Working controller.

modules/lms_certificate_fillpdf/lms_certificate_fillpdf.routing.yml

@@ -5,3 +5,8 @@ lms_certificate.certificate:
     _title: 'Certificate'
   requirements:
     _custom_access: '\Drupal\lms_certificate_fillpdf\Controller\CertificateController::access'
+  options:
+    parameters:
+      type: entity:group
+      bundle:
+        - course

modules/lms_certificate_fillpdf/src/Controller/CertificateController.php

@@ -7,27 +7,78 @@ namespace Drupal\lms_certificate_fillpdf\Controller;
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Controller\ControllerResolverInterface;
+use Drupal\Core\Session\AccountInterface;
 use Drupal\group\Entity\GroupInterface;
 use Drupal\fillpdf\Controller\HandlePdfController;
+use Drupal\fillpdf\Service\FillPdfLinkManipulator;
+use Drupal\lms\TrainingManager;
+use Drupal\lms\Entity\Bundle\Course;
+use Drupal\lms\Entity\CourseStatusInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+
 
 class CertificateController extends ControllerBase {
 
-  public function __construct(protected ControllerResolverInterface $controllerResolver) {}
+  public function __construct(
+    protected ControllerResolverInterface $controllerResolver,
+    protected TrainingManager $trainingManager,
+    protected RequestStack $requestStack,
+    protected FillPdfLinkManipulator $linkManipulator,
+    protected HttpKernelInterface $httpKernel,
+  ) {}
 
   public static function create(ContainerInterface $container) {
     return new static(
-      $container->get('controller_resolver')
+      $container->get('controller_resolver'),
+      $container->get('lms.training_manager'),
+      $container->get('request_stack'),
+      $container->get('fillpdf.link_manipulator'),
+      $container->get('http_kernel'),
     );
   }
 
   public function getCertificate(GroupInterface $group) {
-    $controller_resolver = \Drupal::service('controller_resolver');
-    $controller = $controller_resolver->getControllerFromDefinition(HandlePdfController::class . '::populatePdf');
-    return $controller();
+    // Re-use the fillpdf controller to generate the merged PDF form
+    // certificate. The controller relies on query arguments from the current
+    // URL so call it via a subrequest.
+    // @todo if fill PDF adds an API to generate a PDF from context, use that
+    // instead.
+    $fid = $group->get('certificate')->entity->id();
+    $course_status = $this->trainingManager->loadCourseStatus($group, $this->currentUser(), ['status' => CourseStatusInterface::STATUS_PASSED]);
+    $query = [
+      'fid' => $fid,
+      'entity_ids' => [
+        'user' => [$this->currentUser()->id()],
+        'group' => [$group->id()],
+        'lms_course_status' => [$course_status->id()],
+      ],
+    ];
+
+    $link = $this->linkManipulator->generateLink($query);
+    $sub_request = Request::create($link->toString());
+    $response = $this->httpKernel->handle($sub_request, HttpKernelInterface::SUB_REQUEST);
+    return $response;
   }
 
   public function access(GroupInterface $group) {
-    return AccessResult::allowed();
+    $access_result = AccessResult::allowedIf(!$group->get('certificate')->isEmpty())->addCacheableDependency($group);
+    $course_status = $this->trainingManager->loadCourseStatus($group, $this->currentUser(), ['status' => CourseStatusInterface::STATUS_PASSED]);
+    $access_result->andIf(AccessResult::allowedIf($course_status));
+
+    if ($course_status) {
+      // If the user has passed, cache the result - the situation can only
+      // change if the course status changes again to a non-passed state.
+      $access_result->addCacheableDependency($course_status);
+    }
+    else {
+      $access_result->setcacheMaxAge(0);
+    }
+    // Set to cache per user even though the resulting response may be
+    // uncacheable.
+    $access_result->cachePerUser();
+    return $access_result;
   }
 }