import logging
import pymysql
from pymysql.cursors import DictCursor
from dbutils.pooled_db import PooledDB
import redis

class DBConnectionManager:
    """数据库连接管理器，负责管理MySQL和Redis连接池"""
    
    _instance = None
    
    @classmethod
    def get_instance(cls, mysql_config=None, redis_config=None):
        """获取单例实例
        
        Args:
            mysql_config: MySQL配置
            redis_config: Redis配置
            
        Returns:
            DBConnectionManager实例
        """
        if cls._instance is None:
            cls._instance = cls(mysql_config, redis_config)
        elif mysql_config or redis_config:
            # 如果已经有实例但又传入了配置，则更新配置
            if mysql_config and not cls._instance.mysql_pool:
                cls._instance.init_mysql_pool(mysql_config)
            if redis_config and not cls._instance.redis_pool:
                cls._instance.init_redis_pool(redis_config)
        return cls._instance
    
    def __init__(self, mysql_config=None, redis_config=None):
        """初始化数据库连接管理器
        
        Args:
            mysql_config: MySQL配置
            redis_config: Redis配置
        """
        self.logger = logging.getLogger("DBConnectionManager")
        self.mysql_pool = None
        self.redis_pool = None
        
        # 初始化MySQL连接池
        if mysql_config:
            self.init_mysql_pool(mysql_config)
        
        # 初始化Redis连接池
        if redis_config:
            self.init_redis_pool(redis_config)
    
    def init_mysql_pool(self, config):
        """初始化MySQL连接池
        
        Args:
            config: MySQL配置，包含host, port, user, password, database等
        """
        try:
            if not config:
                self.logger.warning("MySQL配置为空，跳过初始化")
                return
                
            self.mysql_pool = PooledDB(
                creator=pymysql,
                maxconnections=10,  # 连接池最大连接数
                mincached=2,        # 初始化时，连接池中至少创建的空闲的连接
                maxcached=5,        # 连接池中最多闲置的连接
                blocking=True,      # 连接池中如果没有可用连接后，是否阻塞等待
                maxusage=None,      # 一个连接最多被重复使用的次数，None表示无限制
                setsession=[],      # 开始会话前执行的命令列表
                ping=0,             # ping MySQL服务端，检查是否服务可用
                host=config.get('host', 'localhost'),
                port=config.get('port', 3306),
                user=config.get('user', 'root'),
                password=config.get('password', ''),
                database=config.get('database', ''),
                charset=config.get('charset', 'utf8mb4'),
                cursorclass=DictCursor
            )
            self.logger.info("MySQL连接池初始化成功")
        except Exception as e:
            self.logger.error(f"MySQL连接池初始化失败: {e}")
            self.mysql_pool = None
    
    def init_redis_pool(self, config):
        """初始化Redis连接池
        
        Args:
            config: Redis配置，包含host, port, password, db等
        """
        try:
            if not config:
                self.logger.warning("Redis配置为空，跳过初始化")
                return
                
            self.redis_pool = redis.ConnectionPool(
                host=config.get('host', 'localhost'),
                port=config.get('port', 6379),
                password=config.get('password', None),
                db=config.get('db', 0),
                decode_responses=config.get('decode_responses', True),
                max_connections=config.get('max_connections', 10)
            )
            self.logger.info("Redis连接池初始化成功")
        except Exception as e:
            self.logger.error(f"Redis连接池初始化失败: {e}")
            self.redis_pool = None
    
    def get_mysql_connection(self):
        """获取MySQL连接
        
        Returns:
            MySQL连接
        
        Raises:
            Exception: MySQL连接池未初始化
        """
        if self.mysql_pool is None:
            raise Exception("MySQL连接池未初始化")
        
        return self.mysql_pool.connection()
    
    def get_redis_connection(self):
        """获取Redis连接
        
        Returns:
            Redis连接
        
        Raises:
            Exception: Redis连接池未初始化
        """
        if self.redis_pool is None:
            raise Exception("Redis连接池未初始化")
        
        return redis.Redis(connection_pool=self.redis_pool)
    
    def close(self):
        """关闭所有连接池"""
        # MySQL连接池会自动管理连接的关闭
        self.mysql_pool = None
        
        # 关闭Redis连接池
        if self.redis_pool:
            self.redis_pool.disconnect()
            self.redis_pool = None