From abea82a467be8d2a540fb21b067660a23058cbd6 Mon Sep 17 00:00:00 2001
From: Nigel Baillie <nigel@baillie.dev>
Date: Fri, 2 Feb 2024 10:38:30 +0900
Subject: [PATCH] explicitly catch unhandled IPN

---
 .../class-wc-gateway-komoju-ipn-handler.php   | 21 ++++++++++---------
 index.php                                     | 14 +++++++++++--
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/includes/class-wc-gateway-komoju-ipn-handler.php b/includes/class-wc-gateway-komoju-ipn-handler.php
index 5a9accf..f00ec0f 100644
--- a/includes/class-wc-gateway-komoju-ipn-handler.php
+++ b/includes/class-wc-gateway-komoju-ipn-handler.php
@@ -23,21 +23,21 @@ class WC_Gateway_Komoju_IPN_Handler extends WC_Gateway_Komoju_Response
      */
     public function __construct($gateway, $webhookSecretToken = '', $secret_key = '', $invoice_prefix = '', $useOnHold = false)
     {
-        add_action('invoke_komoju_ipn_handler', [$this, 'check_response']);
+        add_filter('invoke_komoju_ipn_handler', [$this, 'check_response'], 10, 1);
         add_action('valid_komoju_standard_ipn_request', [$this, 'valid_response']);
         add_action('komoju_capture_payment_async', [$this, 'payment_complete_async'], 10, 3);
 
-        $this->gateway                = $gateway;
-        $this->webhookSecretToken	  	 = $webhookSecretToken;
-        $this->secret_key	   	        = $secret_key;
-        $this->invoice_prefix			      = $invoice_prefix;
-        $this->useOnHold              = $useOnHold;
+        $this->gateway            = $gateway;
+        $this->webhookSecretToken = $webhookSecretToken;
+        $this->secret_key         = $secret_key;
+        $this->invoice_prefix     = $invoice_prefix;
+        $this->useOnHold          = $useOnHold;
     }
 
     /**
      * Check for Komoju IPN or Session Response
      */
-    public function check_response()
+    public function check_response($_handled)
     {
         // callback from session page
         if (isset($_GET['session_id'])) {
@@ -62,13 +62,13 @@ public function check_response()
                 $payment_url = $order->get_checkout_payment_url(false);
                 wp_redirect($payment_url);
             }
-            exit;
+            return true;
         }
 
         // Quick setup POST from KOMOJU
         if (isset($_POST['secret_key'])) {
             $this->quick_setup($_POST);
-            exit;
+            return true;
         }
 
         // Webhook (IPN)
@@ -78,8 +78,9 @@ public function check_response()
 
             // NOTE: direct function call doesn't work
             do_action('valid_komoju_standard_ipn_request', $webhookEvent);
-            exit;
+            return true;
         }
+
         wp_die('Failed to verify KOMOJU authenticity', 'Komoju IPN', ['response' => 401]);
     }
 
diff --git a/index.php b/index.php
index 12edee6..a38d9e8 100755
--- a/index.php
+++ b/index.php
@@ -78,8 +78,18 @@ function woocommerce_komoju_handle_http_request()
         // Force WC to load our gateway, causing WC_Gateway_Komoju_IPN_Handler to get instantiated.
         WC()->payment_gateways()->payment_gateways();
 
-        // This action is registered when WC_Gateway_Komoju_IPN_Handler is instantiated.
-        do_action('invoke_komoju_ipn_handler');
+        // When WC_Gateway_Komoju_IPN_Handler is instantiated, this filter should be registered.
+        $handled = apply_filters('invoke_komoju_ipn_handler', false);
+
+        // Catch unexpected case where the filter is NOT registered
+        if (!$handled) {
+            header('X-Komoju-Error: komoju gateway not loaded');
+            wp_die(
+                'gateway (and thus IPN handler) not loaded',
+                'KOMOJU WooCommerce plugin',
+                ['status' => 500]
+            );
+        }
     }
 
     add_filter('woocommerce_payment_gateways', 'woocommerce_add_komoju_gateway');