package gitee

import (
	"crypto/rand"
	"encoding/hex"
)

func encodeUUID(u []byte) string {
	buf := make([]byte, 36)
	hex.Encode(buf[0:8], u[0:4])
	buf[8] = '-'
	hex.Encode(buf[9:13], u[4:6])
	buf[13] = '-'
	hex.Encode(buf[14:18], u[6:8])
	buf[18] = '-'
	hex.Encode(buf[19:23], u[8:10])
	buf[23] = '-'
	hex.Encode(buf[24:], u[10:])
	return string(buf)
}

// NewUUID create v4 uuid
// More powerful UUID libraries can be used: https://github.com/google/uuid
func NewUUID() (string, error) {
	b := make([]byte, 16)
	_, err := rand.Read(b)
	if err != nil {
		return "", err
	}
	b[6] = (b[6] & 0x0f) | 0x40
	b[8] = (b[8] & 0x3f) | 0x80
	return encodeUUID(b), nil
}