public static function get_unique_filepath($path) {

    /** To handle uploads with same name : for a given path, suffix it with _<n>

    (keeping trailing extension)

    * till it find a non-preexistant_path and returns it.

    */

    if (file_exists($path)) {

      $info = pathinfo($path);

      $extension = $info['extension'];

      $remain = self::strip_extension($path);

      $n = 0;

      do {

        $n++;

        $fn = sprintf('%s_%d.%s', $remain, $n, $extension);

      } while (file_exists($fn));

      return $fn;

    } else {

      return $path;

    }

  }