class EntityUuidConverter

class EntityUuidConverter extends EntityConverter {
  
  /**
   * The language manager.
   *
   * @var \Drupal\Core\Language\LanguageManagerInterface
   */
  protected $languageManager;
  
  /**
   * Injects the language manager.
   *
   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
   *   The language manager to get the current content language.
   */
  public function setLanguageManager(LanguageManagerInterface $language_manager) {
    $this->languageManager = $language_manager;
  }
  
  /**
   * {@inheritdoc}
   */
  public function convert($value, $definition, $name, array $defaults) {
    $entity_type_id = $this->getEntityTypeFromDefaults($definition, $name, $defaults);
    $uuid_key = $this->entityTypeManager
      ->getDefinition($entity_type_id)
      ->getKey('uuid');
    if ($storage = $this->entityTypeManager
      ->getStorage($entity_type_id)) {
      if (!$entities = $storage->loadByProperties([
        $uuid_key => $value,
      ])) {
        return NULL;
      }
      $entity = reset($entities);
      // If the entity type is translatable, ensure we return the proper
      // translation object for the current context.
      if ($entity instanceof TranslatableInterface && $entity->isTranslatable()) {
        // @see https://www.drupal.org/project/drupal/issues/2624770
        $entity = $this->entityRepository
          ->getTranslationFromContext($entity, NULL, [
          'operation' => 'entity_upcast',
        ]);
        // JSON:API always has only one method per route.
        $method = $defaults[RouteObjectInterface::ROUTE_OBJECT]->getMethods()[0];
        if (in_array($method, [
          'PATCH',
          'DELETE',
        ], TRUE)) {
          $current_content_language = $this->languageManager
            ->getCurrentLanguage(LanguageInterface::TYPE_CONTENT)
            ->getId();
          if ($method === 'DELETE' && (!$entity->isDefaultTranslation() || $entity->language()
            ->getId() !== $current_content_language)) {
            throw new MethodNotAllowedHttpException([
              'GET',
            ], 'Deleting a resource object translation is not yet supported. See https://www.drupal.org/docs/8/modules/jsonapi/translations.');
          }
          if ($method === 'PATCH' && $entity->language()
            ->getId() !== $current_content_language) {
            $available_translations = implode(', ', array_keys($entity->getTranslationLanguages()));
            throw new MethodNotAllowedHttpException([
              'GET',
            ], sprintf('The requested translation of the resource object does not exist, instead modify one of the translations that do exist: %s.', $available_translations));
          }
        }
      }
      return $entity;
    }
    return NULL;
  }
  
  /**
   * {@inheritdoc}
   */
  public function applies($definition, $name, Route $route) {
    return (bool) Routes::getResourceTypeNameFromParameters($route->getDefaults()) && !empty($definition['type']) && str_starts_with($definition['type'], 'entity');
  }

}