Merge pull request #92 from flutter-news-app-full-source-code/Add-Event-Country-and-Source-Country-Filtering

Add event country and source country filtering

Author: fulleni

lib/headlines-feed/bloc/countries_filter_bloc.dart

@@ -27,22 +27,20 @@ class CountriesFilterBloc
       _onCountriesFilterRequested,
       transformer: restartable(),
     );
-    on<CountriesFilterLoadMoreRequested>(
-      _onCountriesFilterLoadMoreRequested,
-      transformer: droppable(),
-    );
   }
 
   final DataRepository<Country> _countriesRepository;
 
-  /// Number of countries to fetch per page.
-  static const _countriesLimit = 20;
-
-  /// Handles the initial request to fetch countries.
+  /// Handles the request to fetch countries based on a specific usage.
+  ///
+  /// This method fetches a non-paginated list of countries, filtered by
+  /// the provided [usage] (e.g., 'eventCountry', 'headquarters').
   Future<void> _onCountriesFilterRequested(
     CountriesFilterRequested event,
     Emitter<CountriesFilterState> emit,
   ) async {
+    // If already loading or successfully loaded, do not re-fetch unless explicitly
+    // designed for a refresh mechanism (which is not the case for this usage-based fetch).
     if (state.status == CountriesFilterStatus.loading ||
         state.status == CountriesFilterStatus.success) {
       return;
@@ -51,53 +49,29 @@ class CountriesFilterBloc
     emit(state.copyWith(status: CountriesFilterStatus.loading));
 
     try {
+      // Build the filter map based on the provided usage.
+      final filter = event.usage != null
+          ? <String, dynamic>{'usage': event.usage}
+          : null;
+
+      // Fetch countries. The API for 'usage' filters is not paginated,
+      // so we expect a complete list.
       final response = await _countriesRepository.readAll(
-        pagination: const PaginationOptions(limit: _countriesLimit),
+        filter: filter,
         sort: [const SortOption('name', SortOrder.asc)],
       );
+
       emit(
         state.copyWith(
           status: CountriesFilterStatus.success,
           countries: response.items,
-          hasMore: response.hasMore,
-          cursor: response.cursor,
+          hasMore: false, // Always false for usage-based filters
+          cursor: null, // Always null for usage-based filters
           clearError: true,
         ),
       );
     } on HttpException catch (e) {
       emit(state.copyWith(status: CountriesFilterStatus.failure, error: e));
     }
   }
-
-  /// Handles the request to load more countries for pagination.
-  Future<void> _onCountriesFilterLoadMoreRequested(
-    CountriesFilterLoadMoreRequested event,
-    Emitter<CountriesFilterState> emit,
-  ) async {
-    if (state.status != CountriesFilterStatus.success || !state.hasMore) {
-      return;
-    }
-
-    emit(state.copyWith(status: CountriesFilterStatus.loadingMore));
-
-    try {
-      final response = await _countriesRepository.readAll(
-        pagination: PaginationOptions(
-          limit: _countriesLimit,
-          cursor: state.cursor,
-        ),
-        sort: [const SortOption('name', SortOrder.asc)],
-      );
-      emit(
-        state.copyWith(
-          status: CountriesFilterStatus.success,
-          countries: List.of(state.countries)..addAll(response.items),
-          hasMore: response.hasMore,
-          cursor: response.cursor,
-        ),
-      );
-    } on HttpException catch (e) {
-      emit(state.copyWith(status: CountriesFilterStatus.failure, error: e));
-    }
-  }
 }

lib/headlines-feed/bloc/countries_filter_event.dart

@@ -8,15 +8,22 @@ sealed class CountriesFilterEvent extends Equatable {
   const CountriesFilterEvent();
 
   @override
-  List<Object> get props => [];
+  List<Object?> get props => [];
 }
 
 /// {@template countries_filter_requested}
 /// Event triggered to request the initial list of countries.
 /// {@endtemplate}
-final class CountriesFilterRequested extends CountriesFilterEvent {}
+final class CountriesFilterRequested extends CountriesFilterEvent {
+  /// {@macro countries_filter_requested}
+  ///
+  /// Optionally includes a [usage] context to filter countries by their
+  /// relevance to headlines (e.g., 'eventCountry' or 'headquarters').
+  const CountriesFilterRequested({this.usage});
 
