import logging
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, Session
from sqlalchemy.exc import SQLAlchemyError
from db.models import Base
from config import config

# 初始化日志
logger = logging.getLogger(__name__)

class Database:
    """数据库连接管理类"""
    
    def __init__(self):
        """初始化数据库连接"""
        self.connection_string = config.get("database.connection_string")
        self.pool_size = config.get("database.pool_size", 10)
        self.timeout = config.get("database.timeout", 30)
        
        if not self.connection_string:
            raise ValueError("数据库连接字符串未配置")
            
        try:
            # 创建数据库引擎
            self.engine = create_engine(
                self.connection_string,
                pool_size=self.pool_size,
                pool_recycle=3600,  # 1小时后回收连接
                connect_args={"connect_timeout": self.timeout}
            )
            
            # 创建会话工厂
            self.SessionLocal = sessionmaker(
                autocommit=False,
                autoflush=False,
                bind=self.engine
            )
            
            # 验证数据库连接
            self._test_connection()
            
            logger.info("数据库连接初始化成功")
            
        except SQLAlchemyError as e:
            logger.error(f"数据库连接初始化失败: {str(e)}")
            raise Exception(f"数据库连接初始化失败: {str(e)}")
        except Exception as e:
            logger.error(f"初始化数据库时发生错误: {str(e)}")
            raise Exception(f"初始化数据库时发生错误: {str(e)}")
    
    def _test_connection(self) -> None:
        """测试数据库连接是否有效"""
        try:
            with self.engine.connect():
                pass  # 连接成功
        except SQLAlchemyError as e:
            raise Exception(f"数据库连接测试失败: {str(e)}")
    
    def create_tables(self) -> None:
        """创建数据库表"""
        try:
            Base.metadata.create_all(bind=self.engine)
            logger.info("数据库表创建/验证成功")
        except SQLAlchemyError as e:
            logger.error(f"创建数据库表失败: {str(e)}")
            raise Exception(f"创建数据库表失败: {str(e)}")
    
    def get_session(self) -> Session:
        """获取数据库会话"""
        session = self.SessionLocal()
        try:
            yield session
        except SQLAlchemyError as e:
            logger.error(f"数据库会话操作失败: {str(e)}")
            session.rollback()
            raise
        finally:
            session.close()

# 全局数据库实例
db = Database()

# 用于FastAPI依赖的会话获取函数
def get_db():
    """FastAPI依赖项：获取数据库会话"""
    yield from db.get_session()