public static function cronExpression($expression) {

        try {

            $cron = CronExpression::factory($expression);

            $s = $cron->getNextRunDate()->format('c');

            $e = $cron->getExpression();

            $e_array = preg_split('/\s/', $e, -1, PREG_SPLIT_NO_EMPTY);

            $e_count = count($e_array);

            if ( $e_count < 5 || $e_count > 6 ) throw new Exception($e." is not a valid cron expression");

            if ( $e_count == 5 ) $e_array[] = "*";

        }
        catch (Exception $e) {

            throw $e;

        }

        return array($s, $e_array);

    }