数据开发平台双十一促销活动

def apply_promotion(user_id, product_id, quantity):
    # 检查用户是否有资格参与促销
    if not is_eligible(user_id):
        return "用户无资格参与促销"
    
    # 获取产品信息和促销规则
    product_info = get_product_info(product_id)
    promotion_rule = get_promotion_rule(product_id)
    
    # 计算优惠后的价格
    original_price = product_info.price * quantity
    discounted_price = original_price * (1 - promotion_rule.discount_rate)
    
    # 记录交易并更新库存
    record_transaction(user_id, product_id, quantity, discounted_price)
    update_inventory(product_id, -quantity)
    
    return f"成功应用促销，优惠后价格为：{discounted_price}"

def is_eligible(user_id):
    # 实现用户资格检查逻辑
    pass

def get_product_info(product_id):
    # 获取产品详细信息
    pass

def get_promotion_rule(product_id):
    # 获取对应的促销规则
    pass

def record_transaction(user_id, product_id, quantity, price):
    # 记录交易详情
    pass

def update_inventory(product_id, change):
    # 更新库存数量
    pass