#include <climits>
#include "date.h"

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
};

date::date(int initial_month, int initial_day, int initial_year)
	throw (bad_month, bad_month_and_day)
{
	year = initial_year;

	if (initial_month < january || initial_month > december) {
		throw bad_month(initial_month);
	}
	month = initial_month;

	if (initial_day < 1 || initial_day > length[month]) {
		throw bad_month_and_day(month, initial_day);
	}
	day = initial_day;
}

date& date::operator++() throw (overflow)   //prefix
{
	if (++day > length[month]) {
		day = 1;
		if (++month > december) {
			month = january;
			if (year >= INT_MAX) {
				//Undo the ++'s in lines 38 and 40.
				month = december;
				day = length[december];
				throw overflow();
			}
			++year;
		}
	}

	return *this;
}

date& date::operator--() throw (underflow)   //prefix
{
	if (--day < 1) {
		if (--month < january) {
			month = december;
			if (year <= INT_MIN) {
				//Undo the --'s in line 57 and 58.
				month = january;
				day = 1;
				throw underflow();
			}
			--year;
		}
		day = length[month];
	}

	return *this;
}