Custom Payment Plugin Notification Not Received

-- HikaShop version -- : HikaShop Starter: 2.6.0
-- Joomla version -- : 3.4.5
-- PHP version -- : 5.4.45

Customising the 'Example' payment plugin to work with the JCC providor here in Cyprus, the Debug for the plugin is turned on.

The plugin posts to the payment gateway ok, i can use their dummy card and receive a success, the gateway then posts the response data to the notify URL i have set (/index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=jcc&tmpl=component) but i get a blank screen and no entry in the plugin log.

Using Chrome i can see the post data send by the gateway are as expected, and looking at my Raw Access Logs from cPanel i get status 200. At a guess the function 'onPaymentNotification' is not being processed, as i would expect to see onscreen debug and entry to logfile ?

What to do ?

After much messing about, i realise that the onPaymentNotification function was 'ready' to be fired, i just had to modify it to actually do something!

So, now, i still get a blank page in the front end, but, on checking the backend, the order status is being amended as expected and the debug log file is being populated.

Next step, display something in the front end other than a blank page ... where am i going wrong ?

Thanks for helpful explanation, i understand now what is happening. In my payment plugin now, if the payment is success or fail, the order status is changed and the user is redirected to one of the two options :

success : HIKASHOP_LIVE.'index.php?option=com_hikashop&ctrl=checkout&task=after_end&order_id='.$order_id.$this->url_itemid;

This option displays "Thank you for your purchase." within the <div id="system-message-container">, the URL shows the order id, what about a menu item id in the URL to add module(s) ? where/how do i 'alter' the message given on this page, to extend it with additional text and variables ?

fail : HIKASHOP_LIVE.'index.php?option=com_hikashop&ctrl=order&task=cancel_order&order_id='.$order_id.$this->url_itemid;

This option displays "The cart is empty" within the <div id="system-message-container">, but the URL is not showing the order ID but showing the Hikashop category listing menu item. As with the above 'status' i`d like to change message provided, and, not return to Hikashop category listing menu item.

I have seen in some payment plugins that a 'thankyou' page is called, but if possible i`d rather use as much of the built in HIKASHOP function as possible before and after the payment process.

As function stands below, the user is redirected as required, and order status changes, however no debug log

But, if part (6b) and (6c) return are not commented, then the debug log is written, but the redirect doesn't work.

How to achieve redirect AND debug log ?

function onPaymentNotification(&$statuses)
	{
		// (1) Create array from the received gateway response parameters
		$vars = array();
		$filter = JFilterInput::getInstance();
		foreach($_REQUEST as $key => $value)
		{
			$key = $filter->clean($key);
			$value = JRequest::getString($key);
			$vars[$key]=$value;
		}
		
		// (2) We load the parameters of the plugin in $this->payment_params and the order data based on the order_id coming from the payment platform
		$order_id = (int)@$vars['OrderID'];
		$dbOrder = $this->getOrder($order_id);
		$this->loadPaymentParams($dbOrder);
		if(empty($this->payment_params))
			return false;
		$this->loadOrderData($dbOrder);
		
		// (3) Configure the "success/fail URLs" to re-direct in (6)
		$return_url = $this->pluginConfig['return_url'][2].'&order_id='.$order_id; //.$this->url_itemid ;
		$cancel_url = $this->pluginConfig['cancel_url'][2].'&order_id='.$order_id; //.$this->url_itemid ;

		// (4) Recalculate the hash to check for (6)
		$hash = $this->jcc_signature($this->payment_params->password,$vars,false,false);

		// (5) Debug mode activated or not
		if($this->payment_params->debug) 
		{
			//Display debug information in the payment log file
			
			echo print_r($vars,true)."\n\n\n";
			echo print_r($dbOrder,true)."\n\n\n";
			echo print_r($hash,true)."\n\n\n";
		}

		
		// (6) Confirm (or not) the order
		
		if (strcasecmp($hash,$vars['ResponseSignature'])!=0) //Different hash between what we calculate and the hash ent by the payment platform so we do not do anything as we consider that the notification doesn't come from the payment platform.
		{

		// (6a) we display debug information in the payment log file available in the configuration's Files section.
			if($this->payment_params->debug)
				echo 'Hash error '.$vars['ResponseSignature'].' - '.$hash."\n\n\n";
			return false;
		}

		// (6b) If gateway response is not success
		elseif($vars['ResponseCode']!='2')
		{

			$this->modifyOrder($order_id, $this->payment_params->invalid_status, true, true); 
			$JCCResponse = "Report by JCC</br>Error : " . $vars['ReasonCodeDesc'];
			$JCCResponseURL = $cancel_url;
			//return false;
		}

		// (6c) If gateway response is not success
		else	
		{
			$this->modifyOrder($order_id, $this->payment_params->verified_status, true, true);
			$JCCResponse = "Report by JCC</br>Success : " . $vars['ReasonCodeDesc'];
			$JCCResponseURL = $return_url;
			//return true;
		}

	$this->app->redirect($JCCResponseURL, $JCCResponse);
	
	}