// $Id: XMLGregorianCalendarImpl.java,v 1.11 2004/07/07 06:16:15 jsuttor Exp $

/*
 * @(#)XMLGregorianCalendarImpl.java	1.4 04/07/26
 * 
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.org.apache.xerces.internal.jaxp.datatype;

import java.io.Serializable;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.TimeZone;
import java.util.SimpleTimeZone;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Date;
import java.util.Locale;

import javax.xml.XMLConstants;
import javax.xml.datatype.DatatypeConstants;
import javax.xml.datatype.Duration;
import javax.xml.datatype.XMLGregorianCalendar;
import javax.xml.namespace.QName;
import com.sun.org.apache.xerces.internal.util.DatatypeMessageFormatter;


/** 
 * <p>Representation for W3C XML Schema 1.0 date/time datatypes.
 * Specifically, these date/time datatypes are 
 * {@link DatatypeConstants#DATETIME dateTime},
 * {@link DatatypeConstants#TIME time},
 * {@link DatatypeConstants#DATE date},
 * {@link DatatypeConstants#GYEARMONTH gYearMonth},
 * {@link DatatypeConstants#GMONTHDAY gMonthDay},
 * {@link DatatypeConstants#GYEAR gYear}, 
 * {@link DatatypeConstants#GMONTH gMonth} and
 * {@link DatatypeConstants#GDAY gDay}
 * defined in the XML Namespace
 * <code>"http://www.w3.org/2001/XMLSchema"</code>.
 * These datatypes are normatively defined in 
 * <a href="http://www.w3.org/TR/xmlschema-2/#dateTime">W3C XML Schema 1.0 Part 2, Section 3.2.7-14</a>.</p>
 *
 * <p>The table below defines the mapping between XML Schema 1.0
 * date/time datatype fields and this class' fields. It also summarizes
 * the value constraints for the date and time fields defined in
 * <a href="http://www.w3.org/TR/xmlschema-2/#isoformats">W3C XML Schema 1.0 Part 2, Appendix D,
 * <i>ISO 8601 Date and Time Formats</i></a>.</p>
 * 
 * <a name="datetimefieldsmapping"/>
 * <table border="2" rules="all" cellpadding="2">
 *   <thead>
 *     <tr>
 *       <th align="center" colspan="3">
 *         Date/time datatype field mapping between XML Schema 1.0 and Java representation
 *       </th>
 *     </tr>
 *   </thead>
 *   <tbody>
 *     <tr>
 *       <th>XML Schema 1.0<br/>
 *           datatype<br/> 
 *            field</th>
 *       <th>Related<br/>XMLGregorianCalendar<br/>Accessor(s)</th>
 *       <th>Value Range</th>
 *     </tr>
 *     <a name="datetimefield-year"/>
 *     <tr>
 *       <td> year </td>
 *       <td> {@link #getYear()} + {@link #getEon()} or<br/>
 *            {@link #getEonAndYear}
 *       </td>
 *       <td> <code>getYear()</code> is a value between -(10^9-1) to (10^9)-1 
 *            or {@link DatatypeConstants#FIELD_UNDEFINED}.<br/>
 *            {@link #getEon()} is high order year value in billion of years.<br/>
 *            <code>getEon()</code> has values greater than or equal to (10^9) or less than or equal to -(10^9).
 *            A value of null indicates field is undefined.</br>
 *            Given that <a href="http://www.w3.org/2001/05/xmlschema-errata#e2-63">XML Schema 1.0 errata</a> states that the year zero
 *            will be a valid lexical value in a future version of XML Schema, 
 *            this class allows the year field to be set to zero. Otherwise,
 *            the year field value is handled exactly as described
 *            in the errata and [ISO-8601-1988]. Note that W3C XML Schema 1.0
 *            validation does not allow for the year field to have a value of zero.
 *            </td>
 *     </tr>
 *     <a name="datetimefield-month"/>
 *     <tr>
 *       <td> month </td>
 *       <td> {@link #getMonth()} </td>
 *       <td> 1 to 12 or {@link DatatypeConstants#FIELD_UNDEFINED} </td>
 *     </tr>
 *     <a name="datetimefield-day"/>
 *     <tr>
 *       <td> day </td>
 *       <td> {@link #getDay()} </td>
 *       <td> Independent of month, max range is 1 to 31 or {@link DatatypeConstants#FIELD_UNDEFINED}.<br/>
 *            The normative value constraint stated relative to month 
 *            field's value is in <a href="http://www.w3.org/TR/xmlschema-2/#isoformats">W3C XML Schema 1.0 Part 2, Appendix D</a>.
 *       </td> 
 *     </tr>
 *     <a name="datetimefield-hour"/>
 *     <tr>
 *       <td> hour </td>
 *       <td> {@link #getHour()} </td>
 *       <td>
 *         0 to 24 or {@link DatatypeConstants#FIELD_UNDEFINED}
 *         <a href="http://www.w3.org/2001/05/xmlschema-errata#e2-45">For a value of 24, the minute and second field must be zero.</a>
 *       </td>
 *     </tr>
 *     <a name="datetimefield-minute"/>
 *     <tr>
 *       <td> minute </td>
 *       <td> {@link #getMinute()} </td>
 *       <td> 0 to 59 or {@link DatatypeConstants#FIELD_UNDEFINED} </td>
 *     </tr>
 *     <a name="datetimefield-second"/>
 *     <tr>
 *       <td>second</td>
 *       <td>
 *         {@link #getSecond()} + {@link #getMillisecond()}/1000 or<br/>
 *         {@link #getSecond()} + {@link #getFractionalSecond()}
 *       </td>
 *       <td>
 *         {@link #getSecond()} from 0 to 60 or {@link DatatypeConstants#FIELD_UNDEFINED}.<br/>
 *         <i>(Note: 60 only allowable for leap second.)</i><br/>
 *         {@link #getFractionalSecond()} allows for infinite precision over the range from 0.0 to 1.0 when 
 *         the {@link #getSecond()} is defined.<br/>
 *         <code>FractionalSecond</code> is optional and has a value of <code>null</code> when it is undefined.<br />
 *            {@link #getMillisecond()} is the convenience 
 *            millisecond precision of value of {@link #getFractionalSecond()}.
 *       </td>
 *     </tr>
 *     <tr id="datetimefield-timezone">
 *       <td> timezone </td>
 *       <td> {@link #getTimezone()} </td>
 *       <td> Number of minutes or {@link DatatypeConstants#FIELD_UNDEFINED}.
 *         Value range from -14 hours (-14 * 60 minutes) to 14 hours (14 * 60 minutes).
 *       </td>
 *     </tr>
 *   </tbody>
 *  </table>
 *
 * <p>All maximum value space constraints listed for the fields in the table 
 * above are checked by factory methods, setter methods and parse methods of
 * this class. <code>IllegalArgumentException</code> is thrown when 
 * parameter's value is outside the maximum value constraint for the field.
 * Validation checks, for example, whether days in month should be 
 * limited to 29, 30 or 31 days, that are dependent on the values of other 
 * fields are not checked by these methods. 
 * </p>
 * 
 * <p>The following operations are defined for this class:
 * <ul>
 *   <li>factory methods to create instances</li>
 *   <li>accessors/mutators for independent date/time fields</li>
 *   <li>conversion between this class and W3C XML Schema 1.0 lexical representation</li>
 *   <li>conversion between this class and <code>java.util.GregorianCalendar</code></li>
 *   <li>partial order relation comparator method, {@link #compare(XMLGregorianCalendar)}</li>
 *   <li>{@link #equals(Object)} defined relative to {@link #compare(XMLGregorianCalendar)}.</li>
 *   <li> addition operation with {@link javax.xml.datatype.Duration}. 
 * instance as defined in <a href="http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes">
 * W3C XML Schema 1.0 Part 2, Appendix E, <i>Adding durations to dateTimes</i></a>.</li>
 * </ul>
 * </p>
 * 
 * @author <a href="mailto:Kohsuke.Kawaguchi@Sun.com">Kohsuke Kawaguchi</a>
 * @author <a href="mailto:Joseph.Fialli@Sun.com">Joseph Fialli</a>
 * @version $Revision: 1.11 $, $Date: 2004/07/07 06:16:15 $    
 * @see javax.xml.datatype.Duration
 * @since 1.5
 */

public class XMLGregorianCalendarImpl
	extends XMLGregorianCalendar
	implements Serializable, Cloneable {

    /**
     * <p>Eon of this <code>XMLGregorianCalendar</code>.</p>
     */
    private BigInteger eon = null;
    
    /**
     * <p>Year of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int year = DatatypeConstants.FIELD_UNDEFINED;

    /**
     * <p>Month of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int month = DatatypeConstants.FIELD_UNDEFINED;
    
    /**
     * <p>Day of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int day = DatatypeConstants.FIELD_UNDEFINED;
    
    /**
     * <p>Timezone of this <code>XMLGregorianCalendar</code> in minutes.</p>
     */
    private int timezone = DatatypeConstants.FIELD_UNDEFINED;
    
    /**
     * <p>Hour of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int hour = DatatypeConstants.FIELD_UNDEFINED;
    
    /**
     * <p>Minute of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int minute = DatatypeConstants.FIELD_UNDEFINED;
    
    /**
     * <p>Second of this <code>XMLGregorianCalendar</code>.</p>
     */
    private int second = DatatypeConstants.FIELD_UNDEFINED ;
    
    /**
     * <p>Fractional second of this <code>XMLGregorianCalendar</code>.</p>
     */
    private BigDecimal fractionalSecond = null;

    /**
     * <p>Constant to represent a billion.</p>
     */
    private static final BigInteger BILLION = new BigInteger("1000000000");

    /**
     *   <p>Obtain a pure Gregorian Calendar by calling
     *   GregorianCalendar.setChange(PURE_GREGORIAN_CHANGE). </p>
     */
    private static final Date PURE_GREGORIAN_CHANGE = 
	new Date(Long.MIN_VALUE);

    /**
     * Year index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int YEAR   = 0;

    /**
     * Month index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int MONTH  = 1;

    /**
     * Day index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int DAY    = 2;

    /**
     * Hour index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int HOUR   = 3;

    /**
     * Minute index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int MINUTE = 4;

    /**
     * Second index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int SECOND = 5;

    /**
     * Second index for MIN_ and MAX_FIELD_VALUES.
     */
    private static final int MILLISECOND = 6;

    /**
     * Timezone index for MIN_ and MAX_FIELD_VALUES
     */
    private static final int TIMEZONE = 7;

    /**
     * Minimum field values indexed by YEAR..TIMEZONE.
     */
    private static final int MIN_FIELD_VALUE[] = { 
	Integer.MIN_VALUE,  //Year field can be smaller than this,
                            // only constraint on integer value of year. 
	DatatypeConstants.JANUARY, 
	1,       //day of month
	0,       //hour
	0,       //minute
	0,       //second
	0,       //millisecond
	-14 * 60 //timezone
    };

    /**
     * Maximum field values indexed by YEAR..TIMEZONE.
     */
    private static final int MAX_FIELD_VALUE[] = { 
	Integer.MAX_VALUE,  // Year field can be bigger than this, 
	                    // only constraint on integer value of year.
		DatatypeConstants.DECEMBER,              
	31,       //day of month                         
	23,       //hour
	59,       //minute
	60,       //second (leap second allows for 60)
	999,      //millisecond
	14 * 60   //timezone
    }; 

    /**
     * field names indexed by YEAR..TIMEZONE.
     */
    private static final String FIELD_NAME[] = { 
	"Year",
	"Month",
	"Day",
	"Hour",
	"Minute",
	"Second",
	"Millisecond",
	"Timezone"
    }; 

    /**
     * <p>Stream Unique Identifier.</p>
     * 
     * <p>TODO: Serialization should use the XML string representation as
     * the serialization format to ensure future compatibility.</p>
     */
    private static final long serialVersionUID = 1L; 

    /**
     * <p>Use as a template for default field values when 
     * converting to a {@link GregorianCalendar}, set to a leap 
     * year date of January 1, 0400 at midnight.</p>
     * 
     * <p>Fields that are optional for an <code>xsd:dateTime</code> instances are defaulted to not being set to any value.
     * <code>XMLGregorianCalendar</code> fields millisecond, fractional second and timezone return the value indicating
     * that the field is not set, {@link DatatypeConstants#FIELD_UNDEFINED} for millisecond and timezone
     * and <code>null</code> for fractional second.</p>
     * 
     * @see #toGregorianCalendar(TimeZone, Locale, XMLGregorianCalendar)
     */
    public static final XMLGregorianCalendar LEAP_YEAR_DEFAULT =
		createDateTime(
			400,  //year
		DatatypeConstants.JANUARY,  //month
			1,  // day
		    0,  // hour
		    0,  // minute
		    0,  // second
		    DatatypeConstants.FIELD_UNDEFINED,  // milliseconds
		    DatatypeConstants.FIELD_UNDEFINED // timezone
		);

