moodle/admin/search.php

<?php

// searches for admin settings

require_once('../config.php');
require_once($CFG->libdir.'/adminlib.php');

$query = trim(optional_param('query', '', PARAM_NOTAGS));  // Search string

$context = context_system::instance();
$PAGE->set_context($context);

admin_externalpage_setup('search', '', array('query' => $query)); // now hidden page

$adminroot = admin_get_root(); // need all settings here
$adminroot->search = $query; // So we can reference it in search boxes later in this invocation
$statusmsg = '';
$errormsg  = '';
$focus = '';

// now we'll deal with the case that the admin has submitted the form with changed settings
if ($data = data_submitted() and confirm_sesskey() and isset($data->action) and $data->action == 'save-settings') {
    require_capability('moodle/site:config', $context);
    if (admin_write_settings($data)) {
        redirect($PAGE->url, get_string('changessaved'), null, \core\output\notification::NOTIFY_SUCCESS);
    }

    if (!empty($adminroot->errors)) {
        $errormsg = get_string('errorwithsettings', 'admin');
        $firsterror = reset($adminroot->errors);
        $focus = $firsterror->id;
    } else {
        redirect($PAGE->url);
    }
}

// and finally, if we get here, then there are matching settings and we have to print a form
// to modify them
echo $OUTPUT->header($focus);

// Display a warning if site is not registered.
if (empty($query)) {
    $adminrenderer = $PAGE->get_renderer('core', 'admin');
    echo $adminrenderer->warn_if_not_registered();
}

echo $OUTPUT->heading(get_string('administrationsite'));

if ($errormsg !== '') {
    echo $OUTPUT->notification($errormsg);

} else if ($statusmsg !== '') {
    echo $OUTPUT->notification($statusmsg, 'notifysuccess');
}

$showsettingslinks = true;

if (has_capability('moodle/site:config', $context)) {
    require_once("admin_settings_search_form.php");
    $form = new admin_settings_search_form();
    $form->display();
    echo '<hr>';
    if ($query) {
        echo admin_search_settings_html($query);
        $showsettingslinks = false;
    }
}

if ($showsettingslinks) {
    $node = $PAGE->settingsnav->find('root', navigation_node::TYPE_SITE_ADMIN);
    if ($node) {
        echo $OUTPUT->render_from_template('core/settings_link_page', ['node' => $node]);
    }
}

echo $OUTPUT->footer();