#include<iostream>
#include<string>
#include<algorithm>
#include<vector>

class DATE_VALIDATOR
{
public:
	bool dateValidator(int year, int month, int day)
	{
		if (year < 1582 && date_in_range(year, month, day)) return true;
		else if (year > 1582 && date_in_range(year, month, day)) return true;
		else return false;
	}

	bool leapYear(int year)
	{
		if (year > 1582 && year % 4 == 0 && year % 100 != 0) return true;
		else if (year > 1582 && year % 400 == 0) return true;
		else return false;
	}

	bool date_in_range(int year, int month, int day)
	{
		std::vector<int>::iterator day30test = find(MONTH30.begin(), MONTH30.end(), month);
		std::vector<int>::iterator day31test = find(MONTH31.begin(), MONTH31.end(), month);
		if (year == 0 || month < 1 || month > 12 || day < 0 || day > 31) return false;
		else if (month == 2) {
			if (!leapYear(year) && day <= 28) return true;
			else if (leapYear(year) && day <= 29) return true;
			else return false;
		}
		else if (day30test != MONTH30.end() && day <= 30) return true;
		else if (day31test != MONTH31.end() && day <= 31) return true;
		else return false;
	}

	int julian_day_number(int year, int month, int day)
	{
		int dayCount = 0;

		for (int i = 1; i < month; ++i) {
			std::vector<int>::iterator day30test = find(MONTH30.begin(), MONTH30.end(), i);
			std::vector<int>::iterator day31test = find(MONTH31.begin(), MONTH31.end(), i);

			if (day31test != MONTH31.end()) dayCount += 31;
			else if (day30test != MONTH30.end()) dayCount += 30;
			else if (i == 2) {
				if (!leapYear(year)) dayCount += 28;
				else dayCount += 29;
			}
		}
		dayCount += day;

		return dayCount;
	}

private:
	std::vector<int> MONTH30 = { 4, 6, 9, 11 };
	std::vector<int> MONTH31 = { 1, 3, 5, 7, 8, 10, 12 };
};

int main()
{
	DATE_VALIDATOR dv;
	int x = 0, year, month, day;
	char contPrgm = 'y';
	
	do {
		std::cout << "\nPlease enter a date (yyyy mm dd): ";
		std::cin >> year >> month >> day;
		
		if (dv.dateValidator(year, month, day)) std::cout << "Date is valid. \nThe Julian date is " << dv.julian_day_number(year, month, day) << std::endl;
		else std::cout << "Date is invalid" << std::endl;

		std::cout << "\nTo stop, type 'n' and hit enter. ";
		std::cin >> contPrgm;
		std::cin.ignore();
		
	} while(contPrgm != 'n');

	system("pause");
	return 0;
}