//This file is leapdate.C
#include <iostream>
#include <cstdlib>
#include "leapdate.h"
using namespace std;

int leapdate::length() const
{
	static const int len[] = {
		0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
	};

	const int y = get_year();

	bool is_leap;                //true if this is a leap year
	if (y % 400 == 0) {          //1600 and 2000 are leap years
		is_leap = true;
	} else if (y % 100 == 0) {   //1700, 1800, and 1900 are not leap years
		is_leap = false;
	} else if (y % 4 == 0) {
		is_leap == true;
	} else {
		is_leap = false;
	}

	const int m = get_month();
	return is_leap && m == february ? 29 : len[m];
}

void leapdate::install(int m, int d, int y)
{
	year = y;

	if (m < january || m > december) {
		cerr << "bad month " << m << "\n";
		exit(EXIT_FAILURE);
	}
	month = m;

	if (d < 1 || d > length()) {
		cerr << "bad day " << d << "\n";
		exit(EXIT_FAILURE);
	}
	day = d;
}

leapdate& leapdate::operator++()   //prefix
{
	if (++day > length()) {
		day = 1;
		if (++month > december) {
			month = january;
			++year;
		}
	}

	return *this;
}

leapdate& leapdate::operator--()   //prefix
{
	if (--day < 1) {
		if (--month < january) {
			month = december;
			--year;
		}
		day = length();
	}

	return *this;
}