shimmie2/ext/downtime/main.php

<?php
/*
 * Name: Downtime
 * Author: Shish <webmaster@shishnet.org>
 * Link: http://code.shishnet.org/shimmie2/
 * License: GPLv2
 * Description: Show a "down for maintenance" page
 * Documentation:
 *  Once installed there will be some more options on the config page --
 *  Ticking "disable non-admin access" will mean that regular and anonymous
 *  users will be blocked from accessing the site, only able to view the
 *  message specified in the box.
 */

class Downtime extends Extension
{
    public function get_priority(): int
    {
        return 10;
    }

    public function onSetupBuilding(SetupBuildingEvent $event)
    {
        $sb = new SetupBlock("Downtime");
        $sb->add_bool_option("downtime", "Disable non-admin access: ");
        $sb->add_longtext_option("downtime_message", "<br>");
        $event->panel->add_block($sb);
    }

    public function onPageRequest(PageRequestEvent $event)
    {
        global $config, $page, $user;

        if ($config->get_bool("downtime")) {
            if (!$user->can("ignore_downtime") && !$this->is_safe_page($event)) {
                $msg = $config->get_string("downtime_message");
                $this->theme->display_message($msg);
                if (!defined("UNITTEST")) {  // hax D:
                    header("HTTP/1.0 {$page->code} Downtime");
                    print($page->data);
                    exit;
                }
            }
            $this->theme->display_notification($page);
        }
    }

    private function is_safe_page(PageRequestEvent $event)
    {
        if ($event->page_matches("user_admin/login")) {
            return true;
        } else {
            return false;
        }
    }
}