/**
  * Delete a course
  * This function deletes a whole course-area from the platform. When the
  * given course is a virtual course, the database and directory will not be
  * deleted.
  * When the given course is a real course, also all virtual courses refering
  * to the given course will be deleted.
  * Considering the fact that we remove all traces of the course in the main
  * database, it makes sense to remove all tracking as well (if stats databases exist)
  * so that a new course created with this code would not use the remains of an older
  * course.
  *
  * @param string The code of the course to delete
  * @todo When deleting a virtual course: unsubscribe users from that virtual
  * course from the groups in the real course if they are not subscribed in
  * that real course.
  * @todo Remove globals
  */
 public static function delete_course($code)
 {
     $table_course = Database::get_main_table(TABLE_MAIN_COURSE);
     $table_course_user = Database::get_main_table(TABLE_MAIN_COURSE_USER);
     $table_session_course = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
     $table_session_course_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
     $table_course_survey = Database::get_main_table(TABLE_MAIN_SHARED_SURVEY);
     $table_course_survey_question = Database::get_main_table(TABLE_MAIN_SHARED_SURVEY_QUESTION);
     $table_course_survey_question_option = Database::get_main_table(TABLE_MAIN_SHARED_SURVEY_QUESTION_OPTION);
     $table_course_rel_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_COURSE);
     $table_stats_hotpots = Database::get_main_table(TABLE_STATISTIC_TRACK_E_HOTPOTATOES);
     $table_stats_attempt = Database::get_main_table(TABLE_STATISTIC_TRACK_E_ATTEMPT);
     $table_stats_exercises = Database::get_main_table(TABLE_STATISTIC_TRACK_E_EXERCISES);
     $table_stats_access = Database::get_main_table(TABLE_STATISTIC_TRACK_E_ACCESS);
     $table_stats_lastaccess = Database::get_main_table(TABLE_STATISTIC_TRACK_E_LASTACCESS);
     $table_stats_course_access = Database::get_main_table(TABLE_STATISTIC_TRACK_E_COURSE_ACCESS);
     $table_stats_online = Database::get_main_table(TABLE_STATISTIC_TRACK_E_ONLINE);
     $table_stats_default = Database::get_main_table(TABLE_STATISTIC_TRACK_E_DEFAULT);
     $table_stats_downloads = Database::get_main_table(TABLE_STATISTIC_TRACK_E_DOWNLOADS);
     $table_stats_links = Database::get_main_table(TABLE_STATISTIC_TRACK_E_LINKS);
     $table_stats_uploads = Database::get_main_table(TABLE_STATISTIC_TRACK_E_UPLOADS);
     $codeFiltered = Database::escape_string($code);
     $sql = "SELECT * FROM {$table_course} WHERE code='" . $codeFiltered . "'";
     $res = Database::query($sql);
     if (Database::num_rows($res) == 0) {
         return;
     }
     $sql = "SELECT * FROM {$table_course}\n                WHERE code = '" . $codeFiltered . "'";
     $res = Database::query($sql);
     $course = Database::fetch_array($res);
     $courseId = $course['id'];
     $count = 0;
     if (api_is_multiple_url_enabled()) {
         $url_id = 1;
         if (api_get_current_access_url_id() != -1) {
             $url_id = api_get_current_access_url_id();
         }
         UrlManager::delete_url_rel_course($courseId, $url_id);
         $count = UrlManager::getCountUrlRelCourse($courseId);
     }
     if ($count == 0) {
         self::create_database_dump($code);
         $course_tables = AddCourse::get_course_tables();
         // Cleaning c_x tables
         if (!empty($courseId)) {
             foreach ($course_tables as $table) {
                 $table = Database::get_course_table($table);
                 $sql = "DELETE FROM {$table} WHERE c_id = {$courseId} ";
                 Database::query($sql);
             }
         }
         $course_dir = api_get_path(SYS_COURSE_PATH) . $course['directory'];
         $archive_dir = api_get_path(SYS_ARCHIVE_PATH) . $course['directory'] . '_' . time();
         if (is_dir($course_dir)) {
             rename($course_dir, $archive_dir);
         }
         // Unsubscribe all users from the course
         $sql = "DELETE FROM {$table_course_user} WHERE c_id='" . $courseId . "'";
         Database::query($sql);
         // Delete the course from the sessions tables
         $sql = "DELETE FROM {$table_session_course} WHERE c_id='" . $courseId . "'";
         Database::query($sql);
         $sql = "DELETE FROM {$table_session_course_user} WHERE c_id='" . $courseId . "'";
         Database::query($sql);
         // Delete from Course - URL
         $sql = "DELETE FROM {$table_course_rel_url} WHERE c_id = '" . $courseId . "'";
         Database::query($sql);
         $sql = 'SELECT survey_id FROM ' . $table_course_survey . ' WHERE course_code="' . $codeFiltered . '"';
         $result_surveys = Database::query($sql);
         while ($surveys = Database::fetch_array($result_surveys)) {
             $survey_id = $surveys[0];
             $sql = 'DELETE FROM ' . $table_course_survey_question . ' WHERE survey_id="' . $survey_id . '"';
             Database::query($sql);
             $sql = 'DELETE FROM ' . $table_course_survey_question_option . ' WHERE survey_id="' . $survey_id . '"';
             Database::query($sql);
             $sql = 'DELETE FROM ' . $table_course_survey . ' WHERE survey_id="' . $survey_id . '"';
             Database::query($sql);
         }
         // Cleaning group categories
         $groupCategories = GroupManager::get_categories($course['code']);
         if (!empty($groupCategories)) {
             foreach ($groupCategories as $category) {
                 GroupManager::delete_category($category['id'], $course['code']);
             }
         }
         // Cleaning groups
         $groups = GroupManager::get_groups();
         if (!empty($groups)) {
             $groupList = array_column($groups, 'id');
             GroupManager::delete_groups($groupList);
         }
         // Delete the course from the stats tables
         $sql = "DELETE FROM {$table_stats_hotpots} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_attempt} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_exercises} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_access} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_lastaccess} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_course_access} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_online} WHERE c_id = {$courseId}";
         Database::query($sql);
         // Do not delete rows from track_e_default as these include course
         // creation and other important things that do not take much space
         // but give information on the course history
         //$sql = "DELETE FROM $table_stats_default WHERE c_id = $courseId";
         //Database::query($sql);
         $sql = "DELETE FROM {$table_stats_downloads} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_links} WHERE c_id = {$courseId}";
         Database::query($sql);
         $sql = "DELETE FROM {$table_stats_uploads} WHERE c_id = {$courseId}";
         Database::query($sql);
         // Delete the course from the database
         $sql = "DELETE FROM {$table_course} WHERE code = '" . $codeFiltered . "'";
         Database::query($sql);
         // delete extra course fields
         $extraFieldValues = new ExtraFieldValue('course');
         $extraFieldValues->deleteValuesByItem($courseId);
         // Add event to system log
         $user_id = api_get_user_id();
         Event::addEvent(LOG_COURSE_DELETE, LOG_COURSE_CODE, $code, api_get_utc_datetime(), $user_id, $courseId);
     }
 }