main.dart

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

void main() {
  runApp(const ProviderScope(child: MyApp()));
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Todo List with Riverpod',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const TodoListPage(),
    );
  }
}


class Todo {
  String title;
  bool completed;

  Todo({
    required this.title,
    this.completed = false,
  });
}

class TodoListNotifier extends StateNotifier<List<Todo>> {
  TodoListNotifier() : super([]);

  void addTodo(String title) {
    state = [...state, Todo(title: title)];
  }

  void toggleCompleted(int index) {
    var todo = state[index];
    state = [
      ...state.sublist(0, index),
      Todo(
        title: todo.title,
        completed: !todo.completed,
      ),
      ...state.sublist(index + 1),
    ];
  }

  void removeTodo(int index) {
    state = [...state.sublist(0, index), ...state.sublist(index + 1)];
  }
}

final todoListProvider = StateNotifierProvider<TodoListNotifier, List<Todo>>((ref) {
  return TodoListNotifier();
});


class TodoListPage extends ConsumerWidget {
  const TodoListPage({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    List<Todo> todos = ref.watch(todoListProvider);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Todo List'),
      ),
      body: ListView.builder(
        itemCount: todos.length,
        itemBuilder: (context, index) {
          final todo = todos[index];
          return ListTile(
            title: Text(todo.title),
            leading: Checkbox(
              value: todo.completed,
              onChanged: (_) => ref.read(todoListProvider.notifier).toggleCompleted(index),
            ),
            trailing: IconButton(
              icon: const Icon(Icons.delete),
              onPressed: () => ref.read(todoListProvider.notifier).removeTodo(index),
            ),
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _showAddTodoDialog(context, ref),
        child: const Icon(Icons.add),
      ),
    );
  }

  void _showAddTodoDialog(BuildContext context, WidgetRef ref) {
    final TextEditingController controller = TextEditingController();
    showDialog(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: const Text('Add Todo'),
          content: TextField(
            controller: controller,
            decoration: const InputDecoration(hintText: 'Todo title'),
          ),
          actions: [
            TextButton(
              onPressed: () {
                ref.read(todoListProvider.notifier).addTodo(controller.text);
                Navigator.of(context).pop();
              },
              child: const Text('Add'),
            ),
          ],
        );
      },
    );
  }
}