<?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/>.

/**
 * Specialised restore for format_topics
 *
 * @package   format_topics
 * @category  backup
 * @copyright 2017 Marina Glancy
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * Specialised restore for format_topics
 *
 * Processes 'numsections' from the old backup files and hides sections that used to be "orphaned"
 *
 * @package   format_topics
 * @category  backup
 * @copyright 2017 Marina Glancy
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class restore_format_topics_plugin extends restore_format_plugin {

    /** @var int */
    protected $originalnumsections = 0;

    /**
     * Checks if backup file was made on Moodle before 3.3 and we should respect the 'numsections'
     * and potential "orphaned" sections in the end of the course.
     *
     * @return bool
     */
    protected function need_restore_numsections() {
        $backupinfo = $this->step->get_task()->get_info();
        $backuprelease = $backupinfo->backup_release;
        return version_compare($backuprelease, '3.3', 'lt');
    }

    /**
     * Creates a dummy path element in order to be able to execute code after restore
     *
     * @return restore_path_element[]
     */
    public function define_course_plugin_structure() {
        global $DB;

        // Since this method is executed before the restore we can do some pre-checks here.
        // In case of merging backup into existing course find the current number of sections.
        $target = $this->step->get_task()->get_target();
        if (($target == backup::TARGET_CURRENT_ADDING || $target == backup::TARGET_EXISTING_ADDING) &&
                $this->need_restore_numsections()) {
            $maxsection = $DB->get_field_sql(
                'SELECT max(section) FROM {course_sections} WHERE course = ?',
                [$this->step->get_task()->get_courseid()]);
            $this->originalnumsections = (int)$maxsection;
        }

        // Dummy path element is needed in order for after_restore_course() to be called.
        return [new restore_path_element('dummy_course', $this->get_pathfor('/dummycourse'))];
    }

    /**
     * Dummy process method
     */
    public function process_dummy_course() {

    }

    /**
     * Executed after course restore is complete
     *
     * This method is only executed if course configuration was overridden
     */
    public function after_restore_course() {
        global $DB;

        if (!$this->need_restore_numsections()) {
            // Backup file was made in Moodle 3.3 or later, we don't need to process 'numsecitons'.
            return;
        }

        $data = $this->connectionpoint->get_data();
        $backupinfo = $this->step->get_task()->get_info();
        if ($backupinfo->original_course_format !== 'topics' || !isset($data['tags']['numsections'])) {
            // Backup from another course format or backup file does not even have 'numsections'.
            return;
        }

        $numsections = (int)$data['tags']['numsections'];
        foreach ($backupinfo->sections as $key => $section) {
            // For each section from the backup file check if it was restored and if was "orphaned" in the original
            // course and mark it as hidden. This will leave all activities in it visible and available just as it was
            // in the original course.
            // Exception is when we restore with merging and the course already had a section with this section number,
            // in this case we don't modify the visibility.
            if ($this->step->get_task()->get_setting_value($key . '_included')) {
                $sectionnum = (int)$section->title;
                if ($sectionnum > $numsections && $sectionnum > $this->originalnumsections) {
                    $DB->execute("UPDATE {course_sections} SET visible = 0 WHERE course = ? AND section = ?",
                        [$this->step->get_task()->get_courseid(), $sectionnum]);
                }
            }
        }
    }
}
