from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from .config import settings

# 创建数据库引擎
engine = create_engine(
    settings.DATABASE_URL,
    pool_pre_ping=True,
    pool_recycle=3600,
    echo=True  # 开发环境打印 SQL
)

# 创建 Session 工厂
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# 创建基类
Base = declarative_base()

# 依赖注入：获取数据库会话
def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()
