"""路由缓存"""

import asyncio
import time
from collections import OrderedDict
from dataclasses import dataclass
from typing import Any


@dataclass
class _CacheEntry:
    value: Any
    timestamp: float


class RouteCache:
    """基于 OrderedDict 的进程内 LRU 缓存，上限 4000 条，默认 TTL 60 秒。

    使用 asyncio.Lock 保护并发访问；批量失效时收集待删除 key 后统一移除。
    """

    def __init__(self, maxsize: int = 4000, ttl_seconds: float = 60) -> None:
        self.maxsize = max(maxsize, 1)
        self.ttl = ttl_seconds
        self._data: OrderedDict[str, _CacheEntry] = OrderedDict()
        self._lock = asyncio.Lock()

    def _is_expired(self, entry: _CacheEntry) -> bool:
        return time.time() - entry.timestamp > self.ttl

    async def get(self, key: str) -> Any | None:
        async with self._lock:
            entry = self._data.get(key)
            if entry is None:
                return None
            if self._is_expired(entry):
                self._data.pop(key, None)
                return None
            self._data.move_to_end(key)
            return entry.value

    async def set(self, key: str, value: Any) -> None:
        async with self._lock:
            if key in self._data:
                self._data.move_to_end(key)
            else:
                while len(self._data) >= self.maxsize:
                    self._data.popitem(last=False)
            self._data[key] = _CacheEntry(value=value, timestamp=time.time())

    async def clear(self) -> None:
        async with self._lock:
            self._data.clear()

    async def invalidate_by_channel(self, channel_type: str) -> int:
        """移除所有以 `channel_type:` 开头的缓存条目，返回移除数量。"""
        prefix = f"{channel_type}:"
        async with self._lock:
            keys_to_remove = [k for k in self._data if k.startswith(prefix)]
            for k in keys_to_remove:
                self._data.pop(k, None)
            return len(keys_to_remove)

    async def invalidate_by_account(self, channel_type: str, account_id: str) -> int:
        """移除所有以 `channel_type:account_id:` 开头的缓存条目，返回移除数量。"""
        prefix = f"{channel_type}:{account_id}:"
        async with self._lock:
            keys_to_remove = [k for k in self._data if k.startswith(prefix)]
            for k in keys_to_remove:
                self._data.pop(k, None)
            return len(keys_to_remove)


_default_route_cache: RouteCache | None = None


def get_default_route_cache() -> RouteCache:
    """返回全局共享的默认路由缓存实例。"""
    global _default_route_cache
    if _default_route_cache is None:
        _default_route_cache = RouteCache(maxsize=4000, ttl_seconds=60)
    return _default_route_cache