fix flickering image. (#343)

lib/blocs/stories/stories_bloc.dart

@@ -35,7 +35,7 @@ class StoriesBloc extends Bloc<StoriesEvent, StoriesState> {
         super(const StoriesState.init()) {
     on<LoadStories>(
       onLoadStories,
-      transformer: sequential(),
+      transformer: concurrent(),
     );
     on<StoriesInitialize>(onInitialize);
     on<StoriesRefresh>(onRefresh);

lib/cubits/fav/fav_cubit.dart

@@ -169,20 +169,26 @@ class FavCubit extends Cubit<FavState> {
     emit(FavState.init());
   }
 
-  Future<void> merge() async {
+  Future<void> merge({required AppExceptionHandler onError}) async {
     if (_authBloc.state.isLoggedIn) {
       emit(state.copyWith(mergeStatus: Status.inProgress));
+      try {
         final Iterable<int> ids = await _hackerNewsWebRepository.fetchFavorites(
           of: _authBloc.state.username,
         );
         final List<int> combinedIds = <int>[...ids, ...state.favIds];
-      final LinkedHashSet<int> mergedIds = LinkedHashSet<int>.from(combinedIds);
+        final LinkedHashSet<int> mergedIds =
+            LinkedHashSet<int>.from(combinedIds);
         await _preferenceRepository.overwriteFav(
           username: username,
           ids: mergedIds,
         );
         emit(state.copyWith(mergeStatus: Status.success));
         refresh();
+      } on RateLimitedException catch (e) {
+        onError(e);
+        emit(state.copyWith(mergeStatus: Status.failure));
+      }
     }
   }
 

lib/extensions/context_extension.dart

@@ -38,9 +38,19 @@ extension ContextExtension on BuildContext {
     );
   }
 
-  void showErrorSnackBar() => showSnackBar(
+  void showErrorSnackBar([String? message]) {
-        content: Constants.errorMessage,
+    ScaffoldMessenger.of(this).showSnackBar(
+      SnackBar(
+        backgroundColor: Theme.of(this).colorScheme.errorContainer,
+        content: Text(
+          message ?? Constants.errorMessage,
+          style: TextStyle(
+            color: Theme.of(this).colorScheme.onErrorContainer,
+          ),
+        ),
+      ),
     );
+  }
 
   Rect? get rect {
     final RenderBox? box = findRenderObject() as RenderBox?;

lib/models/app_exception.dart

@@ -0,0 +1,15 @@
+typedef AppExceptionHandler = void Function(AppException);
+
+class AppException implements Exception {
+  AppException({
+    required this.message,
+    this.stackTrace,
+  });
+
+  final String message;
+  final StackTrace? stackTrace;
+}
+
+class RateLimitedException extends AppException {
+  RateLimitedException() : super(message: 'Rate limited...');
+}

lib/models/models.dart

@@ -1,3 +1,4 @@
+export 'app_exception.dart';
 export 'comments_order.dart';
 export 'discoverable_feature.dart';
 export 'export_destination.dart';

lib/repositories/hacker_news_web_repository.dart

@@ -1,6 +1,7 @@
 import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
-import 'package:hacki/models/item/comment.dart';
+import 'package:hacki/config/constants.dart';
+import 'package:hacki/models/models.dart';
 import 'package:html/dom.dart' hide Comment;
 import 'package:html/parser.dart';
 import 'package:html_unescape/html_unescape.dart';
@@ -25,6 +26,14 @@ class HackerNewsWebRepository {
         '''$_favoritesBaseUrl$username${isComment ? '&comments=t' : ''}&p=$page''',
       );
       final Response response = await get(url);
+
+      if (response.body.contains('Sorry')) {
+        throw RateLimitedException();
+      }
+
+      /// Due to rate limiting, we have a short break here.
+      await Future<void>.delayed(AppDurations.oneSecond);
+
       final Document document = parse(response.body);
       final List<Element> elements = document.querySelectorAll(_aThingSelector);
       final Iterable<int> parsedIds = elements
@@ -45,6 +54,7 @@ class HackerNewsWebRepository {
       page++;
     }
 
+    page = 1;
     while (true) {
       ids = await fetchIds(page, isComment: true);
       if (ids.isEmpty) {

lib/screens/profile/profile_screen.dart

@@ -150,7 +150,11 @@ class _ProfileScreenState extends State<ProfileScreen>
                                 ) =>
                                     TextButton(
                                   onPressed: () {
-                                    context.read<FavCubit>().merge();
+                                    context.read<FavCubit>().merge(
+                                      onError: (AppException e) {
+                                        context.showErrorSnackBar(e.message);
+                                      },
+                                    );
                                   },
                                   child: status == Status.inProgress
                                       ? const SizedBox(

lib/screens/widgets/link_preview/link_view.dart

@@ -119,10 +119,14 @@ class LinkView extends StatelessWidget {
                         : CachedNetworkImage(
                             imageUrl: imageUri!,
                             fit: isIcon ? BoxFit.scaleDown : BoxFit.fitWidth,
-                            memCacheHeight: layoutHeight.toInt() * 4,
                             cacheKey: imageUri,
-                            errorWidget: (_, __, ___) => const Center(
+                            errorWidget: (_, __, ___) => Center(
-                              child: Text(r'¯\_(ツ)_/¯'),
+                              child: Text(
+                                r'¯\_(ツ)_/¯',
+                                style: TextStyle(
+                                  color: Theme.of(context).colorScheme.primary,
+                                ),
+                              ),
                             ),
                           ),
                   ),