智能对话系统优惠卷

def validate_coupon(coupon_code, order_total):
    # 假设从数据库获取优惠券信息
    coupon_info = get_coupon_info_from_db(coupon_code)
    
    if not coupon_info:
        return "无效的优惠券代码"
    
    if coupon_info['expired']:
        return "优惠券已过期"
    
    if order_total < coupon_info['min_amount']:
        return f"订单金额需达到{coupon_info['min_amount']}元才能使用此优惠券"
    
    discount = calculate_discount(coupon_info, order_total)
    return f"优惠成功，减免{discount}元"

def get_coupon_info_from_db(coupon_code):
    # 模拟从数据库获取优惠券信息
    coupons = {
        "SAVE10": {"discount": 10, "min_amount": 100, "expired": False},
        "HALFOFF": {"discount": 0.5, "min_amount": 200, "expired": False}
    }
    return coupons.get(coupon_code, {})

def calculate_discount(coupon_info, order_total):
    if coupon_info['discount'] > 0:
        return min(coupon_info['discount'], order_total)
    elif coupon_info['discount'] == 0.5:
        return order_total * 0.5
    return 0

# 示例调用
print(validate_coupon("SAVE10", 150))  # 输出: 优惠成功，减免10元
print(validate_coupon("HALFOFF", 150))  # 输出: 优惠成功，减免75元
print(validate_coupon("INVALID", 150))  # 输出: 无效的优惠券代码