#pragma once
#include <string>

int64_t JDay(int year, int month, int day) {
    if (month <= 2) {
        year--;
        month += 12;
    }
    int64_t J;
    int A = year / 100;
    A = 2 - A + (A / 4);
    J = 1461L * int64_t(year);
    J /= 4L;
    int64_t K = 306001L * int64_t(month + 1);
    K /= 10000L;
    J += K + day + 1720995L + A;
    return J;
}

void GDate(int64_t JD, int& y, int& m, int& d) {
    int64_t A = (JD * 4L - 7468865L) / 146097L;
    A = (JD > 2299160) ? JD + 1 + A - (A / 4L) : JD;
    int64_t B = A + 1524;
    int64_t C = (B * 20L - 2442L) / 7305L;
    int64_t D = (C * 1461L) / 4L;
    int64_t E = (10000L * (B - D)) / 306001L;
    d = static_cast<int>(B - D - ((E * 306001L) / 10000L));
    m = static_cast<int>((E <= 13) ? E - 1 : E - 13);
    y = static_cast<int>(C - ((m > 2) ? 4716 : 4715));
}

class Date {
 public:
    Date(int y = 0, int m = 0, int d = 0) : day(d), month(m), year(y) {
    }

    bool IsLeap() const {
        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0))
            return true;
        return false;
    }

    std::string ToString() {
        std::string dates = "";
        dates += day < 10 ? (+"0" + std::to_string(day) + ".") :
            (std::to_string(day)) + ".";
        dates += month < 10 ? (+"0" + std::to_string(month) + ".") :
            (std::to_string(month)) + ".";

        dates += year > 999 ? std::to_string(year) : year > 99 ?
            (+"0" + std::to_string(year)) : year > 9 ?
            (+"00" + std::to_string(year)) :
            (+"000" + std::to_string(year));

        return dates;
    }

    Date DaysLater(int days) const {
        
        int y, m, d;
        int64_t jday = JDay(year, month, day);
        GDate(jday + days, y, m, d);
        Date dat(y, m, d);
        return dat;
    }

    int DaysLeft(const Date& date) const {
        int64_t jday1 = JDay(year, month, day);
        int64_t jday2 = JDay(date.year, date.month, date.day);
        return jday2 - jday1;
    }

 private:
    int day;
    int month;
    int year;
};