    // Constructors

    /**
     * Constructs a new XMLGregorianCalendar object.
     * 
     * String parsing documented by {@link #parse(String)}.
     * 
     * Returns a non-null valid XMLGregorianCalendar object that holds the 
     * value indicated by the lexicalRepresentation parameter.
     *
     * @param lexicalRepresentation
     *      Lexical representation of one the eight
     *      XML Schema date/time datatypes.
     * @throws IllegalArgumentException
     *      If the given string does not conform as documented in 
     *      {@link #parse(String)}.
     * @throws NullPointerException
     *      If the given string is null.
     */
    protected XMLGregorianCalendarImpl(String lexicalRepresentation)
		throws IllegalArgumentException {
			
	// compute format string for this lexical representation.
	String format = null;
	String lexRep = lexicalRepresentation;
	final int NOT_FOUND = -1;
	int lexRepLength = lexRep.length();
	
	
	// current parser needs a format string,
	// use following heuristics to figure out what xml schema date/time
	// datatype this lexical string could represent.
	if (lexRep.indexOf('T') != NOT_FOUND) {
	    // found Date Time separater, must be xsd:DateTime
	    format = "%Y-%M-%DT%h:%m:%s" + "%z";
	} else if (lexRepLength >= 3 && lexRep.charAt(2) == ':') {
	    // found ":", must be xsd:Time
	    format = "%h:%m:%s" +"%z";
	} else if (lexRep.startsWith("--")) {
	    // check for GDay || GMonth || GMonthDay
	    if (lexRepLength >= 3 && lexRep.charAt(2) == '-') {
		// GDAY
		// Fix 4971612: invalid SCCS macro substitution in data string
		format = "---%D" + "%z";
	    } else if (lexRepLength >= 6 &&
		       lexRep.charAt(5) == '-' && lexRep.charAt(4) == '-') {
		// GMonth
		// Fix 4971612: invalid SCCS macro substitution in data string
		format = "--%M--%z";
	    } else {
		// GMonthDay or invalid lexicalRepresentation
		format = "--%M-%D" + "%z";
	    }
	} else {
	    // check for Date || GYear | GYearMonth
	    int countSeparator = 0;

	    // start at index 1 to skip potential negative sign for year.
	    
	    
	    int timezoneOffset = lexRep.indexOf(':');
	    if (timezoneOffset != NOT_FOUND) {

		// found timezone, strip it off for distinguishing
		// between Date, GYear and GYearMonth so possible
		// negative sign in timezone is not mistaken as
		// a separator.
		lexRepLength -= 6;
	    }
	    
	    for (int i=1; i < lexRepLength; i++) {
		if (lexRep.charAt(i) == '-') {
			countSeparator++;
		}
	    }
	    if (countSeparator == 0) {
		// GYear
		format = "%Y" + "%z";
	    } else if (countSeparator == 1) {
		// GYearMonth
		format = "%Y-%M" + "%z";
	    } else {
		// Date or invalid lexicalRepresentation
		// Fix 4971612: invalid SCCS macro substitution in data string
		format = "%Y-%M-%D" + "%z";
	    }
	}
	Parser p = new Parser(format, lexRep);
	p.parse();
	
		// check for validity
		if (!isValid()) {
			throw new IllegalArgumentException(
                DatatypeMessageFormatter.formatMessage(null,"InvalidXGCRepresentation", new Object[]{lexicalRepresentation})
				//"\"" + lexicalRepresentation + "\" is not a valid representation of an XML Gregorian Calendar value."
			);
	    }
    }

    /**
     * <p>Create an instance with all date/time datatype fields set to 
     * {@link DatatypeConstants#FIELD_UNDEFINED} or null respectively.</p>
     */
    public XMLGregorianCalendarImpl() {
    	
        // field initializers already do the correct initialization.
    }

    /**
     * <p>Private constructor allowing for complete value spaces allowed by 
     * W3C XML Schema 1.0 recommendation for xsd:dateTime and related 
     * builtin datatypes. Note that <code>year</code> parameter supports
     * arbitrarily large numbers and fractionalSecond has infinite 
     * precision.</p>
     * 
     * @param year of <code>XMLGregorianCalendar</code> to be created.
     * @param month of <code>XMLGregorianCalendar</code> to be created.
     * @param day of <code>XMLGregorianCalendar</code> to be created.
     * @param hour of <code>XMLGregorianCalendar</code> to be created.
     * @param minute of <code>XMLGregorianCalendar</code> to be created.
     * @param second of <code>XMLGregorianCalendar</code> to be created.
     * @param fractionalSecond of <code>XMLGregorianCalendar</code> to be created.
     * @param timezone of <code>XMLGregorianCalendar</code> to be created.
     * 
     */
    protected XMLGregorianCalendarImpl(
        BigInteger year,
        int month,
        int day,
        int hour,
        int minute,
        int second,
        BigDecimal fractionalSecond,
        int timezone) {
        	
		setYear(year);
        setMonth(month);
        setDay(day);
        setTime(hour, minute, second, fractionalSecond);
		setTimezone(timezone);
		
		// check for validity
		if (!isValid()) {
			
            throw new IllegalArgumentException(
                DatatypeMessageFormatter.formatMessage(null, 
                    "InvalidXGCValue-fractional", 
                    new Object[] { year, new Integer(month), new Integer(day), 
                    new Integer(hour), new Integer(minute), new Integer(second),
                    fractionalSecond, new Integer(timezone)})
			);
                    
			/**
                String yearString = "null";
                if (year != null) {
                    yearString = year.toString();
                }
                String fractionalSecondString = "null";
                if (fractionalSecond != null) {
                    fractionalSecondString = fractionalSecond.toString();
                }
             
                throw new IllegalArgumentException(
                    "year = " + yearString
                    + ", month = " + month
                    + ", day = " + day
                    + ", hour = " + hour
                    + ", minute = " + minute
                    + ", second = " + second
                    + ", fractionalSecond = " + fractionalSecondString
                    + ", timezone = " + timezone
                    + ", is not a valid representation of an XML Gregorian Calendar value."
                );
                */
            
		}
		
    }

    /**
     * <p>Private constructor of value spaces that a
     * <code>java.util.GregorianCalendar</code> instance would need to convert to an
     * <code>XMLGregorianCalendar</code> instance.</p>
     *    
     * <p><code>XMLGregorianCalendar eon</code> and 
     * <code>fractionalSecond</code> are set to <code>null</code></p>
     *
     * @param year of <code>XMLGregorianCalendar</code> to be created.
     * @param month of <code>XMLGregorianCalendar</code> to be created.
     * @param day of <code>XMLGregorianCalendar</code> to be created.
     * @param hour of <code>XMLGregorianCalendar</code> to be created.
     * @param minute of <code>XMLGregorianCalendar</code> to be created.
     * @param second of <code>XMLGregorianCalendar</code> to be created.
     * @param millisecond of <code>XMLGregorianCalendar</code> to be created.
     * @param timezone of <code>XMLGregorianCalendar</code> to be created.
     */
    private XMLGregorianCalendarImpl(
        int year,
        int month,
        int day,
        int hour,
        int minute,
        int second,
		int millisecond,
        int timezone) {
        	
		setYear(year);
        setMonth(month);
        setDay(day);
        setTime(hour, minute, second);
		setTimezone(timezone);
		setMillisecond(millisecond);

		if (!isValid()) {		
            
            throw new IllegalArgumentException(
                DatatypeMessageFormatter.formatMessage(null, 
                "InvalidXGCValue-milli", 
                new Object[] { new Integer(year), new Integer(month), new Integer(day), 
                new Integer(hour), new Integer(minute), new Integer(second), 
                new Integer(millisecond), new Integer(timezone)})                
			);
                /*
                throw new IllegalArgumentException(
                    "year = " + year
                    + ", month = " + month
                    + ", day = " + day
                    + ", hour = " + hour
                    + ", minute = " + minute
                    + ", second = " + second
                    + ", millisecond = " + millisecond
                    + ", timezone = " + timezone
                    + ", is not a valid representation of an XML Gregorian Calendar value."
                    );
                 */
            
		}
    }
    
	/**
	 * <p>Convert a <code>java.util.GregorianCalendar</code> to XML Schema 1.0 
	 * representation.</p>
	 *
	 * <table border="2" rules="all" cellpadding="2">
	 *   <thead>
	 *     <tr>
	 *       <th align="center" colspan="2">
	 *          Field by Field Conversion from
	 *          <code>java.util.GregorianCalendar</code> to this class 
	 *       </th>
	 *     </tr>
	 *   </thead>
	 *   <tbody>
	 *     <tr>
	 *        <th><code>javax.xml.datatype.XMLGregorianCalendar</code> field</th>
	 *        <th><code>java.util.GregorianCalendar</code> field</th>
	 *     </tr>
	 *     <tr>
	 *       <th>{@link #setYear(int)}</th>
	 *       <th><code>ERA == GregorianCalendar.BC ? -YEAR : YEAR</code></th>
	 *     </tr>
	 *     <tr>
	 *       <th>{@link #setMonth(int)}</th>
	 *       <th><code>MONTH + 1</code></th>
	 *     </tr>
	 *     <tr>
	 *       <th>{@link #setDay(int)}</th>
	 *       <th><code>DAY_OF_MONTH</code></th>
	 *     </tr>
	 *     <tr>
	 *       <th>{@link #setTime(int,int,int, BigDecimal)}</th>
	 *       <th><code>HOUR_OF_DAY, MINUTE, SECOND, MILLISECOND</code></th>
	 *     </tr>
	 *     <tr>
	 *       <th>{@link #setTimezone(int)}<i>*</i></th>
	 *       <th><code>(ZONE_OFFSET + DST_OFFSET) / (60*1000)</code><br/>
	 *       <i>(in minutes)</i>
	 *       </th>
	 *     </tr>
	 *   </tbody>
	 * </table>
	 * <p><i>*</i>conversion loss of information. It is not possible to represent 
	 * a <code>java.util.GregorianCalendar</code> daylight savings timezone id in the 
	 * XML Schema 1.0 date/time datatype representation.</p>
	 * 
	 * <p>To compute the return value's <code>TimeZone</code> field,
	 * <ul>
	 * <li>when <code>this.getTimezone() != DatatypeConstants.FIELD_UNDEFINED</code>,
	 * create a <code>java.util.TimeZone</code> with a custom timezone id 
	 * using the <code>this.getTimezone()</code>.</li>
	 * <li>else use the <code>GregorianCalendar</code> default timezone value 
	 * for the host is defined as specified by 
	 * <code>java.util.TimeZone.getDefault()</code>.</li></p>     
	 *
	 * @param cal <code>java.util.GregorianCalendar</code> used to create <code>XMLGregorianCalendar</code>
	 */
	public XMLGregorianCalendarImpl(GregorianCalendar cal) {
    	
	int year = cal.get(Calendar.YEAR);
	if (cal.get(Calendar.ERA) == GregorianCalendar.BC) {
		year = -year;
	}
	this.setYear(year);
	
	// Calendar.MONTH is zero based, XSD Date datatype's month field starts
		// with JANUARY as 1.
	this.setMonth(cal.get(Calendar.MONTH) + 1);
	this.setDay(cal.get(Calendar.DAY_OF_MONTH));
	this.setTime(
		cal.get(Calendar.HOUR_OF_DAY),
		cal.get(Calendar.MINUTE), 
		cal.get(Calendar.SECOND),
		cal.get(Calendar.MILLISECOND));
	
	// Calendar ZONE_OFFSET and DST_OFFSET fields are in milliseconds.
	int offsetInMinutes = (cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET)) / (60 * 1000);
	this.setTimezone(offsetInMinutes);
	}

