flutter-rp-example/lib/widgets/login_screen.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:sampleapp/widgets/components/reflex_circular_progress.dart';

import '../services/auth/auth_view_model.dart';

class LoginScreen extends StatefulWidget {
  final VoidCallback onLogin;

  const LoginScreen({Key? key, required this.onLogin}) : super(key: key);

  @override
  _LoginScreenState createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  Future<void> _login() async {
    final authViewModel = context.read<AuthViewModel>();
    final result = await authViewModel.login();
    if (result == true) widget.onLogin();
  }

  @override
  void initState() {
    super.initState();
    _login();
  }

  @override
  Widget build(BuildContext context) {
    final authViewModel = context.watch<AuthViewModel>();
    return Scaffold(
      body: Center(
        child: authViewModel.loggingIn
            ? const ReflexCircularProgress()
            : ElevatedButton(
                onPressed: () async {
                  await _login();
                },
                child: const Padding(
                  padding: EdgeInsets.all(8.0),
                  child: Text('Log in'),
                ),
              ),
      ),
    );
  }
}