#include "Date.h"
#include <iostream>

Date::Date(int day, int month, int year) {
	d = day;
	m = month;
	y = year;
	fix_invalid();
}

	
Date::Date(const Date &o) : d(o.d), m(o.m), y(o.y) {}

Date& Date::operator=(const Date &o) {
	d = o.d;
	m = o.m;
	y = o.y;
	return *this;
}

Date::~Date() {}

void Date::add_days(int n) {
	if (n<0) {
		// too hard for me to bother with...
	}
		
	d+=n;
	int extra_d = d - days_in_month(m,y);
	while (extra_d>0) {
		d -= days_in_month(m,y);
		m+=1;
		if (m==13) {
			m=1;
			y+=1;
		}	
		extra_d -= days_in_month(m,y);
	}
}

int Date::compare(const Date &o) const {
	if (y < o.y)
		return -1;
	else if (y> o.y)
		return 1;
	else if (m < o.m)
		return -1;
	else if (m > o.m)
		return 1;
	else if (d < o.d)
		return -1;
	else if (d > o.d)
		return 1;
	else
		return 0;
}

void Date::fix_invalid() {
	if (d > days_in_month(m,y))
		d = days_in_month(m,y);
}

int Date::days_in_month(int month, int year) const {
	static int days[] = {31,28,31,30,31,30,31,31,30,31,30,31};
	if (m==2 && leap_year())
		return 29;
	else
		return days[month-1];
}

bool Date::leap_year() const {
	if (y%4)
		return false;
	if (!(y%400))
		return true;
	if (!(y%100))
		return false;
	return true;
}

int Date::get_day() const {
	return d;
}

int Date::get_month() const {
	return m;
}

int Date::get_year() const {
	return y;
}

const char* Date::day_of_week() const {
	static const char* days[] = { "Sun", "Mon", "Tue", "Wed", "Thu",
			  "Fri", "Sat" };
	int total = 0;
	int century = y / 100;
	int ex_year = y % 100;

	if (y<=1751 || y==1752 && (m<9 || (m==9 && d<=2)))
		total += 18 - century;
	else 
		total += (3 - century%4)*2;
	if (total>=7)
		total%=7;

	total += ex_year/12+ex_year%12+(ex_year%12)/4;
	if (total>=7)
		total%=7;

	int month_table[] = {-1,0,3,3,6,36,4,34,2,33,0,31,12};
	total+=month_table[m]%7;
	if (total>=7)
		total%=7;

	total+=d;
	if (m==1 || m==2) 
		if (y%4==0 && (y%100!=0 || y%400==0)) {
			if (total==0)
				total+=7;
			total--;
		}
	if (total>=7)
		total%=7;

	return days[total];
}


const char* Date::month_name() const{
	static const char* months[] = { "None", "Jan", "Feb", "Mar", "Apr", "May",
			"Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
	return months[m];
}



ostream& Date::output(ostream& os) const {
	return os << day_of_week() << " " << d << " "<<  month_name() << " " << y;
}


ostream& operator<<(ostream& os, const Date &d) {
	return d.output(os);
}