package auth

import (
	"crypto/rand"
	"fmt"
)

// NewUUID returns a random RFC 4122 version-4 UUID string.
func NewUUID() (string, error) {
	buffer := make([]byte, 16)
	if _, err := rand.Read(buffer); err != nil {
		return "", fmt.Errorf("uuid: %w", err)
	}
	buffer[6] = (buffer[6] & 0x0f) | 0x40
	buffer[8] = (buffer[8] & 0x3f) | 0x80
	return fmt.Sprintf(
		"%x-%x-%x-%x-%x",
		buffer[0:4],
		buffer[4:6],
		buffer[6:8],
		buffer[8:10],
		buffer[10:16],
	), nil
}