feat: implement headline filter bottom sheet

- Added HeadlineFilter model
- Created filter bottom sheet UI
- Implemented filter apply logic

Author: fulleni

lib/app/view/app.dart

@@ -39,6 +39,7 @@ class _AppView extends StatelessWidget {
     return BlocBuilder<AppBloc, AppState>(
       builder: (context, state) {
         return MaterialApp.router(
+          debugShowCheckedModeBanner: false,
           theme:
               state.themeMode == ThemeMode.light ? lightTheme() : darkTheme(),
           routerConfig: appRouter,

lib/headlines-feed/bloc/headlines_feed_bloc.dart

@@ -2,6 +2,7 @@ import 'package:bloc/bloc.dart';
 import 'package:bloc_concurrency/bloc_concurrency.dart';
 import 'package:equatable/equatable.dart';
 import 'package:ht_headlines_repository/ht_headlines_repository.dart';
+import 'package:ht_main/headlines-feed/models/headline_filter.dart';
 
 part 'headlines_feed_event.dart';
 part 'headlines_feed_state.dart';
@@ -16,7 +17,7 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
   /// {@macro headlines_feed_bloc}
   HeadlinesFeedBloc({required HtHeadlinesRepository headlinesRepository})
       : _headlinesRepository = headlinesRepository,
-        super(HeadlinesFeedInitial()) {
+        super(HeadlinesFeedLoading()) {
     on<HeadlinesFeedFetchRequested>(
       _onHeadlinesFeedFetchRequested,
       transformer: sequential(),
@@ -25,10 +26,51 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
       _onHeadlinesFeedRefreshRequested,
       transformer: restartable(),
     );
+    on<HeadlinesFeedFilterChanged>(
+      _onHeadlinesFeedFilterChanged,
+    );
   }
 
   final HtHeadlinesRepository _headlinesRepository;
 
+  Future<void> _onHeadlinesFeedFilterChanged(
+    HeadlinesFeedFilterChanged event,
+    Emitter<HeadlinesFeedState> emit,
+  ) async {
+    emit(HeadlinesFeedLoading());
+    try {
+      final response = await _headlinesRepository.getHeadlines(
+        limit: 20,
+        category: event.category, // Pass category directly
+        source: event.source, // Pass source directly
+        eventCountry: event.eventCountry, // Pass eventCountry directly
+      );
+      final newFilter = (state is HeadlinesFeedLoaded)
+          ? (state as HeadlinesFeedLoaded).filter.copyWith(
+                category: event.category,
+                source: event.source,
+                eventCountry: event.eventCountry,
+              )
+          : HeadlineFilter(
+              category: event.category,
+              source: event.source,
+              eventCountry: event.eventCountry,
+            );
+      emit(
+        HeadlinesFeedLoaded(
+          headlines: response.items,
+          hasMore: response.hasMore,
+          cursor: response.cursor,
+          filter: newFilter,
+        ),
+      );
+    } on HeadlinesFetchException catch (e) {
+      emit(HeadlinesFeedError(message: e.message));
+    } catch (_) {
+      emit(const HeadlinesFeedError(message: 'An unexpected error occurred'));
+    }
+  }
+
   /// Handles [HeadlinesFeedFetchRequested] events.
   ///
   /// Fetches headlines from the repository and emits
@@ -46,12 +88,16 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
         final response = await _headlinesRepository.getHeadlines(
           limit: 20,
           startAfterId: currentState.cursor,
+          category: currentState.filter.category, // Use existing filter
+          source: currentState.filter.source, // Use existing filter
+          eventCountry: currentState.filter.eventCountry, // Use existing filter
         );
         emit(
           HeadlinesFeedLoaded(
             headlines: currentState.headlines + response.items,
             hasMore: response.hasMore,
             cursor: response.cursor,
+            filter: currentState.filter,
           ),
         );
       } on HeadlinesFetchException catch (e) {
@@ -62,12 +108,26 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
     } else {
       emit(HeadlinesFeedLoading());
       try {
-        final response = await _headlinesRepository.getHeadlines(limit: 20);
+        final response = await _headlinesRepository.getHeadlines(
+          limit: 20,
+          category: state is HeadlinesFeedLoaded
+              ? (state as HeadlinesFeedLoaded).filter.category
+              : null,
+          source: state is HeadlinesFeedLoaded
+              ? (state as HeadlinesFeedLoaded).filter.source
+              : null,
+          eventCountry: state is HeadlinesFeedLoaded
+              ? (state as HeadlinesFeedLoaded).filter.eventCountry
+              : null,
+        );
         emit(
           HeadlinesFeedLoaded(
             headlines: response.items,
             hasMore: response.hasMore,
             cursor: response.cursor,
+            filter: state is HeadlinesFeedLoaded
+                ? (state as HeadlinesFeedLoaded).filter
+                : const HeadlineFilter(),
           ),
         );
       } on HeadlinesFetchException catch (e) {
@@ -92,12 +152,26 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
   ) async {
     emit(HeadlinesFeedLoading());
     try {
-      final response = await _headlinesRepository.getHeadlines(limit: 20);
+      final response = await _headlinesRepository.getHeadlines(
+        limit: 20,
+        category: state is HeadlinesFeedLoaded
+            ? (state as HeadlinesFeedLoaded).filter.category
+            : null,
+        source: state is HeadlinesFeedLoaded
+            ? (state as HeadlinesFeedLoaded).filter.source
+            : null,
+        eventCountry: state is HeadlinesFeedLoaded
+            ? (state as HeadlinesFeedLoaded).filter.eventCountry
+            : null,
+      );
       emit(
         HeadlinesFeedLoaded(
           headlines: response.items,
           hasMore: response.hasMore,
           cursor: response.cursor,
+          filter: state is HeadlinesFeedLoaded
+              ? (state as HeadlinesFeedLoaded).filter
+              : const HeadlineFilter(),
         ),
       );
     } on HeadlinesFetchException catch (e) {

lib/headlines-feed/bloc/headlines_feed_event.dart

@@ -8,7 +8,7 @@ sealed class HeadlinesFeedEvent extends Equatable {
   const HeadlinesFeedEvent();
 
