How to add a custom payment gateway to Social Engine

I need to integrate a new payment gateway to our corporate website, which is based on Social Engine. There is an extension for this CMS called Advanced Payment Gateways which allows integration of new gateways. In fact, it gets your gateway name and generates a skeleton structure zipped as a file so you can unzip and upload to your server and thus merge with the application directory.

I'm going to explain how I implement my gateway without Social Engine, and I hope someone can tell me how I can incorporate that into Social Engine.

1. First I connect to my PSP service:

   $client = new nusoap_client('https://example.com/pgwchannel/services/pgw?wsdl');
   

2. I prepare the following parameters in an array to send to bpPayRequest:

   $parameters = array(
   	'terminalId' => $terminalId,
   	'userName' => $userName,
   	'userPassword' => $userPassword,
   	'orderId' => $orderId,
   	'amount' => $amount,
   	'localDate' => $localDate,
   	'localTime' => $localTime,
   	'additionalData' => $additionalData,
   	'callBackUrl' => $callBackUrl,
   	'payerId' => $payerId);
   
   // Call the SOAP method
   $result = $client->call('bpPayRequest', $parameters, $namespace);
   

3. If payment request is accepted, the result is a comma separated string, with the first element being 0.
   Then we can send the second element (reference id) to payment gateway as follows via POST method:

   echo "<script language='javascript' type='text/javascript'>postRefId('" . $res[1] . "');</script>";
   
   <script language="javascript" type="text/javascript">    
   	function postRefId (refIdValue) {
   		var form = document.createElement("form");
   		form.setAttribute("method", "POST");
   		form.setAttribute("action", "https://example.com/pgwchannel/startpay");         
   		form.setAttribute("target", "_self");
   		var hiddenField = document.createElement("input");              
   		hiddenField.setAttribute("name", "RefId");
   		hiddenField.setAttribute("value", refIdValue);
   		form.appendChild(hiddenField);
   
   		document.body.appendChild(form);         
   		form.submit();
   		document.body.removeChild(form);
   	}
   	</script>
   

4. The gateway will return the following parameters via POST method to the call back URL that we provided in payment request:
   RefId (reference id as produced in previous steps)
   ResCode (Result of payment: 0 denotes success)
   saleOrderId (order id as passed during payment request)
   SaleReferenceId (sale reference code is given by PSP to the merchant)

5. If ResCode in the previous step was 0, then we'd need to pass the call bpVerifyRequest with the following parameters to verify payment, otherwise the payment will be canceled.

    $parameters = array(
   	'terminalId' => $terminalId,
   	'userName' => $userName,
   	'userPassword' => $userPassword,
   	'orderId' => $orderId,
   	'saleOrderId' => $verifySaleOrderId,
   	'saleReferenceId' => $verifySaleReferenceId);
   
   // Call the SOAP method
   $result = $client->call('bpVerifyRequest', $parameters, $namespace);
   

6. In case the result of bpVerifyRequest is zero, payment is certain and the merchant has to provide goods or services purchased. However, there is an optional method bpSettleRequest, which is used to request a settlement. It is called as follows:

	$parameters = array(
		'terminalId' => $terminalId,
		'userName' => $userName,
		'userPassword' => $userPassword,
		'orderId' => $orderId,
		'saleOrderId' => $settleSaleOrderId,
		'saleReferenceId' => $settleSaleReferenceId);

	// Call the SOAP method
	$result = $client->call('bpSettleRequest', $parameters, $namespace);

I get confused by looking at default gateways in the Payment Gateways plugin e.g. PayPal, Stripe, 2Checkout, etc. How am I incorporate this code logic into the newly created gateway skeleton? (the structure is shown below):

You can check out the complete source code here:
default.php
callback.php

I solved this by adding the payment code inside the Engine_Payment_Gateway_MyGateway class:

Once the user confirms on the SocialEngine page that they want to pay, the method processTransaction() inside the mentioned class is called and the user is redirected to the PSP's payment secure page. Once they are done with the payment, i.e. paid successfully or failed or canceled the transaction, they PSP's page redirects them to the page we had sent to it earlier as a parameter called callBackUrl. There, you will receive PSP-specific parameters which helps you decide whether the payment was successful and to ask the PSP with another SOAP call to confirm the payment and then optionally ask it to settle (deposit money ASAP into the seller's account):

Add to processTransaction():

        $data = array();
        $rawData = $transaction->getRawData();

        //Save order ID for later
        $this->_orderId = $rawData['vendor_order_id'];
        $this->_grandTotal = $rawData['AMT'];


        $client = new nusoap_client('https://example.com/pgwchannel/services/pgw?wsdl');
        $namespace = 'http://interfaces.core.sw.example.com/';


        // Check for an error
        $err = $client->getError();
        if ($err) {
            echo '<h2>Constructor error</h2><pre>' . $err . '</pre>';
            die();
        }


        /* Set variables */

//Get price from SEAO 
//$order_ids = Engine_Api::_()->getDbTable('orders','sitestoreproduct')->getOrderIds($this->parent_id);
//$price = Engine_Api::_()->getDbTable('orders','sitestoreproduct')->getGrandTotal($this->parent_id);


