نمط BLoC لإدارة الحالة

الواجهة (UI) → تُرسِل Event → [ BLoC ] → يُصدِر State → الواجهة تُعيد البناء

flutter pub add flutter_bloc

// counter_event.dart
abstract class CounterEvent {}
class Increment extends CounterEvent {}
class Decrement extends CounterEvent {}

// counter_state.dart — عدد صحيح بسيط يكفي هنا
typedef CounterState = int;

import 'package:flutter_bloc/flutter_bloc.dart';

class CounterBloc extends Bloc<CounterEvent, CounterState> {
  CounterBloc() : super(0) {
    on<Increment>((event, emit) => emit(state + 1));
    on<Decrement>((event, emit) => emit(state - 1));
  }
}

BlocProvider(
  create: (context) => CounterBloc(),
  child: Scaffold(
    body: Center(
      child: BlocBuilder<CounterBloc, CounterState>(
        builder: (context, count) => Text('العدّاد: $count'),
      ),
    ),
    floatingActionButton: Row(
      mainAxisAlignment: MainAxisAlignment.end,
      children: [
        FloatingActionButton(
          onPressed: () => context.read<CounterBloc>().add(Increment()),
          child: Icon(Icons.add),
        ),
        FloatingActionButton(
          onPressed: () => context.read<CounterBloc>().add(Decrement()),
          child: Icon(Icons.remove),
        ),
      ],
    ),
  ),
)

abstract class TasksEvent {}
class LoadTasks extends TasksEvent {}

abstract class TasksState {}
class TasksLoading extends TasksState {}
class TasksLoaded extends TasksState {
  final List<String> tasks;
  TasksLoaded(this.tasks);
}
class TasksError extends TasksState {
  final String message;
  TasksError(this.message);
}

class TasksBloc extends Bloc<TasksEvent, TasksState> {
  TasksBloc() : super(TasksLoading()) {
    on<LoadTasks>((event, emit) async {
      emit(TasksLoading());
      try {
        final snapshot = await FirebaseFirestore.instance.collection('tasks').get();
        final titles = snapshot.docs.map((d) => d['title'] as String).toList();
        emit(TasksLoaded(titles));
      } catch (e) {
        emit(TasksError(e.toString()));
      }
    });
  }
}

BlocBuilder<TasksBloc, TasksState>(
  builder: (context, state) {
    if (state is TasksLoading) return CircularProgressIndicator();
    if (state is TasksError) return Text('خطأ: ${state.message}');
    if (state is TasksLoaded) {
      return ListView(children: state.tasks.map((t) => Text(t)).toList());
    }
    return SizedBox();
  },
)

class CounterCubit extends Cubit<int> {
  CounterCubit() : super(0);
  void increment() => emit(state + 1);
  void decrement() => emit(state - 1);
}

// الاستخدام: context.read<CounterCubit>().increment();