    // Factories

    /**
     * <p>Create a Java representation of XML Schema builtin datatype <code>dateTime</code>.
     * All possible fields are specified for this factory method.</p>
     * 
     * @param year represents both high-order eons and low-order year.
     * @param month of <code>dateTime</code>
     * @param day of <code>dateTime</code>
     * @param hours of <code>dateTime</code>
     * @param minutes of <code>dateTime</code>
     * @param seconds of <code>dateTime</code>
     * @param fractionalSecond value of null indicates optional field is absent.
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     *
     * @throws IllegalArgumentException if any parameter is outside value 
     * constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public static XMLGregorianCalendar createDateTime(
        BigInteger year,
        int month,
        int day,
        int hours,
        int minutes,
        int seconds,
        BigDecimal fractionalSecond,
        int timezone) {
	
	return new XMLGregorianCalendarImpl(
		year,
		month, 
		day, 
		hours,
		minutes,
		seconds, 
		fractionalSecond,
		timezone);
    }

    /**
     * <p>Create a Java instance of XML Schema builtin datatype dateTime.</p>
     * 
     * @param year represents both high-order eons and low-order year.
     * @param month of <code>dateTime</code>
     * @param day of <code>dateTime</code>
     * @param hour of <code>dateTime</code>
     * @param minute of <code>dateTime</code>
     * @param second of <code>dateTime</code>
     *
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @throws IllegalArgumentException if any parameter is outside value constraints for the field as specified in 
     *   <a href="#datetimefieldmapping">date/time field mapping table</a>.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     */
    public static XMLGregorianCalendar createDateTime(
        int year,
        int month,
        int day,
        int hour,
        int minute,
        int second) {
        	
        return new XMLGregorianCalendarImpl(
            year,
            month,
            day,
            hour,
            minute,
            second,
            DatatypeConstants.FIELD_UNDEFINED,  //millisecond
        	DatatypeConstants.FIELD_UNDEFINED //timezone
        );
    }

    /**
     * <p>Create a Java representation of XML Schema builtin datatype <code>dateTime</code>.
     * All possible fields are specified for this factory method.</p>
     * 
     * @param year represents low-order year.
     * @param month of <code>dateTime</code>
     * @param day of <code>dateTime</code>
     * @param hours of <code>dateTime</code>
     * @param minutes of <code>dateTime</code>
     * @param seconds of <code>dateTime</code>
     * @param milliseconds of <code>dateTime</code>. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     *
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @throws IllegalArgumentException if any parameter is outside value constraints for the field as specified in 
     *   <a href="#datetimefieldmapping">date/time field mapping table</a>.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     */
    public static XMLGregorianCalendar createDateTime(
        int year,
        int month,
        int day,
        int hours,
        int minutes,
        int seconds,
        int milliseconds,
        int timezone) {
        	
        return new XMLGregorianCalendarImpl(
            year,
            month,
            day,
            hours,
            minutes,
            seconds,
            milliseconds,
            timezone);
    }

    /**
     * <p>Create a Java representation of XML Schema builtin datatype <code>date</code> or <code>g*</code>.</p>
     * 
     * <p>For example, an instance of <code>gYear</code> can be created invoking this factory 
     * with <code>month</code> and <code>day</code> parameters set to 
     * {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     * 
     * @param year of <code>XMLGregorianCalendar</code> to be created.
     * @param month of <code>XMLGregorianCalendar</code> to be created.
     * @param day of <code>XMLGregorianCalendar</code> to be created.
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     *
     * @throws IllegalArgumentException if any parameter is outside value 
     * constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public static XMLGregorianCalendar createDate(
        int year,
        int month,
        int day,
        int timezone) {
        	
        return new XMLGregorianCalendarImpl(
            year,
            month,
            day,
            DatatypeConstants.FIELD_UNDEFINED, // hour
            DatatypeConstants.FIELD_UNDEFINED, // minute
            DatatypeConstants.FIELD_UNDEFINED, // second
	    	DatatypeConstants.FIELD_UNDEFINED, // millisecond
            timezone);
    }

    /**
     * Create a Java instance of XML Schema builtin datatype <code>time</code>.
     * @param hours number of hours
     * @param minutes number of minutes
     * @param seconds number of seconds
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     *
     * @throws IllegalArgumentException if any parameter is outside value 
     * constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public static XMLGregorianCalendar createTime(
    	int hours,
    	int minutes,
    	int seconds,
		int timezone) {
			
		return new XMLGregorianCalendarImpl(
			DatatypeConstants.FIELD_UNDEFINED, // Year
			DatatypeConstants.FIELD_UNDEFINED, // Month
			DatatypeConstants.FIELD_UNDEFINED, // Day
			hours,
			minutes,
			seconds, 
			DatatypeConstants.FIELD_UNDEFINED, //Millisecond
			timezone);
    }

    /**
     * <p>Create a Java instance of XML Schema builtin datatype time.</p>
     * 
     * @param hours number of hours
     * @param minutes number of minutes
     * @param seconds number of seconds
     * @param fractionalSecond value of <code>null</code> indicates that this optional field is not set.
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     *
     * @throws IllegalArgumentException if any parameter is outside value 
     * constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public static XMLGregorianCalendar createTime(
        int hours,
        int minutes,
        int seconds,
        BigDecimal fractionalSecond,
        int timezone) {
        	
        return new XMLGregorianCalendarImpl(
            null,            // Year
            DatatypeConstants.FIELD_UNDEFINED, // month
            DatatypeConstants.FIELD_UNDEFINED, // day
            hours,
            minutes,
            seconds,
            fractionalSecond,
            timezone);
    }

    /**
     * <p>Create a Java instance of XML Schema builtin datatype time.</p>
     * 
     * @param hours number of hours
     * @param minutes number of minutes
     * @param seconds number of seconds
     * @param milliseconds number of milliseconds
     * @param timezone offset in minutes. {@link DatatypeConstants#FIELD_UNDEFINED} indicates optional field is not set.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parameter values.
     * 
     * @see DatatypeConstants#FIELD_UNDEFINED
     *
     * @throws IllegalArgumentException if any parameter is outside value 
     * constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public static XMLGregorianCalendar createTime(
        int hours,
        int minutes,
        int seconds,
	int milliseconds,
        int timezone) {
        	
        return new XMLGregorianCalendarImpl(
            DatatypeConstants.FIELD_UNDEFINED, // year
            DatatypeConstants.FIELD_UNDEFINED, // month
            DatatypeConstants.FIELD_UNDEFINED, // day
            hours,
            minutes,
            seconds,
	    milliseconds,
            timezone);
    }

    // Accessors

    /** 
     * <p>Return high order component for XML Schema 1.0 dateTime datatype field for 
     * <code>year</code>.
     * <code>null</code> if this optional part of the year field is not defined.</p>
     * 
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-year">year field of date/time field mapping table</a>.</p>
     * @return eon of this <code>XMLGregorianCalendar</code>. The value 
     * returned is an integer multiple of 10^9.
     * 
     * @see #getYear()
     * @see #getEonAndYear()
     */
    public BigInteger getEon() {
	   return eon;
    }

    /** 
     * <p>Return low order component for XML Schema 1.0 dateTime datatype field for 
     * <code>year</code> or {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     * 
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-year">year field of date/time field mapping table</a>.</p>
     * 
     * @return year  of this <code>XMLGregorianCalendar</code>.
     * 
     * @see #getEon()
     * @see #getEonAndYear()
     */
    public int getYear() {
	   return year;
    }

    /** 
     * <p>Return XML Schema 1.0 dateTime datatype field for 
     * <code>year</code>.</p>
     * 
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-year">year field of date/time field mapping table</a>.</p>
     * 
     * @return sum of <code>eon</code> and <code>BigInteger.valueOf(year)</code>
     * when both fields are defined. When only <code>year</code> is defined, 
     * return it. When both <code>eon</code> and <code>year</code> are not 
     * defined, return <code>null</code>.
     * 
     * @see #getEon()
     * @see #getYear()
     */
    public BigInteger getEonAndYear() {
    	
		// both are defined
		if (year != DatatypeConstants.FIELD_UNDEFINED
			&& eon != null) {
    			
			return eon.add(BigInteger.valueOf((long) year));
		}

		// only year is defined
		if (year != DatatypeConstants.FIELD_UNDEFINED
			&& eon == null) {
    			
			return BigInteger.valueOf((long) year);
		}

    	// neither are defined
    	// or only eon is defined which is not valid without a year 
		return null;
    }

    /** 
     * <p>Return number of month or {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     * 
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-month">month field of date/time field mapping table</a>.</p>
     * 
     * @return year  of this <code>XMLGregorianCalendar</code>.
     * 
     */
    public int getMonth() {
    	return month;
    }

    /** 
     * Return day in month or {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-day">day field of date/time field mapping table</a>.</p>
     * 
     * @see #setDay(int)
     */
    public int getDay() {
	return day;
    }

    /** 
     * Return timezone offset in minutes or 
     * {@link DatatypeConstants#FIELD_UNDEFINED} if this optional field is not defined.
     *
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-timezone">timezone field of date/time field mapping table</a>.</p>
     * 
     * @see #setTimezone(int)
     */
    public int getTimezone() {
	return timezone;
    }

    /** 
     * Return hours or {@link DatatypeConstants#FIELD_UNDEFINED}.
     * Returns {@link DatatypeConstants#FIELD_UNDEFINED} if this field is not defined.
     *
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-hour">hour field of date/time field mapping table</a>.</p>
     * @see #setTime(int, int, int)
     */
    public int getHour() {
	return hour;
    }

    /**
     * Return minutes or {@link DatatypeConstants#FIELD_UNDEFINED}.<\p>
     * Returns {@link DatatypeConstants#FIELD_UNDEFINED} if this field is not defined.
     *
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-minute">minute field of date/time field mapping table</a>.</p>
     * @see #setTime(int, int, int)
     */
    public int getMinute() {
	return minute;
    }

    /** 
     * <p>Return seconds or {@link DatatypeConstants#FIELD_UNDEFINED}.<\p>
     * 
     * <p>Returns {@link DatatypeConstants#FIELD_UNDEFINED} if this field is not defined.
     * When this field is not defined, the optional xs:dateTime 
     * fractional seconds field, represented by 
     * {@link #getFractionalSecond()} and {@link #getMillisecond()},
     * must not be defined.</p>
     * 
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.</p>
     * 
     * @return Second  of this <code>XMLGregorianCalendar</code>.
     * 
     * @see #getFractionalSecond()
     * @see #getMillisecond()
     * @see #setTime(int, int, int)
     */
    public int getSecond() {
	   return second;
    }

    /**
     * @return result of adding second and fractional second field
     */
    private BigDecimal getSeconds() {
    	
	if (second == DatatypeConstants.FIELD_UNDEFINED) {
	    return DECIMAL_ZERO;
	} 
	BigDecimal result = BigDecimal.valueOf((long)second);
	if (fractionalSecond != null){
	    return result.add(fractionalSecond);
	} else {
	    return result;
	}
    }


    /** 
     * <p>Return millisecond precision of {@link #getFractionalSecond()}.<\p>
     * 
     * <p>This method represents a convenience accessor to infinite
     * precision fractional second value returned by 
     * {@link #getFractionalSecond()}. The returned value is the rounded 
     * down to milliseconds value of 
     * {@link #getFractionalSecond()}. When {@link #getFractionalSecond()} 
     * returns <code>null</code>, this method must return 
     * {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * <p>Value constraints for this value are summarized in 
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.</p>
     * 
     * @return Millisecond  of this <code>XMLGregorianCalendar</code>.
     * 
     * @see #getFractionalSecond()
     * @see #setTime(int, int, int)
     */
    public int getMillisecond() {
        if (fractionalSecond == null) {
            return DatatypeConstants.FIELD_UNDEFINED;
        } else {
            // TODO: Non-optimal solution for now.
            // Efficient implementation would only store as BigDecimal
            // when needed and millisecond otherwise.
            return fractionalSecond.movePointRight(3).intValue();
        }
    }

    /** 
     * <p>Return fractional seconds.</p>
     * 
     * <p><code>null</code> is returned when this optional field is not defined.</p>
     * 
     * <p>Value constraints are detailed in
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.</p>
     * 
     * <p>This optional field can only have a defined value when the
     * xs:dateTime second field, represented by ({@link #getSecond()}, 
     * does not return {@link DatatypeConstants#FIELD_UNDEFINED}).</p>
     *
     * @return fractional seconds  of this <code>XMLGregorianCalendar</code>.
     * 
     * @see #getSecond()
     * @see #setTime(int, int, int, BigDecimal)
     */
    public BigDecimal getFractionalSecond() {
	   return fractionalSecond;
    }

