class TourHelpSection

class TourHelpSection extends HelpSectionPluginBase implements ContainerFactoryPluginInterface {
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs a TourHelpSection object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager service.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->entityTypeManager = $entity_type_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('entity_type.manager'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheMaxAge() {
        // The calculation of which URL (if any) gets put on which tour depends
        // on a route access check. This can have a lot of inputs, including user
        // permissions and other factors. Rather than doing a complicated
        // accounting of the cache metadata for all of these possible factors, set
        // the max age of the cache to zero to prevent using incorrect cached
        // information.
        return 0;
    }
    
    /**
     * {@inheritdoc}
     */
    public function listTopics() {
        
        /** @var \Drupal\tour\TourInterface[] $tours */
        $tours = $this->entityTypeManager
            ->getStorage('tour')
            ->loadMultiple();
        // Sort in the manner defined by Tour.
        uasort($tours, [
            'Drupal\\tour\\Entity\\Tour',
            'sort',
        ]);
        // Make a link to each tour, using the first of its routes that can
        // be linked to by this user, if any.
        $topics = [];
        foreach ($tours as $tour) {
            $title = $tour->label();
            $id = $tour->id();
            $routes = $tour->getRoutes();
            $made_link = FALSE;
            foreach ($routes as $route) {
                // Some tours are for routes with parameters. For instance, there is
                // currently a tour in the Language module for the language edit page,
                // which appears on all pages with URLs like:
                // /admin/config/regional/language/edit/LANGCODE.
                // There is no way to make a link to the page that displays the tour,
                // because it is a set of pages. The easiest way to detect this is to
                // use a try/catch exception -- try to make a link, and it will error
                // out with a missing parameter exception if the route leads to a set
                // of pages instead of a single page.
                try {
                    $params = $route['route_params'] ?? [];
                    $url = Url::fromRoute($route['route_name'], $params);
                    // Skip this route if the current user cannot access it.
                    if (!$url->access()) {
                        continue;
                    }
                    // Generate the link HTML directly, using toString(), to catch
                    // missing parameter exceptions now instead of at render time.
                    $topics[$id] = Link::fromTextAndUrl($title, $url)->toString();
                    // If the line above didn't generate an exception, we have a good
                    // link that the user can access.
                    $made_link = TRUE;
                    break;
                } catch (\Exception $e) {
                    // Exceptions are normally due to routes that need parameters. If
                    // there is an exception, just try the next route and see if we can
                    // find one that will work for us.
                }
            }
            if (!$made_link) {
                // None of the routes worked to make a link, so at least display the
                // tour title.
                $topics[$id] = $title;
            }
        }
        return $topics;
    }

}