PIbd-32_Shabunov_O.A._MobileProgramming/lib/presentation/favourites_bloc/favourites_bloc.dart

import 'package:flutter_bloc/flutter_bloc.dart';
import 'favourites_events.dart';
import 'favourites_state.dart';
import 'package:shared_preferences/shared_preferences.dart';

class FavouritesBloc extends Bloc<FavouritesEvent, FavouritesState> {
  static const String _likedPrefsKey = 'liked';

  FavouritesBloc() : super(const FavouritesState(favouritesIds: [])) {
    on<LoadFavouritesEvent>(_onLoadFavouritesIds);
    on<ChangeFavouriteEvent>(_onChangeFavourite);
  }

  Future<void> _onLoadFavouritesIds(
      LoadFavouritesEvent event, Emitter<FavouritesState> emit
  ) async {
    emit(state.copyWith(
      hasFavouritesLoaded: false,
    ));

    final prefs = await SharedPreferences.getInstance();
    final data = prefs.getStringList(_likedPrefsKey);

    emit(state.copyWith(
        favouritesIds: data,
        hasFavouritesLoaded: true,
    ));
  }

  Future<void> _onChangeFavourite(
      ChangeFavouriteEvent event, Emitter<FavouritesState> emit
  ) async {
    final updatedList = List<String>.from(state.favouritesIds ?? []);

    if (updatedList.contains(event.id)) {
      updatedList.remove(event.id);
    } else {
      updatedList.add(event.id);
    }

    final prefs = await SharedPreferences.getInstance();
    prefs.setStringList(_likedPrefsKey, updatedList);

    emit(state.copyWith(
      favouritesIds: updatedList,
      hasFavouritesLoaded: true,
    ));
  }
}