   @override
-  List<Object> get props => [];
+  List<Object?> get props => [];
 }
 
 /// {@template headlines_feed_fetch_requested}
@@ -22,10 +22,34 @@ final class HeadlinesFeedFetchRequested extends HeadlinesFeedEvent {
   final String? cursor;
 
   @override
-  List<Object> get props => [cursor ?? ''];
+  List<Object?> get props => [cursor];
 }
 
 /// {@template headlines_feed_refresh_requested}
 /// Event triggered when the headlines feed needs to be refreshed.
 /// {@endtemplate}
 final class HeadlinesFeedRefreshRequested extends HeadlinesFeedEvent {}
+
+/// {@template headlines_feed_filter_changed}
+/// Event triggered when the filter parameters for the headlines feed change.
+/// {@endtemplate}
+final class HeadlinesFeedFilterChanged extends HeadlinesFeedEvent {
+  /// {@macro headlines_feed_filter_changed}
+  const HeadlinesFeedFilterChanged({
+    this.category,
+    this.source,
+    this.eventCountry,
+  });
+
+  /// The selected category filter.
+  final String? category;
+
+  /// The selected source filter.
+  final String? source;
+
+  /// The selected event country filter.
+  final String? eventCountry;
+
+  @override
+  List<Object?> get props => [category, source, eventCountry];
+}

lib/headlines-feed/bloc/headlines_feed_state.dart

@@ -8,28 +8,25 @@ sealed class HeadlinesFeedState extends Equatable {
   const HeadlinesFeedState();
 
   @override
-  List<Object> get props => [];
+  List<Object?> get props => [];
 }
 
-/// {@template headlines_feed_initial}
-/// The initial state of the headlines feed.
-/// {@endtemplate}
-final class HeadlinesFeedInitial extends HeadlinesFeedState {}
-
 /// {@template headlines_feed_loading}
 /// State indicating that the headlines feed is being loaded.
 /// {@endtemplate}
 final class HeadlinesFeedLoading extends HeadlinesFeedState {}
 
 /// {@template headlines_feed_loaded}
-/// State indicating that the headlines feed has been loaded successfully.
+/// State indicating that the headlines feed has been loaded successfully,
+/// potentially with applied filters.
 /// {@endtemplate}
 final class HeadlinesFeedLoaded extends HeadlinesFeedState {
   /// {@macro headlines_feed_loaded}
   const HeadlinesFeedLoaded({
-    required this.headlines,
-    required this.hasMore,
+    this.headlines = const [],
+    this.hasMore = true,
     this.cursor,
+    this.filter = const HeadlineFilter(),
   });
 
   /// The headlines data.
@@ -41,8 +38,27 @@ final class HeadlinesFeedLoaded extends HeadlinesFeedState {
   /// The cursor for the next page.
   final String? cursor;
 
+  /// The filter applied to the headlines.
+  final HeadlineFilter filter;
+
+  /// Creates a copy of this [HeadlinesFeedLoaded] with the given fields
+  /// replaced with the new values.
+  HeadlinesFeedLoaded copyWith({
+    List<Headline>? headlines,
+    bool? hasMore,
+    String? cursor,
+    HeadlineFilter? filter,
+  }) {
+    return HeadlinesFeedLoaded(
+      headlines: headlines ?? this.headlines,
+      hasMore: hasMore ?? this.hasMore,
+      cursor: cursor ?? this.cursor,
+      filter: filter ?? this.filter,
+    );
+  }
+
   @override
-  List<Object> get props => [headlines, hasMore, cursor ?? ''];
+  List<Object?> get props => [headlines, hasMore, cursor, filter];
 }
 
 /// {@template headlines_feed_error}

lib/headlines-feed/models/headline_filter.dart

@@ -0,0 +1,39 @@
+import 'package:equatable/equatable.dart';
+
+/// {@template headline_filter}
+/// A model representing the filter parameters for headlines.
+/// {@endtemplate}
+class HeadlineFilter extends Equatable {
+  /// {@macro headline_filter}
+  const HeadlineFilter({
+    this.category,
+    this.source,
+    this.eventCountry,
+  });
+
+  /// The selected category filter.
+  final String? category;
+
+  /// The selected source filter.
+  final String? source;
+
+  /// The selected event country filter.
+  final String? eventCountry;
+
+  @override
+  List<Object?> get props => [category, source, eventCountry];
+
+  /// Creates a copy of this [HeadlineFilter] with the given fields
+  /// replaced with the new values.
+  HeadlineFilter copyWith({
+    String? category,
+    String? source,
+    String? eventCountry,
+  }) {
+    return HeadlineFilter(
+      category: category ?? this.category,
+      source: source ?? this.source,
+      eventCountry: eventCountry ?? this.eventCountry,
+    );
+  }
+}