"""数据库连接与会话管理模块"""
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, declarative_base
from app.config import settings

# 处理兼容：如果设置了 DATABASE_URL（单数据库模式），则两个都使用它
if settings.DATABASE_URL:
    inventory_url = settings.DATABASE_URL
    pms_url = settings.DATABASE_URL
else:
    inventory_url = settings.DATABASE_URL_INVENTORY
    pms_url = settings.DATABASE_URL_PMS

# ============ 库存数据库（只读）============

engine_inventory = create_engine(
    inventory_url,
    pool_pre_ping=True,
    pool_size=5,
    max_overflow=10,
    # 库存数据库只读，不需要写入优化
)

SessionLocalInventory = sessionmaker(autocommit=False, autoflush=False, bind=engine_inventory)


def get_db_inventory():
    """获取库存数据库会话的依赖函数（只读）"""
    db = SessionLocalInventory()
    try:
        yield db
    finally:
        db.close()


# ============ PMS 数据库（可读写）============

engine_pms = create_engine(
    pms_url,
    pool_pre_ping=True,
    pool_size=10,
    max_overflow=20,
)

SessionLocalPMS = sessionmaker(autocommit=False, autoflush=False, bind=engine_pms)


def get_db_pms():
    """获取 PMS 数据库会话的依赖函数（可读写）"""
    db = SessionLocalPMS()
    try:
        yield db
    finally:
        db.close()


# ============ 兼容旧接口 ============

# 为向后兼容提供默认的 engine 和 SessionLocal
engine = engine_pms
SessionLocal = SessionLocalPMS
Base = declarative_base()


def get_db():
    """获取数据库会话的依赖函数（兼容旧接口，默认使用 PMS 数据库）"""
    yield from get_db_pms()