class CounterNotifier extends StateNotifier<RemoteState<int>> {
  var _counterClient = CounterClient();

  CounterNotifier() : super(RemoteState.initial()) {
    getCount();
  }

  getCount() async {
    state = RemoteState.loading();

    state = await RemoteState.guard(() => _counterClient.getCount());
  }

  increment() async {
    state = await RemoteState.guard(() => _counterClient.increment());
  }

  decrement() async {
    state = await RemoteState.guard(() => _counterClient.decrement());
  }
}

class ExampleApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: StateNotifierProvider<CounterNotifier, RemoteState<int>>.value(
        value: CounterNotifier(),
        child: HomePage(),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    //2. Resolve counter notifier to update state
    var counterNotifier = Provider.of<CounterNotifier>(context);
    var counterState = Provider.of<RemoteState<int>>(context);

    var textStyle = Theme.of(context).textTheme.headline4;
    final fabPadding = EdgeInsets.symmetric(vertical: 5.0);

    return Scaffold(
      appBar: AppBar(
        title: Text('RemoteState with StateNotifier'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have pushed the button this many times:'),
            //3. Render state changes
            counterState.when(
              initial: () => Text('Not loaded', style: textStyle),
              success: (value) => Text('$value', style: textStyle),
              loading: () => Text('Loading...', style: textStyle),
              error: (_) => Text('Error', style: textStyle),
            ),
          ],
        ),
      ),
      floatingActionButton: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          Padding(
            padding: fabPadding,
            child: FloatingActionButton(
              heroTag: 'inc',
              child: Icon(Icons.add),
              //4. Perform increment action
              onPressed: () => counterNotifier.increment(),
            ),
          ),
          Padding(
            padding: fabPadding,
            child: FloatingActionButton(
              heroTag: 'dec',
              child: Icon(Icons.remove),
              //5. Perform decrement action
              onPressed: () => counterNotifier.decrement(),
            ),
          ),
        ],
      ),
    );
  }
}