#_*_coding:utf-8_*_
‘‘‘
user_passwd 文件内容
{‘user01‘:‘123456‘,‘user02‘:‘123456‘,‘user03‘:‘123456‘}

user_cart 文件内容
{‘user01‘: {"工资":‘‘, ‘余额‘:‘‘, ‘购物车‘: []},‘user02‘: {"工资":‘‘, ‘余额‘:‘‘, ‘购物车‘: []},‘user03‘: {"工资":‘‘, ‘余额‘:‘‘, ‘购物车‘: []},}

product_list 文件内容(仅供打印)
货号：001 |商品名称：iphone 6 |价格：5888元
货号：002 |商品名称：Mac Pro |价格：12000元
货号：003 |商品名称：Coffer |价格：31元
货号：004 |商品名称：Python Alex |价格120元

product_price 文件内容
{‘001‘:‘5888‘,‘002‘:‘12000‘,‘003‘:‘31‘,‘004‘:‘120‘}

‘‘‘

import os
from prettytable import PrettyTable


def pretty_table_list(*arg):  # 定义一个打印meun表的函数
    goodslist = PrettyTable(["ID", "功能菜单"])
    goodslist.align["功能菜单"] = "l"  # l 左对齐 r右对齐，默认居中
    goodslist.padding_width = 2  # 填充的宽度 [左右两边的像素]
    goodslist.add_row(["1", "查询商品列表"])
    goodslist.add_row(["2", "查询购物车"])
    goodslist.add_row(["3", "开始购物"])
    goodslist.add_row(["4", "退出"])
    print(goodslist)


def check_user():  # 定义个用户登录模块，然并卵，挺low的
    with open(‘user_passwd‘,‘r‘,encoding=‘utf-8‘) as f:
        a =f.readline()  # 文件内的字符串存在形式{‘user01‘: ‘123456‘, ‘user02‘: ‘123456‘, ‘user03‘: ‘123456‘}
        username = eval(a) # 此时字符串已经成功字典
    while True:
        user_name = input(‘输入用户名：\n‘)
        if user_name not in username:
            continue
        else:
            break
    keep_going = True
    while keep_going:
        userpasswd = input(‘输入{0}密码：\n‘.format(user_name))
        if userpasswd == username[user_name]:
            return user_name
        elif len(userpasswd) ==0 or userpasswd != username[user_name]:
            a = input(‘按回车继续，或任意键退出。\n‘)
            if len(a) == 0:
                keep_going = True
            elif len(a) != 0:
                keep_going = False
                return False


def print_product_list(*arg):  # 定义一个打印商品列表的函数
    with open(‘product_list‘,‘r‘,encoding=‘utf-8‘) as f:
        for line in f:
            print(line.strip())


def fetch_cart_list(name):  # 定义个查看购物车的函数
    with open(‘user_cart‘, ‘r‘, encoding=‘utf-8‘) as old_cart:
        for line in old_cart:
            cart = eval(line)  # 将user_cart文件读出的内容，转换成字典给cart
        if len(cart[name][‘购物车‘]) == 0:
            print("购物车为空")  # 033这个我还是不会用
        else:
            print(cart[name][‘购物车‘])
    pass


def buy(name):  # 定义一个购物车的函数
    with open(‘user_cart‘,‘r‘,encoding=‘utf-8‘) as old_cart,            open(‘product_price‘,‘r‘,encoding=‘utf-8‘) as p_p,            open(‘product_name‘,‘r‘,encoding=‘utf-8‘) as p_n: # 打开老用户购物车文件，写一个新购物车文件
        for line in old_cart:
            cart = eval(line)  # 将user_cart文件读出的内容，转换成字典给cart
        for line in p_p:
            price = eval(line)  # 将product_price文件读出的内容，转换成字典给price
        for line in p_n:
            goods = eval(line)  # 将product_name文件读出的内容，转换成字典给goods

        # print(type(cart),cart)
        # print(type(price),price)
        # print(type(goods),goods)
        # print(type(cart[name][‘购物车‘]), cart[name][‘购物车‘])

        keep_going = True
        while True:
            balance = input("输入预算金额：\n")  # 用这个方法可以把用户输入非数字内容的报错消除，挺low的，但是可以用
            try:
                balance = int(balance)
                break
            except:
                continue

        while keep_going:
            print_product_list()  #调用读货物架的函数
            cart_number = input("输入需要的物品编号：\n")
            if cart_number in goods:
                if balance - int(price[cart_number]) > 0:
                    a = goods[cart_number]
                    cart[name][‘购物车‘].append(a)
                    print(a)
                    balance = balance - int(price[cart_number])
                    kp = input("继续购买按任意键，或按q退出")
                    if kp != ‘q‘ or len(kp) == 0:
                        keep_going = True
                    else:
                        keep_going = False
                elif balance - int(price[cart_number]) < 0:
                    print("余额不足，请重新输入。\n")
                    print(cart[name][‘购物车‘])
                    kp = input("继续购买按任意键，或按q退出")
                    if kp != ‘q‘ or len(kp) == 0:
                        keep_going = True
                    else:
                        keep_going = False

        with open(‘user_cart-new‘, ‘w‘, encoding=‘utf-8‘) as new_cart:
            new_cart.write(str(cart))
    os.rename(‘user_cart‘,‘user_cart_bk‘)
    os.rename(‘user_cart-new‘,‘user_cart‘)
    os.remove(‘user_cart_bk‘)


def main():  # 程序开始的地方
    name = check_user()
    while True:
        pretty_table_list()
        meun_dic = {
            ‘1‘: print_product_list,
            ‘2‘: fetch_cart_list,
            ‘3‘: buy,
            ‘4‘: exit
        }
        choice = input(">>>输入操作编号").strip()
        if len(choice) == 0 or choice not in meun_dic:
            continue
        elif choice == 4:
            break
        else:
            meun_dic[choice](name)

if __name__ == "__main__":
    main()