-/// {@template countries_filter_load_more_requested}
-/// Event triggered to request the next page of countries for pagination.
-/// {@endtemplate}
-final class CountriesFilterLoadMoreRequested extends CountriesFilterEvent {}
+  /// The usage context for filtering countries (e.g., 'eventCountry', 'headquarters').
+  final String? usage;
+
+  @override
+  List<Object?> get props => [usage];
+}

lib/headlines-feed/bloc/headlines_feed_bloc.dart

@@ -81,6 +81,16 @@ class HeadlinesFeedBloc extends Bloc<HeadlinesFeedEvent, HeadlinesFeedState> {
         r'$in': filter.sources!.map((s) => s.id).toList(),
       };
     }
+    if (filter.eventCountries?.isNotEmpty ?? false) {
+      queryFilter['eventCountry.id'] = {
+        r'$in': filter.eventCountries!.map((c) => c.id).toList(),
+      };
+    }
+    if (filter.sourceCountries?.isNotEmpty ?? false) {
+      queryFilter['source.headquarters.id'] = {
+        r'$in': filter.sourceCountries!.map((c) => c.id).toList(),
+      };
+    }
     return queryFilter;
   }
 

lib/headlines-feed/models/headline_filter.dart

@@ -11,24 +11,31 @@ class HeadlineFilter extends Equatable {
     this.sources,
     this.selectedSourceCountryIsoCodes,
     this.selectedSourceSourceTypes,
+    this.eventCountries,
+    this.sourceCountries,
     this.isFromFollowedItems = false,
   });
 
-  /// The list of selected topic filters.
-  /// Headlines matching *any* of these topics will be included (OR logic).
+  /// The list of selected topics to filter headlines by.
   final List<Topic>? topics;
 
-  /// The list of selected source filters.
-  /// Headlines matching *any* of these sources will be included (OR logic).
+  /// The list of selected sources to filter headlines by.
   final List<Source>? sources;
 
-  /// The set of selected country ISO codes for source filtering.
+  /// The set of ISO codes for countries selected to filter sources by their
+  /// headquarters.
   final Set<String>? selectedSourceCountryIsoCodes;
 
-  /// The set of selected source types for source filtering.
+  /// The set of source types selected to filter sources by.
   final Set<SourceType>? selectedSourceSourceTypes;
 
-  /// Indicates if this filter was generated from the user's followed items.
+  /// The list of selected event countries to filter headlines by.
+  final List<Country>? eventCountries;
+
+  /// The list of selected source headquarters countries to filter headlines by.
+  final List<Country>? sourceCountries;
+
+  /// Whether the filter is based on the user's followed items.
   final bool isFromFollowedItems;
 
   @override
@@ -37,16 +44,20 @@ class HeadlineFilter extends Equatable {
     sources,
     selectedSourceCountryIsoCodes,
     selectedSourceSourceTypes,
+    eventCountries,
+    sourceCountries,
     isFromFollowedItems,
   ];
 
-  /// Creates a copy of this [HeadlineFilter] with the given fields
+  /// Creates a copy of this [HeadlineFilter] but with the given fields
   /// replaced with the new values.
   HeadlineFilter copyWith({
     List<Topic>? topics,
     List<Source>? sources,
     Set<String>? selectedSourceCountryIsoCodes,
     Set<SourceType>? selectedSourceSourceTypes,
+    List<Country>? eventCountries,
+    List<Country>? sourceCountries,
     bool? isFromFollowedItems,
   }) {
     return HeadlineFilter(
@@ -56,6 +67,8 @@ class HeadlineFilter extends Equatable {
           selectedSourceCountryIsoCodes ?? this.selectedSourceCountryIsoCodes,
       selectedSourceSourceTypes:
           selectedSourceSourceTypes ?? this.selectedSourceSourceTypes,
+      eventCountries: eventCountries ?? this.eventCountries,
+      sourceCountries: sourceCountries ?? this.sourceCountries,
       isFromFollowedItems: isFromFollowedItems ?? this.isFromFollowedItems,
     );
   }

lib/headlines-feed/view/country_filter_page.dart

@@ -18,7 +18,14 @@ import 'package:ui_kit/ui_kit.dart';
 /// {@endtemplate}
 class CountryFilterPage extends StatefulWidget {
   /// {@macro country_filter_page}
-  const CountryFilterPage({super.key});
+  const CountryFilterPage({required this.title, this.usage, super.key});
+
+  /// The title to display in the app bar for this filter page.
+  final String title;
+
+  /// The usage context for filtering countries (e.g., 'eventCountry', 'headquarters').
+  /// If null, fetches all countries (though this is not the primary use case for this page).
+  final String? usage;
 
   @override
   State<CountryFilterPage> createState() => _CountryFilterPageState();
@@ -27,7 +34,7 @@ class CountryFilterPage extends StatefulWidget {
 /// State for the [CountryFilterPage].
 ///
 /// Manages the local selection state ([_pageSelectedCountries]) and interacts
-/// with [CountriesFilterBloc] for data fetching and pagination.
+/// with [CountriesFilterBloc] for data fetching.
 class _CountryFilterPageState extends State<CountryFilterPage> {
   /// Stores the countries selected by the user *on this specific page*.
   /// This state is local to the `CountryFilterPage` lifecycle.
@@ -37,10 +44,6 @@ class _CountryFilterPageState extends State<CountryFilterPage> {
   /// from the main filter page when this page loads.
   late Set<Country> _pageSelectedCountries;
 
