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

class LoginState {
  final String email;
  final String password;
  final bool isLoading;
  final String? error;

  const LoginState({
    this.email = '',
    this.password = '',
    this.isLoading = false,
    this.error,
  });

  LoginState copyWith({
    String? email,
    String? password,
    bool? isLoading,
    String? error,
  }) {
    return LoginState(
      email: email ?? this.email,
      password: password ?? this.password,
      isLoading: isLoading ?? this.isLoading,
      error: error,
    );
  }
}

class LoginController extends StateNotifier<LoginState> {
  LoginController() : super(const LoginState());

  void emailChanged(String value) {
    state = state.copyWith(email: value, error: null);
  }

  void passwordChanged(String value) {
    state = state.copyWith(password: value, error: null);
  }

  Future<void> submit() async {
    if (state.email.isEmpty || state.password.isEmpty) {
      state = state.copyWith(error: 'فیلدها را پر کنید');
      return;
    }
    state = state.copyWith(isLoading: true, error: null);

    await Future.delayed(const Duration(seconds: 1));

    state = state.copyWith(isLoading: false);
  }
}

final loginProvider =
    StateNotifierProvider<LoginController, LoginState>((ref) {
  return LoginController();
});

class MyListPage extends StatelessWidget {
  const MyListPage({super.key});

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: 100,
      itemBuilder: (context, index) {
        return const _MyListItem();
      },
    );
  }
}

class _MyListItem extends StatelessWidget {
  const _MyListItem({super.key});

  @override
  Widget build(BuildContext context) {
    return ListTile(
      leading: const Icon(Icons.person),
      title: const Text('User'),
      subtitle: const Text('Subtitle'),
    );
  }
}

itemBuilder: (context, index) {
  return ListTile(
    leading: const Icon(Icons.person),
    title: Text('User $index'),
  );
}

class CounterViewModel extends ChangeNotifier {
  int _count = 0;

  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (_) => CounterViewModel(),
      child: MaterialApp(
        home: CounterPage(),
      ),
    );
  }
}

class CounterPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final viewModel = context.watch<CounterViewModel>();

    return Scaffold(
      appBar: AppBar(title: const Text('Counter')),
      body: Center(
        child: Text(
          'Count: ${viewModel.count}',
          style: const TextStyle(fontSize: 32),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: viewModel.increment,
        child: const Icon(Icons.add),
      ),
    );
  }
}