markdown support for talk messages

lib/view/pages/talk/widgets/answer_reference.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import '../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../api/marianumcloud/talk/chat/rich_object_string_processor.dart';
 import '../data/chat_bubble_styles.dart';
+import '../data/talk_markdown.dart';
 
 class AnswerReference extends StatelessWidget {
   final GetChatResponseObject referenceMessage;
@@ -43,10 +44,15 @@ class AnswerReference extends StatelessWidget {
               ),
             ),
             Text(
-              RichObjectStringProcessor.parseToString(
-                referenceMessage.message,
-                referenceMessage.messageParameters,
-              ),
+              () {
+                final text = RichObjectStringProcessor.parseToString(
+                  referenceMessage.message,
+                  referenceMessage.messageParameters,
+                );
+                return referenceMessage.markdown
+                    ? markdownToPlainText(text)
+                    : text;
+              }(),
               maxLines: 2,
               style: TextStyle(
                 overflow: TextOverflow.ellipsis,

lib/view/pages/talk/widgets/chat_bubble.dart

@@ -157,7 +157,7 @@ class _ChatBubbleState extends State<ChatBubble>
   /// `onTap: null` on the bubble's `GestureDetector` so its
   /// `TapGestureRecognizer` does not enter the gesture arena — otherwise
   /// it competes with (and blocks) the per-link `TapGestureRecognizer`s
-  /// that `HighlightedLinkify` attaches to URL spans.
+  /// that `HighlightedLinkify` / the Markdown renderer attach to link spans.
   bool get _hasTapAction {
     final obj = message.originalData?['object'];
     if (obj?.type == RichObjectStringObjectType.talkPoll) return true;
@@ -280,6 +280,10 @@ class _ChatBubbleState extends State<ChatBubble>
                 messageWidget: message.getWidget(
                   highlightQuery: widget.highlightQuery,
                   style: _messageTextStyle(context),
+                  renderMarkdown:
+                      widget.bubbleData.markdown &&
+                      widget.bubbleData.messageType ==
+                          GetRoomResponseObjectMessageType.comment,
                 ),
                 parent: parent,
                 bubbleData: widget.bubbleData,

lib/view/pages/talk/widgets/chat_tile.dart

@@ -20,6 +20,7 @@ import '../../../../widget/confirm_dialog.dart';
 import '../../../../widget/debug/debug_tile.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/user_avatar.dart';
+import '../data/talk_markdown.dart';
 import '../talk_navigator.dart';
 
 class ChatTile extends StatefulWidget {
@@ -62,6 +63,18 @@ class _ChatTileState extends State<ChatTile> {
 
   void _refreshList() => context.read<ChatListBloc>().refresh();
 
+  /// One-line preview of the last message: rich-object placeholders resolved,
+  /// newlines flattened and — for Markdown messages — formatting stripped so
+  /// the list shows readable text rather than raw markers.
+  String _lastMessagePreview() {
+    final last = widget.data.lastMessage;
+    final text = RichObjectStringProcessor.parseToString(
+      last.message.replaceAll('\n', ' '),
+      last.messageParameters,
+    );
+    return last.markdown ? markdownToPlainText(text) : text;
+  }
+
   Future<void> _setCurrentAsRead() async {
     final token = widget.data.token;
     final lastId = widget.data.lastMessage.id;
@@ -142,7 +155,7 @@ class _ChatTileState extends State<ChatTile> {
       ),
       subtitle: Text(
         '${DateTime.fromMillisecondsSinceEpoch(widget.data.lastMessage.timestamp * 1000).formatRelative()}: '
-        '${RichObjectStringProcessor.parseToString(widget.data.lastMessage.message.replaceAll("\n", " "), widget.data.lastMessage.messageParameters)}',
+        '${_lastMessagePreview()}',
         overflow: TextOverflow.ellipsis,
       ),
       trailing: widget.data.unreadMessages <= 0

