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    <h3>Editing: DceSecurityGenerator.php</h3>
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/**
 * This file is part of the ramsey/uuid library
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 *
 * @copyright Copyright (c) Ben Ramsey &lt;ben@benramsey.com&gt;
 * @license http://opensource.org/licenses/MIT MIT
 */

declare(strict_types=1);

namespace Ramsey\Uuid\Generator;

use Ramsey\Uuid\Converter\NumberConverterInterface;
use Ramsey\Uuid\Exception\DceSecurityException;
use Ramsey\Uuid\Provider\DceSecurityProviderInterface;
use Ramsey\Uuid\Type\Hexadecimal;
use Ramsey\Uuid\Type\Integer as IntegerObject;
use Ramsey\Uuid\Uuid;

use function hex2bin;
use function in_array;
use function pack;
use function str_pad;
use function strlen;
use function substr_replace;

use const STR_PAD_LEFT;

/**
 * DceSecurityGenerator generates strings of binary data based on a local
 * domain, local identifier, node ID, clock sequence, and the current time
 */
class DceSecurityGenerator implements DceSecurityGeneratorInterface
{
    private const DOMAINS = [
        Uuid::DCE_DOMAIN_PERSON,
        Uuid::DCE_DOMAIN_GROUP,
        Uuid::DCE_DOMAIN_ORG,
    ];

    /**
     * Upper bounds for the clock sequence in DCE Security UUIDs.
     */
    private const CLOCK_SEQ_HIGH = 63;

    /**
     * Lower bounds for the clock sequence in DCE Security UUIDs.
     */
    private const CLOCK_SEQ_LOW = 0;

    /**
     * @var NumberConverterInterface
     */
    private $numberConverter;

    /**
     * @var TimeGeneratorInterface
     */
    private $timeGenerator;

    /**
     * @var DceSecurityProviderInterface
     */
    private $dceSecurityProvider;

    public function __construct(
        NumberConverterInterface $numberConverter,
        TimeGeneratorInterface $timeGenerator,
        DceSecurityProviderInterface $dceSecurityProvider
    ) {
        $this-&gt;numberConverter = $numberConverter;
        $this-&gt;timeGenerator = $timeGenerator;
        $this-&gt;dceSecurityProvider = $dceSecurityProvider;
    }

    public function generate(
        int $localDomain,
        ?IntegerObject $localIdentifier = null,
        ?Hexadecimal $node = null,
        ?int $clockSeq = null
    ): string {
        if (!in_array($localDomain, self::DOMAINS)) {
            throw new DceSecurityException(
                'Local domain must be a valid DCE Security domain'
            );
        }

        if ($localIdentifier &amp;&amp; $localIdentifier-&gt;isNegative()) {
            throw new DceSecurityException(
                'Local identifier out of bounds; it must be a value between 0 and 4294967295'
            );
        }

        if ($clockSeq &gt; self::CLOCK_SEQ_HIGH || $clockSeq &lt; self::CLOCK_SEQ_LOW) {
            throw new DceSecurityException(
                'Clock sequence out of bounds; it must be a value between 0 and 63'
            );
        }

        switch ($localDomain) {
            case Uuid::DCE_DOMAIN_ORG:
                if ($localIdentifier === null) {
                    throw new DceSecurityException(
                        'A local identifier must be provided for the org domain'
                    );
                }

                break;
            case Uuid::DCE_DOMAIN_PERSON:
                if ($localIdentifier === null) {
                    $localIdentifier = $this-&gt;dceSecurityProvider-&gt;getUid();
                }

                break;
            case Uuid::DCE_DOMAIN_GROUP:
            default:
                if ($localIdentifier === null) {
                    $localIdentifier = $this-&gt;dceSecurityProvider-&gt;getGid();
                }

                break;
        }

        $identifierHex = $this-&gt;numberConverter-&gt;toHex($localIdentifier-&gt;toString());

        // The maximum value for the local identifier is 0xffffffff, or
        // 4294967295. This is 8 hexadecimal digits, so if the length of
        // hexadecimal digits is greater than 8, we know the value is greater
        // than 0xffffffff.
        if (strlen($identifierHex) &gt; 8) {
            throw new DceSecurityException(
                'Local identifier out of bounds; it must be a value between 0 and 4294967295'
            );
        }

        $domainByte = pack('n', $localDomain)[1];
        $identifierBytes = (string) hex2bin(str_pad($identifierHex, 8, '0', STR_PAD_LEFT));

        if ($node instanceof Hexadecimal) {
            $node = $node-&gt;toString();
        }

        // Shift the clock sequence 8 bits to the left, so it matches 0x3f00.
        if ($clockSeq !== null) {
            $clockSeq = $clockSeq &lt;&lt; 8;
        }

        $bytes = $this-&gt;timeGenerator-&gt;generate($node, $clockSeq);

        // Replace bytes in the time-based UUID with DCE Security values.
        $bytes = substr_replace($bytes, $identifierBytes, 0, 4);
        $bytes = substr_replace($bytes, $domainByte, 9, 1);

        return $bytes;
    }
}
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