import 'package:flutter/material.dart';
import 'package:rx_redux/rx_redux.dart';
import 'package:rxdart/rxdart.dart';
import 'package:random_string/random_string.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(primarySwatch: Colors.red),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

// actions

abstract class Action {}

class AddTodo implements Action {
  final Todo todo;

  AddTodo(this.todo);
}

class RemoveTodo implements Action {
  final Todo todo;

  RemoveTodo(this.todo);
}

class ToggleTodo implements Action {
  final Todo todo;

  ToggleTodo(this.todo);
}

class TodoAdded implements Action {
  final Todo todo;

  TodoAdded(this.todo);
}

class TodoRemoved implements Action {
  final Todo todo;

  TodoRemoved(this.todo);
}

class TodoToggled implements Action {
  final Todo todo;

  TodoToggled(this.todo);
}

// view state

class Todo {
  final int id;
  final String title;
  final bool completed;

  const Todo(this.id, this.title, this.completed);
}

class ViewState {
  final List<Todo> todos;

  const ViewState(this.todos);
}

class _MyHomePageState extends State<MyHomePage> {
  static var _id = 0;
  final actionS = PublishSubject<Action>();
  ValueObservable<ViewState> state$;

  @override
  void initState() {
    super.initState();

    const initialVS = ViewState([]);
    state$ = actionS
        .transform(
          ReduxStoreStreamTransformer<Action, ViewState>(
            initialStateSupplier: () => initialVS,
            reducer: (ViewState vs, Action action) {
              if (action is AddTodo) return vs;
              if (action is RemoveTodo) return vs;
              if (action is ToggleTodo) return vs;

              if (action is TodoAdded) {
                return ViewState([...vs.todos, action.todo]);
              }

              if (action is TodoRemoved) {
                return ViewState(
                  vs.todos.where((t) => t.id != action.todo.id).toList(),
                );
              }

              if (action is TodoToggled) {
                return ViewState(
                  vs.todos.map((t) {
                    if (t.id != action.todo.id) {
                      return t;
                    } else {
                      return Todo(
                        t.id,
                        t.title,
                        !t.completed,
                      );
                    }
                  }).toList(),
                );
              }

              return vs;
            },
            sideEffects: [
              (action$, state) {
                return action$
                    .whereType<AddTodo>()
                    .map((action) => action.todo)
                    .flatMap((todo) async* {
                  await Future.delayed(const Duration(milliseconds: 500));
                  yield TodoAdded(todo);
                });
              },
              (action$, state) {
                return action$
                    .whereType<RemoveTodo>()
                    .map((action) => action.todo)
                    .flatMap((todo) async* {
                  await Future.delayed(const Duration(milliseconds: 500));
                  yield TodoRemoved(todo);
                });
              },
              (action$, state) {
                return action$
                    .whereType<ToggleTodo>()
                    .map((action) => action.todo)
                    .flatMap((todo) async* {
                  await Future.delayed(const Duration(milliseconds: 500));
                  yield TodoToggled(todo);
                });
              },
            ],
          ),
        )
        .shareValueSeeded(initialVS);
  }

  @override
  void dispose() {
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('RxRedux demo'),
      ),
      body: StreamBuilder<ViewState>(
        initialData: state$.value,
        stream: state$,
        builder: (context, snapshot) {
          final todos = snapshot.data.todos;

          return ListView.builder(
            itemCount: todos.length,
            itemBuilder: (context, index) {
              final todo = todos[index];

              return CheckboxListTile(
                title: Text(todo.title),
                onChanged: (_) => actionS.add(ToggleTodo(todo)),
                value: todo.completed,
                secondary: IconButton(
                  icon: Icon(
                    Icons.delete,
                    color: Theme.of(context).accentColor,
                  ),
                  onPressed: () => actionS.add(RemoveTodo(todo)),
                ),
              );
            },
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          actionS.add(
            AddTodo(
              Todo(
                ++_id,
                randomString(10),
                false,
              ),
            ),
          );
        },
      ),
    );
  }
}