package util

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

const (
	Alphanumeric = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

func RandomString(length int, charsets ...string) string {
	charset := strings.Join(charsets, "")
	if charset == "" {
		charset = Alphanumeric
	}
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[rand.Int63()%int64(len(charset))]
	}
	return string(b)
}