# cache_service.py
import json
import hashlib
import logging
import redis
from typing import Optional, Dict, Any

class CacheService:
    def __init__(self, host: str = 'localhost', port: int = 6379, 
                 db: int = 0, password: str = None, ttl: int = 2592000):
        """
        初始化Redis缓存服务
        :param ttl: 默认缓存时间(秒)，默认24小时
        """
        self.client = redis.Redis(
            host=host,
            port=port,
            db=db,
            password=password,
            decode_responses=True,
            socket_connect_timeout=5,
            socket_timeout=5
        )
        self.ttl = ttl
        self.logger = logging.getLogger(__name__)
        
    def _generate_cache_key(self, request_body: Dict[str, Any]) -> str:
        """
        根据请求体生成唯一的缓存键
        """
        request_str = json.dumps(request_body, sort_keys=True)
        return f"health:cache:{hashlib.sha256(request_str.encode()).hexdigest()}"
    
    def get_cached_response(self, request_body: Dict[str, Any]) -> Optional[Dict[str, Any]]:
        """
        获取缓存结果
        :return: 如果存在则返回缓存结果，否则返回None
        """
        cache_key = self._generate_cache_key(request_body)
        try:
            cached = self.client.get(cache_key)
            if cached:
                self.logger.info(f"缓存命中: {cache_key}")
                return json.loads(cached)
            return None
        except Exception as e:
            self.logger.error(f"获取缓存失败: {str(e)}")
            return None
    
    def set_cached_response(self, request_body: Dict[str, Any], 
                          response_data: Dict[str, Any], 
                          ttl: int = None) -> bool:
        """
        设置缓存结果
        """
        cache_key = self._generate_cache_key(request_body)
        try:
            expire_time = ttl if ttl is not None else self.ttl
            self.client.setex(
                cache_key,
                expire_time,
                json.dumps(response_data)
            )
            self.logger.info(f"缓存已设置: {cache_key} (TTL: {expire_time}s)")
            return True
        except Exception as e:
            self.logger.error(f"设置缓存失败: {str(e)}")
            return False
    
    def clear_cache(self, request_body: Dict[str, Any]) -> bool:
        """清除指定请求的缓存"""
        cache_key = self._generate_cache_key(request_body)
        try:
            self.client.delete(cache_key)
            self.logger.info(f"缓存已清除: {cache_key}")
            return True
        except Exception as e:
            self.logger.error(f"清除缓存失败: {str(e)}")
            return False

    def ping(self) -> bool:
        """检查Redis连接是否正常"""
        try:
            return self.client.ping()
        except Exception as e:
            self.logger.error(f"Redis连接测试失败: {str(e)}")
            return False