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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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declare(strict_types=1);
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namespace mod_scorm\cache;
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use cache_definition;
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/**
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* Cache data source for the scorm elements.
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*
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* @package mod_scorm
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* @copyright 2023 Catalyst IT Ltd
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* @author Dan Marsden <dan@danmarsden.com>
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class elements implements \cache_data_source {
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/** @var elements the singleton instance of this class. */
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protected static $instance = null;
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/**
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* Returns an instance of the data source class that the cache can use for loading data using the other methods
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* specified by this interface.
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*
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* @param cache_definition $definition
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* @return object
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*/
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public static function get_instance_for_cache(cache_definition $definition): elements {
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if (is_null(self::$instance)) {
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self::$instance = new elements();
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}
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return self::$instance;
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}
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/**
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* Loads the data for the key provided ready formatted for caching.
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*
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* @param string|int $key The key to load.
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* @return string What ever data should be returned, or null if it can't be loaded.
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* @throws \coding_exception
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*/
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public function load_for_cache($key): ?string {
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global $DB;
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$element = $DB->get_field('scorm_element', 'id', ['element' => $key]);
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// Return null instead of false, because false will not be cached.
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return $element ?: null;
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}
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/**
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* Loads several keys for the cache.
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*
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* @param array $keys An array of keys each of which will be string|int.
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* @return array An array of matching data items.
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*/
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public function load_many_for_cache(array $keys): array {
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global $DB;
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list ($elementsql, $params) = $DB->get_in_or_equal($keys);
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$sql = "SELECT element, id
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FROM {scorm_element}
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WHERE element ".$elementsql;
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return $DB->get_records_sql_menu($sql, $params);
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}
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}
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