    // setters

    /**
     * <p>Set low and high order component of XSD <code>dateTime</code> year field.</p>
     * 
     * <p>Unset this field by invoking the setter with a parameter value of <code>null</code>.</p>
     *
     * @param year value constraints summarized in <a href="#datetimefield-year">year field of date/time field mapping table</a>.     
     *
     * @throws IllegalArgumentException if <code>year</code> parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setYear(BigInteger year) {
	if (year == null) {
	    this.eon = null;
	    this.year = DatatypeConstants.FIELD_UNDEFINED;
	} else {
	    BigInteger temp = year.remainder(BILLION);
	    this.year = temp.intValue();
	    setEon(year.subtract(temp));
	}
    }

    /**
     * <p>Set year of XSD <code>dateTime</code> year field.</p>
     *
     * <p>Unset this field by invoking the setter with a parameter value of 
     * {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * <p>Note: if the absolute value of the <code>year</code> parameter 
     * is less than 10^9, the eon component of the XSD year field is set to 
     * <code>null</code> by this method.</p>
     *
     * @param year value constraints are summarized in <a href="#datetimefield-year">year field of date/time field mapping table</a>.
     *   If year is {@link DatatypeConstants#FIELD_UNDEFINED}, then eon is set to <code>null</code>.
     */
    public void setYear(int year) { 
	if (year == DatatypeConstants.FIELD_UNDEFINED) {
	    this.year = DatatypeConstants.FIELD_UNDEFINED;
	    this.eon = null;
	} else if (Math.abs(year) < BILLION.intValue()) {
	    this.year = year;
	    this.eon = null;
	} else {
	    BigInteger theYear = BigInteger.valueOf((long) year);
	    BigInteger remainder = theYear.remainder(BILLION);
	    this.year = remainder.intValue();
	    setEon(theYear.subtract(remainder));
	}
    }

    /**
     * <p>Set high order part of XSD <code>dateTime</code> year field.</p>
     *
     * <p>Unset this field by invoking the setter with a parameter value of 
     * <code>null</code>.</p>
     *
     * @param eon value constraints summarized in <a href="#datetimefield-year">year field of date/time field mapping table</a>.
     */
    private void setEon(BigInteger eon) {
        if (eon != null && eon.compareTo(BigInteger.ZERO) == 0) {
            // Treat ZERO as field being undefined.
            this.eon = null;
        } else {
            this.eon = eon;
        }
    }

    /**
     * <p>Set month.</p>
     *
     * <p>Unset this field by invoking the setter with a parameter value of {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * @param month value constraints summarized in <a href="#datetimefield-month">month field of date/time field mapping table</a>.
     *
     * @throws IllegalArgumentException if <code>month</code> parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setMonth(int month) { 
	checkFieldValueConstraint(MONTH, month);
	this.month = month;
    }

    /**
     * <p>Set days in month.</p>
     *
     * <p>Unset this field by invoking the setter with a parameter value of {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * @param day value constraints summarized in <a href="#datetimefield-day">day field of date/time field mapping table</a>.
     *
     * @throws IllegalArgumentException if <code>day</code> parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setDay(int day) {  
	checkFieldValueConstraint(DAY, day);
	this.day = day;
    }

    /**
     * <p>Set the number of minutes in the timezone offset.</p>
     *
     * <p>Unset this field by invoking the setter with a parameter value of {@link DatatypeConstants#FIELD_UNDEFINED}.</p>
     *
     * @param offset value constraints summarized in <a href="#datetimefield-timezone">
     *   timezone field of date/time field mapping table</a>.
     *
     * @throws IllegalArgumentException if <code>offset</code> parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setTimezone(int offset) {
	checkFieldValueConstraint(TIMEZONE, offset);
	this.timezone = offset;
    }

    /**
     * <p>Set time as one unit.</p>
     *
     * @param hour value constraints are summarized in 
     * <a href="#datetimefield-hour">hour field of date/time field mapping table</a>.
     * @param minute value constraints are summarized in 
     * <a href="#datetimefield-minute">minute field of date/time field mapping table</a>.
     * @param second value constraints are summarized in 
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.
     *
     * @see #setTime(int, int, int, BigDecimal)
     *
     * @throws IllegalArgumentException if any parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setTime(int hour, int minute, int second) {
	setTime(hour, minute, second, null);
    }

    private void checkFieldValueConstraint(int field, int value)
	throws IllegalArgumentException 
    {
	if ((value < MIN_FIELD_VALUE[field] && value != DatatypeConstants.FIELD_UNDEFINED) ||
	    value > MAX_FIELD_VALUE[field]) {
         /**
            throw new IllegalArgumentException("invalid value " + value +
					       " for " + FIELD_NAME[field] +
					       " field");
             */
        throw new IllegalArgumentException(
            DatatypeMessageFormatter.formatMessage(null, "InvalidFieldValue", new Object[]{ new Integer(value), FIELD_NAME[field]})
        );
	}
    }

    public void setHour(int hour) {
	checkFieldValueConstraint(HOUR, hour);
	this.hour = hour;
    }

    public void setMinute(int minute) {
	checkFieldValueConstraint(MINUTE, minute);
	this.minute = minute;
    }

    public void setSecond(int second) {
	checkFieldValueConstraint(SECOND, second);
	this.second  = second;
    }

    /**
     * <p>Set time as one unit, including the optional infinite precison 
     * fractional seconds.</p>
     *
     * @param hour value constraints are summarized in 
     * <a href="#datetimefield-hour">hour field of date/time field mapping table</a>.
     * @param minute value constraints are summarized in 
     * <a href="#datetimefield-minute">minute field of date/time field mapping table</a>.
     * @param second value constraints are summarized in 
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.
     * @param fractional value of <code>null</code> indicates this optional 
     *                   field is not set.
     *
     * @throws IllegalArgumentException if any parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setTime(
        int hour,
        int minute,
        int second,
        BigDecimal fractional) {
	setHour(hour);
        setMinute(minute);
        setSecond(second);
        setFractionalSecond(fractional);
    }
    

    /**
     * <p>Set time as one unit, including optional milliseconds.</p>
     *
     * @param hour value constraints are summarized in 
     * <a href="#datetimefield-hour">hour field of date/time field mapping table</a>.
     * @param minute value constraints are summarized in 
     * <a href="#datetimefield-minute">minute field of date/time field mapping table</a>.
     * @param second value constraints are summarized in 
     * <a href="#datetimefield-second">second field of date/time field mapping table</a>.
     * @param millisecond value of {@link DatatypeConstants#FIELD_UNDEFINED} indicates this 
     *                    optional field is not set. 
     *
     * @throws IllegalArgumentException if any parameter is 
     * outside value constraints for the field as specified in 
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.
     */
    public void setTime(int hour, int minute, int second, int millisecond) {
        setHour(hour);
        setMinute(minute);
        setSecond(second);
        setMillisecond(millisecond);
    }

    // comparisons
    /**
     * <p>Compare two instances of W3C XML Schema 1.0 date/time datatypes 
     * according to partial order relation defined in 
     * <a href="http://www.w3.org/TR/xmlschema-2/#dateTime-order">W3C XML Schema 1.0 Part 2, Section 3.2.7.3,
     * <i>Order relation on dateTime</i></a>.</p>
     *
     * <p><code>xsd:dateTime</code> datatype field mapping to accessors of
     * this class are defined in
     * <a href="#datetimefieldmapping">date/time field mapping table</a>.</p>
     * 
     * @param rhs instance of <code>XMLGregorianCalendar</code> to compare
     * 
     * @return the relationship between <code>lhs</code> and <code>rhs</code> as 
     *   {@link DatatypeConstants#LESSER},
     *   {@link DatatypeConstants#EQUAL},
     *   {@link DatatypeConstants#GREATER} or
     *   {@link DatatypeConstants#INDETERMINATE}.
     *
     * @throws NullPointerException if <code>lhs</code> or <code>rhs</code> 
     * parameters are null. 
     */
    public int compare(XMLGregorianCalendar rhs) {
        	
		XMLGregorianCalendar lhs = this;

	int result = DatatypeConstants.INDETERMINATE;
        XMLGregorianCalendarImpl P = (XMLGregorianCalendarImpl) lhs;
        XMLGregorianCalendarImpl Q = (XMLGregorianCalendarImpl) rhs;

        if (P.getTimezone() == Q.getTimezone()) {
	    // Optimization: 
	    // both instances are in same timezone or
	    // both are FIELD_UNDEFINED. 
	    // Avoid costly normalization of timezone to 'Z' time.
	    return internalCompare(P, Q);

	} else if (P.getTimezone() != DatatypeConstants.FIELD_UNDEFINED &&
		   Q.getTimezone() != DatatypeConstants.FIELD_UNDEFINED) {

	    // Both instances have different timezones.
	    // Normalize to UTC time and compare.
	    P = (XMLGregorianCalendarImpl) P.normalize();
	    Q = (XMLGregorianCalendarImpl) Q.normalize();
	    return internalCompare(P, Q);
	} else if (P.getTimezone() != DatatypeConstants.FIELD_UNDEFINED) {
	    
	    if (P.getTimezone() != 0) {
		P = (XMLGregorianCalendarImpl) P.normalize();
	    }
	    
	    // C. step 1
	    XMLGregorianCalendar MinQ = Q.normalizeToTimezone(DatatypeConstants.MIN_TIMEZONE_OFFSET);
	    result = internalCompare(P, MinQ);
	    if (result == DatatypeConstants.LESSER) {
		return result;
	    } 

	    // C. step 2
	    XMLGregorianCalendar MaxQ = Q.normalizeToTimezone(DatatypeConstants.MAX_TIMEZONE_OFFSET);
	    result = internalCompare(P, MaxQ);
	    if (result == DatatypeConstants.GREATER) {
		return result;
	    } else {
		// C. step 3
		return DatatypeConstants.INDETERMINATE;
	    }
	} else { // Q.getTimezone() != DatatypeConstants.FIELD_UNDEFINED
	    // P has no timezone and Q does.
	    if (Q.getTimezone() != 0 ) { 
			Q = (XMLGregorianCalendarImpl) Q.normalizeToTimezone(Q.getTimezone());
	    }
	    
	    // D. step 1
	    XMLGregorianCalendar MaxP = P.normalizeToTimezone(DatatypeConstants.MAX_TIMEZONE_OFFSET);
	    result = internalCompare(MaxP, Q);
	    if (result == DatatypeConstants.LESSER) {
		return result;
	    } 

	    // D. step 2
	    XMLGregorianCalendar MinP = P.normalizeToTimezone(DatatypeConstants.MIN_TIMEZONE_OFFSET);
	    result = internalCompare(MinP, Q);
	    if (result == DatatypeConstants.GREATER) {
		return result;
	    } else {
		// D. step 3
		return DatatypeConstants.INDETERMINATE;
	    }
        }
    }

    /**
     * <p>Normalize this instance to UTC.</p>
     *
     * <p>2000-03-04T23:00:00+03:00 normalizes to 2000-03-04T20:00:00Z</p>
     * <p>Implements W3C XML Schema Part 2, Section 3.2.7.3 (A).</p>
     */
    public XMLGregorianCalendar normalize() {

        XMLGregorianCalendar normalized = normalizeToTimezone(timezone);
        
        // if timezone was undefined, leave it undefined
        if (getTimezone() == DatatypeConstants.FIELD_UNDEFINED) {
            normalized.setTimezone(DatatypeConstants.FIELD_UNDEFINED);
        }
        
        // if milliseconds was undefined, leave it undefined
        if (getMillisecond() == DatatypeConstants.FIELD_UNDEFINED) {
            normalized.setMillisecond(DatatypeConstants.FIELD_UNDEFINED);
        }
        
        return normalized;
    }
    
	/**
	 * <p>Normalize this instance to UTC.</p>
	 *
	 * <p>2000-03-04T23:00:00+03:00 normalizes to 2000-03-04T20:00:00Z</p>
	 * <p>Implements W3C XML Schema Part 2, Section 3.2.7.3 (A).</p>
	 */
	private XMLGregorianCalendar normalizeToTimezone(int timezone) {

	int minutes = timezone;    	
	XMLGregorianCalendar result = (XMLGregorianCalendar) this.clone();
	
	// normalizing to UTC time negates the timezone offset before 
	// addition.
	minutes = -minutes;
	Duration d = new DurationImpl(minutes >= 0, // isPositive
				  0, //years
				  0, //months
				  0, //days
				  0, //hours
				  minutes < 0 ? -minutes : minutes, // absolute
				  0  //seconds
				  );
	result.add(d);

