"""
数据持久化模块，负责Todo数据的保存和加载
"""

import json
import os
from typing import Dict
from .todo import Todo


class Storage:
    """数据存储类"""
    
    def __init__(self, filepath: str = "todos.json"):
        self.filepath = filepath
    
    def save(self, todo: Todo) -> bool:
        """保存Todo数据到文件"""
        try:
            data = todo.to_dict()
            with open(self.filepath, 'w', encoding='utf-8') as f:
                json.dump(data, f, ensure_ascii=False, indent=2)
            return True
        except Exception as e:
            print(f"保存失败: {e}")
            return False
    
    def load(self) -> Todo:
        """从文件加载Todo数据"""
        todo = Todo()
        
        if not os.path.exists(self.filepath):
            return todo
        
        try:
            with open(self.filepath, 'r', encoding='utf-8') as f:
                data = json.load(f)
            todo.from_dict(data)
        except json.JSONDecodeError:
            print(f"警告: {self.filepath} 文件格式错误，将创建新文件")
        except Exception as e:
            print(f"加载失败: {e}")
        
        return todo
    
    def exists(self) -> bool:
        """检查存储文件是否存在"""
        return os.path.exists(self.filepath)
    
    def delete(self) -> bool:
        """删除存储文件"""
        try:
            if self.exists():
                os.remove(self.filepath)
            return True
        except Exception as e:
            print(f"删除文件失败: {e}")
            return False