<?php
/**
 * @category   Horde
 * @package    Support
 * @copyright  2008-2009 The Horde Project (http://www.horde.org/)
 * @license    http://opensource.org/licenses/bsd-license.php
 */

/**
 * Class for generating RFC 4122 UUIDs. Usage:
 *
 * <code>
 *  <?php
 *
 *  $uuid = (string)new Horde_Support_Uuid;
 *
 *  ?>
 * </code>
 *
 * @category   Horde
 * @package    Support
 * @copyright  2008-2009 The Horde Project (http://www.horde.org/)
 * @license    http://opensource.org/licenses/bsd-license.php
 */
class Horde_Support_Uuid
{
    /**
     * Generated UUID
     * @var string
     */
    private $_uuid;

    /**
     * New UUID
     */
    public function __construct()
    {
        $this->generate();
    }

    /**
     * Generate a 36-character RFC 4122 UUID, without the urn:uuid: prefix.
     *
     * @see http://www.ietf.org/rfc/rfc4122.txt
     * @see http://labs.omniti.com/alexandria/trunk/OmniTI/Util/UUID.php
     *
     * @return string
     */
    public function generate()
    {
        list($time_mid, $time_low) = explode(' ', microtime());
        $time_low = (int)$time_low;
        $time_mid = (int)substr($time_mid, 2) & 0xffff;
        $time_high = mt_rand(0, 0x0fff) | 0x4000;

        $clock = mt_rand(0, 0x3fff) | 0x8000;

        $node_low = function_exists('zend_thread_id') ?
            zend_thread_id() : getmypid();
        $node_high = isset($_SERVER['SERVER_ADDR']) ?
            ip2long($_SERVER['SERVER_ADDR']) : crc32(php_uname());
        $node = bin2hex(pack('nN', $node_low, $node_high));

        $this->_uuid = sprintf('%08x-%04x-%04x-%04x-%s',
            $time_low, $time_mid, $time_high, $clock, $node);
    }

    /**
     * Cooerce to string
     *
     * @return string
     */
    public function __toString()
    {
        return $this->_uuid;
    }

}