// Copyright 2017 The OPA Authors.  All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.

package uuid

import (
	"fmt"
	"io"
)

// New Create a version 4 random UUID
func New(r io.Reader) (string, error) {
	bs := make([]byte, 16)
	n, err := io.ReadFull(r, bs)
	if n != len(bs) || err != nil {
		return "", err
	}
	bs[8] = bs[8]&^0xc0 | 0x80
	bs[6] = bs[6]&^0xf0 | 0x40
	return fmt.Sprintf("%x-%x-%x-%x-%x", bs[0:4], bs[4:6], bs[6:8], bs[8:10], bs[10:]), nil
}