private function getDateCase()
    {
        $from = $this->from;
        $to = $this->to;

        // single date event
        if (!$to || $to->format('Ymd') === $from->format('Ymd')) {
            return 'single';
        }

        $fromDate = [
            'day'   => $from->format('d'),
            'month' => $from->format('m'),
            'year'  => $from->format('y')
        ];

        $toDate = [
            'day'   => $to->format('d'),
            'month' => $to->format('m'),
            'year'  => $to->format('y')
        ];

        $case = null;
        $case = $fromDate['day'] !== $toDate['day'] ? 'different_day' : $case;
        $case = $fromDate['month'] !== $toDate['month'] ? 'different_month' : $case;
        $case = $fromDate['year'] !== $toDate['year'] ? 'different_year' : $case;

        return $case;
    }