package gdcore

import (
	crand "crypto/rand"
	"fmt"
	mrand "math/rand"
	"time"
)

// UUID UUID
type UUID [16]byte

// Hex Hex
func (obj UUID) Hex() string {
	x := [16]byte(obj)
	return fmt.Sprintf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
		x[0], x[1], x[2], x[3], x[4],
		x[5], x[6],
		x[7], x[8],
		x[9], x[10], x[11], x[12], x[13], x[14], x[15])
}

// NewUUID NewUUID
func NewUUID() UUID {
	var ret [16]byte
	randBytes(ret[:])
	ret[6] = (ret[6] & 0x0F) | 0x40
	ret[8] = (ret[8] & 0x3F) | 0x80
	return ret
}

func randBytes(x []byte) {
	length := len(x)
	if n, err := crand.Read(x); n != length || err != nil {
		mrand.Seed(time.Now().UnixNano())

		for length > 0 {
			length--
			x[length] = byte(mrand.Int31n(256))
		}
	}
}