/**
  * Performs the data importation from Moodle core tables (courses, enrolled users, logs). This importation is done only if
  * database_helper->has_data_to_be_imported() returns true.
  *
  * @param int $courseid The current course id for which the data has to be imported.
  */
 protected function import_data($courseid)
 {
     $courseyear = $this->db->get_course_start_week_and_year($courseid)['year'];
     $previouscourses = $this->db->find_course_previous_teaching_ids_core_tables($courseid, $courseyear);
     foreach ($previouscourses as $previouscourse) {
         $this->db->dump_previous_core_info_to_historic_tables($previouscourse);
     }
     $previouscourses = $this->db->find_course_previous_teachings_ids_historic_tables($courseid, $courseyear);
     $this->db->insert_courses_associations($courseid, $previouscourses);
 }