class UserDialog extends StatefulWidget{
  @override
  _addToCMSState createState() => _addToCMSState();
}
enum Answer{AdminUser, StdUser, AuthUser, BasicUser}

class _addToCMSState extends State<UserDialog> {
  String _answer = "";
  void setUserAuth(String value) {
    setState(() {
      _answer = value;
    });
  }
  Future<Null> _askUser() async {
    switch (
    await showDialog(context: context, builder: (BuildContext context) {
      return SimpleDialog(
        title: Text('Choose User Rights'),
        children: <Widget>[
          SimpleDialogOption(
            onPressed: () {
              Navigator.pop(context, Answer.AdminUser);
            },
            child: Text('Admin User'),
          ),
          SimpleDialogOption(
            onPressed: () {
              Navigator.pop(context, Answer.StdUser);
            },
            child: Text('Standard User'),
          ), SimpleDialogOption(
            onPressed: () {
              Navigator.pop(context, Answer.AuthUser);
            },
            child: Text('Author User'),
          ),
          SimpleDialogOption(
            onPressed: () {
              Navigator.pop(context, Answer.BasicUser);
            },
            child: Text('Basic User'),
          ),
        ],
      );
    }
    )) {
      case Answer.AdminUser:
        setUserAuth('Admin User');
        break;
      case Answer.StdUser:
        setUserAuth('Standard User');
        break;
      case Answer.AuthUser:
        setUserAuth('Author User');
        break;
      case Answer.BasicUser:
        setUserAuth('Basic User');
        break;
    }
  }
  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
}