# 1.充值
# 2. 加载中
# 3. 读取数据
# 4. 商品展示
# 5. 购买商品

import time
import json
rmb = 0
car = {}

def chongzhi():
    global rmb
    while True:
        num = input("请充值吧亲:")
        if num.isdecimal():
            print(num)
            rmb = int(num)
            print("恭喜,充值成功,充值金额{}".format(rmb))
            break
        else:
            print("充值失败,请输入一个数字")

def myprocess(percent):
    if percent > 1:
        percent - 1
    strvar = int(percent * 50) * "■"
    print("\r[%-50s]%d%%"%(strvar,percent * 100),end="")

def exe_process():
    recv_size = 0
    total_size = 1000
    while recv_size < total_size:
        time.sleep(0.01)
        recv_size += 10
        percent = recv_size/total_size
        myprocess(percent)

def loading():
    print("商品正在加载中...")
    exe_process()
    print()

def read_data(filename):
    lst = []
    with open(filename,mode="r+",encoding="utf-8") as fp:
        for i in fp:
            dic = json.loads(i)
            lst.append(dic)
        return lst

def show_goods(data):
    strvar = "商品名称".center(18)
    print("序号"+"strvar"+"价格")
    for k,v in enumerate(data,start=1):
        v['num'] = k
        print("{v[num]:<10}{v[name]:<12}{v[price]}".format(v=v))

def error():
    strvar = '''
    +----------------------------------------------------------------+
    |       你输入的选项不存在,请重新输入!        |
    +----------------------------------------------------------------+
    '''
    print(strvar)
    time.sleep(1)

def add_car(num,data):
    if num not in car:
        car[num] = {
            "name":data[num-1]["name"],
            "price":data[num-1]["price"],
            "account":1
        }
    else:
        car[num]["account"] += 1

def show_car(num):
    print("+" + "-" * 60 + "+")
    print("你选择的商品具体信息:")
    print("*-商品名称{}".format(car[num]["name"]))
    print("*-商品单价{}".format(car[num]["price"]))
    print("*-高品数量{}".format(car[num]["account"]))
    print("已经成功加入到购物车~请继续购物~")
    print('请输入n结算!')
    print("+" + "-" * 60 + "+")

def jiesuan():
    total = 0
    print("+------------------- 你购物车中的商品信息如下: ---------------------+")
    for k,v in car.items():
        v["num"] = k
        v["mysum"] = v["price"] * v["account"]
        total += v["mysum"]
        print("序号:{v[num]} 商品名称:{v[name]} 商品单价:{v[price]} 此商品总价:{v[mysum]}".format(v=v))
    return total

def success(total,rmb):
    print("正在结算商品中...")
    exe_process()
    print("请稍后...")
    print("[一共{}元]".format(total))
    print("你已经成功购买以上商品,全额还剩{},欢迎下次光临".format(rmb-total))
    time.sleep(1)

def del_goods(total,rmb):
    print("余额不足,还差{},请忍痛割爱,删除一些商品吧,".format(total-rmb))
    num = input("+-------------------------------- 请输入你要删除的商品序号 ---------------------------------+")
    if num.isdecimal():
        num = int(num)
        if num in car:
            car[num]["account"] -= 1
            if not car[num]["account"]:
                car.pop(num)
            else:
                error()
        else:
            error()
def myexit():
    print("+--------------------------- 欢迎下次光临 -----------------------------+")
    time.sleep(1)

def main():
    chongzhi()
    loading()
    data = read_data("shopping_data.json")
    show_goods(data)
    sign = True
    while sign:
        num = input("请输入你要购买的商品序号:")
        if num.isdecimal():
            num = int(num)
            if 1 <= num <= len(data):
                add_car(num,data)
                show_car(num)
            else:
                error()

        elif num.upper() == "N":
            while True:
                total = jiesuan()
                print(total)
                if total > rmb:
                    del_goods(total, rmb)
                else:
                    success(total, rmb)
                    sign = False
                    break

        elif num.upper() == "Q":
            myexit()
            sign = False
        else:
            error()


main()

shopping_data.json  文件

{"name":"电脑","price":2999}
{"name":"鼠标","price":30}
{"name":"手机","price":1566}
{"name":"键盘","price":998}
{"name":"奶茶","price":10}