	// set to zulu UTC time.
	result.setTimezone(0);
	return result;
	}

    /** 
     * 
     *  <p>Implements Step B from http://www.w3.org/TR/xmlschema-2/#dateTime-order </p>
     * @param P calendar instance with normalized timezone offset or 
     *          having same timezone as Q
     * @param Q calendar instance with normalized timezone offset or 
     *          having same timezone as P
     * 
     * @return result of comparing P and Q, value of
     *   {@link DatatypeConstants#EQUAL},
     *   {@link DatatypeConstants#LESSER},
     *   {@link DatatypeConstants#GREATER} or 
     *   {@link DatatypeConstants#INDETERMINATE}.
     */
    private static int internalCompare(XMLGregorianCalendar P,
				       XMLGregorianCalendar Q) {

	int result;

	// compare Year.
	if (P.getEon() == Q.getEon()) {
	    
	    // Eon field is only equal when null.
	    // optimized case for comparing year not requiring eon field.
	    result = compareField(P.getYear(), Q.getYear());
	    if (result != DatatypeConstants.EQUAL) {
		return result;
	    }
	} else {
	    result = compareField(P.getEonAndYear(), Q.getEonAndYear());
	    if (result != DatatypeConstants.EQUAL) {
		return result;
	    }
	}

	result = compareField(P.getMonth(), Q.getMonth());
	if (result != DatatypeConstants.EQUAL) {
	    return result;
	}

	result = compareField(P.getDay(), Q.getDay());
	if (result != DatatypeConstants.EQUAL) {
	    return result;
	}

	result = compareField(P.getHour(), Q.getHour());
	if (result != DatatypeConstants.EQUAL) {
	    return result;
	}
	
	result = compareField(P.getMinute(), Q.getMinute());
	if (result != DatatypeConstants.EQUAL) {
		return result;
	}
	result = compareField(P.getSecond(), Q.getSecond());
	if (result != DatatypeConstants.EQUAL) {
		return result;
	}
	
	result = compareField(P.getFractionalSecond(), Q.getFractionalSecond());
	return result;
   }

    /**
     * <p>Implement Step B from 
     * http://www.w3.org/TR/xmlschema-2/#dateTime-order.</p>
     */
    private static int compareField(int Pfield, int Qfield) {
	if (Pfield == Qfield) {

	    //fields are either equal in value or both undefined.
	    // Step B. 1.1 AND optimized result of performing 1.1-1.4.
	    return DatatypeConstants.EQUAL;
	} else {
	    if (Pfield == DatatypeConstants.FIELD_UNDEFINED || Qfield == DatatypeConstants.FIELD_UNDEFINED) {
		// Step B. 1.2
		return DatatypeConstants.INDETERMINATE;
	    } else {
		// Step B. 1.3-4.
		return (Pfield < Qfield ? DatatypeConstants.LESSER : DatatypeConstants.GREATER);
	    }
	}
    }

    private static int compareField(BigInteger Pfield, BigInteger Qfield) {
	if (Pfield == null) {
	    return (Qfield == null ? DatatypeConstants.EQUAL : DatatypeConstants.INDETERMINATE);
	}
	if (Qfield == null) {
	    return DatatypeConstants.INDETERMINATE;
	}
	return Pfield.compareTo(Qfield);
    }

    private static int compareField(BigDecimal Pfield, BigDecimal Qfield) {
	// optimization. especially when both arguments are null.
	if (Pfield == Qfield) {
	    return DatatypeConstants.EQUAL;
	}

	if (Pfield == null) {
	    Pfield = DECIMAL_ZERO;
	}

	if (Qfield == null) {
	    Qfield = DECIMAL_ZERO;
	}
	
	return Pfield.compareTo(Qfield);
    }

    /**
     * <p>Indicates whether parameter <code>obj</code> is "equal to" this one.</p>
     * 
     * @param obj to compare.
     *
     * @return <code>true</code> when <code>compare(this,(XMLGregorianCalendar)obj) == EQUAL.</code>.
     */
    public boolean equals(Object obj) {
	   boolean result = false;
	   if (obj instanceof XMLGregorianCalendar) {
	       result = compare((XMLGregorianCalendar) obj) == DatatypeConstants.EQUAL;
	   }
	   return result;
    }

    /**
     * <p>Returns a hash code consistent with the definition of the equals method.</p>
     * 
     * @return hash code of this object.
     */
    public int hashCode() {

	// Following two dates compare to EQUALS since in different timezones.
	// 2000-01-15T12:00:00-05:00 == 2000-01-15T13:00:00-04:00 	
	//
	// Must ensure both instances generate same hashcode by normalizing 
	// this to UTC timezone.
	int timezone = getTimezone();
	if (timezone == DatatypeConstants.FIELD_UNDEFINED){
	    timezone = 0;
	}
	XMLGregorianCalendar gc = this;
	if (timezone != 0) {
	    gc = this.normalizeToTimezone(getTimezone());
	}
	return gc.getYear() + gc.getMonth() + gc.getDay() + 
	    gc.getHour() + gc.getMinute() + gc.getSecond();
    }
    
    
    /**
     * <p>Constructs a new XMLGregorianCalendar object by
     * parsing its lexical string representation as defined in 
     * <a href="http://www.w3.org/TR/xmlschema-2/#dateTime-order">XML Schema 1.0 Part 2, Section 3.2.[7-14].1,
     * <i>Lexical Representation</i>.</a></p>
     * 
     * <p>The string representation may not have any leading and trailing whitespaces.</p>
     * 
     * <p>The parsing is done field by field so that   
     * the following holds for any lexically correct string x:</p>
     * <pre>
     * new XMLGregorianCalendar(x).toXMLFormat().equals(x)
     * </pre>
     * Except for the noted lexical/canonical representation mismatches
     * listed in <a href="http://www.w3.org/2001/05/xmlschema-errata#e2-45">
     * XML Schema 1.0 errata, Section 3.2.7.2</a>.
     * 
     * <p>Returns a non-null valid XMLGregorianCalendar object that holds the value
     * indicated by the lexicalRepresentation parameter.</p>
     *
     * @param lexicalRepresentation Lexical representation of one the 8 XML Schema calendar datatypes.
     * 
     * @return <code>XMLGregorianCalendar</code> created from parsing <code>lexicalRepresentation</code> parameter.
     * 
     * @throws IllegalArgumentException
     *      If the given string does not conform to the aforementioned
     *      specification.
     * @throws NullPointerException
     *      If the given string is null.
     */
    public static XMLGregorianCalendar parse(String lexicalRepresentation) {
    	
		return new XMLGregorianCalendarImpl(lexicalRepresentation);
    }

    /**
     * <p>Return the lexical representation of <code>this</code> instance. 
     * The format is specified in 
     * <a href="http://www.w3.org/TR/xmlschema-2/#dateTime-order">XML Schema 1.0 Part 2, Section 3.2.[7-14].1,
     * <i>Lexical Representation</i>".</a></p>
     * 
     * <p>Specific target lexical representation format is determined by 
     * {@link #getXMLSchemaType()}.</p>
     * 
     * @return XML, as <code>String</code>, representation of this <code>XMLGregorianCalendar</code> 
     * 
     * @throws java.lang.IllegalStateException if the combination of set fields
     *    does not match one of the eight defined XML Schema builtin date/time datatypes. 
     */
    public String toXMLFormat() {
    	
	QName typekind = getXMLSchemaType();
	
	String formatString = null;
	if (typekind == DatatypeConstants.DATETIME) {
	    formatString = "%Y-%M-%DT%h:%m:%s"+ "%z";
	} else if (typekind == DatatypeConstants.DATE) {
	    // Fix 4971612: invalid SCCS macro substitution in data string
	    formatString = "%Y-%M-%D" +"%z";
	} else if (typekind == DatatypeConstants.TIME) {
	    formatString = "%h:%m:%s"+ "%z";
	} else if (typekind == DatatypeConstants.GMONTH) {
	    formatString = "--%M--%z";
	} else if (typekind == DatatypeConstants.GDAY) {
	    // Fix 4971612: invalid SCCS macro substitution in data string
	    formatString = "---%D" + "%z";
	} else if (typekind == DatatypeConstants.GYEAR) {
	    formatString = "%Y" + "%z";
	} else if (typekind == DatatypeConstants.GYEARMONTH) {
	    // Fix 4971612: invalid SCCS macro substitution in data string
	    formatString = "%Y-%M" + "%z";
	} else if (typekind == DatatypeConstants.GMONTHDAY) {
	    // Fix 4971612: invalid SCCS macro substitution in data string
	    formatString = "--%M-%D" +"%z";
	}
	return format(formatString);
    }
    
    /**
     * <p>Return the name of the XML Schema date/time type that this instance 
     * maps to. Type is computed based on fields that are set.</p>
     *
     * <table border="2" rules="all" cellpadding="2">
     *   <thead>
     *     <tr>
     *       <th align="center" colspan="7">
     *         Required fields for XML Schema 1.0 Date/Time Datatypes.<br/>
     *         <i>(timezone is optional for all date/time datatypes)</i>
     *       </th>
     *     </tr>
     *   </thead>
     *   <tbody>
     *     <tr>
     *       <td>Datatype</td>
     *       <td>year</td>
     *       <td>month</td>
     *       <td>day</td>
     *       <td>hour</td>
     *       <td>minute</td>
     *       <td>second</td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#DATETIME}</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#DATE}</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#TIME}</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#GYEARMONTH}</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#GMONTHDAY}</td>
     *       <td></td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#GYEAR}</td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#GMONTH}</td>
     *       <td></td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#GDAY}</td>
     *       <td></td>
     *       <td></td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *   </tbody>
     * </table>
     * 
     * @throws java.lang.IllegalStateException if the combination of set fields
     *    does not match one of the eight defined XML Schema builtin 
     *    date/time datatypes.
     * @return One of the following class constants:
     *   {@link DatatypeConstants#DATETIME},
     *   {@link DatatypeConstants#TIME},
     *   {@link DatatypeConstants#DATE},
     *   {@link DatatypeConstants#GYEARMONTH},
     *   {@link DatatypeConstants#GMONTHDAY},
     *   {@link DatatypeConstants#GYEAR},
     *   {@link DatatypeConstants#GMONTH} or
     *   {@link DatatypeConstants#GDAY}.
     */
    public QName getXMLSchemaType() {
    	
    	// DATETIME
    	if (year != DatatypeConstants.FIELD_UNDEFINED
    		&& month != DatatypeConstants.FIELD_UNDEFINED
			&& day != DatatypeConstants.FIELD_UNDEFINED
			&& hour != DatatypeConstants.FIELD_UNDEFINED
			&& minute != DatatypeConstants.FIELD_UNDEFINED
			&& second != DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.DATETIME;
    	}

    	// DATE
    	if (year != DatatypeConstants.FIELD_UNDEFINED
    		&& month != DatatypeConstants.FIELD_UNDEFINED
			&& day != DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.DATE;
    	}

    	// TIME
    	if (year == DatatypeConstants.FIELD_UNDEFINED
    		&& month == DatatypeConstants.FIELD_UNDEFINED
			&& day == DatatypeConstants.FIELD_UNDEFINED
			&& hour != DatatypeConstants.FIELD_UNDEFINED
			&& minute != DatatypeConstants.FIELD_UNDEFINED
			&& second != DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.TIME;
    	}


    	// GYEARMONTH
    	if (year != DatatypeConstants.FIELD_UNDEFINED
    		&& month != DatatypeConstants.FIELD_UNDEFINED
			&& day == DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.GYEARMONTH;
    	}

    	// GMONTHDAY
    	if (year == DatatypeConstants.FIELD_UNDEFINED
    		&& month != DatatypeConstants.FIELD_UNDEFINED
			&& day != DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.GMONTHDAY;
    	}

    	// GYEAR
    	if (year != DatatypeConstants.FIELD_UNDEFINED
    		&& month == DatatypeConstants.FIELD_UNDEFINED
			&& day == DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.GYEAR;
    	}

    	// GMONTH
    	if (year == DatatypeConstants.FIELD_UNDEFINED
    		&& month != DatatypeConstants.FIELD_UNDEFINED
			&& day == DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.GMONTH;
    	}

    	// GDAY
    	if (year == DatatypeConstants.FIELD_UNDEFINED
    		&& month == DatatypeConstants.FIELD_UNDEFINED
			&& day != DatatypeConstants.FIELD_UNDEFINED
			&& hour == DatatypeConstants.FIELD_UNDEFINED
			&& minute == DatatypeConstants.FIELD_UNDEFINED
			&& second == DatatypeConstants.FIELD_UNDEFINED) {
    		return DatatypeConstants.GDAY;
    	}

    	// unknown
		throw new IllegalStateException(
			this.getClass().getName()
			+ "#getXMLSchemaType() :"
            + DatatypeMessageFormatter.formatMessage(null, "InvalidXGCFields", null)
		);
    }

    
    /**
     * Validate instance by <code>getXMLSchemaType()</code> constraints.
     * @return true if data values are valid.
     */
    public boolean isValid() {
	// since setters do not allow for invalid values, 
	// (except for exceptional case of year field of zero),
	// no need to check for anything except for constraints
	// between fields. 

