((example.expectedNodes[0] as ListNode)
+        .items[0][1] as ImageNodeList).images;
+      final images = tester.widgetList<RealmContentNetworkImage>(
+        find.byType(RealmContentNetworkImage));
+      check(images.map((i) => i.src.toString()).toList())
+        .deepEquals(expectedImages.map((n) => n.srcUrl));
+    });
   });
 
   group('RealmContentNetworkImage', () {