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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   * Time splitting method that generates predictions regularly.
  19   *
  20   * @package   core_analytics
  21   * @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
  22   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  namespace core_analytics\local\time_splitting;
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  /**
  30   * Time splitting method that generates predictions periodically.
  31   *
  32   * @package   core_analytics
  33   * @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
  34   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  35   */
  36  abstract class past_periodic extends periodic implements before_now {
  37  
  38      /**
  39       * Gets the next range with start on the provided time.
  40       *
  41       * The next range is based on the past period so we substract this
  42       * range's periodicity from $time.
  43       *
  44       * @param  \DateTimeImmutable $time
  45       * @return array
  46       */
  47      protected function get_next_range(\DateTimeImmutable $time) {
  48  
  49          $end = $time->getTimestamp();
  50          $start = $time->sub($this->periodicity())->getTimestamp();
  51  
  52          if ($start < $this->analysable->get_start()) {
  53              // We skip the first range generated as its start is prior to the analysable start.
  54              return false;
  55          }
  56  
  57          return [
  58              'start' => $start,
  59              'end' => $end,
  60              'time' => $end
  61          ];
  62      }
  63  
  64      /**
  65       * Get the start of the first time range.
  66       *
  67       * @return int A timestamp.
  68       */
  69      protected function get_first_start() {
  70          return $this->analysable->get_start();
  71      }
  72  
  73      /**
  74       * Guarantees that the last range dates end right now.
  75       *
  76       * @param  array  $ranges
  77       * @return array
  78       */
  79      protected function update_last_range(array $ranges) {
  80          $lastrange = end($ranges);
  81  
  82          if ($lastrange['time'] > time()) {
  83              // We just need to wait in this case.
  84              return $lastrange;
  85          }
  86  
  87          $timetoenddiff = time() - $lastrange['time'];
  88  
  89          $ranges[count($ranges) - 1] = [
  90              'start' => $lastrange['start'] + $timetoenddiff,
  91              'end' => $lastrange['end'] + $timetoenddiff,
  92              'time' => $lastrange['time'] + $timetoenddiff,
  93          ];
  94  
  95          return $ranges;
  96      }
  97  }