#include <iostream>
#include <cstdlib>
#include "date.h"
using namespace std;

const int date_length[] = {
	 0,   //dummy element so that january will have subscript 1
	31,   //january
	28,   //february
	31,   //march
	30,   //april
	31,   //may
	30,   //june
	31,   //july
	31,   //august
	30,   //september
	31,   //october
	30,   //november
	31    //december
};

date::date(int initial_month, int initial_day, int initial_year)
{
	if (initial_month < january || initial_month > december) {
		cerr << "bad month " << initial_month << "/" << initial_day
			<< "/" << initial_year << "\n";
		exit(EXIT_FAILURE);
	}

	if (initial_day < 1 || initial_day > date_length[initial_month]) {
		cerr << "bad day " << initial_month << "/" << initial_day
			<< "/" << initial_year << "\n";
		exit(EXIT_FAILURE);
	}

	year = initial_year;
	month = initial_month;
	day = initial_day;
}

void date::next(int count)
{
	div_t divide = div(count, 365);
	if (divide.rem < 0) {
		divide.rem += 365;
		--divide.quot;
	}

	year += divide.quot;
	day  += divide.rem;

	while (day > date_length[month]) {
		day -= date_length[month];
		if (++month > december) {
			month = january;
			++year;
		}
	}
}