"""Redis 缓存服务层。

提供统一的缓存读写接口，供各 API 端点使用：
- 品牌列表（TTL: 5 分钟）
- 仪表盘统计数据（TTL: 2 分钟）
- 用户配置信息（TTL: 10 分钟）
"""
import json
import logging

from app.core.redis import get_redis

logger = logging.getLogger(__name__)

# TTL 常量（秒）
TTL_BRANDS = 300        # 5 分钟
TTL_DASHBOARD = 120     # 2 分钟
TTL_USER_PROFILE = 600  # 10 分钟


class CacheService:
    """异步 Redis 缓存服务。使用全局统一 Redis 连接池。"""

    @property
    def redis(self):
        """获取全局 Redis 连接（懒加载）。"""
        from app.core.redis import _redis
        return _redis

    async def get(self, key: str) -> str | None:
        """从缓存读取字符串值，不存在或出错时返回 None。"""
        try:
            redis = await get_redis()
            return await redis.get(key)
        except Exception as exc:
            logger.warning("Cache GET failed for key=%s: %s", key, exc)
            return None

    async def get_json(self, key: str) -> dict | list | str | int | float | bool | None:
        """从缓存读取并反序列化 JSON 值。"""
        raw = await self.get(key)
        if raw is None:
            return None
        try:
            return json.loads(raw)
        except json.JSONDecodeError:
            return None

    async def set(self, key: str, value: str, expire: int = 300) -> None:
        """写入缓存字符串值，expire 单位为秒。"""
        try:
            redis = await get_redis()
            await redis.set(key, value, ex=expire)
        except Exception as exc:
            logger.warning("Cache SET failed for key=%s: %s", key, exc)

    async def set_json(self, key: str, value: dict | list | str | int | float | bool, expire: int = 300) -> None:
        """序列化为 JSON 后写入缓存。"""
        try:
            await self.set(key, json.dumps(value, default=str), expire=expire)
        except Exception as exc:
            logger.warning("Cache SET_JSON failed for key=%s: %s", key, exc)

    async def delete(self, key: str) -> None:
        """删除指定缓存键。"""
        try:
            redis = await get_redis()
            await redis.delete(key)
        except Exception as exc:
            logger.warning("Cache DELETE failed for key=%s: %s", key, exc)

    async def invalidate_pattern(self, pattern: str) -> int:
        """批量删除匹配 pattern 的所有缓存键，返回删除数量。"""
        try:
            redis = await get_redis()
            keys = await redis.keys(pattern)
            if keys:
                return await redis.delete(*keys)
            return 0
        except Exception as exc:
            logger.warning("Cache INVALIDATE_PATTERN failed for pattern=%s: %s", pattern, exc)
            return 0


# 模块级单例
_cache_service: CacheService | None = None


def get_cache_service() -> CacheService:
    """获取全局缓存服务单例。"""
    global _cache_service
    if _cache_service is None:
        _cache_service = CacheService()
    return _cache_service