信誉查询服务优惠卷

class Coupon:
    def __init__(self, code, discount_percentage, expiration_date):
        self.code = code
        self.discount_percentage = discount_percentage
        self.expiration_date = expiration_date

    def is_valid(self, current_date):
        return current_date <= self.expiration_date

def apply_coupon(total_amount, coupon):
    if coupon.is_valid(datetime.now()):
        discounted_amount = total_amount * (1 - coupon.discount_percentage / 100)
        return discounted_amount
    else:
        return total_amount

# 示例使用
from datetime import datetime

coupon = Coupon(code="SAVE20", discount_percentage=20, expiration_date=datetime(2023, 12, 31))
total_bill = 100
final_amount = apply_coupon(total_bill, coupon)
print(f"Final amount after discount: ${final_amount}")