Fix pixel not appending properly with Gravity Forms redirect confirma…

…tions (#3)

Summary:
### Description
This PR fixes an issue where Gravity Forms confirmations do not process properly when the Facebook Pixel is added to a redirect type confirmation.

When a redirect type confirmation is used, the confirmation is updated to return the Facebook Pixel along with a Javascript based redirect rather than using Gravity Forms' header based redirect.

(Related Issue: #2)

### Testing Instructions
1. Create a Gravity Forms form.
1. Set the default confirmation to the Text type.
1. Submit the form.
1. Confirm the Facebook Pixel is properly included and event was registered.
1. Change the default confirmation to the Page type.
1. Submit the form.
1. Confirm the Facebook Pixel is properly included, the event was registered and user was redirected to selected page.
1. Change the default confirmation to the Redirect type.
1. Submit the form.
1. Confirm the Facebook Pixel is properly included, the event was registered and user was redirected to the defined redirect URL.
Pull Request resolved: #3

Differential Revision: D18713432

Pulled By: vinothsa

fbshipit-source-id: b869218d5454b5d26915edc012f3ce4c1afbdff1

integration/FacebookWordpressGravityForms.php

@@ -27,15 +27,15 @@ class FacebookWordpressGravityForms extends FacebookWordpressIntegrationBase {
   const TRACKING_NAME = 'gravity-forms';
 
   public static function injectPixelCode() {
-    add_action(
+    add_filter(
       'gform_confirmation',
       array(__CLASS__, 'injectLeadEvent'),
-      10, 4);
+      99, 4);
   }
 
-  public static function injectLeadEvent($confimation, $form, $entry, $ajax) {
+  public static function injectLeadEvent($confirmation, $form, $entry, $ajax) {
     if (FacebookPluginUtils::isAdmin()) {
-      return $confimation;
+      return $confirmation;
     }
 
     $pixel_code = FacebookPixel::getPixelLeadCode(array(), self::TRACKING_NAME, false);
@@ -47,7 +47,18 @@ public static function injectLeadEvent($confimation, $form, $entry, $ajax) {
     <!-- End Facebook Pixel Event Code -->
     ", $pixel_code);
 
-    $confimation .= $code;
-    return $confimation;
+    if (is_string($confirmation)) {
+        $confirmation .= $code;
+    } elseif ( is_array($confirmation) && isset($confirmation['redirect'])) {
+        $redirect_code = sprintf("
+            <!-- Facebook Pixel Gravity Forms Redirect Code -->
+            <script>%sdocument.location.href=%s;%s</script>
+            <!-- End Facebook Pixel Gravity Forms Redirect Code -->
+            ", apply_filters('gform_cdata_open', ''), defined('JSON_HEX_TAG') ? json_encode($confirmation['redirect'], JSON_HEX_TAG) : json_encode($confirmation['redirect']), apply_filters('gform_cdata_close', '')
+		);
+        $confirmation = $code . $redirect_code;
+    }
+
+    return $confirmation;
   }
 }