refactor(content_management): simplify source creation form data handling

fulleni · fulleni · commit 5f10e99494d9 · 2025-08-02T19:04:31.000+01:00
- Remove pagination and background fetching for countries and languages
- Load full lists of countries and languages at once
- Cache countries and languages in ContentManagementBloc
- Update CreateSourceBloc to use cached lists
- Simplify UI logic for dropdowns
diff --git a/lib/content_management/bloc/create_source/create_source_bloc.dart b/lib/content_management/bloc/create_source/create_source_bloc.dart
@@ -8,26 +8,20 @@ import 'package:uuid/uuid.dart';
 part 'create_source_event.dart';
 part 'create_source_state.dart';
 
-final class _FetchNextCountryPage extends CreateSourceEvent {
-  const _FetchNextCountryPage();
-}
-
-final class _FetchNextLanguagePage extends CreateSourceEvent {
-  const _FetchNextLanguagePage();
-}
-
 /// A BLoC to manage the state of creating a new source.
 class CreateSourceBloc extends Bloc<CreateSourceEvent, CreateSourceState> {
   /// {@macro create_source_bloc}
   CreateSourceBloc({
     required DataRepository<Source> sourcesRepository,
-    required DataRepository<Country> countriesRepository,
-    required DataRepository<Language> languagesRepository,
-  }) : _sourcesRepository = sourcesRepository,
-       _countriesRepository = countriesRepository,
-       _languagesRepository = languagesRepository,
-       super(const CreateSourceState()) {
-    on<CreateSourceDataLoaded>(_onDataLoaded);
+    required List<Country> countries,
+    required List<Language> languages,
+  })  : _sourcesRepository = sourcesRepository,
+        super(
+          CreateSourceState(
+            countries: countries,
+            languages: languages,
+          ),
+        ) {
     on<CreateSourceNameChanged>(_onNameChanged);
     on<CreateSourceDescriptionChanged>(_onDescriptionChanged);
     on<CreateSourceUrlChanged>(_onUrlChanged);
@@ -36,65 +30,11 @@ class CreateSourceBloc extends Bloc<CreateSourceEvent, CreateSourceState> {
     on<CreateSourceHeadquartersChanged>(_onHeadquartersChanged);
     on<CreateSourceStatusChanged>(_onStatusChanged);
     on<CreateSourceSubmitted>(_onSubmitted);
-    on<_FetchNextCountryPage>(_onFetchNextCountryPage);
-    on<_FetchNextLanguagePage>(_onFetchNextLanguagePage);
   }
 
   final DataRepository<Source> _sourcesRepository;
-  final DataRepository<Country> _countriesRepository;
-  final DataRepository<Language> _languagesRepository;
   final _uuid = const Uuid();
 
-  Future<void> _onDataLoaded(
-    CreateSourceDataLoaded event,
-    Emitter<CreateSourceState> emit,
-  ) async {
-    emit(state.copyWith(status: CreateSourceStatus.loading));
-    try {
-      final responses = await Future.wait([
-        _countriesRepository.readAll(
-          sort: [const SortOption('name', SortOrder.asc)],
-          filter: {'status': ContentStatus.active.name},
-        ),
-        _languagesRepository.readAll(
-          sort: [const SortOption('name', SortOrder.asc)],
-          filter: {'status': ContentStatus.active.name},
-        ),
-      ]);
-      final countriesPaginated = responses[0] as PaginatedResponse<Country>;
-      final languagesPaginated = responses[1] as PaginatedResponse<Language>;
-      emit(
-        state.copyWith(
-          status: CreateSourceStatus.initial,
-          countries: countriesPaginated.items,
-          countriesCursor: countriesPaginated.cursor,
-          countriesHasMore: countriesPaginated.hasMore,
-          languages: languagesPaginated.items,
-          languagesCursor: languagesPaginated.cursor,
-          languagesHasMore: languagesPaginated.hasMore,
-        ),
-      );
-
-      // After the initial page is loaded, start background processes to
-      // fetch all remaining pages for countries and languages.
-      if (state.countriesHasMore) {
-        add(const _FetchNextCountryPage());
-      }
-      if (state.languagesHasMore) {
-        add(const _FetchNextLanguagePage());
-      }
-    } on HttpException catch (e) {
-      emit(state.copyWith(status: CreateSourceStatus.failure, exception: e));
-    } catch (e) {
-      emit(
-        state.copyWith(
-          status: CreateSourceStatus.failure,
-          exception: UnknownException('An unexpected error occurred: $e'),
-        ),
-      );
-    }
-  }
-
   void _onNameChanged(
     CreateSourceNameChanged event,
     Emitter<CreateSourceState> emit,
@@ -150,84 +90,6 @@ class CreateSourceBloc extends Bloc<CreateSourceEvent, CreateSourceState> {
   }
 
