#include <sstream>
#include "Date.hpp"

namespace OpenVic2 {
	bool Timespan::operator<  (Timespan const& other) const { return days <  other.days; }
	bool Timespan::operator>  (Timespan const& other) const { return days >  other.days; }
	bool Timespan::operator<= (Timespan const& other) const { return days <= other.days; }
	bool Timespan::operator>= (Timespan const& other) const { return days >= other.days; }
	bool Timespan::operator== (Timespan const& other) const { return days == other.days; }
	bool Timespan::operator!= (Timespan const& other) const { return days != other.days; }

	Timespan Timespan::operator+ (Timespan const& other) const { return Timespan(days + other.days); }
	Timespan Timespan::operator- (Timespan const& other) const { return Timespan(days - other.days); }
	Timespan Timespan::operator* (int64_t const& factor) const { return Timespan(days * factor); }
	Timespan Timespan::operator/ (int64_t const& factor) const { return Timespan(days / factor); }

	Timespan& Timespan::operator+= (Timespan const& other) {
		days += other.days;
		return *this;
	}
	Timespan& Timespan::operator-= (Timespan const& other) {
		days -= other.days;
		return *this;
	}

	Timespan fromYearZero(year_t year, month_t month, date_t day) {
		int64_t daysElapsed = year * DAYS_IN_YEAR;
		size_t daysSinceMonthStart = (day == 0) ? 0 : day - 1; //Underflow protection
		for (size_t x = 0; x < month && x < MONTHS_IN_YEAR; x++) {
			daysElapsed += DAYS_IN_MONTH[x];
		}
		daysElapsed += daysSinceMonthStart;
		return Timespan(daysElapsed);
	}

	//This function is not set up to handle dates before Year 0
	YearMonthDayBundle toGregorianDate(Timespan const& timespan) {
		year_t year = 0;
		month_t month = 0;
		date_t day = 0;

		if (timespan >= 0) {
			year = timespan.days / DAYS_IN_YEAR;
			int64_t remainingDays = timespan.days % DAYS_IN_YEAR;

			for (size_t x = 0; x < MONTHS_IN_YEAR && remainingDays >= DAYS_IN_MONTH[x]; x++) {
				remainingDays -= DAYS_IN_MONTH[x];
				month++;
			}

			//Corrects month and day to be 1-indexed
			month++;
			day++;
		}
		return std::make_tuple(year, month, day);
	}


	Date::Date(Timespan const& timespan) : ts(timespan) { updateDate(ts); }

	Date::Date(year_t year, month_t month, date_t day) {
		ts = fromYearZero(year, month, day);
		updateDate(ts);
	}

	void Date::updateDate(Timespan const& timespan) {
		gregorianDate = toGregorianDate(timespan);
	}

	size_t Date::getDay()   const { return std::get<2>(gregorianDate); }
	size_t Date::getMonth() const { return std::get<1>(gregorianDate); }
	size_t Date::getYear()  const { return std::get<0>(gregorianDate); }

	bool Date::operator<  (Date const& other) const { return ts <  other.ts; }
	bool Date::operator>  (Date const& other) const { return ts >  other.ts; }
	bool Date::operator<= (Date const& other) const { return ts <= other.ts; }
	bool Date::operator>= (Date const& other) const { return ts >= other.ts; }
	bool Date::operator== (Date const& other) const { return ts == other.ts; }
	bool Date::operator!= (Date const& other) const { return ts != other.ts; }

	Date Date::operator+ (Timespan timespan) const { return Date(ts + timespan); }
	Timespan Date::operator- (Date const& other) const { return ts - other.ts; }

	Date& Date::operator+= (Timespan const& timespan) {
		ts += timespan;
		updateDate(ts);
		return *this;
	}
	Date& Date::operator-= (Timespan const& timespan) {
		ts -= timespan;
		updateDate(ts);
		return *this;
	}
	Date Date::operator++ (int) {
		Date oldCopy = *this;
		(*this) += 1;
		return oldCopy;
	}

	Date::operator std::string() const {
		std::stringstream ss;
		ss << getYear() << '.' << getMonth() << '.' << getDay();
		return ss.str();
	}
	std::ostream &operator<<(std::ostream &out, Date const& date) {
		return out << static_cast<std::string>(date);
	}
}