from __future__ import annotations

from typing import Optional

try:
    import redis
except Exception:
    redis = None


class CacheBase:
    """缓存接口"""

    def get(self, key: str) -> Optional[str]:
        raise NotImplementedError

    def set(self, key: str, value: str, ttl: int) -> None:
        raise NotImplementedError


class NoopCache(CacheBase):
    """空实现缓存"""

    def get(self, key: str) -> Optional[str]:
        return None

    def set(self, key: str, value: str, ttl: int) -> None:
        return None


class RedisCache(CacheBase):
    """Redis 缓存"""

    def __init__(self, url: str, db: int = 0):
        if redis is None:
            raise ImportError("未安装 redis 依赖")
        self._client = redis.Redis.from_url(url, db=db, decode_responses=True)

    def get(self, key: str) -> Optional[str]:
        return self._client.get(key)

    def set(self, key: str, value: str, ttl: int) -> None:
        self._client.set(key, value, ex=ttl)