class StartUpScreen extends StatelessWidget {  const StartUpScreen({Key? key}) : super(key: key);  @override  Widget build(BuildContext context) {    var userProvider = context.read<UserProvider>();    return ViewModelBuilder<StartUpViewModel>.reactive(      viewModelBuilder: () => StartUpViewModel(),      onModelReady: (model) => model.handleStartUpLogic(),      builder: (context, model, child) => Scaffold(          backgroundColor: Colors.white,          body: model.isBusy              ? const CircularProgressIndicator()              : model.isLogged                  ? const HomeScreen()                  : LoginScreen()),    );  }}

class StartUpViewModel extends BaseViewModel {  final AuthenticationService _authenticationService = locator<AuthenticationService>();  bool _isLogged = false;  bool get isLogged {    return _isLogged;  }  Future handleStartUpLogic() async {    setBusy(true);    bool hasLoggedInUser = _authenticationService.isUserLoggedIn();    if (hasLoggedInUser) {      _isLogged = true;      setBusy(false);    } else {      _isLogged = false;      setBusy(false);    }  }}

class LoginScreen extends StatelessWidget {  LoginScreen({Key? key}) : super(key: key);  final emailController = TextEditingController();  final passwordController = TextEditingController();  @override  Widget build(BuildContext context) {    return ViewModelBuilder<LoginViewModel>.reactive(      viewModelBuilder: () => LoginViewModel(),      builder: (context, model, child) => Scaffold(        backgroundColor: Colors.white,        body: Padding(          padding: const EdgeInsets.symmetric(horizontal: 50),          child: Column(            mainAxisSize: MainAxisSize.max,            mainAxisAlignment: MainAxisAlignment.center,            crossAxisAlignment: CrossAxisAlignment.center,            children: <Widget>[              SizedBox(                height: 150,                child: Image.asset('assets/images/title.png'),              ),              InputField(                placeholder: 'Email',                controller: emailController,              ),              verticalSpaceSmall,              InputField(                placeholder: 'Password',                password: true,                controller: passwordController,              ),              verticalSpaceMedium,              Row(                mainAxisSize: MainAxisSize.max,                mainAxisAlignment: MainAxisAlignment.end,                children: [                  BusyButton(                    title: 'Login',                    busy: model.isBusy,                    onPressed: () {                      model.login(                        email: emailController.text,                        password: passwordController.text,                      );                    },                  )                ],              ),              verticalSpaceMedium,            ],          ),        ),      ),    );  }}

class LoginViewModel extends BaseViewModel {  final AuthenticationService _authenticationService = locator<AuthenticationService>();  final DialogService _dialogService = locator<DialogService>();  Future<void> login({    required String email,    required String password,  }) async {    try {      setBusy(true);      await _authenticationService.loginWithEmail(        email: "myemail",        password: "mypass!",      );      setBusy(false);    } catch (e) {      setBusy(false);      await _dialogService.showDialog(        title: 'Login Failure',        description: 'General login failure. Please try again later',      );    }  }}