#3363955 use frontend theme for rendering

src/TextExtractor.php

@@ -2,20 +2,32 @@
 
 namespace Drupal\yoast_analysis;
 
+use Drupal\Core\Config\ConfigFactory;
+use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Render\RendererInterface;
+use Drupal\Core\Theme\ActiveTheme;
+use Drupal\Core\Theme\MissingThemeDependencyException;
+use Drupal\Core\Theme\ThemeInitializationInterface;
+use Drupal\Core\Theme\ThemeManagerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 class TextExtractor {
   protected EntityTypeManagerInterface $entityTypeManager;
   protected RendererInterface $renderer;
   protected ContainerInterface $container;
+  protected ThemeManagerInterface $themeManager;
+  protected ThemeInitializationInterface $themeInitializer;
+  protected ConfigFactoryInterface $configFactory;
 
-  public function __construct(EntityTypeManagerInterface $entityTypeManager, RendererInterface $renderer, ContainerInterface $container) {
-    $this->entityTypeManager = $entityTypeManager;
+  public function __construct(EntityTypeManagerInterface $entity_type_manager, RendererInterface $renderer, ContainerInterface $container, ThemeInitializationInterface $theme_initilizer, ThemeManagerInterface $theme_manager, ConfigFactoryInterface $config_factory) {
+    $this->entityTypeManager = $entity_type_manager;
     $this->renderer = $renderer;
     $this->container = $container;
+    $this->themeInitializer = $theme_initilizer;
+    $this->themeManager = $theme_manager;
+    $this->configFactory = $config_factory;
   }
 
   public function getEntityHtml(EntityInterface $entity, $view_mode = 'yoast_analysis'): string {
@@ -26,7 +38,11 @@ class TextExtractor {
     $build['#entity_type'] = $entity->getEntityTypeId();
     $build['#' . $build['#entity_type']] = $entity;
 
-    return (string) $this->renderer->render($build);
+    $original_theme = $this->switchToDefaultTheme();
+    $output = $this->renderer->render($build);
+    $this->switchThemeBack($original_theme);
+
+    return (string) $output;
   }
 
   /**
@@ -61,4 +77,36 @@ class TextExtractor {
     return $this->getEntityMetatags($entity)['description'];
   }
 
+  private function switchToDefaultTheme(): ?ActiveTheme {
+    $activeTheme = $this->themeManager->getActiveTheme();
+    $defaultTheme = $this->configFactory
+      ->get('system.theme')
+      ->get('default');
+    try {
+      $defaultTheme = $this->themeInitializer
+        ->getActiveThemeByName($defaultTheme);
+    }
+    catch (MissingThemeDependencyException) {
+      return NULL;
+    }
+    if ($defaultTheme->getName() === $activeTheme->getName()) {
+      return NULL;
+    }
+
+    $this->themeManager->setActiveTheme($defaultTheme);
+    // Ensure that statically cached default variables are reset correctly,
+    // especially the directory variable.
+    drupal_static_reset('template_preprocess');
+    // Return the previously active theme, for switching back.
+    return $activeTheme;
+  }
+
+  private function switchThemeBack(?ActiveTheme $previousTheme): void {
+    if ($previousTheme === NULL
+      || $previousTheme === $this->themeManager->getActiveTheme()) {
+      return;
+    }
+    $this->themeManager->setActiveTheme($previousTheme);
+    drupal_static_reset('template_preprocess');
+  }
 }