msglist: Handle loading state in MarkAsReadWidget

MarkAsReadWidget needs to be disabled during loading state to prevent
multiple requests to the server.

Additionally it is needed for styling/animation convenience.

Author: Khader-1

lib/widgets/message_list.dart

@@ -438,30 +438,41 @@ class ScrollToBottomButton extends StatelessWidget {
   }
 }
 
-class MarkAsReadWidget extends StatelessWidget {
+class MarkAsReadWidget extends StatefulWidget {
   const MarkAsReadWidget({super.key, required this.narrow});
 
   final Narrow narrow;
 
+  @override
+  State<MarkAsReadWidget> createState() => MarkAsReadWidgetState();
+}
+
+class MarkAsReadWidgetState extends State<MarkAsReadWidget> {
+  @visibleForTesting
+  bool loading = false;
+
   void _handlePress(BuildContext context) async {
     if (!context.mounted) return;
 
     final store = PerAccountStoreWidget.of(context);
     final connection = store.connection;
     final useLegacy = connection.zulipFeatureLevel! < 155;
+    setState(() => loading = true);
 
     try {
-      await markNarrowAsRead(context, narrow, useLegacy);
+      await markNarrowAsRead(context, widget.narrow, useLegacy);
     } catch (e) {
       if (!context.mounted) return;
       final zulipLocalizations = ZulipLocalizations.of(context);
-      await showErrorDialog(context: context,
+      showErrorDialog(context: context,
         title: zulipLocalizations.errorMarkAsReadFailedTitle,
         message: e.toString()); // TODO(#741): extract user-facing message better
       return;
+    } finally {
+      setState(() => loading = false);
     }
     if (!context.mounted) return;
-    if (narrow is CombinedFeedNarrow && !useLegacy) {
+    if (widget.narrow is CombinedFeedNarrow && !useLegacy) {
       PerAccountStoreWidget.of(context).unreads.handleAllMessagesReadSuccess();
     }
   }
@@ -470,13 +481,13 @@ class MarkAsReadWidget extends StatelessWidget {
   Widget build(BuildContext context) {
     final zulipLocalizations = ZulipLocalizations.of(context);
     final store = PerAccountStoreWidget.of(context);
-    final unreadCount = store.unreads.countInNarrow(narrow);
+    final unreadCount = store.unreads.countInNarrow(widget.narrow);
     final areMessagesRead = unreadCount == 0;
 
     return IgnorePointer(
       ignoring: areMessagesRead,
       child: AnimatedOpacity(
-        opacity: areMessagesRead ? 0 : 1,
+        opacity: areMessagesRead ? 0 : loading ? 0.5 : 1,
         duration: Duration(milliseconds: areMessagesRead ? 2000 : 300),
         curve: Curves.easeOut,
         child: SizedBox(width: double.infinity,
@@ -487,8 +498,6 @@ class MarkAsReadWidget extends StatelessWidget {
             padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 10 - ((48 - 38) / 2)),
             child: FilledButton.icon(
               style: FilledButton.styleFrom(
-                // TODO(#95) need dark-theme colors (foreground and background)
-                backgroundColor: _UnreadMarker.color,
                 minimumSize: const Size.fromHeight(38),
                 textStyle:
                   // Restate [FilledButton]'s default, which inherits from
@@ -502,8 +511,13 @@ class MarkAsReadWidget extends StatelessWidget {
                     height: (23 / 18))
                   .merge(weightVariableTextStyle(context, wght: 400))),
                 shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(7)),
+              ).copyWith(
+                // clobber `FilledButton`'s default disabled state
+                // TODO(#95) need dark-theme colors (foreground and background)
+                foregroundColor: WidgetStateColor.resolveWith((_) => Colors.white),
+                backgroundColor: WidgetStateColor.resolveWith((_) => _UnreadMarker.color),
               ),
-              onPressed: () => _handlePress(context),
+              onPressed: loading ? null : () => _handlePress(context),
               icon: const Icon(Icons.playlist_add_check),
               label: Text(zulipLocalizations.markAllAsReadLabel))))));
   }

test/widgets/message_list_test.dart

@@ -753,6 +753,68 @@ void main() {
           unreadMessageIds: [message.id]),
       ]);
 
+      group('MarkAsReadAnimation', () {
+        void checkAppearsLoading(WidgetTester tester, bool expected) {
+          final semantics = tester.firstWidget<Semantics>(find.descendant(
+            of: find.byType(MarkAsReadWidget),
+            matching: find.byType(Semantics)));
+          check(semantics.properties.enabled).equals(!expected);
+
+          final opacity = tester.widget<AnimatedOpacity>(find.descendant(
+            of: find.byType(MarkAsReadWidget),
+            matching: find.byType(AnimatedOpacity)));
+          check(opacity.opacity).equals(expected ? 0.5 : 1.0);
+        }
+
+        testWidgets('loading is changed correctly', (WidgetTester tester) async {
+          final narrow = TopicNarrow.ofMessage(message);
+          await setupMessageListPage(tester,
+            narrow: narrow, messages: [message], unreadMsgs: unreadMsgs);
+          check(isMarkAsReadButtonVisible(tester)).isTrue();
+
+          connection.prepare(
+            delay: const Duration(milliseconds: 2000),
+            json: UpdateMessageFlagsForNarrowResult(
+              processedCount: 11, updatedCount: 3,
+              firstProcessedId: null, lastProcessedId: null,
+              foundOldest: true, foundNewest: true).toJson());
+
+          checkAppearsLoading(tester, false);
+
+          await tester.tap(find.byType(MarkAsReadWidget));
+          await tester.pump();
+          checkAppearsLoading(tester, true);
+
+          await tester.pump(const Duration(milliseconds: 2000));
+          checkAppearsLoading(tester, false);
+        });
+
+        testWidgets('loading is changed correctly if request fails', (WidgetTester tester) async {
+          final narrow = TopicNarrow.ofMessage(message);
+          await setupMessageListPage(tester,
+            narrow: narrow, messages: [message], unreadMsgs: unreadMsgs);
+          check(isMarkAsReadButtonVisible(tester)).isTrue();
+
+          connection.prepare(httpStatus: 400, json: {
+            'code': 'BAD_REQUEST',
+            'msg': 'Invalid message(s)',
+            'result': 'error',
+          });
+
+          final state = tester.state<MarkAsReadWidgetState>(find.byType(MarkAsReadWidget));
+          check(state.loading).isFalse();
+
+          await tester.tap(find.byType(MarkAsReadWidget));
+          await tester.pump();
+          check(state.loading).isTrue();
+
+          await tester.idle();
+          await tester.pump();
+
+          check(state.loading).isFalse();
+        });
+      });
+
       testWidgets('smoke test on modern server', (WidgetTester tester) async {
         final narrow = TopicNarrow.ofMessage(message);
         await setupMessageListPage(tester,