#include <iostream> //for cout
#include <chrono>   //for class system_clock
#include <ctime>    //for the function localtime
#include "date.h"
using namespace std;

const int date::length[] {
	 0,   //dummy, so that January will have subscript 1
	31,   //January
	28,   //February.  Pretend there are no leap years.
	31,   //March
	30,   //April
	31,   //May
	30,   //June
	31,   //July
	31,   //August
	30,   //September
	31,   //October
	30,   //November
	31    //December
};

date::date(int m, int d, int y)
	: day(365 * y + d - 1)
{
	for (int month {1}; month < m; ++month) {
		day += length[month];
	}
}

date::date()   //today's date
{
	const auto now {chrono::system_clock::now()};
	const time_t t {chrono::system_clock::to_time_t(now)};
        const tm *const p {localtime(&t)};


	day = 365 * (p->tm_year + 1900) + p->tm_yday;
}

ostream& operator<<(ostream& os, const date& d)
{
	const int year {d.day / 365};
	int dayOfYear  {d.day % 365 + 1};  //1 to 365 inclusive

	int month {1};
	for (; dayOfYear > date::length[month]; ++month) {
		dayOfYear -= date::length[month];
	}

	os << month << "/" << dayOfYear << "/" << year;
	return os;
}

istream& operator>>(istream& is, date& d)
{
	int month {0};
	int dayOfMonth {0};
	int year {0};
	char slash1 {'\0'};
	char slash2 {'\0'};

	if (!(is >> month >> slash1 >> dayOfMonth >> slash2 >> year)) {
		return is;
	}

	if (slash1 != '/' || slash2 != '/') {
		is.setstate(ios::failbit);
		return is;
	}

	if (month < 1 || month > 12) {
		is.setstate(ios::failbit);
		return is;
	}

	if (dayOfMonth < 1 || dayOfMonth > date::length[month]) {
		is.setstate(ios::failbit);
		return is;
	}

	d = date {month, dayOfMonth, year};
	return is;
}

int operator-(const date& a, const date& b)
{
	return a.day - b.day;
}

bool operator==(const date& a, const date& b)
{
	return a.day == b.day;
}

bool operator<(const date& a, const date& b)
{
	return a.day < b.day;
}