	//check if days in month is valid. Can be dependent on leap year.
	if (getMonth() == DatatypeConstants.FEBRUARY) {
		// years could not be set
		int maxDays = DatatypeConstants.FIELD_UNDEFINED;
		BigInteger years = getEonAndYear();
		if (years != null) {
			maxDays = maximumDayInMonthFor(getEonAndYear(), DatatypeConstants.FEBRUARY);
		} else {
			// year is undefined, allow 29 days
			maxDays = 29;
		}
	    if (getDay() > maxDays) {
		return false;
	    }
	}

	// http://www.w3.org/2001/05/xmlschema-errata#e2-45
	if (getHour() == 24) {
	    if(getMinute() != 0) {
		return false;
	    } else if (getSecond() != 0) {
		return false;
	    }
	}

	// XML Schema 1.0 specification defines year value of zero as
	// invalid. Allow this class to set year field to zero
	// since XML Schema 1.0 errata states that lexical zero will 
	// be allowed in next version and treated as 1 B.C.E.
	if (eon == null) {
	    // optimize check.
	    if (year == 0) {
		return false;
	    }
	} else {
	    BigInteger yearField = getEonAndYear();
	    if (yearField != null) {
		int result = compareField(yearField, BigInteger.ZERO);
		if (result == DatatypeConstants.EQUAL) {
		    return false;
		}
	    }
	}
	return true;
    }

    /**
     * <p>Add <code>duration</code> to this instance.<\p>
     * 
     * <p>The computation is specified in
     * <a href="http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes">XML Schema 1.0 Part 2, Appendix E,
     * <i>Adding durations to dateTimes</i>></a>.
     * <a href="#datetimefieldsmapping">date/time field mapping table</a>
     * defines the mapping from XML Schema 1.0 <code>dateTime</code> fields 
     * to this class' representation of those fields.</p>
     * 
     * @param duration Duration to add to this <code>XMLGregorianCalendar</code>.
     * 
     * @throws NullPointerException  when <code>duration</code> parameter is <code>null</code>.
     */
    public void add(Duration duration) {
    	
		/*
		 * Extracted from 
		 * http://www.w3.org/TR/xmlschema-2/#adding-durations-to-dateTimes 
		 * to ensure implemented properly. See spec for definitions of methods
		 * used in algorithm.
		 * 
		 * Given a dateTime S and a duration D, specifies how to compute a 
		 * dateTime E where E is the end of the time period with start S and 
		 * duration D i.e. E = S + D.
		 * 
		 * The following is the precise specification. 
		 * These steps must be followed in the same order. 
		 * If a field in D is not specified, it is treated as if it were zero.
		 * If a field in S is not specified, it is treated in the calculation 
		 * as if it were the minimum allowed value in that field, however, 
		 * after the calculation is concluded, the corresponding field in 
		 * E is removed (set to unspecified).
		 * 
		 * Months (may be modified additionally below)
	         *  temp := S[month] + D[month]
	         *  E[month] := modulo(temp, 1, 13)
	         *  carry := fQuotient(temp, 1, 13)
		 */
	 
		boolean fieldUndefined[] = {
			false,
			false,
			false, 
			false,
			false,
			false
		};
		
		int signum = duration.getSign();
		
		int startMonth = getMonth();
		if (startMonth == DatatypeConstants.FIELD_UNDEFINED) {
		    startMonth = MIN_FIELD_VALUE[MONTH];
		    fieldUndefined[MONTH] = true;
		}
		
		BigInteger dMonths = sanitize(duration.getField(DatatypeConstants.MONTHS), signum);
		BigInteger temp = BigInteger.valueOf((long) startMonth).add(dMonths);
		setMonth(temp.subtract(BigInteger.ONE).mod(TWELVE).intValue() + 1);
		BigInteger carry =
			new BigDecimal(temp.subtract(BigInteger.ONE)).divide(new BigDecimal(TWELVE), BigDecimal.ROUND_FLOOR).toBigInteger();

		 /* Years (may be modified additionally below)
		  *  E[year] := S[year] + D[year] + carry
		  */
		BigInteger startYear = getEonAndYear();
		if (startYear == null) {
		    fieldUndefined[YEAR] = true;
		    startYear = BigInteger.ZERO;
		}
		BigInteger dYears = sanitize(duration.getField(DatatypeConstants.YEARS), signum);
		BigInteger endYear = startYear.add(dYears).add(carry);
		setYear(endYear);

		/* Zone
	         *  E[zone] := S[zone]
		 * 
		 * no-op since adding to this, not to a new end point.
		 */
	
		 /* Seconds
		  *  temp := S[second] + D[second]
		  *  E[second] := modulo(temp, 60)
		  *  carry := fQuotient(temp, 60)
		  */
		BigDecimal startSeconds;
		if (getSecond() == DatatypeConstants.FIELD_UNDEFINED) {
		    fieldUndefined[SECOND] = true;
		    startSeconds = DECIMAL_ZERO;
		} else {
		    // seconds + fractionalSeconds
		    startSeconds = getSeconds();
		}

		// Duration seconds is SECONDS + FRACTIONALSECONDS.
		BigDecimal dSeconds = DurationImpl.sanitize((BigDecimal) duration.getField(DatatypeConstants.SECONDS), signum);
		BigDecimal tempBD = startSeconds.add(dSeconds);
	    BigDecimal fQuotient = 
		    new BigDecimal(new BigDecimal(tempBD.toBigInteger()).divide(DECIMAL_SIXTY, BigDecimal.ROUND_FLOOR).toBigInteger());
	    BigDecimal endSeconds = tempBD.subtract(fQuotient.multiply(DECIMAL_SIXTY));

		carry = fQuotient.toBigInteger();
		setSecond(endSeconds.intValue());
		BigDecimal tempFracSeconds = endSeconds.subtract(new BigDecimal(BigInteger.valueOf((long) getSecond())));
		if (tempFracSeconds.compareTo(DECIMAL_ZERO) < 0) {
		    setFractionalSecond(DECIMAL_ONE.add(tempFracSeconds));
		    if (getSecond() == 0) {
				setSecond(59);
				carry = carry.subtract(BigInteger.ONE);
		    } else {
				setSecond(getSecond() - 1);
		    }
		} else {
		    setFractionalSecond(tempFracSeconds);
		}
 
		/* Minutes
	         *  temp := S[minute] + D[minute] + carry
	         *  E[minute] := modulo(temp, 60)
	         *  carry := fQuotient(temp, 60)
		 */
		int startMinutes = getMinute();
		if (startMinutes == DatatypeConstants.FIELD_UNDEFINED) {
		    fieldUndefined[MINUTE] = true;
		    startMinutes = MIN_FIELD_VALUE[MINUTE];
		}
		BigInteger dMinutes = sanitize(duration.getField(DatatypeConstants.MINUTES), signum);
		
		temp = BigInteger.valueOf(startMinutes).add(dMinutes).add(carry);
		setMinute(temp.mod(SIXTY).intValue());
		carry = new BigDecimal(temp).divide(DECIMAL_SIXTY, BigDecimal.ROUND_FLOOR).toBigInteger();

		/* Hours
	         *  temp := S[hour] + D[hour] + carry
	         *  E[hour] := modulo(temp, 24)
	         *  carry := fQuotient(temp, 24)
		 */
		int startHours = getHour();
		if (startHours == DatatypeConstants.FIELD_UNDEFINED) {
		    fieldUndefined[HOUR] = true;
		    startHours = MIN_FIELD_VALUE[HOUR];
		}
		BigInteger dHours = sanitize(duration.getField(DatatypeConstants.HOURS), signum);
		
		temp = BigInteger.valueOf(startHours).add(dHours).add(carry);
		setHour(temp.mod(TWENTY_FOUR).intValue());
		carry = new BigDecimal(temp).divide(new BigDecimal(TWENTY_FOUR), BigDecimal.ROUND_FLOOR).toBigInteger();
	
		/* Days
	     *  if S[day] > maximumDayInMonthFor(E[year], E[month])
	     *       + tempDays := maximumDayInMonthFor(E[year], E[month])
	     *  else if S[day] < 1
	     *       + tempDays := 1
	     *  else
	     *       + tempDays := S[day]
	     *  E[day] := tempDays + D[day] + carry
	     *  START LOOP
	     *       + IF E[day] < 1
	     *             # E[day] := E[day] + 
	 	 *                 maximumDayInMonthFor(E[year], E[month] - 1)
	     *             # carry := -1
	     *       + ELSE IF E[day] > maximumDayInMonthFor(E[year], E[month])
	     *             # E[day] := 
	 	 *                    E[day] - maximumDayInMonthFor(E[year], E[month])
	     *             # carry := 1
	     *       + ELSE EXIT LOOP
	     *       + temp := E[month] + carry
	     *       + E[month] := modulo(temp, 1, 13)
	     *       + E[year] := E[year] + fQuotient(temp, 1, 13)
	     *       + GOTO START LOOP
		 */
		BigInteger tempDays;
		int startDay = getDay();
		if (startDay == DatatypeConstants.FIELD_UNDEFINED) {
		    fieldUndefined[DAY] = true;
		    startDay = MIN_FIELD_VALUE[DAY];
		}
		BigInteger dDays = sanitize(duration.getField(DatatypeConstants.DAYS), signum);
	    int maxDayInMonth = maximumDayInMonthFor(getEonAndYear(), getMonth());
		if (startDay > maxDayInMonth) {
	            tempDays =  BigInteger.valueOf(maxDayInMonth);
		} else if (startDay < 1) {
		    tempDays = BigInteger.ONE;
		} else {
		    tempDays = BigInteger.valueOf(startDay);
		}
		BigInteger endDays = tempDays.add(dDays).add(carry);
		int monthCarry;
		int intTemp;
		while (true) {
		    if (endDays.compareTo(BigInteger.ONE) < 0) {
		    	// calculate days in previous month, watch for month roll over
				BigInteger mdimf = null;
				if (month >= 2) {
					mdimf = BigInteger.valueOf(maximumDayInMonthFor(getEonAndYear(), getMonth() - 1));
				} else {
					// roll over to December of previous year
					mdimf = BigInteger.valueOf(maximumDayInMonthFor(getEonAndYear().subtract(BigInteger.valueOf((long) 1)), 12));
				}
				endDays = endDays.add(mdimf);
				monthCarry = -1;
		    } else if (endDays.compareTo(BigInteger.valueOf(maximumDayInMonthFor(getEonAndYear(), getMonth()))) > 0) {
				endDays = endDays.add(BigInteger.valueOf(-maximumDayInMonthFor(getEonAndYear(), getMonth())));
				monthCarry = 1;
		    } else {
		    	break;
		    } 

		    intTemp = getMonth() + monthCarry;
		    int endMonth = (intTemp - 1) % (13 - 1);
		    int quotient;
		    if (endMonth < 0) {
				endMonth = (13 - 1) + endMonth + 1;
				quotient = new BigDecimal(intTemp - 1).divide(new BigDecimal(TWELVE), BigDecimal.ROUND_UP).intValue();
		    } else {
				quotient = (intTemp - 1) / (13 - 1);
				endMonth += 1;
		    }
		    setMonth(endMonth);
		    if (quotient != 0)  {
				setYear(getEonAndYear().add(BigInteger.valueOf(quotient)));
	    	} 
		}
		setDay(endDays.intValue());
	