lib/view/pages/talk/widgets/message_markdown.dart

@@ -0,0 +1,118 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_markdown_plus/flutter_markdown_plus.dart';
+
+import '../../../../utils/url_opener.dart';
+import '../data/talk_markdown.dart';
+
+/// Renders a Talk chat-message body as Markdown, matching the subset the
+/// official Nextcloud Talk clients render.
+///
+/// Supported (the intentional "Rahmen", kept in sync with Talk's GFM-based
+/// renderer): bold, italic, strikethrough, inline code, links (explicit and
+/// bare autolinks), headings, ordered/unordered/task lists, fenced code
+/// blocks, block quotes, horizontal rules and tables.
+///
+/// Deliberately unsupported, mirroring Talk's restrictions: raw HTML is shown
+/// literally (never interpreted) and images are not fetched/rendered — only
+/// their alt text (or URL) is shown, so a message can never pull a remote
+/// resource on display.
+class MessageMarkdown extends StatelessWidget {
+  final String data;
+  final TextStyle? style;
+
+  const MessageMarkdown({required this.data, this.style, super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final base =
+        style ??
+        theme.textTheme.bodyMedium ??
+        DefaultTextStyle.of(context).style;
+    final baseSize = base.fontSize ?? 14;
+    final muted = (base.color ?? theme.colorScheme.onSurface).withValues(
+      alpha: 0.55,
+    );
+    final codeBackground = theme.colorScheme.surfaceContainerHighest.withValues(
+      alpha: 0.6,
+    );
+    final codeStyle = base.copyWith(
+      fontFamily: 'monospace',
+      fontFamilyFallback: const ['monospace'],
+      fontSize: baseSize * 0.92,
+    );
+
+    final styleSheet = MarkdownStyleSheet.fromTheme(theme).copyWith(
+      p: base,
+      a: base.copyWith(
+        color: Colors.blue,
+        decoration: TextDecoration.underline,
+      ),
+      em: base.copyWith(fontStyle: FontStyle.italic),
+      strong: base.copyWith(fontWeight: FontWeight.bold),
+      del: base.copyWith(decoration: TextDecoration.lineThrough),
+      // Talk levels headings down so they stay readable inside a chat bubble;
+      // we cap them at modest multiples of the body size instead of the theme's
+      // display sizes.
+      h1: base.copyWith(fontSize: baseSize * 1.5, fontWeight: FontWeight.bold),
+      h2: base.copyWith(fontSize: baseSize * 1.4, fontWeight: FontWeight.bold),
+      h3: base.copyWith(fontSize: baseSize * 1.3, fontWeight: FontWeight.bold),
+      h4: base.copyWith(fontSize: baseSize * 1.15, fontWeight: FontWeight.bold),
+      h5: base.copyWith(fontSize: baseSize * 1.05, fontWeight: FontWeight.bold),
+      h6: base.copyWith(fontWeight: FontWeight.bold),
+      code: codeStyle.copyWith(backgroundColor: codeBackground),
+      codeblockPadding: const EdgeInsets.all(8),
+      codeblockDecoration: BoxDecoration(
+        color: codeBackground,
+        borderRadius: BorderRadius.circular(6),
+      ),
+      blockquote: base.copyWith(color: muted),
+      blockquotePadding: const EdgeInsets.only(left: 12, top: 2, bottom: 2),
+      blockquoteDecoration: BoxDecoration(
+        border: Border(left: BorderSide(color: muted, width: 4)),
+      ),
+      listBullet: base,
+      checkbox: base,
+      horizontalRuleDecoration: BoxDecoration(
+        border: Border(top: BorderSide(color: muted)),
+      ),
+      tableHead: base.copyWith(fontWeight: FontWeight.bold),
+      tableBody: base,
+      tableBorder: TableBorder.all(color: muted, width: 0.8),
+      tableCellsPadding: const EdgeInsets.symmetric(
+        horizontal: 6,
+        vertical: 3,
+      ),
+      // Keep multi-block messages compact; the default spacing is too airy for
+      // a chat bubble.
+      blockSpacing: baseSize * 0.5,
+    );
+
+    return MarkdownBody(
+      data: data,
+      styleSheet: styleSheet,
+      extensionSet: talkMarkdownExtensionSet,
+      // Talk turns a single newline into a line break (`breaks: true`);
+      // standard Markdown would collapse it into a space.
+      softLineBreak: true,
+      onTapLink: (text, href, title) {
+        if (href != null && href.isNotEmpty) unawaited(UrlOpener.openUrl(href));
+      },
+      // No remote fetch: render the alt text (or URL) instead of the image.
+      imageBuilder: (uri, title, alt) => Text(
+        (alt != null && alt.isNotEmpty) ? alt : uri.toString(),
+        style: base,
+      ),
+      checkboxBuilder: (checked) => Padding(
+        padding: const EdgeInsets.only(right: 4),
+        child: Icon(
+          checked ? Icons.check_box_outlined : Icons.check_box_outline_blank,
+          size: baseSize + 2,
+          color: base.color,
+        ),
+      ),
+    );
+  }
+}