   // --- Background Data Fetching for Dropdown ---
-  // The DropdownButtonFormField widget does not natively support on-scroll
-  // pagination. To preserve UI consistency across the application, this BLoC
-  // employs an event-driven background fetching mechanism.
-  //
-  // After the first page of items is loaded, a chain of events is initiated
-  // to progressively fetch all remaining pages. This process is throttled
-  // and runs in the background, ensuring the UI remains responsive while the
-  // full list of dropdown options is populated over time.
-  Future<void> _onFetchNextCountryPage(
-    _FetchNextCountryPage event,
-    Emitter<CreateSourceState> emit,
-  ) async {
-    if (!state.countriesHasMore || state.countriesIsLoadingMore) return;
-
-    try {
-      emit(state.copyWith(countriesIsLoadingMore: true));
-
-      // ignore: inference_failure_on_instance_creation
-      await Future.delayed(const Duration(milliseconds: 400));
-
-      final nextCountries = await _countriesRepository.readAll(
-        pagination: PaginationOptions(cursor: state.countriesCursor),
-        sort: [const SortOption('name', SortOrder.asc)],
-      );
-
-      emit(
-        state.copyWith(
-          countries: List.of(state.countries)..addAll(nextCountries.items),
-          countriesCursor: nextCountries.cursor,
-          countriesHasMore: nextCountries.hasMore,
-          countriesIsLoadingMore: false,
-        ),
-      );
-
-      if (nextCountries.hasMore) {
-        add(const _FetchNextCountryPage());
-      }
-    } catch (e) {
-      emit(state.copyWith(countriesIsLoadingMore: false));
-      // Optionally log the error without disrupting the user
-    }
-  }
-
-  Future<void> _onFetchNextLanguagePage(
-    _FetchNextLanguagePage event,
-    Emitter<CreateSourceState> emit,
-  ) async {
-    if (!state.languagesHasMore || state.languagesIsLoadingMore) return;
-
-    try {
-      emit(state.copyWith(languagesIsLoadingMore: true));
-
-      // ignore: inference_failure_on_instance_creation
-      await Future.delayed(const Duration(milliseconds: 400));
-
-      final nextLanguages = await _languagesRepository.readAll(
-        pagination: PaginationOptions(cursor: state.languagesCursor),
-        sort: [const SortOption('name', SortOrder.asc)],
-      );
-
-      emit(
-        state.copyWith(
-          languages: List.of(state.languages)..addAll(nextLanguages.items),
-          languagesCursor: nextLanguages.cursor,
-          languagesHasMore: nextLanguages.hasMore,
-          languagesIsLoadingMore: false,
-        ),
-      );
-
-      if (nextLanguages.hasMore) {
-        add(const _FetchNextLanguagePage());
-      }
-    } catch (e) {
-      emit(state.copyWith(languagesIsLoadingMore: false));
-      // Optionally log the error without disrupting the user
-    }
-  }
-
   Future<void> _onSubmitted(
     CreateSourceSubmitted event,
     Emitter<CreateSourceState> emit,
diff --git a/lib/content_management/bloc/create_source/create_source_event.dart b/lib/content_management/bloc/create_source/create_source_event.dart
@@ -8,11 +8,6 @@ sealed class CreateSourceEvent extends Equatable {
   List<Object?> get props => [];
 }
 
