/*******************************************************************************
 *
 * Copyright (c) 2010-2011 Sonatype, Inc.
 *
 * 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: 
 *
 *   
 *     
 *
 *******************************************************************************/ 

package org.hudsonci.utils.common;

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

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Helper for working with dates.
 *
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @since 2.1.0
 */
public class Dates
{
    private static final int MILLISECONDS_IN_DAY = 1000 * 60 * 60 * 24;

    public static long countDaysBetween(final Date start, final Date end) {
        checkNotNull(start);
        checkNotNull(end);

        //reset all hours mins and secs to zero on start date
        Calendar startCal = GregorianCalendar.getInstance();
        startCal.setTime(start);
        startCal.set(Calendar.HOUR_OF_DAY, 0);
        startCal.set(Calendar.MINUTE, 0);
        startCal.set(Calendar.SECOND, 0);
        long startTime = startCal.getTimeInMillis();

        //reset all hours mins and secs to zero on end date
        Calendar endCal = GregorianCalendar.getInstance();
        endCal.setTime(end);
        endCal.set(Calendar.HOUR_OF_DAY, 0);
        endCal.set(Calendar.MINUTE, 0);
        endCal.set(Calendar.SECOND, 0);
        long endTime = endCal.getTimeInMillis();

        return (endTime - startTime) / MILLISECONDS_IN_DAY;
    }
}