uuid.go

// @description make uuid, support short uuid
// @reference   https://github.com/stochastic-technologies/shortuuid
// @authors     Odin

package utils

import (
	//"code.google.com/p/go-uuid/uuid"
	"fmt"
	"math/big"
	"strings"

	gouuid "github.com/nu7hatch/gouuid"
)

const (
	alphabet = "23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
	shortlen = 22 //这个长度是根据alphabet得来的,省略计算步骤
)

func ShortenUUID(s string) (ss string) {
	//uuInt, tr, tm, off := new(big.Int), new(big.Int), new(big.Int), new(big.Int)
	uuInt, off := new(big.Int), new(big.Int)
	//remove "-"
	s = strings.ToLower(strings.Replace(s, "-", "", -1))
	//fmt.Sscan("0x"+s, uuInt)
	uuInt.SetString(s, 16)

	alphaLen := big.NewInt(int64(len(alphabet)))
	for uuInt.Cmp(big.NewInt(0)) > 0 {
		//uuInt, off = tr.DivMod(uuInt, alphaLen, tm)
		uuInt, off = uuInt.DivMod(uuInt, alphaLen, off)
		ss += string(alphabet[off.Int64()])
	}
	//如果不足22位,用第一个字符补全
	if diff := shortlen - len(ss); diff > 0 {
		ss += strings.Repeat(string(alphabet[0]), diff)
	}

	return
}

func LengthenUUID(s string) (ls string) {
	uuInt, off := new(big.Int), new(big.Int)
	alphaLen := big.NewInt(int64(len(alphabet)))
	//需要倒序
	for i := len(s) - 1; i >= 0; i-- {
		char := s[i]
		off = big.NewInt(int64(strings.Index(alphabet, string(char))))
		uuInt = uuInt.Add(uuInt.Mul(uuInt, alphaLen), off)
	}
	//转为16进制
	if b := fmt.Sprintf("%x", uuInt); b != "" {
		//fmt.Println(b)
		//b := []byte(b)
		ll := len(b)
		//考虑到前缀为零的情况. 倒过来,先满足后面的字符位数
		ls = fmt.Sprintf("%08v-%04v-%04v-%04v-%012v",
			b[:ll-24], b[ll-24:ll-20], b[ll-20:ll-16], b[ll-16:ll-12], b[ll-12:])
	}
	return
}

//default, version 4
func NewUUID() string {
	//return uuid.New()
	u4, _ := gouuid.NewV4()
	return u4.String()
}

func NewShortUUID() string {
	newUUID := NewUUID()
	return ShortenUUID(newUUID)
}

// generate uuid v5
// namespace直接写域名或者url
func NewUUID5(namespace, data string) string {
	//以http开头的为URL, 其余都为DNS
	if strings.HasPrefix(strings.ToLower(namespace), "http") {
		//return gouuid.NewV5(uuid.NameSpace_URL, []byte(namespace+data)).String()
		u5, _ := gouuid.NewV5(gouuid.NamespaceURL, []byte(namespace+data))
		return u5.String()
	} else {
		//return uuid.NewSHA1(uuid.NameSpace_DNS, []byte(namespace+data)).String()
		u5, _ := gouuid.NewV5(gouuid.NamespaceDNS, []byte(namespace+data))
		return u5.String()
	}
}

func NewShortUUID5(namespace, data string) string {
	newUUID := NewUUID5(namespace, data)
	return ShortenUUID(newUUID)
}