class DialogRenderer

class DialogRenderer implements MainContentRendererInterface {
    
    /**
     * The title resolver.
     *
     * @var \Drupal\Core\Controller\TitleResolverInterface
     */
    protected $titleResolver;
    
    /**
     * The renderer.
     *
     * @var \Drupal\Core\Render\RendererInterface
     */
    protected $renderer;
    
    /**
     * Constructs a new DialogRenderer.
     *
     * @param \Drupal\Core\Controller\TitleResolverInterface $title_resolver
     *   The title resolver.
     * @param \Drupal\Core\Render\RendererInterface $renderer
     *   The renderer.
     */
    public function __construct(TitleResolverInterface $title_resolver, RendererInterface $renderer) {
        $this->titleResolver = $title_resolver;
        $this->renderer = $renderer;
    }
    
    /**
     * {@inheritdoc}
     */
    public function renderResponse(array $main_content, Request $request, RouteMatchInterface $route_match) {
        $response = new AjaxResponse();
        // First render the main content, because it might provide a title.
        $content = $this->renderer
            ->renderRoot($main_content);
        // Attach the library necessary for using the OpenDialogCommand and set the
        // attachments for this Ajax response.
        $main_content['#attached']['library'][] = 'core/drupal.dialog.ajax';
        $response->setAttachments($main_content['#attached']);
        // Determine the title: use the title provided by the main content if any,
        // otherwise get it from the routing information.
        $title = $main_content['#title'] ?? $this->titleResolver
            ->getTitle($request, $route_match->getRouteObject());
        // Determine the dialog options and the target for the OpenDialogCommand.
        $options = $request->request
            ->get('dialogOptions', []);
        $target = $this->determineTargetSelector($options, $route_match);
        $response->addCommand(new OpenDialogCommand($target, $title, $content, $options));
        return $response;
    }
    
    /**
     * Determine the target selector for the OpenDialogCommand.
     *
     * @param array &$options
     *   The 'target' option, if set, is used, and then removed from $options.
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   When no 'target' option is set in $options, $route_match is used instead
     *   to determine the target.
     *
     * @return string
     *   The target selector.
     */
    protected function determineTargetSelector(array &$options, RouteMatchInterface $route_match) {
        // Generate the target wrapper for the dialog.
        if (isset($options['target'])) {
            // If the target was nominated in the incoming options, use that.
            $target = $options['target'];
            // Ensure the target includes the #.
            if (substr($target, 0, 1) != '#') {
                $target = '#' . $target;
            }
            // This shouldn't be passed on to jQuery.ui.dialog.
            unset($options['target']);
        }
        else {
            // Generate a target based on the route id.
            $route_name = $route_match->getRouteName();
            $target = '#' . Html::getUniqueId("drupal-dialog-{$route_name}");
        }
        return $target;
    }

}