package corelib

import (
	"math/rand"
	"time"
)

func randomString(n int, allowedChars []rune) string {
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	b := make([]rune, n)
	for i := range b {
		b[i] = allowedChars[r.Intn(len(allowedChars))]
	}
	return string(b)
}

// 生成随机字符串
func generateRandom(randType int, length int) string {
	var res string
	const special = "~!@#$%^&*()_+=-"
	const number = "0123456789"
	const capitalLetter = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	const lowerLetter = "abcdefghijklmnopqrstuvwxyz"
	switch {
	case randType == 1: // 特俗符号
		res = special
	case randType == 2: // 数字
		res = number
	case randType == 3: // 大写字母
		res = capitalLetter
	case randType == 4: // 小写字母
		res = lowerLetter
	case randType == 5: // 大写字母+小写字母
		res = capitalLetter + lowerLetter
	case randType == 6: // 大写字母+小写字母+数字
		res = capitalLetter + lowerLetter + number
	default: // 大写字母+小写字母+数字+特殊符号
		res = capitalLetter + lowerLetter + number + special

	}
	return randomString(length, []rune(res))
}

// GenerateSalt 生成一个随机盐
func GenerateSalt() string {
	const saltSize = 16 // 16字节的随机盐
	return generateRandom(0, saltSize)
}