login

main.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

void main() {
  runApp(MultiProvider(providers: [
    ChangeNotifierProvider<AuthProvider>(
      create: (_) => AuthProvider(),
    ),
  ], child: MyApp()));
}

class MyApp extends StatelessWidget {
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My Poor App',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primaryColor: Color(0xff29c17e),
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: LoginScreen(),
      onGenerateRoute: (settings) {
        if (settings.name == '/logout') {
          return MaterialPageRoute(builder: (context) => LoginScreen());
        } else if (settings.name == '/home') {
          return MaterialPageRoute(builder: (context) => HomeScreen());
        } else if (settings.name == '/category') {
          return MaterialPageRoute(builder: (context) => CategoryScreen());
        } else {
          throw UnimplementedError('Url not fount');
        }
      },
    );
  }
}

class LoginScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Consumer<AuthProvider>(builder: (context, auth, child) {
          if (auth.isBusy) {
            return CircularProgressIndicator();
          } else {
            return MaterialButton(
              onPressed: () async {
                if (await auth.isLogin('user@email.com', 'pass')) {
                  Navigator.pushReplacementNamed(context, '/home');
                } else {
                  // print some auth error
                }
              },
              child: Text('Login'),
            );
          }
        }),
      ),
    );
  }
}

class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final auth = Provider.of<AuthProvider>(context, listen: false);
    return Scaffold(
      body: Center(
        child: MaterialButton(
            elevation: 2,
            onPressed: () {
              Navigator.pushNamed(context, '/category');
            },
            child: Text('Reset')),
      ),
    );
  }
}

class AuthProvider extends ChangeNotifier {
  bool _isAuthenticated = false;

  bool get isAuthenticated => _isAuthenticated;

  bool _isBusy = false;

  bool get isBusy => _isBusy;

  Future<bool> isLogin(String email, String password) async {
    _isBusy = true;
    notifyListeners();
    await Future.delayed(Duration(seconds: 1));
    _isAuthenticated = true;
    notifyListeners();

    _isBusy = false;
    return true;
  }

  Future logout() async {
    _isBusy = true;
    notifyListeners();

    await Future.delayed(Duration(seconds: 1));
    _isAuthenticated = false;
    notifyListeners();

    _isBusy = false;
  }
}

class CategoryScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Consumer<AuthProvider>(
          builder: (context, auth, child) {
            if (auth.isBusy) {
              return CircularProgressIndicator();
            } else {
              return RaisedButton(
                onPressed: () async {
                  await auth.logout();
                  Navigator.pushReplacementNamed(context, '/logout');
                  // print(auth.isAuthenticated);
                },
                child: Text('Category Logout'),
              );
            }
          },
        ),
      ),
    );
  }
}