from sqlalchemy.orm import Session
from app.models.coupon import CouponDB, UserCouponDB
from app.models.user import UserDB
from datetime import datetime
from typing import Optional, List

class CouponManager:
    def __init__(self, coupon: CouponDB = None):
        self.coupon = coupon

    # 发放优惠券
    def add_coupon(
        self,
        user_id: int,
        coupon_id: int,
        count: int = 1,
        expire_time: datetime = None
    ) -> UserCouponDB:
        """
        为用户发放优惠券
        
        Args:
            user_id: 用户ID
            coupon_id: 优惠券ID
            count: 发放数量
            expire_time: 过期时间
            
        Returns:
            UserCouponDB: 创建的用户优惠券对象
            
        Raises:
            ValueError: 当优惠券对象不存在时抛出
        """
        # 检查优惠券对象是否存在
        if not self.coupon:
            raise ValueError("优惠券对象不存在")
        
        # 发放优惠券
        user_coupon = UserCouponDB(
            user_id=user_id,
            coupon_id=coupon_id,
            coupon_name=self.coupon.name,
            coupon_amount=self.coupon.amount,
            coupon_type=self.coupon.coupon_type,
            expire_time=expire_time,
        )
        
        return user_coupon