interface MaintenanceModeInterface

interface MaintenanceModeInterface {
    
    /**
     * Returns whether the site is in maintenance mode.
     *
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   The current route match.
     *
     * @return bool
     *   TRUE if the site is in maintenance mode.
     */
    public function applies(RouteMatchInterface $route_match);
    
    /**
     * Determines whether a user has access to the site in maintenance mode.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The logged in user.
     *
     * @return bool
     *   TRUE if the user should be exempted from maintenance mode.
     */
    public function exempt(AccountInterface $account);
    
    /**
     * Gets the site maintenance message.
     *
     * @return \Drupal\Component\Render\MarkupInterface
     *   The formatted site maintenance message.
     */
    public function getSiteMaintenanceMessage();

}