class MenuLinkContentHooks

class MenuLinkContentHooks {
    
    /**
     * Implements hook_help().
     */
    public function help($route_name, RouteMatchInterface $route_match) {
        switch ($route_name) {
            case 'help.page.menu_link_content':
                $output = '';
                $output .= '<h2>' . t('About') . '</h2>';
                $output .= '<p>' . t('The Custom Menu Links module allows users to create menu links. These links can be translated if multiple languages are used for the site.');
                if (\Drupal::moduleHandler()->moduleExists('menu_ui')) {
                    $output .= ' ' . t('It is required by the Menu UI module, which provides an interface for managing menus and menu links. For more information, see the <a href=":menu-help">Menu UI module help page</a> and the <a href=":drupal-org-help">online documentation for the Custom Menu Links module</a>.', [
                        ':menu-help' => Url::fromRoute('help.page', [
                            'name' => 'menu_ui',
                        ])->toString(),
                        ':drupal-org-help' => 'https://www.drupal.org/documentation/modules/menu_link',
                    ]);
                }
                else {
                    $output .= ' ' . t('For more information, see the <a href=":drupal-org-help">online documentation for the Custom Menu Links module</a>. If you install the Menu UI module, it provides an interface for managing menus and menu links.', [
                        ':drupal-org-help' => 'https://www.drupal.org/documentation/modules/menu_link',
                    ]);
                }
                $output .= '</p>';
                return $output;
        }
    }
    
    /**
     * Implements hook_entity_type_alter().
     */
    public function entityTypeAlter(array &$entity_types) : void {
        // @todo Moderation is disabled for custom menu links until when we have an UI
        //   for them.
        //   @see https://www.drupal.org/project/drupal/issues/2350939
        $entity_types['menu_link_content']->setHandlerClass('moderation', '');
    }
    
    /**
     * Implements hook_menu_delete().
     */
    public function menuDelete(MenuInterface $menu) {
        $storage = \Drupal::entityTypeManager()->getStorage('menu_link_content');
        $menu_links = $storage->loadByProperties([
            'menu_name' => $menu->id(),
        ]);
        $storage->delete($menu_links);
    }
    
    /**
     * Implements hook_ENTITY_TYPE_insert() for 'path_alias'.
     */
    public function pathAliasInsert(PathAliasInterface $path_alias) {
        _menu_link_content_update_path_alias($path_alias->getAlias());
    }
    
    /**
     * Implements hook_ENTITY_TYPE_update() for 'path_alias'.
     */
    public function pathAliasUpdate(PathAliasInterface $path_alias) {
        if ($path_alias->getAlias() != $path_alias->original
            ->getAlias()) {
            _menu_link_content_update_path_alias($path_alias->getAlias());
            _menu_link_content_update_path_alias($path_alias->original
                ->getAlias());
        }
        elseif ($path_alias->getPath() != $path_alias->original
            ->getPath()) {
            _menu_link_content_update_path_alias($path_alias->getAlias());
        }
    }
    
    /**
     * Implements hook_ENTITY_TYPE_delete() for 'path_alias'.
     */
    public function pathAliasDelete(PathAliasInterface $path_alias) {
        _menu_link_content_update_path_alias($path_alias->getAlias());
    }
    
    /**
     * Implements hook_entity_predelete().
     */
    public function entityPredelete(EntityInterface $entity) {
        
        /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
        $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
        $entity_type_id = $entity->getEntityTypeId();
        foreach ($entity->uriRelationships() as $rel) {
            $url = $entity->toUrl($rel);
            // Entities can provide uri relationships that are not routed, in this case
            // getRouteParameters() will throw an exception.
            if (!$url->isRouted()) {
                continue;
            }
            $route_parameters = $url->getRouteParameters();
            if (!isset($route_parameters[$entity_type_id])) {
                // Do not delete links which do not relate to this exact entity. For
                // example, "collection", "add-form", etc.
                continue;
            }
            // Delete all MenuLinkContent links that point to this entity route.
            $result = $menu_link_manager->loadLinksByRoute($url->getRouteName(), $route_parameters);
            if ($result) {
                foreach ($result as $id => $instance) {
                    if ($instance->isDeletable() && str_starts_with($id, 'menu_link_content:')) {
                        $instance->deleteLink();
                    }
                }
            }
        }
    }

}