feat(content_management): enhance ArchivedTopicsBloc with pagination and restore functionality

Author: fulleni

lib/content_management/bloc/archived_topics/archived_topics_bloc.dart

@@ -1,13 +1,92 @@
 import 'package:bloc/bloc.dart';
+import 'package:core/core.dart';
+import 'package:data_repository/data_repository.dart';
 import 'package:equatable/equatable.dart';
 
 part 'archived_topics_event.dart';
 part 'archived_topics_state.dart';
 
-class ArchivedTopicsBloc extends Bloc<ArchivedTopicsEvent, ArchivedTopicsState> {
-  ArchivedTopicsBloc() : super(ArchivedTopicsInitial()) {
-    on<ArchivedTopicsEvent>((event, emit) {
-      // TODO: implement event handler
-    });
+class ArchivedTopicsBloc
+    extends Bloc<ArchivedTopicsEvent, ArchivedTopicsState> {
+  ArchivedTopicsBloc({
+    required DataRepository<Topic> topicsRepository,
+  })  : _topicsRepository = topicsRepository,
+        super(const ArchivedTopicsState()) {
+    on<LoadArchivedTopicsRequested>(_onLoadArchivedTopicsRequested);
+    on<RestoreTopicRequested>(_onRestoreTopicRequested);
+  }
+
+  final DataRepository<Topic> _topicsRepository;
+
+  Future<void> _onLoadArchivedTopicsRequested(
+    LoadArchivedTopicsRequested event,
+    Emitter<ArchivedTopicsState> emit,
+  ) async {
+    emit(state.copyWith(status: ArchivedTopicsStatus.loading));
+    try {
+      final isPaginating = event.startAfterId != null;
+      final previousTopics = isPaginating ? state.topics : <Topic>[];
+
+      final paginatedTopics = await _topicsRepository.readAll(
+        filter: {'status': ContentStatus.archived.name},
+        sort: [const SortOption('updatedAt', SortOrder.desc)],
+        pagination: PaginationOptions(
+          cursor: event.startAfterId,
+          limit: event.limit,
+        ),
+      );
+      emit(
+        state.copyWith(
+          status: ArchivedTopicsStatus.success,
+          topics: [...previousTopics, ...paginatedTopics.items],
+          cursor: paginatedTopics.cursor,
+          hasMore: paginatedTopics.hasMore,
+        ),
+      );
+    } on HttpException catch (e) {
+      emit(
+        state.copyWith(
+          status: ArchivedTopicsStatus.failure,
+          exception: e,
+        ),
+      );
+    } catch (e) {
+      emit(
+        state.copyWith(
+          status: ArchivedTopicsStatus.failure,
+          exception: UnknownException('An unexpected error occurred: $e'),
+        ),
+      );
+    }
+  }
+
+  Future<void> _onRestoreTopicRequested(
+    RestoreTopicRequested event,
+    Emitter<ArchivedTopicsState> emit,
+  ) async {
+    final originalTopics = List<Topic>.from(state.topics);
+    final topicIndex = originalTopics.indexWhere((t) => t.id == event.id);
+    if (topicIndex == -1) return;
+
+    final topicToRestore = originalTopics[topicIndex];
+    final updatedTopics = originalTopics..removeAt(topicIndex);
+
+    emit(state.copyWith(topics: updatedTopics));
+
+    try {
+      await _topicsRepository.update(
+        id: event.id,
+        item: topicToRestore.copyWith(status: ContentStatus.active),
+      );
+    } on HttpException catch (e) {
+      emit(state.copyWith(topics: originalTopics, exception: e));
+    } catch (e) {
+      emit(
+        state.copyWith(
+          topics: originalTopics,
+          exception: UnknownException('An unexpected error occurred: $e'),
+        ),
+      );
+    }
   }
 }