/*******************************************************************************
 * Copyright (c) 2011 The University of York.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Louis Rose - initial API and implementation
 ******************************************************************************/
package simulator.execution.model;

import java.util.Calendar;
import java.util.Date;

public class DateUtils {

	public static Date add(Date augend, int unit, int amount) {
		final Calendar calendar = Calendar.getInstance();
		
		calendar.setTime(augend);
		calendar.add(unit, amount);
		return calendar.getTime();
	}
	
	public static Date todayAt(int hours, int minutes) {
		final Calendar calendar = Calendar.getInstance();
		calendar.setTime(new Date());
		calendar.set(Calendar.HOUR_OF_DAY, hours);
		calendar.set(Calendar.MINUTE, minutes);
		return calendar.getTime();
	}
	
	/**
	 * Checks whether the two parameters represent the same
	 * date (but not necessarily the same time).
	 */
	public static boolean sameDate(Date first, Date second) {
		return getDayOfYearOf(first) == getDayOfYearOf(second) &&
		       getYearOf(first) == getYearOf(second);
	}

	private static int getDayOfYearOf(Date date) {
		return getFieldOf(date, Calendar.DAY_OF_YEAR);
	}
	
	private static int getYearOf(Date date) {
		return getFieldOf(date, Calendar.YEAR);
	}
	
	private static int getFieldOf(Date date, int field) {
		final Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		return calendar.get(field);
	}
}