-  /// Scroll controller to detect when the user reaches the end of the list
-  /// for pagination.
-  final _scrollController = ScrollController();
-
   @override
   void initState() {
     super.initState();
@@ -61,39 +64,18 @@ class _CountryFilterPageState extends State<CountryFilterPage> {
 
       // 3. Trigger the page-specific BLoC (CountriesFilterBloc) to start
       //    fetching the list of *all available* countries that the user can
-      //    potentially select from. The BLoC handles fetching, pagination,
-      //    loading states, and errors for the *list of options*.
-      context.read<CountriesFilterBloc>().add(CountriesFilterRequested());
+      //    potentially select from, using the specified usage filter.
+      context.read<CountriesFilterBloc>().add(
+        CountriesFilterRequested(usage: widget.usage),
+      );
     });
-    // Add listener for pagination logic.
-    _scrollController.addListener(_onScroll);
   }
 
   @override
   void dispose() {
-    _scrollController
-      ..removeListener(_onScroll)
-      ..dispose();
     super.dispose();
   }
 
-  /// Callback function for scroll events.
-  ///
-  /// Checks if the user has scrolled near the bottom of the list and triggers
-  /// fetching more countries via the BLoC if available.
-  void _onScroll() {
-    if (!_scrollController.hasClients) return;
-    final maxScroll = _scrollController.position.maxScrollExtent;
-    final currentScroll = _scrollController.offset;
-    final bloc = context.read<CountriesFilterBloc>();
-    // Fetch more when nearing the bottom, if BLoC has more and isn't already loading more
-    if (currentScroll >= (maxScroll * 0.9) &&
-        bloc.state.hasMore &&
-        bloc.state.status != CountriesFilterStatus.loadingMore) {
-      bloc.add(CountriesFilterLoadMoreRequested());
-    }
-  }
-
   @override
   Widget build(BuildContext context) {
     final l10n = AppLocalizationsX(context).l10n;
@@ -103,7 +85,7 @@ class _CountryFilterPageState extends State<CountryFilterPage> {
     return Scaffold(
       appBar: AppBar(
         title: Text(
-          l10n.headlinesFeedFilterEventCountryLabel,
+          widget.title, // Use the dynamic title
           style: textTheme.titleLarge,
         ),
         actions: [
@@ -148,8 +130,9 @@ class _CountryFilterPageState extends State<CountryFilterPage> {
         state.countries.isEmpty) {
       return FailureStateWidget(
         exception: state.error ?? const UnknownException('Unknown error'),
-        onRetry: () =>
-            context.read<CountriesFilterBloc>().add(CountriesFilterRequested()),
+        onRetry: () => context.read<CountriesFilterBloc>().add(
+          CountriesFilterRequested(usage: widget.usage),
+        ),
       );
     }
 
@@ -163,45 +146,13 @@ class _CountryFilterPageState extends State<CountryFilterPage> {
       );
     }
 
-    // Handle loaded state (success or loading more)
+    // Handle loaded state (success)
     return ListView.builder(
-      controller: _scrollController,
       padding: const EdgeInsets.symmetric(
         vertical: AppSpacing.paddingSmall,
       ).copyWith(bottom: AppSpacing.xxl),
-      itemCount:
-          state.countries.length +
-          ((state.status == CountriesFilterStatus.loadingMore ||
-                  (state.status == CountriesFilterStatus.failure &&
-                      state.countries.isNotEmpty))
-              ? 1
-              : 0),
+      itemCount: state.countries.length,
       itemBuilder: (context, index) {
-        if (index >= state.countries.length) {
-          if (state.status == CountriesFilterStatus.loadingMore) {
-            return const Padding(
-              padding: EdgeInsets.symmetric(vertical: AppSpacing.lg),
-              child: Center(child: CircularProgressIndicator()),
-            );
-          } else if (state.status == CountriesFilterStatus.failure) {
-            return Padding(
-              padding: const EdgeInsets.symmetric(
-                vertical: AppSpacing.md,
-                horizontal: AppSpacing.lg,
-              ),
-              child: Center(
-                child: Text(
-                  l10n.loadMoreError,
-                  style: textTheme.bodySmall?.copyWith(
-                    color: colorScheme.error,
-                  ),
-                ),
-              ),
-            );
-          }
-          return const SizedBox.shrink();
-        }
-
         final country = state.countries[index];
         final isSelected = _pageSelectedCountries.contains(country);
 

lib/headlines-feed/view/headlines_feed_page.dart

@@ -139,6 +139,8 @@ class _HeadlinesFeedPageState extends State<HeadlinesFeedPage> {
                 final isFilterApplied =
                     (state.filter.topics?.isNotEmpty ?? false) ||
                     (state.filter.sources?.isNotEmpty ?? false) ||
+                    (state.filter.eventCountries?.isNotEmpty ?? false) ||
+                    (state.filter.sourceCountries?.isNotEmpty ?? false) ||
                     state.filter.isFromFollowedItems;
                 return Stack(
                   children: [