Как создать новый метод оплаты для minishop2?

<?php

if (!class_exists('msPaymentInterface')) {
    require_once dirname(__FILE__, 3) . '/handlers/mspaymenthandler.class.php';
}

class EpayHalykBank extends msPaymentHandler implements msPaymentInterface
{

    /**
    * EpayHalykBank constructor.
    *
    * @param xPDOObject $object
    * @param array $config
    */
    function __construct(xPDOObject $object, $config = array())
    {
        parent::__construct($object, $config);

        $siteUrl = $this->modx->getOption('site_url');
        $assetsUrl = $this->modx->getOption('assets_url') . 'components/minishop2/';
        $paymentUrl = $siteUrl . substr($assetsUrl, 1) . 'payment/mspepayhalykbank.php';

        $this->config = array_merge(array(
            'grant_type' => 'client_credentials',
            'debug' => $modx->getOption('epay_debug'),
            'epayTokenAuthUrl' => $this->config['debug'] == 1 ? $modx->getOption('epay_test_auth_url') : $modx->getOption('epay_prod_auth_url'),
            'payPageUrl' => $this->config['debug'] == 1 ? $modx->getOption('epay_test_pay_page_url') : $modx->getOption('epay_pay_page_url'),
            'scope' => 'webapi usermanagement email_send verification statement statistics payment',
            'client_id' => $modx->getOption('epay_client_id'),
            'client_secret' => $modx->getOption('epay_client_secret'),
            'currency' => $modx->getOption('epay_payment_currency'),
            'terminal_id' => $modx->getOption('epay_terminal_id'),
            'postLink' => $modx->makeUrl($modx->getOption('epay_post_success_page_id')),
            'failurePostLink' => $modx->makeUrl($modx->getOption('epay_post_error_page_id'))
        ), $config);
    }



    /**
    * Create Auth Token
    *
    * @param 
    *
    * @return string
    */
    public function paymentAuth(msOrder $order)
    {
        $authUrl = $this->config['epayTokenAuthUrl'];

        $params = array(
            'grant_type' => $this->config['grant_type'],
            'scope' => $this->config['scope'],
            'client_id' => $this->config['client_id'],
            'client_secret' => $this->config['client_secret'],
            'invoiceID' => $this->getOrderHash($order),
            'amount' => $order->get('cost'),
            'currency' => $this->config['currency'],
            'terminal' => $this->config['terminal_id'],
            'postLink' => $this->config['postLink'],
            'failurePostLink' => $this->config['failurePostLink']
        );

        $myCurl = curl_init();
        curl_setopt_array($myCurl, array(
            CURLOPT_URL => $authUrl,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_POST => true,
            CURLOPT_POSTFIELDS => http_build_query($params)
        ));

        $response = curl_exec($myCurl);
        curl_close($myCurl);

        return json_decode($response, true);

    }


    /**
    * Returns a direct link for continue payment process of existing order
    *
    * @param msOrder $order
    *
    * @return string
    */
    public function getPaymentLink(msOrder $order)
    {

        $authResponse = $this->paymentAuth($order);

        $msAddress = $order->getOne('Address');
        $orderPhone = $msAddress->get('phone');
        $orderEmail = $msAddress->get('email');
        $orderReceiver = $msAddress->get('receiver');
        $orderComment = $msAddress->get('comment');

        if(substr($orderPhone, 0, 1) == '7'){
            $orderPhone = '+' . $orderPhone;
        }
        // if($authResponse['access_token'])
        // 'data' => "{\"statement\":{\"name\":\"Arman      Ali\",\"invoiceID\":\"80000016\"}}",

        return $this->config['payPageUrl'] . '?' .
        http_build_query(array(
            'action' => 'continue',
            'msorder' => $order->get('id'),
            'mscode' => $this->getOrderHash($order),
            'invoiceId' => $this->getOrderHash($order),
            'backLink' => $this->config['postLink'].'?action=success',
            'failureBackLink' => $this->config['failurePostLink'].'?action=error',
            'postLink' => $this->$siteUrl,
            'failurePostLink' => $this->config['failurePostLink'].'?action=error',
            'language' => 'rus',
            'description' => 'Оплата в интернет магазине',
            'accountId' => $this->config['client_id'],
            'terminal' => $this->config['terminal_id'],
            'amount' => $order->get('cost'),
            'data' => array(
                'name' => $orderReceiver,
                'orderId' => $order->get('id'),
                'invoiceId' => $this->getOrderHash($order),
                'phone' => $orderPhone,
                'email' => $orderEmail,                
                'comment' => $orderComment
            ),
            'currency' => $this->config['currency'],
            'phone' => $orderPhone,
            'email' => $orderEmail,
            'cardSave' => true,
            'auth' => $authResponse

        ));
    }
}

if ($miniShop2 = $modx->getService('miniShop2')) {
    $miniShop2->addService('payment', 'EpayHalykBank',
        '{core_path}components/minishop2/custom/payment/epayhalykbank.class.php'
    );
}