Method getInvoiceDueDate

public static function getInvoiceDueDate($orderId, $date = false, $dueDate = false, $formatOutput = '')
{
    if ($dueDate) {
        if ($formatOutput != '') {
            return HTMLHelper::date($dueDate, $formatOutput);
        }
        return $dueDate;
        // the due date is stored in database yet
    }
    $paramsC = PhocacartUtils::getComponentParameters();
    $invoice_due_date_days = $paramsC->get('invoice_due_date_days', 5);
    $date = !$date ? self::getOrderDate($orderId) : $date;
    $dateTime = new DateTime($date);
    $dateTime->add(new DateInterval('P' . (int) $invoice_due_date_days . 'D'));
    //return $dateTime->format('Y-m-d h:m:s');
    // default format output: 'DATE_FORMAT_LC4'
    if ($formatOutput != '') {
        return HTMLHelper::date($dateTime->format('Y-m-d h:m:s'), $formatOutput);
    } else {
        return $dateTime->format('Y-m-d h:m:s');
    }
}