import json
import os
from pathlib import Path
from typing import Dict, Any, Optional
from datetime import datetime
import threading

class DataStore:
    """数据持久化存储服务"""
    
    def __init__(self, storage_dir: str = "data"):
        self.storage_dir = Path(storage_dir)
        self.storage_dir.mkdir(exist_ok=True)
        
        # 数据文件路径
        self.data_file = self.storage_dir / "reports_data.json"
        
        # 内存缓存
        self._cache: Dict[str, Any] = {}
        
        # 线程锁，防止并发写入冲突
        self._lock = threading.Lock()
        
        # 启动时加载数据
        self._load_data()
    
    def _load_data(self):
        """从文件加载数据"""
        if self.data_file.exists():
            try:
                with open(self.data_file, 'r', encoding='utf-8') as f:
                    self._cache = json.load(f)
                print(f"✓ 成功加载 {len(self._cache)} 份报告数据")
            except Exception as e:
                print(f"⚠ 加载数据失败: {e}，将使用空数据")
                self._cache = {}
        else:
            print("✓ 数据文件不存在，将创建新文件")
            self._cache = {}
    
    def _save_data(self):
        """保存数据到文件"""
        try:
            with self._lock:
                # 创建临时文件，避免写入过程中断导致数据损坏
                temp_file = self.data_file.with_suffix('.json.tmp')
                with open(temp_file, 'w', encoding='utf-8') as f:
                    json.dump(self._cache, f, ensure_ascii=False, indent=2)
                
                # 原子性替换
                temp_file.replace(self.data_file)
        except Exception as e:
            print(f"⚠ 保存数据失败: {e}")
    
    def get_all(self) -> Dict[str, Any]:
        """获取所有报告数据"""
        return self._cache.copy()
    
    def get(self, file_id: str) -> Optional[Dict[str, Any]]:
        """获取单个报告数据"""
        return self._cache.get(file_id)
    
    def set(self, file_id: str, data: Dict[str, Any]) -> None:
        """设置/更新报告数据"""
        self._cache[file_id] = data
        self._save_data()
    
    def update(self, file_id: str, updates: Dict[str, Any]) -> None:
        """更新报告数据的部分字段"""
        if file_id in self._cache:
            self._cache[file_id].update(updates)
            self._save_data()
        else:
            raise KeyError(f"报告 {file_id} 不存在")
    
    def delete(self, file_id: str) -> None:
        """删除报告数据"""
        if file_id in self._cache:
            del self._cache[file_id]
            self._save_data()
    
    def exists(self, file_id: str) -> bool:
        """检查报告是否存在"""
        return file_id in self._cache
    
    def count(self) -> int:
        """获取报告总数"""
        return len(self._cache)
    
    def cleanup_orphaned_files(self, upload_dir: Path) -> int:
        """清理孤立的文件（数据库中有记录但文件不存在）"""
        cleaned = 0
        orphaned_ids = []
        
        for file_id, report in self._cache.items():
            filepath = report.get('filepath')
            if filepath and not os.path.exists(filepath):
                orphaned_ids.append(file_id)
        
        for file_id in orphaned_ids:
            self.delete(file_id)
            cleaned += 1
        
        if cleaned > 0:
            print(f"✓ 清理了 {cleaned} 条孤立记录")
        
        return cleaned
    
    def export_backup(self, backup_path: Optional[str] = None) -> str:
        """导出备份"""
        if backup_path is None:
            timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
            backup_path = self.storage_dir / f"backup_{timestamp}.json"
        else:
            backup_path = Path(backup_path)
        
        with open(backup_path, 'w', encoding='utf-8') as f:
            json.dump(self._cache, f, ensure_ascii=False, indent=2)
        
        print(f"✓ 数据已备份到: {backup_path}")
        return str(backup_path)
    
    def import_backup(self, backup_path: str) -> None:
        """从备份恢复数据"""
        backup_path = Path(backup_path)
        if not backup_path.exists():
            raise FileNotFoundError(f"备份文件不存在: {backup_path}")
        
        with open(backup_path, 'r', encoding='utf-8') as f:
            imported_data = json.load(f)
        
        self._cache.update(imported_data)
        self._save_data()
        
        print(f"✓ 已从备份恢复 {len(imported_data)} 份报告")