import 'bloc.dart';
import 'notifier.dart';

/// BAD: `bumpWithoutNotifying` mutates state and never notifies.
class StaleNotifier extends ChangeNotifier {
  int _count = 0;

  int get count => _count;

  void bumpWithoutNotifying() {
    _count = _count + 1;
  }

  /// GOOD: notifies directly.
  void bump() {
    _count = _count + 1;
    notifyListeners();
  }

  /// GOOD: mutates, but a notifying method calls it, so the caller announces
  /// the change.
  void setQuiet(int next) {
    _count = next;
  }

  void setAndAnnounce(int next) {
    setQuiet(next);
    notifyListeners();
  }
}

/// BAD: consumed by a Consumer but has no notifying path at all, so that
/// Consumer can never rebuild.
class InertNotifier extends ChangeNotifier {
  int _value = 0;

  int get value => _value;

  void setValue(int next) {
    _value = next;
  }
}

/// GOOD: consumed and it notifies.
class LiveNotifier extends ChangeNotifier {
  int _value = 0;

  int get value => _value;

  void setValue(int next) {
    _value = next;
    notifyListeners();
  }
}

/// Consumed by the UI, but `unusedFlag` is read nowhere: dead state the user can
/// never see, while `value` is displayed.
class PartiallyReadNotifier extends ChangeNotifier {
  int _value = 0;
  bool _unusedFlag = false;

  int get value => _value;

  bool get unusedFlag => _unusedFlag;

  void setValue(int next) {
    _value = next;
    notifyListeners();
  }
}

/// A union whose variants are matched ONLY through typed variable patterns
/// (`case PatternA value:`), which an object-pattern-only matcher misses.
abstract class PatternState {
  const PatternState();
}

class PatternA extends PatternState {
  const PatternA();
}

class PatternB extends PatternState {
  const PatternB();
}

class PatternEvent {}

class PatternBloc extends Bloc<PatternEvent, PatternState> {
  PatternBloc() : super(const PatternA());

  void go() => emit(const PatternB());
}

/// A loading variant emitted on a path whose catch DOES resolve it. The negative
/// control for `loading-not-reset`: reporting every loading-emit-then-await would
/// flag this cubit, and it must stay silent.
abstract class GuardedState {
  const GuardedState();
}

class GuardedLoading extends GuardedState {
  const GuardedLoading();
}

class GuardedReady extends GuardedState {
  const GuardedReady();
}

class GuardedCubit extends Bloc<PatternEvent, GuardedState> {
  GuardedCubit() : super(const GuardedReady());

  Future<void> load() async {
    emit(const GuardedLoading());
    try {
      await Future<void>.delayed(Duration.zero);
      emit(const GuardedReady());
    } catch (error) {
      emit(const GuardedReady());
    }
  }
}

/// A flag that defaults to FALSE, awaited from the constructor. Nothing is in
/// flight, so `loading-flag-not-reset` must stay silent - the negative control
/// for that rule, and the regression guard for the missing `defaultsTrue` check.
class QuietState {
  const QuietState({this.loading = false, this.saved = false});

  final bool loading;
  final bool saved;

  QuietState copyWith({bool? loading, bool? saved}) => QuietState(
        loading: loading ?? this.loading,
        saved: saved ?? this.saved,
      );
}

class QuietCubit extends Bloc<PatternEvent, QuietState> {
  QuietCubit() : super(const QuietState()) {
    _warmUp();
  }

  Future<void> _warmUp() async {
    await Future<void>.delayed(Duration.zero);
  }

  /// Sets the flag in flight and resolves it on every path.
  Future<void> save() async {
    emit(state.copyWith(loading: true));
    try {
      await Future<void>.delayed(Duration.zero);
      emit(state.copyWith(loading: false, saved: true));
    } catch (error) {
      emit(state.copyWith(loading: false));
    }
  }
}