abstract class BaseAuth {
  Future<void> signOut();
}

Future<void> signOut() async {
  return _firebaseAuth.signOut();
}

final BaseAuth auth;
final VoidCallback onSignedOut;

_signOut() async {
  try {
    await widget.auth.signOut();
    widget.onSignedOut();
  } catch (e) {
    print(e);
  }
}

@override
  Widget build(BuildContext context) {
    switch (authStatus) {
      case AuthStatus.NOT_DETERMINED:
        return _buildWaitingScreen();
        break;
      case AuthStatus.NOT_LOGGED_IN:
        return new LoginSignUpPage(
          auth: widget.auth,
          onSignedIn: _onLoggedIn,
        );
        break;
      case AuthStatus.LOGGED_IN:
        if (_userId.length > 0 && _userId != null) {
          return new HomePage(
            userId: _userId,
            auth: widget.auth,
            onSignedOut: _onSignedOut,
          );
        } else return _buildWaitingScreen();
        break;
      default:
        return _buildWaitingScreen();
    }
  }