feat: Implement CreateHeadlineBloc

- Manage headline creation state
- Load sources and categories
- Handle form input changes
- Submit new headline to repository

Author: fulleni

lib/content_management/bloc/create_headline/create_headline_bloc.dart

@@ -0,0 +1,152 @@
+import 'package:bloc/bloc.dart';
+import 'package:equatable/equatable.dart';
+import 'package:flutter/foundation.dart' hide Category;
+import 'package:ht_data_repository/ht_data_repository.dart';
+import 'package:ht_shared/ht_shared.dart';
+
+part 'create_headline_event.dart';
+part 'create_headline_state.dart';
+
+/// A BLoC to manage the state of creating a new headline.
+class CreateHeadlineBloc
+    extends Bloc<CreateHeadlineEvent, CreateHeadlineState> {
+  /// {@macro create_headline_bloc}
+  CreateHeadlineBloc({
+    required HtDataRepository<Headline> headlinesRepository,
+    required HtDataRepository<Source> sourcesRepository,
+    required HtDataRepository<Category> categoriesRepository,
+  }) : _headlinesRepository = headlinesRepository,
+       _sourcesRepository = sourcesRepository,
+       _categoriesRepository = categoriesRepository,
+       super(const CreateHeadlineState()) {
+    on<CreateHeadlineDataLoaded>(_onDataLoaded);
+    on<CreateHeadlineTitleChanged>(_onTitleChanged);
+    on<CreateHeadlineDescriptionChanged>(_onDescriptionChanged);
+    on<CreateHeadlineUrlChanged>(_onUrlChanged);
+    on<CreateHeadlineImageUrlChanged>(_onImageUrlChanged);
+    on<CreateHeadlineSourceChanged>(_onSourceChanged);
+    on<CreateHeadlineCategoryChanged>(_onCategoryChanged);
+    on<CreateHeadlineSubmitted>(_onSubmitted);
+  }
+
+  final HtDataRepository<Headline> _headlinesRepository;
+  final HtDataRepository<Source> _sourcesRepository;
+  final HtDataRepository<Category> _categoriesRepository;
+
+  Future<void> _onDataLoaded(
+    CreateHeadlineDataLoaded event,
+    Emitter<CreateHeadlineState> emit,
+  ) async {
+    emit(state.copyWith(status: CreateHeadlineStatus.loading));
+    try {
+      final [sourcesResponse, categoriesResponse] = await Future.wait([
+        _sourcesRepository.readAll(),
+        _categoriesRepository.readAll(),
+      ]);
+
+      final sources = (sourcesResponse as PaginatedResponse<Source>).items;
+      final categories =
+          (categoriesResponse as PaginatedResponse<Category>).items;
+
+      emit(
+        state.copyWith(
+          status: CreateHeadlineStatus.initial,
+          sources: sources,
+          categories: categories,
+        ),
+      );
+    } on HtHttpException catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateHeadlineStatus.failure,
+          errorMessage: e.message,
+        ),
+      );
+    } catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateHeadlineStatus.failure,
+          errorMessage: e.toString(),
+        ),
+      );
+    }
+  }
+
+  void _onTitleChanged(
+    CreateHeadlineTitleChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(title: event.title));
+  }
+
+  void _onDescriptionChanged(
+    CreateHeadlineDescriptionChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(description: event.description));
+  }
+
+  void _onUrlChanged(
+    CreateHeadlineUrlChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(url: event.url));
+  }
+
+  void _onImageUrlChanged(
+    CreateHeadlineImageUrlChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(imageUrl: event.imageUrl));
+  }
+
+  void _onSourceChanged(
+    CreateHeadlineSourceChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(source: () => event.source));
+  }
+
+  void _onCategoryChanged(
+    CreateHeadlineCategoryChanged event,
+    Emitter<CreateHeadlineState> emit,
+  ) {
+    emit(state.copyWith(category: () => event.category));
+  }
+
+  Future<void> _onSubmitted(
+    CreateHeadlineSubmitted event,
+    Emitter<CreateHeadlineState> emit,
+  ) async {
+    if (!state.isFormValid) return;
+
+    emit(state.copyWith(status: CreateHeadlineStatus.submitting));
+    try {
+      final newHeadline = Headline(
+        title: state.title,
+        description: state.description.isNotEmpty ? state.description : null,
+        url: state.url.isNotEmpty ? state.url : null,
+        imageUrl: state.imageUrl.isNotEmpty ? state.imageUrl : null,
+        source: state.source,
+        category: state.category,
+      );
+
+      await _headlinesRepository.create(item: newHeadline);
+      emit(state.copyWith(status: CreateHeadlineStatus.success));
+    } on HtHttpException catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateHeadlineStatus.failure,
+          errorMessage: e.message,
+        ),
+      );
+    } catch (e) {
+      emit(
+        state.copyWith(
+          status: CreateHeadlineStatus.failure,
+          errorMessage: e.toString(),
+        ),
+      );
+    }
+  }
+}