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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Statement result for xAPI structure checking and usage.
  19   *
  20   * @package    core_xapi
  21   * @copyright  2020 Ferran Recio
  22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  namespace core_xapi\local\statement;
  26  
  27  use core_xapi\xapi_exception;
  28  use DateInterval;
  29  use Exception;
  30  use stdClass;
  31  
  32  /**
  33   * Abstract xAPI result class.
  34   *
  35   * @copyright  2020 Ferran Recio
  36   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  37   */
  38  class item_result extends item {
  39  
  40      /** @var int The second of duration if present. */
  41      protected $duration;
  42  
  43      /** @var item_score the result score if present. */
  44      protected $score;
  45  
  46      /**
  47       * Function to create a result from part of the xAPI statement.
  48       *
  49       * @param stdClass $data the original xAPI element
  50       * @param int $duration duration in seconds
  51       * @param item_score $score the provided score
  52       */
  53      protected function __construct(stdClass $data, int $duration = null, item_score $score = null) {
  54          parent::__construct($data);
  55          $this->duration = $duration;
  56          $this->score = $score;
  57      }
  58  
  59      /**
  60       * Function to create an item from part of the xAPI statement.
  61       *
  62       * @param stdClass $data the original xAPI element
  63       * @return item item_result xAPI generated
  64       */
  65      public static function create_from_data(stdClass $data): item {
  66  
  67          $duration = null;
  68          if (!empty($data->duration)) {
  69              try {
  70                  // Duration uses ISO 8601 format which is ALMOST compatible with PHP DateInterval.
  71                  // Because we are mesuring human time we get rid of milliseconds, which are not
  72                  // compatible with DateInterval (More info: https://bugs.php.net/bug.php?id=53831),
  73                  // all other fractions like "P1.5Y" will throw an exception.
  74                  $value = preg_replace('/[.,][0-9]*S/', 'S', $data->duration);
  75                  $interval = new DateInterval($value);
  76                  $duration = date_create('@0')->add($interval)->getTimestamp();
  77              } catch (Exception $e) {
  78                  throw new xapi_exception('Invalid duration format.');
  79              }
  80          }
  81  
  82          $score = null;
  83          if (!empty($data->score)) {
  84              $score = item_score::create_from_data($data->score);
  85          }
  86  
  87          return new self($data, $duration, $score);
  88      }
  89  
  90      /**
  91       * Returns the duration in seconds (if present).
  92       *
  93       * @return int|null duration in seconds
  94       */
  95      public function get_duration(): ?int {
  96          return $this->duration;
  97      }
  98  
  99      /**
 100       * Returns the score.
 101       *
 102       * @return item_score|null the score item
 103       */
 104      public function get_score(): ?item_score {
 105          return $this->score;
 106      }
 107  }