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

const int date::length[] = {
	 0,   //dummy
	31,   //january
	29,   //february
	31,   //march
	30,   //april
	31,   //may
	30,   //june
	31,   //july
	31,   //august
	30,   //september
	31,   //october
	30,   //november
	31    //december
};

void date::install(int m, int d, int y)   //called by each constructor
{
	year = y;

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

	if (d < 1 || d > length[month]) {
		cerr << "bad day " << m << "/" << d << "/" << y << "\n";
		exit(EXIT_FAILURE);
	}
	day = d;
}

date::date()                              //Initialize to the current date.
{
	const time_t t = time(0);

	if (t == static_cast<time_t>(-1)) {
		cerr << "time failed\n";
		exit(EXIT_FAILURE);
	}

	const tm *const s = localtime(&t);
	install(s->tm_mon + 1, s->tm_mday, s->tm_year + 1900);
}

date& date::operator++()
{
	if (++day > length[month]) {
		day = 1;
		if (++month > december) {
			month = january;
			++year;
		}
	}

	return *this;
}

date& date::operator--()
{
	if (--day < 1) {
		if (--month < january) {
			month = december;
			--year;
		}
		day = length[month];
	}

	return *this;
}