/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file ai_date.hpp Everything to query and manipulate date related information. */

#ifndef AI_DATE_HPP
#define AI_DATE_HPP

#include "ai_object.hpp"

/**
 * Class that handles all date related (calculation) functions.
 *
 * @note Months and days of month are 1-based; the first month of the
 *       year is 1 and the first day of the month is also 1.
 * @note Years are zero based; they start with the year 0.
 * @note Dates can be used to determine the number of days between
 *       two different moments in time because they count the number
 *       of days since the year 0.
 */
class AIDate : public AIObject {
public:
	static const char *GetClassName() { return "AIDate"; }

	/**
	 * Get the current date.
	 * This is the number of days since epoch under the assumption that
	 *  there is a leap year every 4 years, except when dividable by
	 *  100 but not by 400.
	 * @return The current date.
	 */
	static int32 GetCurrentDate();

	/**
	 * Get the year of the given date.
	 * @param date The date to get the year of.
	 * @return The year.
	 */
	static int32 GetYear(int32 date);

	/**
	 * Get the month of the given date.
	 * @param date The date to get the month of.
	 * @return The month.
	 */
	static int32 GetMonth(int32 date);

	/**
	 * Get the day (of the month) of the given date.
	 * @param date The date to get the day of.
	 * @return The day.
	 */
	static int32 GetDayOfMonth(int32 date);

	/**
	 * Get the date given a year, month and day of month.
	 * @param year The year of the to-be determined date.
	 * @param month The month of the to-be determined date.
	 * @param day_of_month The day of month of the to-be determined date.
	 * @return The date.
	 */
	static int32 GetDate(int32 year, int32 month, int32 day_of_month);
};

#endif /* AI_DATE_HPP */
