🎯 로컬 스토리지 활용 할일 관리 앱

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

void main() => runApp(TodoApp());

class TodoApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: '할 일 관리 앱',
      home: TodoListScreen(),
    );
  }
}

class TodoListScreen extends StatefulWidget {
  @override
  _TodoListScreenState createState() => _TodoListScreenState();
}

class _TodoListScreenState extends State<TodoListScreen> {
  final TextEditingController _controller = TextEditingController();
  List<Map<String, dynamic>> _todos = [];

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

  Future<void> _loadTodos() async {
    final prefs = await SharedPreferences.getInstance();
    final storedTodos = prefs.getStringList('todos');
    if (storedTodos != null) {
      setState(() {
        _todos = storedTodos.map((todo) => Map<String, dynamic>.from(jsonDecode(todo))).toList();
      });
    }
  }

  Future<void> _saveTodos() async {
    final prefs = await SharedPreferences.getInstance();
    final encodedTodos = _todos.map((todo) => jsonEncode(todo)).toList();
    await prefs.setStringList('todos', encodedTodos);
  }

  void _addTodo(String text) {
    if (text.trim().isEmpty) return;

    setState(() {
      _todos.add({
        'id': DateTime.now().microsecondsSinceEpoch.toString(),
        'text': text,
        'completed': false,
      });
      _controller.text = '';
    });

    _saveTodos();
  }

  void _toggleComplete(String id) {
    setState(() {
      final index = _todos.indexWhere((todo) => todo['id'] == id);
      if (index != -1) {
        _todos[index]['completed'] = !_todos[index]['completed'];
        _saveTodos();
      }
    });
  }

  void _deleteTodo(String id) {
    setState(() {
      final index = _todos.indexWhere((todo) => todo['id'] == id);
      if (index != -1) {
        _todos.removeAt(index);
        _saveTodos();
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('할 일 관리 앱')),
      body: Column(
        children: [
          Container(
            padding: EdgeInsets.all(16),
            child: Row(
              children: [
                Expanded(
                  child: TextField(
                    controller: _controller,
                    onSubmitted: (value) => _addTodo(value),
                    decoration: InputDecoration(labelText: '할 일 추가'),
                  ),
                ),
                IconButton(
                  icon: Icon(Icons.add),
                  onPressed: () => _addTodo(_controller.text),
                ),
              ],
            ),
          ),
          Expanded(
            child: ListView.builder(
              itemCount: _todos.length,
              itemBuilder: (context, index) {
                final todo = _todos[index];
                return ListTile(
                  title: Text(todo['text']),
                  trailing: Checkbox(
                    value: todo['completed'],
                    onChanged: (value) => _toggleComplete(todo['id']),
                  ),
                  onLongPress: () => _deleteTodo(todo['id']),
                );
              },
            ),
          ),
        ],
      ),
    );
  }
}