"""Redis 缓存工具 — 键前缀统一、优雅降级（Redis 不可用时透明跳过）"""
import json
import logging
from typing import Any, Optional

import redis.asyncio as aioredis

from app.config import settings

logger = logging.getLogger(__name__)

_redis: Optional[aioredis.Redis] = None


async def get_redis() -> Optional[aioredis.Redis]:
    global _redis
    if _redis is None:
        try:
            _redis = aioredis.from_url(
                settings.REDIS_URL,
                encoding="utf-8",
                decode_responses=True,
                socket_connect_timeout=1,
                socket_timeout=1,
            )
            await _redis.ping()
        except Exception as e:
            logger.warning("Redis unavailable, caching disabled: %s", e)
            _redis = None
    return _redis


_PREFIX = "sme:"


async def cache_get(key: str) -> Any:
    r = await get_redis()
    if r is None:
        return None
    try:
        raw = await r.get(f"{_PREFIX}{key}")
        return json.loads(raw) if raw is not None else None
    except Exception:
        return None


async def cache_set(key: str, value: Any, ttl: int = 300) -> None:
    r = await get_redis()
    if r is None:
        return
    try:
        await r.set(f"{_PREFIX}{key}", json.dumps(value, default=str), ex=ttl)
    except Exception:
        pass


async def cache_delete(key: str) -> None:
    r = await get_redis()
    if r is None:
        return
    try:
        await r.delete(f"{_PREFIX}{key}")
    except Exception:
        pass


async def cache_delete_pattern(pattern: str) -> None:
    r = await get_redis()
    if r is None:
        return
    try:
        keys = await r.keys(f"{_PREFIX}{pattern}")
        if keys:
            await r.delete(*keys)
    except Exception:
        pass