class BigPipeHooks

class BigPipeHooks {
    
    /**
     * Implements hook_help().
     */
    public function help($route_name, RouteMatchInterface $route_match) {
        switch ($route_name) {
            case 'help.page.big_pipe':
                $output = '<h2>' . t('About') . '</h2>';
                $output .= '<p>' . t('The BigPipe module sends pages with dynamic content in a way that allows browsers to show them much faster. For more information, see the <a href=":big_pipe-documentation">online documentation for the BigPipe module</a>.', [
                    ':big_pipe-documentation' => 'https://www.drupal.org/documentation/modules/big_pipe',
                ]) . '</p>';
                $output .= '<h2>' . t('Uses') . '</h2>';
                $output .= '<dl>';
                $output .= '<dt>' . t('Speeding up your site') . '</dt>';
                $output .= '<dd>' . t('The module requires no configuration. Every part of the page contains metadata that allows BigPipe to figure this out on its own.') . '</dd>';
                $output .= '</dl>';
                return $output;
        }
    }
    
    /**
     * Implements hook_page_attachments().
     *
     * @see \Drupal\big_pipe\Controller\BigPipeController::setNoJsCookie()
     */
    public function pageAttachments(array &$page) {
        // Routes that don't use BigPipe also don't need no-JS detection.
        if (\Drupal::routeMatch()->getRouteObject()
            ->getOption('_no_big_pipe')) {
            return;
        }
        $request = \Drupal::request();
        // BigPipe is only used when there is an actual session, so only add the no-JS
        // detection when there actually is a session.
        // @see \Drupal\big_pipe\Render\Placeholder\BigPipeStrategy.
        $session_exists = \Drupal::service('session_configuration')->hasSession($request);
        $page['#cache']['contexts'][] = 'session.exists';
        // Only do the no-JS detection while we don't know if there's no JS support:
        // avoid endless redirect loops.
        $has_big_pipe_nojs_cookie = $request->cookies
            ->has(BigPipeStrategy::NOJS_COOKIE);
        $page['#cache']['contexts'][] = 'cookies:' . BigPipeStrategy::NOJS_COOKIE;
        if ($session_exists) {
            if (!$has_big_pipe_nojs_cookie) {
                // Let server set the BigPipe no-JS cookie.
                $page['#attached']['html_head'][] = [
                    [
                        // Redirect through a 'Refresh' meta tag if JavaScript is disabled.
'#tag' => 'meta',
                        '#noscript' => TRUE,
                        '#attributes' => [
                            'http-equiv' => 'Refresh',
                            'content' => '0; URL=' . Url::fromRoute('big_pipe.nojs', [], [
                                'query' => \Drupal::service('redirect.destination')->getAsArray(),
                            ])
                                ->toString(),
                        ],
                    ],
                    'big_pipe_detect_nojs',
                ];
            }
            else {
                // Let client delete the BigPipe no-JS cookie.
                $page['#attached']['html_head'][] = [
                    [
                        '#tag' => 'script',
                        '#value' => 'document.cookie = "' . BigPipeStrategy::NOJS_COOKIE . '=1; path=/; expires=Thu, 01 Jan 1970 00:00:00 GMT"',
                    ],
                    'big_pipe_detect_js',
                ];
            }
        }
    }
    
    /**
     * Implements hook_theme().
     */
    public function theme() : array {
        return [
            'big_pipe_interface_preview' => [
                'variables' => [
                    'callback' => NULL,
                    'arguments' => NULL,
                    'preview' => NULL,
                ],
            ],
        ];
    }

}