public static function getWorkingDays($startDate, $endDate)
    {
        $holidays = [
            "01-01-2017", // Yılbaşı
            "23-04-2017", // 23 Nisan
            "01-05-2017", // 1 Mayıs
            "19-05-2017", // 19 Mayıs
            "24-06-2017", // Ramazan Bayramı Arifesi
            "25-06-2017", // 25 Haziran Ramazan Bayramı 1.gün
            "26-06-2017", // 26 Haziran Ramazan Bayramı 2.gün
            "27-06-2017", // 27 Haziran Ramazan Bayramı 3.gün
            "15-07-2017", // 15 Temmuz
            "30-08-2017", // 30 Ağustos
            "31-08-2017", // Kurban Bayramı Arifesi
            "01-09-2017", // Kurban Bayramı 1.gün
            "02-09-2017", // Kurban Bayramı 2.gün
            "03-09-2017", // Kurban Bayramı 3.gün
            "04-09-2017", // Kurban Bayramı 4.gün
            "29-10-2017"  // 29 Ekim
        ];

        $endDate = strtotime($endDate);
        $startDate = strtotime($startDate);

        $days = ($endDate - $startDate) / 86400 + 1;
        $no_full_weeks = floor($days / 7);
        $no_remaining_days = fmod($days, 7);

        $the_first_day_of_week = date("N", $startDate);
        $the_last_day_of_week = date("N", $endDate);

        if ($the_first_day_of_week <= $the_last_day_of_week) {
            if ($the_first_day_of_week <= 6 && 6 <= $the_last_day_of_week)
                $no_remaining_days--;
            if ($the_first_day_of_week <= 7 && 7 <= $the_last_day_of_week)
                $no_remaining_days--;
        } else {
            if ($the_first_day_of_week == 7) {
                $no_remaining_days--;
                if ($the_last_day_of_week == 6) {
                    $no_remaining_days--;
                }
            } else {
                $no_remaining_days -= 2;
            }
        }

        $workingDays = $no_full_weeks * 5;
        if ($no_remaining_days > 0) {
            $workingDays += $no_remaining_days;
        }

        foreach ($holidays as $holiday) {
            $time_stamp = strtotime($holiday);
            if ($startDate <= $time_stamp && $time_stamp <= $endDate && date("N", $time_stamp) != 6 && date("N", $time_stamp) != 7)
                $workingDays--;
        }

        return $workingDays;
    }