        $terminalId = '1111111';
        $userName = 'username';
        $userPassword = '1111111';
        $orderId = $rawData['vendor_order_id'];

        $amount = $rawData['AMT'];
        $localDate = date("Y") . date("m") . date("d");
        $localTime = date("h") . date("i") . date("s");
        $additionalData = $rawData['return_url'];
        $callBackUrl = 'https://example.com/pgateway/pay/callback';
        $payerId = '0';







        /* Define parameters array 	 */

        $parameters = array(
            'terminalId' => $terminalId,
            'userName' => $userName,
            'userPassword' => $userPassword,
            'orderId' => $orderId,
            'amount' => $amount,
            'localDate' => $localDate,
            'localTime' => $localTime,
            'additionalData' => $additionalData,
            'callBackUrl' => $callBackUrl,
            'payerId' => $payerId
        );



        $result = $client->call('bpPayRequest', $parameters, $namespace);



        if ($client->fault) {
            echo '<h2>Fault</h2><pre>';
            print_r($result);
            echo '</pre>';
            die();
        } else { //Check for errors
            $error = $client->getError();
            if ($error) {
                echo "An error occurred: ";
                print_r($error);
                die();
            } else {
                //break the code
                $resultSegmts = explode(',', $result);
                $ResCode = $resultSegmts [0];


                if ($ResCode == "0") {
                    //Notify admin of the order                    
                    echo '<h3>Redirecting you to the payment page. Please wait...</h3><br/>';
                    echo '<script language="javascript" type="text/javascript">
					  postRefId("' . $resultSegmts[1] . '");
					</script>';
                } elseif ($ResCode == "25") {
                    echo "<h3>Purchase successful</h3>";
                } else {
                    echo "<h3>PSP response is: $ResCode</h3>";
                } 
            }
        }

Add to your callBack action:

    $this->view->message = 'This is callback action for PayController';
    $RefId = $_POST['RefId'];
    $ResCode = $_POST['ResCode'];
    $saleOrderId = $_POST['SaleOrderId'];
    $saleReferenceId = $_POST['SaleReferenceId'];

    $this->_orderId = $saleOrderId;

        $this->view->RefId = $RefId;
        $this->view->saleOlderId = $saleOrderId;
        $this->view->saleReferenceId = $saleReferenceId;
    }
    if ($ResCode == "0") {
        try {
            $client = new nusoap_client('https://example.com/pgwchannel/services/pgw?wsdl');
        } catch (Exception $e) {
            die($e->getMessage());
        }

        $namespace = 'http://interfaces.core.sw.example.com/';
        $terminalId = "111111";
        $userName = "username";
        $userPassword = "11111111";


        $parameters = array(
            'terminalId' => $terminalId,
            'userName' => $userName,
            'userPassword' => $userPassword,
            'orderId' => $saleOrderId,
            'saleOrderId' => $saleOrderId,
            'saleReferenceId' => $saleReferenceId
        );
        $resVerify = $client->call('bpVerifyRequest', $parameters, $namespace);



        if ($resVerify->fault) { //Check for fault 
            echo "<h1>Fault: </h1>";
            print_r($result);
            die();
        } else { //No fault: check for errors now 
            $err = $client->getError();
            if ($err) {
                echo "<h1>Error: " . $err . " </h1>";
            } else {
                if ($resVerify == "0") {//Check verification response: if 0, then purchase was successful. 
                    echo "<div class='center content green'>Payment successful. Thank you for your order.</div>";
                    $this->view->message = $this->_translate('Thanks for your purchase.');
                    $this->dbSave(); //update database table
                } else
                    echo "<script language='javascript' type='text/javascript'>alert(    'Verification Response: " . $resVerify . "');</script>";
            }
        }

        //Note that we need to send bpSettleRequest to PSP service to request settlement once we have verified the payment 
        if ($resVerify == "0") {
            // Update table, Save RefId
            //Create parameters array for settle
            $this->sendEmail();
            $this->sendSms();

            $resSettle = $client->call('bpSettleRequest', $parameters, $namespace);
            //Check for fault 
            if ($resSettle->fault) {
                echo "<h1>Fault: </h1><br/><pre>";
                print_r($resSettle);
                echo "</pre>";
                die();
            } else { //No fault in bpSettleRequest result 
                $err = $client->getError();
                if ($err) {
                    echo "<h1>Error: </h1><pre>" . $err . "</pre>";
                    die();
                } else {
                    if ($resSettle == "0" || $resSettle == "45") {//Settle request successful 
                        // echo "<script language='javascript' type='text/javascript'>alert('Payment successful');</script>";
                    }
                }
            }
        }
    } else {
        echo "<div class='center content error'>Payment failed. Please try again later.</div> ";
        // log error in app
        // Update table, log the error
        // Show proper message to user
    }
    $returnUrl = 'https://example.com/stores/products'; //Go to store home for now. Later I'll set this to the last page 
    echo "<div class='center'>";
    echo "<form action=$returnUrl method='POST'>";
    echo "<input class='center' id='returnstore' type='submit' value='Return to store'/>";
    echo "</form>";
    echo "</div>";