WIP backup engine

Signed-off-by: Camille Tardy <camille.tardy@unige.ch>

backup/moodle2/backup_report_group_plugin.class.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/>.
+
+/**
+ * @package    moodlecore
+ * @subpackage backup-moodle2
+ * @copyright  2020 onwards Camille Tardy, University of Geneva
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+
+defined('MOODLE_INTERNAL') || die();
+
+
+/**
+ * Provides the information to backup group quiz info
+ */
+class backup_report_group_plugin extends backup_report_plugin {
+
+    /**
+     * Returns the quiz report information to attach to quiz element
+     */
+    protected function define_quiz_plugin_structure() {
+        // Define virtual plugin element, only backup report if conditions (get_include_condition) are met
+        $plugin = $this->get_plugin_element(null, $this->get_include_condition(), 'include');
+
+        // Create plugin container element with standard name
+        $pluginwrapper = new backup_nested_element($this->get_recommended_name());
+
+        // Add wrapper to plugin
+        $plugin->add_child($pluginwrapper);
+
+//TODO define backup datat and DB link
+
+        // Set up quiz report's own structure and add to wrapper
+        $groupquiz = new backup_nested_element('quiz_group', array('id'), array(
+            'groupingid'));
+        $pluginwrapper->add_child($groupquiz);
+
+        // Use database to get source
+        $groupquiz->set_source_table('quiz_group',
+                array('quizid' => backup::VAR_QUIZID));
+
+
+        return $plugin;
+    }
+
+   /**
+    * Returns a condition for whether we include this report in the backup
+    * or not. If no record with the quiz id exist, do not backup.
+    * @return array Condition array
+    */
+   protected function get_include_condition() {
+       global $DB;
+       //TODO get quizid here.
+       $quizid = 0;
+
+       if ($DB->record_exists('quiz_group',
+               array('quizid' => $quizid))) {
+           $result = 'include';
+       } else {
+           $result = ;
+       }
+       return array('sqlparam' => $result);
+   }
+
+
+}