/*
 * aTunes 2.1.0-SNAPSHOT
 * Copyright (C) 2006-2011 Alex Aranda, Sylvain Gaudard and contributors
 *
 * See http://www.atunes.org/wiki/index.php?title=Contributing for information about contributors
 *
 * http://www.atunes.org
 * http://sourceforge.net/projects/atunes
 *
 * This program 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; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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.
 */

package net.sourceforge.atunes.utils;


import java.util.Locale;

import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

/**
 * The Class DateUtils.
 */
public final class DateUtils {

    /*
     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
     * 
     * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
     * 
     * The contents of this file are subject to the terms of either the GNU
     * General Public License Version 2 only ("GPL") or the Common Development
     * and Distribution License("CDDL") (collectively, the "License"). You may
     * not use this file except in compliance with the License. You can obtain a
     * copy of the License at
     * https://glassfish.dev.java.net/public/CDDL+GPL.html or
     * glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
     * language governing permissions and limitations under the License.
     * 
     * When distributing the software, include this License Header Notice in
     * each file and include the License file at
     * glassfish/bootstrap/legal/LICENSE.txt. Sun designates this particular
     * file as subject to the "Classpath" exception as provided by Sun in the
     * GPL Version 2 section of the License file that accompanied this code. If
     * applicable, add the following below the License Header, with the fields
     * enclosed by brackets [] replaced by your own identifying information:
     * "Portions Copyrighted [year] [name of copyright owner]"
     * 
     * Contributor(s):
     * 
     * If you wish your version of this file to be governed by only the CDDL or
     * only the GPL Version 2, indicate your decision by adding "[Contributor]
     * elects to include this software in this distribution under the [CDDL or
     * GPL Version 2] license." If you don't indicate a single choice of
     * license, a recipient has the option to distribute your version of this
     * file under either the CDDL, the GPL Version 2 or to extend the choice of
     * license to its licensees as provided above. However, if you add GPL
     * Version 2 code and therefore, elected the GPL Version 2 license, then the
     * option applies only if the new code is made subject to such option by the
     * copyright holder.
     */

    private DateUtils() {
    }

    /**
     * Returns the current year.
     * 
     * @return the current year
     */
    public static int getCurrentYear() {
        return new DateTime().getYear();
    }

    private static final DateTimeFormatter RFC3339_1 = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss'Z'").withLocale(Locale.US);
    private static final DateTimeFormatter RFC3339_2 = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'").withLocale(Locale.US);
    private static final DateTimeFormatter RFC3339_3 = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ssZ").withLocale(Locale.US);
    private static final DateTimeFormatter RFC3339_4 = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ").withLocale(Locale.US);
    
    /*
     * -> http://hatori42.com/RFC3339Date.txt
     * 
     * Feel free to use this in your code, but I'd appreciate it if you keep
     * this note in the code if you distribute it. Thanks!
     * 
     * For people who might be googling: The date format parsed by this goes by:
     * atomDateConstruct, xsd:dateTime, RFC3339 and is compatable with:
     * ISO.8601.1988, W3C.NOTE-datetime-19980827 and
     * W3C.REC-xmlschema-2-20041028 (that I know of)
     * 
     * Copyright 2007, Chad Okere (ceothrow1 at gmail dotcom) OMG NO WARRENTY
     * EXPRESSED OR IMPLIED!!!
     * 
     * 
     * 
     * 
     * 2011/09/13: Alex Aranda: Code refactored
     */
    /**
     * Parses a RFC 3339 date string.
     * 
     * @param dateStr
     *            A RFC 3339 date as string
     * 
     * @return The accordant Date object or <code>null</code> if the
     *         date couldn't be parsed
     */
    public static DateTime parseRFC3339Date(String dateStr) {
    	//if there is no time zone, we don't need to do any special parsing.
    	if (dateStr.endsWith("Z")) {
    		try {
    			return RFC3339_1.parseDateTime(dateStr);
    		} catch (IllegalArgumentException e) {
    			try {
    				return RFC3339_2.parseDateTime(dateStr);
    			} catch (IllegalArgumentException e2) {
    				return null;
    			}
    		}            	
    	} else if (dateStr.indexOf('-') != -1) {
    		//step one, split off the timezone. 
    		String firstpart = dateStr.substring(0, dateStr.lastIndexOf('-'));
    		String secondpart = dateStr.substring(dateStr.lastIndexOf('-'));

    		if (secondpart.indexOf(':') != -1) {
    			//step two, remove the colon from the timezone offset
    			secondpart = StringUtils.getString(secondpart.substring(0, secondpart.indexOf(':')), secondpart.substring(secondpart.indexOf(':') + 1));
    			String dateString = StringUtils.getString(firstpart, secondpart);

    			try {
    				return RFC3339_3.parseDateTime(dateString);
    			} catch (IllegalArgumentException e) {
    				try {
    					return RFC3339_4.parseDateTime(dateString);
    				} catch (IllegalArgumentException e2) {
    					return null;
    				}
    			}            	
    		}

    	}
    	return null;
    }

    /**
     * Parses a RFC 822 date string.
     * 
     * @param dateString
     *            A RFC 822 date as string
     * 
     * @return The accordant Date object or <code>null</code> if the
     *         date couldn't be parsed
     */
    public static DateTime parseRFC822Date(String dateString) {
    	try {
    		return DateTimeFormat.forPattern("EEE, dd MMM yyyy HH:mm:ss ZZ").withLocale(Locale.US).parseDateTime(dateString);
    	} catch (IllegalArgumentException e) {
    		return null;
    	}
    }

    /**
     * Returns a String with locale representation of Date, replacing / for -.
     * 
     * @param objDate
     *            the obj date
     * 
     * @return the string
     */
    public static String toPathString(DateTime objDate) {
        return DateTimeFormat.shortDateTime().print(objDate).replaceAll("/", "-");
    }

}
