package main

import (
	"fmt"
)

/*
需求：实现用户用户特权，可以满足下面1个或多个条件
1. 红名
2. 达人
3. Vip会员
4. vip超级会员
5. 蓝钻用户
6. 红钻用户

实现方法一：可以根据数据库字段，每个特权用一个字段，进行判断
缺点：每增加一个特权，要进行表字段扩展，代码修改

实现方法二：用一个字段表示多个特权，这个方式需要用到位操作概念

假设定义一个8位无符号int，它的二进制表示如下，每个位置用0、1表示
             红钻   蓝钻  超级vip  vip   达人   红名
0      0      0      0      0      0      0      0

一、设置其中一位为1
用1 左移 n 与目标数做 或操作

二、判断其中一位是否等于1
用1 左移 n 与目标数做 &操作

三、清除其中一位
用1 左移 n 与目标数做 异或操作

代码实现如下：
 */

const (
	HongMing  = 1 << 0
	DaRen     = 1 << 1
	Vip       = 1 << 2
	SuperVip  = 1 << 3
	LanZhuan  = 1 << 4
	HongZhuan = 1 << 5
)

type User struct {
	name string
	flag uint8
}

func set_flag(user User, isSet bool, flag uint8) User {
	if isSet == true {
		user.flag = user.flag | flag
	} else {
		user.flag = user.flag ^ flag
	}
	return user
}

func is_set_flag(user User, flag uint8) bool {
	result := user.flag & flag
	return result == flag
}


func auth() {
	var user User
	user.name = "test01"
	user.flag = 0

	result := is_set_flag(user, HongMing)
	fmt.Printf("user is hongming:%t\n", result)

	user = set_flag(user, true, HongMing)
	result = is_set_flag(user, HongMing)
	fmt.Printf("user is hongming:%t\n", result)

	//user = set_flag(user, false, HongMing)
	//result = is_set_flag(user, HongMing)
	//fmt.Printf("user is hongming:%t\n", result)

	fmt.Printf("%v\n", user.flag)

	result = is_set_flag(user, DaRen)
	fmt.Printf("user is DaRen:%t\n", result)

	user = set_flag(user, true, DaRen)
	result = is_set_flag(user, DaRen)
	fmt.Printf("user is DaRen:%t\n", result)

	//user = set_flag(user, false, DaRen)
	//result = is_set_flag(user, DaRen)
	//fmt.Printf("user is DaRen:%t\n", result)

	fmt.Printf("%v\n", user.flag)

	result = is_set_flag(user, Vip)
	fmt.Printf("user is Vip:%t\n", result)

	user = set_flag(user, true, Vip)
	result = is_set_flag(user, Vip)
	fmt.Printf("user is Vip:%t\n", result)

	//user = set_flag(user, false, Vip)
	//result = is_set_flag(user, Vip)
	//fmt.Printf("user is Vip:%t\n", result)

	fmt.Printf("%v\n", user.flag)

	result = is_set_flag(user, SuperVip)
	fmt.Printf("user is SuperVip:%t\n", result)

	user = set_flag(user, true, SuperVip)
	result = is_set_flag(user, SuperVip)
	fmt.Printf("user is SuperVip:%t\n", result)

	//user = set_flag(user, false, SuperVip)
	//result = is_set_flag(user, SuperVip)
	//fmt.Printf("user is SuperVip:%t\n", result)

	fmt.Printf("%v\n", user.flag)

	result = is_set_flag(user, LanZhuan)
	fmt.Printf("user is LanZhuan:%t\n", result)

	user = set_flag(user, true, LanZhuan)
	result = is_set_flag(user, LanZhuan)
	fmt.Printf("user is LanZhuan:%t\n", result)

	//user = set_flag(user, false, LanZhuan)
	//result = is_set_flag(user, LanZhuan)
	//fmt.Printf("user is LanZhuan:%t\n", result)

	fmt.Printf("%v\n", user.flag)

	result = is_set_flag(user, HongZhuan)
	fmt.Printf("user is HongZhuan:%t\n", result)

	user = set_flag(user, true, HongZhuan)
	result = is_set_flag(user, HongZhuan)
	fmt.Printf("user is HongZhuan:%t\n", result)

	//user = set_flag(user, false, HongZhuan)
	//result = is_set_flag(user, HongZhuan)
	//fmt.Printf("user is HongZhuan:%t\n", result)

	fmt.Printf("%v\n", user.flag)

}

func main() {
	auth()
}