wip narrow: Support MentionsNarrow.

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

assets/l10n/app_en.arb

@@ -344,6 +344,10 @@
   "@loginErrorMissingUsername": {
     "description": "Error message when an empty username was provided."
   },
+  "mentionsPageTitle": "Mentions",
+  "@mentionsPageTitle": {
+    "description": "Title for the page of @-mentions."
+  },
   "topicValidationErrorTooLong": "Topic length shouldn't be greater than 60 characters.",
   "@topicValidationErrorTooLong": {
     "description": "Topic validation error when topic is too long."

lib/widgets/app.dart

@@ -276,6 +276,12 @@ class HomePage extends StatelessWidget {
                 narrow: const CombinedFeedNarrow())),
             child: Text(zulipLocalizations.combinedFeedPageTitle)),
           const SizedBox(height: 16),
+          ElevatedButton(
+            onPressed: () => Navigator.push(context,
+              MessageListPage.buildRoute(context: context,
+                narrow: const MentionsNarrow())),
+            child: Text(zulipLocalizations.mentionsPageTitle)),
+          const SizedBox(height: 16),
           ElevatedButton(
             onPressed: () => Navigator.push(context,
               InboxPage.buildRoute(context: context)),

lib/widgets/compose_box.dart

@@ -967,7 +967,7 @@ class ComposeBox extends StatelessWidget {
       return _FixedDestinationComposeBox(key: controllerKey, narrow: narrow);
     } else if (narrow is DmNarrow) {
       return _FixedDestinationComposeBox(key: controllerKey, narrow: narrow);
-    } else if (narrow is CombinedFeedNarrow) {
+    } else if (narrow is CombinedFeedNarrow || narrow is MentionsNarrow) {
       return const SizedBox.shrink();
     } else {
       throw Exception("impossible narrow"); // TODO(dart-3): show this statically

lib/widgets/message_list.dart

@@ -63,6 +63,7 @@ class _MessageListPageState extends State<MessageListPage> {
     bool removeAppBarBottomBorder = false;
     switch(widget.narrow) {
       case CombinedFeedNarrow():
+      case MentionsNarrow():
         appBarBackgroundColor = null; // i.e., inherit
 
       case StreamNarrow(:final streamId):
@@ -149,6 +150,8 @@ class MessageListAppBarTitle extends StatelessWidget {
     switch (narrow) {
       case CombinedFeedNarrow():
         return Text(zulipLocalizations.combinedFeedPageTitle);
+      case MentionsNarrow():
+        return Text(zulipLocalizations.mentionsPageTitle);
 
       case StreamNarrow(:var streamId):
         final store = PerAccountStoreWidget.of(context);
@@ -340,7 +343,7 @@ class _MessageListState extends State<MessageList> with PerAccountStoreAwareStat
           return _buildItem(data, i);
         }));
 
-    if (widget.narrow is CombinedFeedNarrow) {
+    if (widget.narrow is CombinedFeedNarrow || widget.narrow is MentionsNarrow) {
       // TODO(#311) If we have a bottom nav, it will pad the bottom
       //   inset, and this shouldn't be necessary
       sliver = SliverSafeArea(sliver: sliver);
@@ -521,7 +524,7 @@ class RecipientHeader extends StatelessWidget {
     final message = this.message;
     return switch (message) {
       StreamMessage() => StreamMessageRecipientHeader(message: message,
-        showStream: narrow is CombinedFeedNarrow),
+        showStream: narrow is CombinedFeedNarrow || narrow is MentionsNarrow),
       DmMessage() => DmRecipientHeader(message: message),
     };
   }
@@ -1097,6 +1100,13 @@ Future<void> _legacyMarkNarrowAsRead(BuildContext context, Narrow narrow) async
   switch (narrow) {
     case CombinedFeedNarrow():
       await markAllAsRead(connection);
+    case MentionsNarrow():
+    final unreadMentions = store.unreads.mentions.toList();
+    if (unreadMentions.isEmpty) return;
+    await updateMessageFlags(connection,
+      messages: unreadMentions,
+      op: UpdateMessageFlagsOp.add,
+      flag: MessageFlag.read);
     case StreamNarrow(:final streamId):
       await markStreamAsRead(connection, streamId: streamId);
     case TopicNarrow(:final streamId, :final topic):