"""
数据库连接和会话管理
"""

from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.pool import NullPool
from typing import AsyncGenerator

from .config import settings

# 创建异步数据库引擎
engine = create_async_engine(
    settings.DATABASE_URL,
    echo=settings.DATABASE_ECHO,
    poolclass=NullPool,  # 对于异步使用NullPool
    future=True
)

# 创建异步会话工厂
AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False
)

# 创建基础模型类
Base = declarative_base()


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """
    数据库会话依赖注入
    用于FastAPI路由中获取数据库会话
    """
    async with AsyncSessionLocal() as session:
        try:
            yield session
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db():
    """初始化数据库表"""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db():
    """关闭数据库连接"""
    await engine.dispose()


async def check_db_connection() -> bool:
    """检查数据库连接是否正常"""
    try:
        async with AsyncSessionLocal() as session:
            await session.execute("SELECT 1")
            return True
    except Exception:
        return False


async def get_db_session():
    """获取数据库会话的简化版本"""
    return AsyncSessionLocal()