<?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/>.

/**
 * @package    mod_chat
 * @subpackage backup-moodle2
 * @copyright 2010 onwards Dongsheng Cai <dongsheng@moodle.com>
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

/**
 * Define all the backup steps that will be used by the backup_chat_activity_task
 */
class backup_chat_activity_structure_step extends backup_activity_structure_step {
    protected function define_structure() {
        $userinfo = $this->get_setting_value('userinfo');

        // Define each element separated.
        $chat = new backup_nested_element('chat', array('id'), array(
            'name', 'intro', 'introformat', 'keepdays', 'studentlogs',
            'chattime', 'schedule', 'timemodified'));
        $messages = new backup_nested_element('messages');

        $message = new backup_nested_element('message', array('id'), array(
            'userid', 'groupid', 'system', 'message_text', 'timestamp'));

        // It is not cool to have two tags with same name, so we need to rename message field to message_text.
        $message->set_source_alias('message', 'message_text');
        // Renamed 'issystem' into 'system', for backward compatibility: 'system' is now a reserved word in MySQL 8.0.3+.
        $message->set_source_alias('issystem', 'system');

        // Build the tree.
        $chat->add_child($messages);
        $messages->add_child($message);

        // Define sources.
        $chat->set_source_table('chat', array('id' => backup::VAR_ACTIVITYID));

        // User related messages only happen if we are including user info.
        if ($userinfo) {
            $message->set_source_table('chat_messages', array('chatid' => backup::VAR_PARENTID));
        }

        // Define id annotations.
        $message->annotate_ids('user', 'userid');
        $message->annotate_ids('group', 'groupid');

        // Annotate the file areas in chat module.
        $chat->annotate_files('mod_chat', 'intro', null); // The chat_intro area doesn't use itemid.

        // Return the root element (chat), wrapped into standard activity structure.
        return $this->prepare_activity_structure($chat);
    }
}