import 'package:token_bloc/token_bloc.dart';

/// A bloc that manages a counter.
class CounterBloc extends TokenBloc {
  /// Creates a [CounterBloc] and sets the action handlers.
  CounterBloc() {
    /// When an [incrementCounterAction] is dispatched, the [_onIncrementAction] method is called.
    onVoid(incrementCounterAction, _onIncrementAction);
    /// When an [decrementCounterAction] is dispatched, the [_onDecrementAction] method is called.
    onVoid(decrementCounterAction, _onDecrementAction);
  }

  /// The state of the counter with an initial value of 0.
  final counterState = TokenState<int>.seeded(0);

  /// The action to increment the counter.
  final incrementCounterAction = TokenActionVoid();

  /// The action to decrement the counter.
  final decrementCounterAction = TokenActionVoid();

  void _onIncrementAction() {
    /// The current value of the counter is obtained with the [valueOf] method.
    final newValue = valueOf(counterState) + 1;

    /// The new value is emitted with the [emitStateOf] method.
    emitStateOf(counterState, newValue);
  }

  void _onDecrementAction() {
    final newValue = valueOf(counterState) - 1;
    emitStateOf(counterState, newValue);
  }

  /// The [subjects] getter is used to obtain the token subjects that the bloc manages.
  @override
  List<TokenSubject<dynamic>> get subjects => [
        counterState,
        incrementCounterAction,
        decrementCounterAction,
      ];
}

Future<void> main() async {
  /// Create the `bloc`.
  final bloc = CounterBloc();

  /// Listen to the counter state changes.
  bloc.counterState.listen((state) {
    print('Counter: ${state.value}');
  });

  /// Dispatch the increment action.
  bloc.incrementCounterAction();

  /// Dispatch the decrement action.
  bloc.decrementCounterAction();

  /// Dispose the `bloc` when it is no longer needed.
  await subscription.dispose();
}