firebase_auto_sign_in_snipet

Future<Null> _handleSignIn() async {
    print("handleSignIn");
    try {
      GoogleSignInAccount googleUser = await _googleSignIn.signIn();
      GoogleSignInAuthentication googleAuth = await googleUser.authentication;
      await _auth.signInWithGoogle(
        accessToken: googleAuth.accessToken,
        idToken: googleAuth.idToken,
      );
    } catch (error) {
      print(error);
    }
  }
  
  
  
  *******************************************************************************************
  
  
  class MyApp extends StatelessWidget {

//  Widget home = new MyHomePage(title: 'Gymie');

  Future<FirebaseUser> _checkUser () async {
    final FirebaseUser currentUser = await auth.currentUser();
//    if (currentUser != null) home = new ChatHome();
    return currentUser;
  }

  @override
  Widget build (BuildContext context) {

    Widget home = new MyHomePage(title: 'Gymie');

    _checkUser().then((FirebaseUser user) {
        home = new ChatHome();
      }
    );

//    _checkUser();

    return new MaterialApp(
      title: 'Gymie',
      home: home,
      routes: <String, WidgetBuilder> {
        '/login': (BuildContext context) => new Login(),
        '/signup': (BuildContext context) => new Signup(),
        '/chat' : (BuildContext context) => new ChatHome()
      }
    );
  }
}





************************************************************************************************************
************************************************************************************************************


void main() {
  runApp(new MyApp());
}

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

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

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

class _MyHomePageState extends State<MyHomePage> {

  int _counter = 0;

  @override
  initState() {
    super.initState();
    mostraUID();
  }



  Future<Null> mostraUID() async {

    print("Entrei na mostraUID");

    GoogleSignInAccount user = googleSignIn.currentUser;
    if(user == null)
      user = await googleSignIn.signInSilently();
    if(user == null) {
      user = await googleSignIn.signIn();
    }

    // O gerenciamento de TOKEN é implícito
    if(await auth.currentUser() == null) {
      GoogleSignInAuthentication credentials = await googleSignIn.currentUser.authentication;
      await auth.signInWithGoogle(
        idToken: credentials.idToken,
        accessToken: credentials.accessToken,
      );
    }

    _loggedUser = user.email;

    FirebaseUser userFirebase = await FirebaseAuth.instance.currentUser();
    print("User no Firebase: " + userFirebase.uid);
    print("User no GoogleSignIn: " + user.email);

  }




  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {

    print("Entrei no Widget build(Build Context context)");

    setState(() {
      _loggedUserTitle = _loggedUser;
    });

    return new Scaffold(
      appBar: new AppBar(
        //title: new Text(widget.title),

        // *************************************************************************************************** //
        // I'll use "message/$_loggedUser" to compose my database reference (Firebase) to show user's messages
        title: new Text(_loggedUserTitle),
        // *************************************************************************************************** //

      ),
      body: new Center(
        child: new Text(
          'Button tapped $_counter time${ _counter == 1 ? '' : 's' }.',
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

}