instance4:购物车优化版 (作业)

购物车程序：
1、启动程序后，输入用户名密码后，如果是第一次登录，让用户输入工资，然后打印商品列表
2、允许用户根据商品编号购买商品
3、用户选择商品后，检测余额是否够，够就直接扣款，不够就提醒
4、可随时退出，退出时，打印已购买商品和余额
5、在用户使用过程中， 关键输出，如余额，商品已加入购物车等消息，需高亮显示
6、用户下一次登录后，输入用户名密码，直接回到上次的状态，即上次消费的余额什么的还是那些，再次登录可继续购买
7、允许查询之前的消费记录

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# __author__ = "Deakin"
# Email: 469792427@qq.com
# Date: 2018/1/17

product_list=[
    ["iphone",8000],
    ["computer",6000],
    ["car",30000],
    ["coffee",30],
    ["watch",500],
    ["book",80],
]
shopping_list=[]
file=open('user','r+',encoding='utf-8')
f=eval(file.read())
file1=open('history','r+',encoding='utf-8')
f1=eval(file1.read())
account=input("pls key in your account:")
while True:
    if account in f:
        password=input("pls key in your password:")
        if password in f[account]:
            salary=int(f[account][password])
            print('welcome %s,your balance salary is %s'%(account,salary))
            print('-----below is your shopping car history-----')
            if account in f1:
                historylist=f1[account]
            else:
                historylist=[]
            print(historylist)
            while True:
                select=input('do you want to buy sth now?yes or no:')
                if select=='yes':
                    while True:
                        for index,item in enumerate(product_list):
                            print(index,item)
                        userchoice = input("pls select the product number,press 'q' to quit:")
                        if userchoice.isdigit():
                            userchoice=int(userchoice)
                            if userchoice<len(product_list) and userchoice>=0:
                                price=product_list[userchoice]
                                if price[1]<salary:
                                    confirm=input('pls confirm your selection,yes or no:')
                                    if confirm=='yes':
                                        shopping_list.append(price)
                                        salary-=price[1]
                                        print('add \033[31;1m%s\033[0m in your shopping_list,your \033[31;1mbalance salary is %s\033[0m'%(price,salary))
                                        f[account][password]=str(salary)
                                        file.seek(0)
                                        file.write(str(f))
                                        file.tell()
                                    elif confirm=='no':
                                        pass
                                    else:
                                        print('invalid option')
                                else:
                                    print("you don't have enough money")
                        elif userchoice=='q':
                            print("------shopping list------")
                            for p in shopping_list:
                                print(p)
                            f1[account]=shopping_list
                            file1.seek(0)
                            file1.write(str(f1))
                            print('your repeated salary is %s'%(salary))
                            exit()
                        else:
                            print('option invalid')
                elif select=='no':
                    exit()
                else:
                    print('invalid option')
        else:
            print("password is incorrect,pls try again")
    else:
        newpwdsal={}
        password_new=input("account don't exist,pls set up your password to register:")
        salary_new=input("first time to log in, pls key in your salary:")
        sal_new=int(salary_new)
        newpwdsal[password_new]=sal_new #工资对应新密码
        f[account]=newpwdsal #用户名对应密码和工资的小字典
        file.seek(0)
        file.write(str(f))
        file.tell()