Piwigo get_fs_directories

/**
 * Returns an array containing sub-directories which are potentially
 * a category.
 * Directories named ".svn", "thumbnail", "pwg_high" or "pwg_representative"
 * are omitted.
 * Directories are sorted by mtime.
 *
 * @param string $basedir (eg: ./galleries)
 * @return string[]
 */
function get_fs_directories($path, $recursive = true)
{
  global $conf;

  $lsdir = array();
  $dirs = array();
  $path = rtrim($path, '/');

  $exclude_folders = array_merge(
    $conf['sync_exclude_folders'],
    array(
      '.', '..', '.svn',
      'thumbnail', 'pwg_high',
      'pwg_representative',
      )
    );
  $exclude_folders = array_flip($exclude_folders);

  if (is_dir($path))
  {
    $lsdir = glob("$path/{,.}*", GLOB_ONLYDIR | GLOB_BRACE);
    usort($lsdir, function($a, $b) {
      return filemtime($a) > filemtime($b);
    });
    foreach ($lsdir as $i => $node)
    {
      if (!isset($exclude_folders[preg_replace("/.*\//", '', $node)]))
      {
        $dirs[] = $node;
        if ($recursive)
        {
          $dirs = array_merge($dirs, get_fs_directories($node));
        }
      }
    }
  }
  return $dirs;
}