public function getStats(string $listID = ''): array
    {
        $result = [];
        $result['upcomingTasksCount'] = 0;
        $result['upcomingTasks'] = [];
        $result['nextTaskStartTime'] = null;

        $currentTime = time();
        $list = $this->getListData($listID);
        foreach ($list as $taskID => $taskListData) {
            $result['upcomingTasksCount'] ++;
            if ($taskListData[0] === 1) { // version check
                $startTime = $taskListData[1];
                $result['upcomingTasks'][] = ['id' => $taskID, 'startTime' => $startTime];
                $tempStartTime = $startTime === null ? $currentTime : $startTime;
                if ($result['nextTaskStartTime'] === null || $result['nextTaskStartTime'] > $tempStartTime) {
                    $result['nextTaskStartTime'] = $tempStartTime;
                }
            }
        }

        return $result;
    }