// Copyright 2019  github.com. All rights reserved.
// Use of this source code is governed by  github.com.
package utils

import (
	"fmt"
	"math/rand"
	"time"
)

const (
	NUmStr  = "0123456789"
	//CharStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
	CharStr = "abcdefghijklmnopqrstuvwxyz"
	SpecStr = "+=-@#~,.[]()!%^*$"
)

func GenerateRandomStr(length int, charset string) string {
	time.Sleep(1*time.Microsecond)
	rand.Seed(time.Now().UnixNano())
	//初始化密码切片
	var passwd []byte = make([]byte, length, length)
	//源字符串
	var sourceStr string
	//判断字符类型,如果是数字
	if charset == "num" {
		sourceStr = NUmStr
		//如果选的是字符
	} else if charset == "char" {
		sourceStr = charset
		//如果选的是混合模式
	} else if charset == "mix" {
		sourceStr = fmt.Sprintf("%s%s", NUmStr, CharStr)
		//如果选的是高级模式
	} else if charset == "advance" {
		sourceStr = fmt.Sprintf("%s%s%s", NUmStr, CharStr, SpecStr)
	} else {
		sourceStr = fmt.Sprintf("%s%s%s", NUmStr, CharStr, SpecStr)
	}
	//遍历，生成一个随机index索引,
	for i := 0; i < length; i++ {
		index := rand.Intn(len(sourceStr))
		passwd[i] = sourceStr[index]
	}
	return string(passwd)
}