<?php

require_once('config.php');
require_once($CFG->dirroot.'/lib/formslib.php');

class test_form extends moodleform {

    function definition() {

        $mform = $this->_form;

        $fieldname = 'firstformelement';
        $elementgroup = array();
        $elementgroup[] = $mform->createElement('checkbox', $fieldname.'_1', '', 'Spain');
        $elementgroup[] = $mform->createElement('checkbox', $fieldname.'_2', '', 'France');
        $elementgroup[] = $mform->createElement('checkbox', $fieldname.'_3', '', 'Germany');
        $elementgroup[] = $mform->createElement('checkbox', $fieldname.'_4', '', 'Italy');
        $mform->addGroup($elementgroup, $fieldname.'_group', 'Choose all the nations you like', '<br />', false);

        $fieldname = 'secondformelement';
        $options = array('first option', 'second option', 'third option');
        $mform->addElement('select', $fieldname, 'Just a drop down menu', $options);

        $test = 3;
        switch ($test) {
        case 1:
            $mform->disabledIf('secondformelement', 'firstformelement_1', 'eq', 0);
            $mform->disabledIf('secondformelement', 'firstformelement_2', 'eq', 1);
            $mform->disabledIf('secondformelement', 'firstformelement_3', 'eq', 1);
            $mform->disabledIf('secondformelement', 'firstformelement_4', 'eq', 0);
            break;
        case 2:
            $mform->disabledIf('secondformelement', 'firstformelement_1', 'eq', 0);
            $mform->disabledIf('secondformelement', 'firstformelement_2', 'checked');
            $mform->disabledIf('secondformelement', 'firstformelement_3', 'checked');
            $mform->disabledIf('secondformelement', 'firstformelement_4', 'eq', 0);
            break;
        case 3:
            $mform->disabledIf('secondformelement', 'firstformelement_1', 'notchecked');
            $mform->disabledIf('secondformelement', 'firstformelement_2', 'eq', 1);
            $mform->disabledIf('secondformelement', 'firstformelement_3', 'eq', 1);
            $mform->disabledIf('secondformelement', 'firstformelement_4', 'notchecked');
            break;
        case 4:
            $mform->disabledIf('secondformelement', 'firstformelement_1', 'notchecked');
            $mform->disabledIf('secondformelement', 'firstformelement_2', 'checked');
            $mform->disabledIf('secondformelement', 'firstformelement_3', 'checked');
            $mform->disabledIf('secondformelement', 'firstformelement_4', 'notchecked');
            break;
        default:

        }

        $this->add_action_buttons();
    }
}

// ===================

$PAGE->set_context(context_system::instance());
$PAGE->set_url('/mform_test.php');
$PAGE->set_title('mform_test');

$mform = new test_form(new moodle_url('/mform_test.php'));

if ($mform->is_cancelled()) {

}

if ($data = $mform->get_data()) {

}

echo $OUTPUT->header();
$mform->display();

echo $OUTPUT->footer();