-/// Event to signal that the data for dropdowns should be loaded.
-final class CreateSourceDataLoaded extends CreateSourceEvent {
-  const CreateSourceDataLoaded();
-}
-
 /// Event for when the source's name is changed.
 final class CreateSourceNameChanged extends CreateSourceEvent {
   const CreateSourceNameChanged(this.name);
diff --git a/lib/content_management/bloc/create_source/create_source_state.dart b/lib/content_management/bloc/create_source/create_source_state.dart
@@ -30,13 +30,7 @@ final class CreateSourceState extends Equatable {
     this.language,
     this.headquarters,
     this.countries = const [],
-    this.countriesHasMore = true,
-    this.countriesIsLoadingMore = false,
-    this.countriesCursor,
     this.languages = const [],
-    this.languagesHasMore = true,
-    this.languagesIsLoadingMore = false,
-    this.languagesCursor,
     this.contentStatus = ContentStatus.active,
     this.exception,
     this.createdSource,
@@ -50,13 +44,7 @@ final class CreateSourceState extends Equatable {
   final Language? language;
   final Country? headquarters;
   final List<Country> countries;
-  final bool countriesHasMore;
-  final bool countriesIsLoadingMore;
-  final String? countriesCursor;
   final List<Language> languages;
-  final bool languagesHasMore;
-  final bool languagesIsLoadingMore;
-  final String? languagesCursor;
   final ContentStatus contentStatus;
   final HttpException? exception;
   final Source? createdSource;
@@ -79,13 +67,7 @@ final class CreateSourceState extends Equatable {
     ValueGetter<Language?>? language,
     ValueGetter<Country?>? headquarters,
     List<Country>? countries,
-    bool? countriesHasMore,
-    bool? countriesIsLoadingMore,
-    String? countriesCursor,
     List<Language>? languages,
-    bool? languagesHasMore,
-    bool? languagesIsLoadingMore,
-    String? languagesCursor,
     ContentStatus? contentStatus,
     HttpException? exception,
     Source? createdSource,
@@ -99,15 +81,7 @@ final class CreateSourceState extends Equatable {
       language: language != null ? language() : this.language,
       headquarters: headquarters != null ? headquarters() : this.headquarters,
       countries: countries ?? this.countries,
-      countriesHasMore: countriesHasMore ?? this.countriesHasMore,
-      countriesIsLoadingMore:
-          countriesIsLoadingMore ?? this.countriesIsLoadingMore,
-      countriesCursor: countriesCursor ?? this.countriesCursor,
       languages: languages ?? this.languages,
-      languagesHasMore: languagesHasMore ?? this.languagesHasMore,
-      languagesIsLoadingMore:
-          languagesIsLoadingMore ?? this.languagesIsLoadingMore,
-      languagesCursor: languagesCursor ?? this.languagesCursor,
       contentStatus: contentStatus ?? this.contentStatus,
       exception: exception,
       createdSource: createdSource ?? this.createdSource,
@@ -124,13 +98,7 @@ final class CreateSourceState extends Equatable {
     language,
     headquarters,
     countries,
-    countriesHasMore,
-    countriesIsLoadingMore,
-    countriesCursor,
     languages,
-    languagesHasMore,
-    languagesIsLoadingMore,
-    languagesCursor,
     contentStatus,
     exception,
     createdSource,
diff --git a/lib/content_management/view/create_source_page.dart b/lib/content_management/view/create_source_page.dart
@@ -21,12 +21,19 @@ class CreateSourcePage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    // The lists of all countries and languages are fetched once and cached in
+    // the ContentManagementBloc. We read them here and provide them to the
+    // CreateSourceBloc.
+    final contentManagementState = context.read<ContentManagementBloc>().state;
+    final allCountries = contentManagementState.allCountries;
+    final allLanguages = contentManagementState.allLanguages;
+
     return BlocProvider(
       create: (context) => CreateSourceBloc(
         sourcesRepository: context.read<DataRepository<Source>>(),
-        countriesRepository: context.read<DataRepository<Country>>(),
-        languagesRepository: context.read<DataRepository<Language>>(),
-      )..add(const CreateSourceDataLoaded()),
+        countries: allCountries,
+        languages: allLanguages,
+      ),
       child: const _CreateSourceView(),
     );
   }
@@ -114,9 +121,9 @@ class _CreateSourceViewState extends State<_CreateSourceView> {
           if (state.status == CreateSourceStatus.failure) {
             return FailureStateWidget(
               exception: state.exception!,
-              onRetry: () => context.read<CreateSourceBloc>().add(
-                const CreateSourceDataLoaded(),
-              ),
+              onRetry: () => context
+                  .read<ContentManagementBloc>()
+                  .add(const SharedDataRequested()),
             );
           }
 
@@ -167,9 +174,6 @@ class _CreateSourceViewState extends State<_CreateSourceView> {
                       decoration: InputDecoration(
                         labelText: l10n.language,
                         border: const OutlineInputBorder(),
-                        helperText: state.languagesIsLoadingMore
-                            ? l10n.loadingFullList
-                            : null,
                       ),
                       items: [
                         DropdownMenuItem(value: null, child: Text(l10n.none)),
@@ -180,11 +184,9 @@ class _CreateSourceViewState extends State<_CreateSourceView> {
                           ),
                         ),
                       ],
-                      onChanged: state.languagesIsLoadingMore
-                          ? null
-                          : (value) => context.read<CreateSourceBloc>().add(
-                              CreateSourceLanguageChanged(value),
-                            ),
+                      onChanged: (value) => context
+                          .read<CreateSourceBloc>()
+                          .add(CreateSourceLanguageChanged(value)),
                     ),
                     const SizedBox(height: AppSpacing.lg),
                     DropdownButtonFormField<SourceType?>(
@@ -212,9 +214,6 @@ class _CreateSourceViewState extends State<_CreateSourceView> {
                       decoration: InputDecoration(
                         labelText: l10n.headquarters,
                         border: const OutlineInputBorder(),
-                        helperText: state.countriesIsLoadingMore
-                            ? l10n.loadingFullList
-                            : null,
                       ),
                       items: [
                         DropdownMenuItem(value: null, child: Text(l10n.none)),
@@ -241,11 +240,9 @@ class _CreateSourceViewState extends State<_CreateSourceView> {
                           ),
                         ),
                       ],
-                      onChanged: state.countriesIsLoadingMore
-                          ? null
-                          : (value) => context.read<CreateSourceBloc>().add(
-                              CreateSourceHeadquartersChanged(value),
-                            ),
+                      onChanged: (value) => context
+                          .read<CreateSourceBloc>()
+                          .add(CreateSourceHeadquartersChanged(value)),
                     ),
                     const SizedBox(height: AppSpacing.lg),
                     DropdownButtonFormField<ContentStatus>(
