teacherskey/teacherskey/settings.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * enrol_teacherskey file description here.
 *
 * @package    enrol_teacherskey
 * @copyright  2022 Alex Sidorov <alex.sidorov@ya.ru>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


defined("MOODLE_INTERNAL") || die();

if($ADMIN->fulltree){

    $option = get_default_enrol_roles(context_system::instance());
    $settings->add(new admin_setting_heading('enrol_teacherskey_settings', '', get_string('pluginname_desc', 'enrol_teacherskey')));

    $settings->add(new admin_setting_heading('enrol_teacherskey_defaults',
        get_string('enrolinstancedefaults', 'admin'), get_string('enrolinstancedefaults_desc', 'admin')));

    $settings->add(new admin_setting_configcheckbox('enrol_teacherskey/defaultenrol',
        get_string('defaultenrol', 'enrol'), get_string('defaultenrol_desc', 'enrol'), 1));

    if (!during_initial_install()) {
        $options = get_default_enrol_roles(context_system::instance());
        $student = get_archetype_roles('student');
        $student = reset($student);
        $settings->add(new admin_setting_configselect('enrol_teacherskey/roleid',
            get_string('defaultrole', 'enrol_teacherskey'),
            get_string('defaultrole_desc', 'enrol_teacherskey'),
            $student->id ?? null,
            $options));
    }

}