import asyncio
import json
import logging
from pathlib import Path
from typing import Any, Dict, List, Optional

log = logging.getLogger("qwen2api.db")

# ──────────────────────────────────────────────
#  JSON 文件存储（本地开发 / Docker 卷模式）
# ──────────────────────────────────────────────

class AsyncJsonDB:
    """带异步读写锁的 JSON 文件存储，防止并发损坏。"""
    def __init__(self, path: str | Path, default_data: Any = None):
        self.path = Path(path)
        self.default_data = default_data if default_data is not None else []
        self._lock = asyncio.Lock()
        self._data: Any = None
        self._init_file()

    def _init_file(self):
        if not self.path.exists():
            self.path.parent.mkdir(parents=True, exist_ok=True)
            self.path.write_text(json.dumps(self.default_data, indent=2, ensure_ascii=False), encoding="utf-8")

    async def load(self) -> Any:
        async with self._lock:
            if not self.path.exists():
                self._data = self.default_data
                return self._data
            try:
                content = self.path.read_text(encoding="utf-8")
                self._data = json.loads(content)
            except Exception as e:
                log.error(f"Failed to load JSON from {self.path}: {e}")
                self._data = self.default_data
            return self._data

    async def save(self, data: Any):
        async with self._lock:
            self._data = data
            try:
                self.path.write_text(json.dumps(self._data, indent=2, ensure_ascii=False), encoding="utf-8")
            except Exception as e:
                log.error(f"Failed to save JSON to {self.path}: {e}")

    async def get(self) -> Any:
        if self._data is None:
            return await self.load()
        return self._data


# ──────────────────────────────────────────────
#  MongoDB Atlas 持久化（Hugging Face 等无状态环境）
# ──────────────────────────────────────────────

class AsyncMongoDB:
    """MongoDB Atlas 持久化存储，接口与 AsyncJsonDB 完全兼容。

    每个实例对应一个 MongoDB collection，
    将整个 list 作为单个文档存储（_id="data", value=<list>），
    保证最小改动即可替换 AsyncJsonDB。
    """

    def __init__(self, collection_name: str, db, default_data: Any = None):
        self._collection = db[collection_name]
        self.default_data = default_data if default_data is not None else []
        self._lock = asyncio.Lock()
        self._data: Any = None

    async def load(self) -> Any:
        async with self._lock:
            try:
                doc = await self._collection.find_one({"_id": "data"})
                self._data = doc["value"] if doc else self.default_data
            except Exception as e:
                log.error(f"MongoDB load failed for {self._collection.name}: {e}")
                self._data = self.default_data
            return self._data

    async def save(self, data: Any):
        async with self._lock:
            self._data = data
            try:
                await self._collection.replace_one(
                    {"_id": "data"},
                    {"_id": "data", "value": data},
                    upsert=True,
                )
            except Exception as e:
                log.error(f"MongoDB save failed for {self._collection.name}: {e}")

    async def get(self) -> Any:
        if self._data is None:
            return await self.load()
        return self._data


# ──────────────────────────────────────────────
#  工厂函数：根据配置自动选择存储后端
# ──────────────────────────────────────────────

_mongo_client = None
_mongo_db = None


async def init_mongo(uri: str, db_name: str, timeout_ms: int = 5000):
    """初始化全局 MongoDB 连接，在 lifespan 启动时调用一次。"""
    global _mongo_client, _mongo_db
    from motor.motor_asyncio import AsyncIOMotorClient
    _mongo_client = AsyncIOMotorClient(
        uri,
        serverSelectionTimeoutMS=timeout_ms,
        connectTimeoutMS=timeout_ms,
    )
    _mongo_db = _mongo_client[db_name]
    # 验证连接
    await _mongo_client.admin.command("ping")
    log.info(f"MongoDB Atlas 已连接 → db={db_name}")


async def close_mongo():
    """关闭 MongoDB 连接，在 lifespan 关闭时调用。"""
    global _mongo_client, _mongo_db
    if _mongo_client:
        _mongo_client.close()
        _mongo_client = None
        _mongo_db = None
        log.info("MongoDB 连接已关闭")


def get_mongo_db():
    """返回当前 MongoDB database 实例（可能为 None）。"""
    return _mongo_db


def create_db(collection_name: str, file_path: str, default_data: Any = None):
    """工厂函数：有 MongoDB 时返回 AsyncMongoDB，否则回退到 AsyncJsonDB。"""
    if _mongo_db is not None:
        return AsyncMongoDB(collection_name, _mongo_db, default_data)
    return AsyncJsonDB(file_path, default_data)