from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker, AsyncSession
from sqlalchemy.orm import declarative_base
from app.core.config import settings

# 创建异步引擎
print(settings.DATABASE_URL)
engine = create_async_engine(
    settings.DATABASE_URL,
    echo=False,
    pool_size=20,
    max_overflow=10,
    pool_recycle=3600, # 自动回收连接，防止 MySQL gone away
    pool_pre_ping=True,
)

# 会话工厂
AsyncSessionLocal = async_sessionmaker(
    bind=engine,
    class_=AsyncSession,
    expire_on_commit=False
)

Base = declarative_base()

async def get_db():
    """依赖注入用的 DB Session"""
    async with AsyncSessionLocal() as session:
        yield session