public static function secondsToTime($seconds)
  {
    $dtF = new DateTime('@0');
    $dtT = new DateTime("@$seconds");
    $res = $dtF->diff($dtT);
    
    $days    = $res->format('%a');
    $hours   = $res->format('%h');
    $minutes = $res->format('%i');
    $seconds = $res->format('%s');
    
    $str = [];
    if ( intval($days) > 0 ){
      $str[] = $days.' '.($days===1?'day':'days');
    }
    if ( intval($hours) > 0 ){
      $str[] = $hours.' '.($hours===1?'hour':'hours');
    }
    if ( intval($minutes) > 0 ){
      $str[] = $minutes.' '.($minutes===1?'minute':'minutes');
    }
    if ( intval($seconds) > 0 ){
      $str[] = $seconds.' '.($seconds===1?'second':'seconds');
    }
    
    return implode(' ', $str);
  }