        // set fields that where undefined before this addition, back to undefined.
		for (int i = YEAR; i <= SECOND; i++) {
		    if (fieldUndefined[i]) {
				switch (i) {
				case YEAR:
				    setYear(DatatypeConstants.FIELD_UNDEFINED);
				    break;
				case MONTH:
				    setMonth(DatatypeConstants.FIELD_UNDEFINED);
				    break;
				case DAY:
				    setDay(DatatypeConstants.FIELD_UNDEFINED);
				    break;
				case HOUR:
				    setHour(DatatypeConstants.FIELD_UNDEFINED);
				    break;
				case MINUTE:
				    setMinute(DatatypeConstants.FIELD_UNDEFINED);
				    break;
				case SECOND:
				    setSecond(DatatypeConstants.FIELD_UNDEFINED);
				    setFractionalSecond(null);
				    break;
				}
		    }
		}
    }

    private static final BigInteger FOUR = BigInteger.valueOf(4);
    private static final BigInteger HUNDRED = BigInteger.valueOf(100);
    private static final BigInteger FOUR_HUNDRED = BigInteger.valueOf(400);
    private static final BigInteger SIXTY = BigInteger.valueOf(60);
    private static final BigInteger TWENTY_FOUR = BigInteger.valueOf(24);
    private static final BigInteger TWELVE = BigInteger.valueOf(12);
    private static final BigDecimal DECIMAL_ZERO = new BigDecimal("0");
    private static final BigDecimal DECIMAL_ONE = new BigDecimal("1");
    private static final BigDecimal DECIMAL_SIXTY = new BigDecimal("60");


    private static int daysInMonth[] = { 0,  // XML Schema months start at 1.
				       31, 28, 31, 30, 31, 30,
                                       31, 31, 30, 31, 30, 31};

    private static int maximumDayInMonthFor(BigInteger year, int month) {
	if (month != DatatypeConstants.FEBRUARY) {
	    return daysInMonth[month];
	} else {
	    if (year.mod(FOUR_HUNDRED).equals(BigInteger.ZERO) || 
		(!year.mod(HUNDRED).equals(BigInteger.ZERO) &&
		 year.mod(FOUR).equals(BigInteger.ZERO))) {
		// is a leap year.
		return 29;
	    } else {
		return daysInMonth[month];
	    }
	}
    }

    private static int maximumDayInMonthFor(int year, int month) {
	if (month != DatatypeConstants.FEBRUARY) {
	    return daysInMonth[month];
	} else {
	    if ( ((year %400) == 0) || 
		 ( ((year % 100) != 0) && ((year % 4) == 0))) {
		// is a leap year.
		return 29;
	    } else {
		return daysInMonth[DatatypeConstants.FEBRUARY];
	    }
	}
    }

    /**
     * <p>Convert <code>this</code> to <code>java.util.GregorianCalendar</code>.</p>
     * 
     * <p>When <code>this</code> instance has an undefined field, this
     * conversion relies on the <code>java.util.GregorianCalendar</code> default 
     * for its corresponding field. A notable difference between
     * XML Schema 1.0 date/time datatypes and <code>java.util.GregorianCalendar</code>
     * is that Timezone value is optional for date/time datatypes and it is
     * a required field for <code>java.util.GregorianCalendar</code>. See javadoc
     * for <code>java.util.TimeZone.getDefault()</code> on how the default
     * is determined. To explicitly specify the <code>TimeZone</code>
     * instance, see 
     * {@link #toGregorianCalendar(TimeZone, Locale, XMLGregorianCalendar)}.</p>
     * 
     * <table border="2" rules="all" cellpadding="2">
     *   <thead>
     *     <tr>
     *       <th align="center" colspan="2">
     *          Field by Field Conversion from this class to 
     *          <code>java.util.GregorianCalendar</code>
     *       </th>
     *     </tr>
     *   </thead>
     *   <tbody>
     *     <tr>
     *        <th><code>java.util.GregorianCalendar</code> field</th>
     *        <th><code>javax.xml.datatype.XMLGregorianCalendar</code> field</th>
     *     </tr>
     *     <tr>
     *       <th><code>ERA</code></th>
     *       <th>{@link #getEonAndYear()}<code>.signum() < 0 ? GregorianCalendar.BC : GregorianCalendar.AD</code></th>
     *     </tr>
     *     <tr>
     *       <th><code>YEAR</code></th>
     *       <th>{@link #getEonAndYear()}<code>.abs().intValue()</code><i>*</i></th>
     *     </tr>
     *     <tr>
     *       <th><code>MONTH</code></th>
     *       <th>{@link #getMonth()}<code> - 1</code></th>
     *     </tr>
     *     <tr>
     *       <th><code>DAY_OF_MONTH</code></th>
     *       <th>{@link #getDay()}</th>
     *     </tr>
     *     <tr>
     *       <th><code>AM_PM</code></th>
     *       <th>{@link #getHour()} < 12 : Calendar.AM : Calendar.PM</th>
     *     </tr>
     *     <tr>
     *       <th><code>HOUR_OF_DAY</code></th>
     *       <th>{@link #getHour()}</th>
     *     </tr>
     *     <tr>
     *       <th><code>MINUTE</code></th>
     *       <th>{@link #getMinute()}</th>
     *     </tr>
     *     <tr>
     *       <th><code>SECOND</code></th>
     *       <th>{@link #getSecond()}</th>
     *     </tr>
     *     <tr>
     *       <th><code>MILLISECOND</code></th>
     *       <th>get millisecond order from {@link #getFractionalSecond()}<i>*</i> </th>
     *     </tr>
     *     <tr>
     *       <th><code>GregorianCalendar.setTimeZone(TimeZone)</code></th>
     *       <th>{@link #getTimezone()} formatted into Custom timezone id</th>
     *     </tr>
     *   </tbody>
     * </table>
     * <i>*</i> designates possible loss of precision during the conversion due
     * to source datatype having higer precison than target datatype.
     * 
     * <p>To ensure consistency in conversion implementations, the new
     * <code>GregorianCalendar</code> should be instantiated in following
     * manner.
     * <ul>
     *   <li>Using <code>timeZone</code> value as defined above, create a new 
     * <code>java.util.GregorianCalendar(timeZone,Locale.getDefault())</code>.
     *   </li>
     *   <li>Initialize all GregorianCalendar fields by calling {(@link GegorianCalendar#clear()}.</li>
     *   <li>Obtain a pure Gregorian Calendar by invoking
     *   <code>GregorianCalendar.setGregorianChange(
     *   new Date(Long.MIN_VALUE))</code>.</li>
     *   <li>Its fields ERA, YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, 
     *       MINUTE, SECOND and MILLISECOND are set using the method 
     *       <code>Calendar.set(int,int)</code></li>
     * </ul>
     * </p>
     * 
     * @see #toGregorianCalendar(java.util.TimeZone, java.util.Locale, XMLGregorianCalendar)
     */
    public java.util.GregorianCalendar toGregorianCalendar() {

	GregorianCalendar result = null;
	final int DEFAULT_TIMEZONE_OFFSET = DatatypeConstants.FIELD_UNDEFINED;
	TimeZone tz = getTimeZone(DEFAULT_TIMEZONE_OFFSET);
	Locale locale = java.util.Locale.getDefault();

	result = new GregorianCalendar(tz, locale);
	result.clear();
	result.setGregorianChange(PURE_GREGORIAN_CHANGE);
	
	// if year( and eon) are undefined, leave default Calendar values
	BigInteger year = getEonAndYear();
	if (year != null) {
		result.set(Calendar.ERA, year.signum() == -1 ? GregorianCalendar.BC : GregorianCalendar.AD);
		result.set(Calendar.YEAR, year.abs().intValue());
	}
	
	// only set month if it is set
	if (month != DatatypeConstants.FIELD_UNDEFINED) { 
		// Calendar.MONTH is zero based while XMLGregorianCalendar month field is not.
		result.set(Calendar.MONTH, month  - 1);
	}
	
	// only set day if it is set
	if (day != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.DAY_OF_MONTH, day);
	}
	
	// only set hour if it is set
	if (hour != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.HOUR_OF_DAY, hour);
	}
	
	// only set minute if it is set
	if (minute != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.MINUTE, minute);
	}
	
	// only set second if it is set
	if (second != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.SECOND, second);
	}
	
	// only set millisend if it is set
	if (fractionalSecond != null) {
		result.set(Calendar.MILLISECOND, getMillisecond());
	}

	return result;
    }

    /**
     * <p>Convert <code>this</code> along with provided parameters
     * to <code>java.util.GregorianCalendar</code> instance.</p>
     * 
     * <p> Since XML Schema 1.0 date/time datetypes has no concept of
     * timezone ids or daylight savings timezone ids, this conversion operation
     * allows the user to explicitly specify one with
     * <code>timezone</code> parameter.</p>
     * 
     * <p>To compute the return value's <code>TimeZone</code> field,
     * <ul>
     * <li>when parameter <code>timeZone</code> is non-null, 
     * it is the timezone field.</li>
     * <li>else when <code>this.getTimezone() != DatatypeConstants.FIELD_UNDEFINED</code>,
     * create a <code>java.util.TimeZone</code> with a custom timezone id 
     * using the <code>this.getTimezone()</code>.</li>
     * <li>else when <code>defaults.getTimezone() != DatatypeConstants.FIELD_UNDEFINED</code>, 
     * create a <code>java.util.TimeZone</code> with a custom timezone id 
     * using <code>defaults.getTimezone()</code>.</li>
     * <li>else use the <code>GregorianCalendar</code> default timezone value 
     * for the host is definedas specified by 
     * <code>java.util.TimeZone.getDefault()</code>.</li></p>
     * 
     * <p>To ensure consistency in conversion implementations, the new
     * <code>GregorianCalendar</code> should be instantiated in following
     * manner.
     * <ul>
     *   <li>Create a new <code>java.util.GregorianCalendar(TimeZone, 
     *       Locale)</code> with TimeZone set as specified above and the
     *       <code>Locale</code> parameter. 
     *   </li>
     *   <li>Initialize all GregorianCalendar fields by calling {(@link GegorianCalendar#clear()}.</li>
     *   <li>Obtain a pure Gregorian Calendar by invoking
     *   <code>GregorianCalendar.setGregorianChange(
     *   new Date(Long.MIN_VALUE))</code>.</li>
     *   <li>Its fields ERA, YEAR, MONTH, DAY_OF_MONTH, HOUR_OF_DAY, 
     *       MINUTE, SECOND and MILLISECOND are set using the method 
     *       <code>Calendar.set(int,int)</code></li>
     * </ul>
     * 
     * @param timezone provide Timezone. <code>null</code> is a legal value.
     * @param aLocale  provide explicit Locale. Use default GregorianCalendar locale if
     *                 value is <code>null</code>.
     * @param defaults provide default field values to use when corresponding
     *                 field for this instance is DatatypeConstants.FIELD_UNDEFINED or null. 
     *                 If <code>defaults</code>is <code>null</code> or a field
     *                 within the specified <code>defaults</code> is undefined,
     *                 just use <code>java.util.GregorianCalendar</code> defaults.
     * @return a java.util.GregorianCalendar conversion of this instance.
     *
     * @see #LEAP_YEAR_DEFAULT
     */
    public GregorianCalendar toGregorianCalendar(java.util.TimeZone timezone, 
					 java.util.Locale aLocale,
					 XMLGregorianCalendar defaults) {
	GregorianCalendar result = null;
	TimeZone tz = timezone;
	if (tz == null) {
	    int defaultZoneoffset = DatatypeConstants.FIELD_UNDEFINED;
	    if (defaults != null) {
	    	defaultZoneoffset = defaults.getTimezone();
	    }
	    tz = getTimeZone(defaultZoneoffset);
	}
	if (aLocale == null) {
	    aLocale = java.util.Locale.getDefault();
	}
	result = new GregorianCalendar(tz, aLocale);
	result.clear();
	result.setGregorianChange(PURE_GREGORIAN_CHANGE);

	// if year( and eon) are undefined, leave default Calendar values
	BigInteger year = getEonAndYear();
	if (year != null) {
		result.set(Calendar.ERA, year.signum() == -1 ? GregorianCalendar.BC : GregorianCalendar.AD);
		result.set(Calendar.YEAR, year.abs().intValue());
	} else {
		// use default if set
		BigInteger defaultYear = (defaults != null) ? defaults.getEonAndYear() : null;
		if (defaultYear != null) {
			result.set(Calendar.ERA, defaultYear.signum() == -1 ? GregorianCalendar.BC : GregorianCalendar.AD);
			result.set(Calendar.YEAR, defaultYear.abs().intValue());
		}
	}
	
