#include <iostream>  //for the object cout
#include <ctime>     //for the functions time and localtime
#include "date.h"
using namespace std; //because invalid_argument and cout belong to namespace std

const int date::length[] {
	 0,   //dummy, so that January will have subscript 1
	31,   //January
	28,   //February.  We'll do leap years later in the course.
	31,   //March
	30,   //April
	31,   //May
	30,   //June
	31,   //July
	31,   //August
	30,   //September
	31,   //October
	30,   //November
	31    //December
};

//The constructor installs 3 valid values into a newborn date object,
//or it throws an exception.

date::date(int init_month, int init_day, int init_year)
        : year {init_year}, month {init_month}, day {init_day}
{
	if (month < 1 || month > 12) {
		throw invalid_argument("bad month");
	}

	if (day < 1 || day > length[month]) {
		throw invalid_argument("bad day of the month");
	}
}

date::date()    //Default constructor puts today's date into the newborn object.
{
	const time_t t {time(nullptr)};
        const tm *const p {localtime(&t)};

	year = p->tm_year + 1900;
	month = p->tm_mon + 1;
	day = p->tm_mday;
}

void date::print() const  //This member function can't change the date object.
{
	cout << month << "/" << day << "/" << year;
}

void date::next(int n)    //This member function can change the object struct.
{
	for (int i {0}; i < n; ++i) {
		next(); //Call the other next function, the one with no argument
	}
}

void date::next()   //Move this date object one day into the future.
{
	if (day < length[month]) {
		++day;
	} else {
		day = 1;             //Advance into the next month.
		if (month < 12) {
			++month;
		} else {
			month = 1;   //Advance into the next year.
			year;
		}
	}
}