Finalize referrer form finisher by adding request middlewareπ

public/typo3conf/ext/ep_theme/Classes/Form/AddReferrerFinisher.php

@@ -8,8 +8,14 @@ class AddReferrerFinisher extends AbstractFinisher
 {
     protected function executeInternal()
     {
-        $referrer = 'FooBarBaz';
+        // Look for key 'referrer' in frontend session
+        $referrer = $GLOBALS['TSFE']->fe_user->getKey('ses', 'referrer');
 
+        if (null === $referrer) {
+            return;
+        }
+
+        // Add textfield to form containing referrer value
         $field = $this->finisherContext
             ->getFormRuntime()
             ->getFormDefinition()
@@ -20,10 +26,15 @@ class AddReferrerFinisher extends AbstractFinisher
         $field->setDataType('string');
         $field->setLabel('Referrer');
 
+        // Add finisher variable for potential later use
         $this->finisherContext->getFinisherVariableProvider()->add(
             $this->shortFinisherIdentifier,
             'referrer',
             $referrer
         );
+
+        // Remove session key
+        $GLOBALS['TSFE']->fe_user->setKey('ses', 'referrer', null);
+        $GLOBALS['TSFE']->fe_user->storeSessionData();
     }
 }

public/typo3conf/ext/ep_theme/Classes/Middleware/ReferrerMiddleware.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace EP\EpTheme\Middleware;
+
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use TYPO3\CMS\Core\Exception\SiteNotFoundException;
+use TYPO3\CMS\Core\Site\SiteFinder;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+
+class ReferrerMiddleware implements MiddlewareInterface
+{
+    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
+    {
+        $queryParams = $request->getQueryParams();
+
+        if (!array_key_exists('ref', $queryParams)) {
+            return $handler->handle($request);
+        }
+
+        $ref = $queryParams['ref'];
+
+        /** @var SiteFinder $siteFinder */
+        $siteFinder = GeneralUtility::makeInstance(SiteFinder::class);
+
+        try {
+            $site = $siteFinder->getSiteByPageId($ref);
+            $url = $site->getRouter()->generateUri($ref);
+            $GLOBALS['TSFE']->fe_user->setKey('ses', 'referrer', $url);
+            $GLOBALS['TSFE']->fe_user->storeSessionData();
+        }
+        catch (SiteNotFoundException $exception) {
+        }
+
+        return $handler->handle($request);
+    }
+}

public/typo3conf/ext/ep_theme/Configuration/RequestMiddlewares.php

@@ -0,0 +1,12 @@
+<?php
+
+return [
+    'frontend' => [
+        'ep/referrer' => [
+            'target' => \EP\EpTheme\Middleware\ReferrerMiddleware::class,
+            'after' => [
+                'typo3/cms-frontend/site',
+            ],
+        ],
+    ],
+];

public/typo3conf/ext/ep_theme/Configuration/Yaml/FormSetup.yaml

@@ -1,29 +0,0 @@
-TYPO3:
-  CMS:
-    Form:
-      persistenceManager:
-        allowedExtensionPaths:
-          10: EXT:ep_theme/Resources/Private/Forms/
-
-      prototypes:
-        standard:
-          finishersDefinition:
-            BpnApiFinisher:
-              implementationClassName: 'EP\EpTheme\Form\BpnApiFinisher'
-          formElementsDefinition:
-            Form:
-              renderingOptions:
-                templateRootPaths:
-                  100: 'EXT:ep_theme/Resources/Private/Templates/Form/'
-                partialRootPaths:
-                  100: 'EXT:ep_theme/Resources/Private/Partials/Form/'
-                layoutRootPaths:
-                  100: 'EXT:ep_theme/Resources/Private/Layouts/Form/'
-
-        contactform:
-          __inheritances:
-            10: 'TYPO3.CMS.Form.prototypes.standard'
-
-        applicationform:
-          __inheritances:
-            10: 'TYPO3.CMS.Form.prototypes.standard'