// Every time the button is tapped, an action is dispatched and
// run through the reducer. After the reducer updates the state,
// the Widget will be automatically rebuilt with the latest
// count. No need to manually manage subscriptions or Streams!
new StoreConnector<int, String>(
  converter: (store) => store.state.toString(),
  builder: (context, count) {
    return new Text(
      count,
      style: Theme.of(context).textTheme.display1,
    );
  },
)

// Creates the base [NextDispatcher].
//
// The base NextDispatcher will be called after all other middleware provided
// by the user have been run. Its job is simple: Run the current state through
// the reducer, save the result, and notify any subscribers.
NextDispatcher _createReduceAndNotify(bool distinct) {
  return (dynamic action) {
    final state = reducer(_state, action);

    if (distinct && state == _state) return;

    _state = state;
    _changeController.add(state);
  };
}

void _bindStateSubject() {
  Event currentEvent;

  (transform(_eventSubject) as Observable<Event>).concatMap((Event event) {
    currentEvent = event;
    return mapEventToState(_stateSubject.value, event);
  }).forEach(
    (State nextState) {
      final transition = Transition(
        currentState: _stateSubject.value,
        event: currentEvent,
        nextState: nextState,
      );
      BlocSupervisor().delegate?.onTransition(transition);
      onTransition(transition);
      _stateSubject.add(nextState);
    },
  );
}

return BlocBuilder<LoginEvent, LoginState>(
  bloc: widget.loginBloc,
  builder: (
    BuildContext context,
    LoginState loginState,
  ) {
    if (_loginSucceeded(loginState)) {
      widget.authBloc.dispatch(Login(token: loginState.token));
      widget.loginBloc.dispatch(LoggedIn());
    }
  }
);

/// Action
///
/// every action should extends this class
abstract class BRAction<T> {
  T payload;
}

/// State
///
/// Input are used to change state.
/// usually filled with StreamController / BehaviorSubject.
/// handled by blocs.
///
/// implements disposable because stream controllers needs to be disposed.
/// they will be called within store's dispose method.
abstract class BRStateInput implements Disposable {}

/// Output are streams.
/// followed by input. like someController.stream
/// UI will use it as data source.
abstract class BRStateOutput {}

/// State
///
/// Combine these two into one.
abstract class BRState<T extends BRStateInput, U extends BRStateOutput> {
  T input;
  U output;
}

/// Bloc
///
/// like reducers in redux, but don't return a new state.
/// when they found something needs to change, just update state's input
/// then state's output will change accordingly.
typedef Bloc<T extends BRStateInput> = void Function(BRAction action, T input);

/// Store
///
/// widget use `store.dispatch` to send action
/// store will iterate all blocs to handle this action
///
/// if this is an async action, blocs can dispatch another action
/// after data has received from remote.
abstract class BRStore<T extends BRStateInput, U extends BRState>
    implements Disposable {
  List<Bloc<T>> blocs;
  U state;

  void dispatch(BRAction action) {
    blocs.forEach((f) => f(action, state.input));
  }

  dispose() {
    state.input.dispose();
  }
}

/// Actions
class ColorActionSelect extends BRAction<Color> {}

/// State
class ColorStateInput extends BRStateInput {
  final BehaviorSubject<Color> selectedColor = BehaviorSubject();
  final BehaviorSubject<List<ColorModel>> colors = BehaviorSubject();

  dispose() {
    selectedColor.close();
    colors.close();
  }
}

class ColorStateOutput extends BRStateOutput {
  StreamWithInitialData<Color> selectedColor;
  StreamWithInitialData<List<ColorModel>> colors;

  ColorStateOutput(ColorStateInput input) {
    selectedColor = StreamWithInitialData(
        input.selectedColor.stream, input.selectedColor.value);
    colors = StreamWithInitialData(input.colors.stream, input.colors.value);
  }
}

class ColorState extends BRState<ColorStateInput, ColorStateOutput> {
  ColorState() {
    input = ColorStateInput();
    output = ColorStateOutput(input);
  }
}

/// Blocs
Bloc<ColorStateInput> colorSelectHandler = (action, input) {
  if (action is ColorActionSelect) {
    input.selectedColor.add(action.payload);
    var colors = input.colors.value
        .map((colorModel) => colorModel
          ..isSelected = colorModel.color.value == action.payload.value)
        .toList();
    input.colors.add(colors);
  }
};

/// Store
class ColorStore extends BRStore<ColorStateInput, ColorState> {
  ColorStore() {
    state = ColorState();
    blocs = [colorSelectHandler];

    // init
    var _colors = List<ColorModel>.generate(
        30, (int index) => ColorModel(RandomColor(index).randomColor()));
    _colors[0].isSelected = true;
    state.input.colors.add(_colors);
    state.input.selectedColor.add(_colors[0].color);
  }
}

class ColorsWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final store = StoreProvider.of<ColorStore>(context);
    final colors = store.state.output.colors;

    return StreamBuilder<List<ColorModel>>(
      stream: colors.stream,
      initialData: colors.initialData,
      builder: (context, snapshot) {
        final colors = snapshot.data;
        return SliverGrid.count(
            crossAxisCount: 6,
            children: colors.map((colorModel) {
              return GestureDetector(
                onTap: () {
                  store.dispatch(
                      ColorActionSelect()..payload = colorModel.color);
                },
                child: Container(
                  decoration: BoxDecoration(
                      color: colorModel.color,
                      border: Border.all(width: colorModel.isSelected ? 4 : 0)),
                ),
              );
            }).toList());
      },
    );
  }
}