MaintenanceModeSubscriber.php

<?php

namespace Drupal\Core\EventSubscriber;

use Drupal\Component\Render\FormattableMarkup;
use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\Render\BareHtmlPageRendererInterface;
use Drupal\Core\Messenger\MessengerInterface;
use Drupal\Core\Routing\RouteMatch;
use Drupal\Core\Routing\UrlGeneratorInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Site\MaintenanceModeInterface;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\StringTranslation\TranslationInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

/**
 * Maintenance mode subscriber for controller requests.
 */
class MaintenanceModeSubscriber implements EventSubscriberInterface {
    use StringTranslationTrait;
    
    /**
     * The maintenance mode.
     *
     * @var \Drupal\Core\Site\MaintenanceModeInterface
     */
    protected $maintenanceMode;
    
    /**
     * The current account.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $account;
    
    /**
     * The config factory.
     *
     * @var \Drupal\Core\Config\ConfigFactoryInterface
     */
    protected $config;
    
    /**
     * The url generator.
     *
     * @var \Drupal\Core\Routing\UrlGeneratorInterface
     */
    protected $urlGenerator;
    
    /**
     * The bare HTML page renderer.
     *
     * @var \Drupal\Core\Render\BareHtmlPageRendererInterface
     */
    protected $bareHtmlPageRenderer;
    
    /**
     * The messenger.
     *
     * @var \Drupal\Core\Messenger\MessengerInterface
     */
    protected $messenger;
    
    /**
     * Constructs a new MaintenanceModeSubscriber.
     *
     * @param \Drupal\Core\Site\MaintenanceModeInterface $maintenance_mode
     *   The maintenance mode.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The config factory.
     * @param \Drupal\Core\StringTranslation\TranslationInterface $translation
     *   The string translation.
     * @param \Drupal\Core\Routing\UrlGeneratorInterface $url_generator
     *   The url generator.
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The current user.
     * @param \Drupal\Core\Render\BareHtmlPageRendererInterface $bare_html_page_renderer
     *   The bare HTML page renderer.
     * @param \Drupal\Core\Messenger\MessengerInterface $messenger
     *   The messenger.
     */
    public function __construct(MaintenanceModeInterface $maintenance_mode, ConfigFactoryInterface $config_factory, TranslationInterface $translation, UrlGeneratorInterface $url_generator, AccountInterface $account, BareHtmlPageRendererInterface $bare_html_page_renderer, MessengerInterface $messenger) {
        $this->maintenanceMode = $maintenance_mode;
        $this->config = $config_factory;
        $this->stringTranslation = $translation;
        $this->urlGenerator = $url_generator;
        $this->account = $account;
        $this->bareHtmlPageRenderer = $bare_html_page_renderer;
        $this->messenger = $messenger;
    }
    
    /**
     * Returns the site maintenance page if the site is offline.
     *
     * @param \Symfony\Component\HttpKernel\Event\GetResponseEvent $event
     *   The event to process.
     */
    public function onKernelRequestMaintenance(GetResponseEvent $event) {
        $request = $event->getRequest();
        $route_match = RouteMatch::createFromRequest($request);
        if ($this->maintenanceMode
            ->applies($route_match)) {
            // Don't cache maintenance mode pages.
            \Drupal::service('page_cache_kill_switch')->trigger();
            if (!$this->maintenanceMode
                ->exempt($this->account)) {
                // Deliver the 503 page if the site is in maintenance mode and the
                // logged in user is not allowed to bypass it.
                // If the request format is not 'html' then show default maintenance
                // mode page else show a text/plain page with maintenance message.
                if ($request->getRequestFormat() !== 'html') {
                    $response = new Response($this->getSiteMaintenanceMessage(), 503, [
                        'Content-Type' => 'text/plain',
                    ]);
                    $event->setResponse($response);
                    return;
                }
                drupal_maintenance_theme();
                $response = $this->bareHtmlPageRenderer
                    ->renderBarePage([
                    '#markup' => $this->getSiteMaintenanceMessage(),
                ], $this->t('Site under maintenance'), 'maintenance_page');
                $response->setStatusCode(503);
                $event->setResponse($response);
            }
            else {
                // Display a message if the logged in user has access to the site in
                // maintenance mode. However, suppress it on the maintenance mode
                // settings page.
                if ($route_match->getRouteName() != 'system.site_maintenance_mode') {
                    if ($this->account
                        ->hasPermission('administer site configuration')) {
                        $this->messenger
                            ->addMessage($this->t('Operating in maintenance mode. <a href=":url">Go online.</a>', [
                            ':url' => $this->urlGenerator
                                ->generate('system.site_maintenance_mode'),
                        ]), 'status', FALSE);
                    }
                    else {
                        $this->messenger
                            ->addMessage($this->t('Operating in maintenance mode.'), 'status', FALSE);
                    }
                }
            }
        }
    }
    
    /**
     * Gets the site maintenance message.
     *
     * @return \Drupal\Component\Render\MarkupInterface
     *   The formatted site maintenance message.
     */
    protected function getSiteMaintenanceMessage() {
        return new FormattableMarkup($this->config
            ->get('system.maintenance')
            ->get('message'), [
            '@site' => $this->config
                ->get('system.site')
                ->get('name'),
        ]);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() {
        $events[KernelEvents::REQUEST][] = [
            'onKernelRequestMaintenance',
            30,
        ];
        $events[KernelEvents::EXCEPTION][] = [
            'onKernelRequestMaintenance',
        ];
        return $events;
    }

}