	// only set month if it is set
	if (month != DatatypeConstants.FIELD_UNDEFINED) { 
		// Calendar.MONTH is zero based while XMLGregorianCalendar month field is not.
		result.set(Calendar.MONTH, month  - 1);
	} else {
		// use default if set
		int defaultMonth = (defaults != null) ? defaults.getMonth() : DatatypeConstants.FIELD_UNDEFINED;
		if (defaultMonth != DatatypeConstants.FIELD_UNDEFINED) { 
			// Calendar.MONTH is zero based while XMLGregorianCalendar month field is not.
			result.set(Calendar.MONTH, defaultMonth  - 1);
		}
	}
		
	// only set day if it is set
	if (day != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.DAY_OF_MONTH, day);
	} else {
		// use default if set
		int defaultDay = (defaults != null) ? defaults.getDay() : DatatypeConstants.FIELD_UNDEFINED;
		if (defaultDay != DatatypeConstants.FIELD_UNDEFINED) { 
			result.set(Calendar.DAY_OF_MONTH, defaultDay);
		}
	}
	
	// only set hour if it is set
	if (hour != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.HOUR_OF_DAY, hour);
	} else {
		// use default if set
		int defaultHour = (defaults != null) ? defaults.getHour() : DatatypeConstants.FIELD_UNDEFINED;
		if (defaultHour != DatatypeConstants.FIELD_UNDEFINED) { 
			result.set(Calendar.HOUR_OF_DAY, defaultHour);
		}
	}
	
	// only set minute if it is set
	if (minute != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.MINUTE, minute);
	} else {
		// use default if set
		int defaultMinute = (defaults != null) ? defaults.getMinute() : DatatypeConstants.FIELD_UNDEFINED;
		if (defaultMinute != DatatypeConstants.FIELD_UNDEFINED) { 
			result.set(Calendar.MINUTE, defaultMinute);
		}
	}
	
	// only set second if it is set
	if (second != DatatypeConstants.FIELD_UNDEFINED) {
		result.set(Calendar.SECOND, second);
	} else {
		// use default if set
		int defaultSecond = (defaults != null) ? defaults.getSecond() : DatatypeConstants.FIELD_UNDEFINED;
		if (defaultSecond != DatatypeConstants.FIELD_UNDEFINED) { 
			result.set(Calendar.SECOND, defaultSecond);
		}
	}
	
	// only set millisend if it is set
	if (fractionalSecond != null) {
		result.set(Calendar.MILLISECOND, getMillisecond());
	} else {
		// use default if set
		BigDecimal defaultFractionalSecond = (defaults != null) ? defaults.getFractionalSecond() : null;
		if (defaultFractionalSecond != null) { 
			result.set(Calendar.MILLISECOND, defaults.getMillisecond());
		}
	}

	return result;
    }

    /**
     * <p>Returns a <code>java.util.TimeZone</code> for this class.</p>
     * 
     * <p>If timezone field is defined for this instance, 
     * returns TimeZone initialized with custom timezone id
     * of zoneoffset. If timezone field is undefined, 
     * try the defaultZoneoffset that was passed in. 
     * If defaultZoneoffset is DatatypeConstants.FIELD_UNDEFINED, return
     * default timezone for this host.
     * (Same default as java.util.GregorianCalendar).</p>
     *
     * @param defaultZoneoffset default zoneoffset if this zoneoffset is 
     * {@link DatatypeConstants#FIELD_UNDEFINED}.
     *
     * @return TimeZone for this.
     */
    public TimeZone getTimeZone(int defaultZoneoffset) {
	TimeZone result = null;
	int zoneoffset = getTimezone();

	if (zoneoffset == DatatypeConstants.FIELD_UNDEFINED) {
	    zoneoffset = defaultZoneoffset;
	}
	if (zoneoffset == DatatypeConstants.FIELD_UNDEFINED) {
	    result = TimeZone.getDefault();
	} else {
	    // zoneoffset is in minutes. Convert to custom timezone id format.
	    char sign = zoneoffset < 0 ? '-' : '+';
	    if (sign == '-') {
		zoneoffset = -zoneoffset;
	    }
	    int hour = zoneoffset / 60;
	    int minutes = zoneoffset - (hour * 60);
		
	    // Javadoc for java.util.TimeZone documents max length
	    // for customTimezoneId is 8 when optional ':' is not used.
	    // Format is 
	    // "GMT" ('-'|''+') (digit digit?) (digit digit)?
	    //                   hour          minutes
	    StringBuffer customTimezoneId = new StringBuffer(8);
	    customTimezoneId.append("GMT");
	    customTimezoneId.append(sign);
	    customTimezoneId.append(hour);
	    if (minutes != 0) {
		customTimezoneId.append(minutes);
	    }
	    result = TimeZone.getTimeZone(customTimezoneId.toString());
	}
	return result;
    }
    
    /**
     * <p>Creates and returns a copy of this object.</p>
     * 
     * @return copy of this <code>Object</code>
     */
   public Object clone() {
        // Both this.eon and this.fractionalSecond are instances
        // of immutable classes, so they do not need to be cloned.
       return new XMLGregorianCalendarImpl(getEonAndYear(),
                        this.month, this.day, 
			this.hour, this.minute, this.second,
			this.fractionalSecond,
			this.timezone);
    }

    /**
     * <p>Unset all fields to undefined.</p>
     *
     * <p>Set all int fields to {@link DatatypeConstants#FIELD_UNDEFINED} and reference fields 
     * to null.</p>
     */
    public void clear() {
	eon = null;
	year = DatatypeConstants.FIELD_UNDEFINED;
	month = DatatypeConstants.FIELD_UNDEFINED;
	day = DatatypeConstants.FIELD_UNDEFINED;
	timezone = DatatypeConstants.FIELD_UNDEFINED;  // in minutes
	hour = DatatypeConstants.FIELD_UNDEFINED;
	minute = DatatypeConstants.FIELD_UNDEFINED;
	second = DatatypeConstants.FIELD_UNDEFINED;
	fractionalSecond = null;
    }

    public void setMillisecond(int millisecond) {
	if (millisecond == DatatypeConstants.FIELD_UNDEFINED) {
	    fractionalSecond = null;
	} else {
	    checkFieldValueConstraint(MILLISECOND, millisecond);
	    fractionalSecond = new BigDecimal((long) millisecond).movePointLeft(3);
	} 
    }

    public void setFractionalSecond(BigDecimal fractional) {
	if (fractional != null) {
	    if ((fractional.compareTo(DECIMAL_ZERO) < 0) ||
		(fractional.compareTo(DECIMAL_ONE) > 0)) {
		throw new IllegalArgumentException(DatatypeMessageFormatter.formatMessage(null, 
            "InvalidFractional", new Object[]{fractional}));
	    }            	                             
	}
	this.fractionalSecond = fractional;
    }

    private final class Parser {
        private final String format;
        private final String value;

        private final int flen;
        private final int vlen;

        private int fidx;
        private int vidx;

        private Parser(String format, String value) {
            this.format = format;
            this.value = value;
            this.flen = format.length();
            this.vlen = value.length();
        }
        
        /**
         * <p>Parse a formated <code>String</code> into an <code>XMLGregorianCalendar</code>.</p>
         * 
         * <p>If <code>String</code> is not formated as a legal <code>XMLGregorianCalendar</code> value,
         * an <code>IllegalArgumentException</code> is thrown.</p>
         * 
         * @throws IllegalArgumentException If <code>String</code> is not formated as a legal <code>XMLGregorianCalendar</code> value.
         */
        public void parse() throws IllegalArgumentException {
            while (fidx < flen) {
                char fch = format.charAt(fidx++);

                if (fch != '%') { // not a meta character
                    skip(fch);
                    continue;
                }

                // seen meta character. we don't do error check against the format
                switch (format.charAt(fidx++)) {
                    case 'Y' : // year
                        setYear(parseBigInteger(4));
                        break;

                    case 'M' : // month
                        setMonth(parseInt(2, 2));
                        break;

                    case 'D' : // days
                        setDay(parseInt(2, 2));
                        break;

                    case 'h' : // hours
                        setHour(parseInt(2, 2));
                        break;

                    case 'm' : // minutes
                        setMinute(parseInt(2, 2));
                        break;

                    case 's' : // parse seconds.
                        setSecond(parseInt(2, 2));

                        if (peek() == '.') {
			    setFractionalSecond(parseBigDecimal());
                        }
                        break;

                    case 'z' : // time zone. missing, 'Z', or [+-]nn:nn
                        char vch = peek();
                        if (vch == 'Z') {
                            vidx++;
                            setTimezone(0);
                        } else if (vch == '+' || vch == '-') {
                            vidx++;
                            int h = parseInt(2, 2);
                            skip(':');
                            int m = parseInt(2, 2);
                            setTimezone((h * 60 + m) * (vch == '+' ? 1 : -1));
                        }
			
                        break;

                    default :
                        // illegal meta character. impossible.
                        throw new InternalError();
                }
            }

            if (vidx != vlen) {
                // some tokens are left in the input
                throw new IllegalArgumentException(value); //,vidx);
            }
        }
        
        private char peek() throws IllegalArgumentException {
            if (vidx == vlen) {
                return (char) -1;
            }
            return value.charAt(vidx);
        }
        
        private char read() throws IllegalArgumentException {
            if (vidx == vlen) {
                throw new IllegalArgumentException(value); //,vidx);
            }
            return value.charAt(vidx++);
        }
        
        private void skip(char ch) throws IllegalArgumentException {
            if (read() != ch) {
                throw new IllegalArgumentException(value); //,vidx-1);
            }
        }
        
        private int parseInt(int minDigits, int maxDigits)
            throws IllegalArgumentException {
            int vstart = vidx;
            while (isDigit(peek()) && (vidx - vstart) <= maxDigits) {
                vidx++;
            }
            if ((vidx - vstart) < minDigits) {
                // we are expecting more digits
                throw new IllegalArgumentException(value); //,vidx);
            }

            // NumberFormatException is IllegalArgumentException            
            //           try {
            return Integer.parseInt(value.substring(vstart, vidx));
            //            } catch( NumberFormatException e ) {
            //                // if the value is too long for int, NumberFormatException is thrown
            //                throw new IllegalArgumentException(value,vstart);
            //            }
        }

        private BigInteger parseBigInteger(int minDigits)
            throws IllegalArgumentException {
            int vstart = vidx;

	    // skip leading negative, if it exists
	    if (peek() == '-') {
		vidx++;
	    }
            while (isDigit(peek())) {
                vidx++;
            }
            if ((vidx - vstart) < minDigits) {
                // we are expecting more digits
                throw new IllegalArgumentException(value); //,vidx);
            }

            return new BigInteger(value.substring(vstart, vidx));
        }

        private BigDecimal parseBigDecimal()
            throws IllegalArgumentException {
            int vstart = vidx;

	    if (peek() == '.') {
		vidx++;
	    } else {
                throw new IllegalArgumentException(value);
	    }
            while (isDigit(peek())) {
                vidx++;
            }
            return new BigDecimal(value.substring(vstart, vidx));
        }
    }

    private static boolean isDigit(char ch) {
        return '0' <= ch && ch <= '9';
    }

    private String format( String format ) {
        StringBuffer buf = new StringBuffer();
        int fidx=0,flen=format.length();
        
        while(fidx<flen) {
            char fch = format.charAt(fidx++);
            if(fch!='%') {// not a meta char
                buf.append(fch);
                continue;
            }
            
            switch(format.charAt(fidx++)) {
            case 'Y':
                printNumber(buf,getEonAndYear(), 4);
                break;
            case 'M':
                printNumber(buf,getMonth(),2);
                break;
            case 'D':
                printNumber(buf,getDay(),2);
                break;
            case 'h':
                printNumber(buf,getHour(),2);
                break;
            case 'm':
                printNumber(buf,getMinute(),2);
                break;
            case 's':
                printNumber(buf,getSecond(),2);
		if (getFractionalSecond() != null) {
		    String frac = getFractionalSecond().toString();
		    //skip leading zero.
		    buf.append(frac.substring(1, frac.length()));
		} 
                break;
            case 'z':
		int offset = getTimezone();
                if(offset == 0) {
		    buf.append('Z');
		} else if (offset != DatatypeConstants.FIELD_UNDEFINED) {
		    if(offset<0) {
			buf.append('-');
			offset *= -1; 
		    } else {
			buf.append('+');
		    }
		    printNumber(buf,offset60,2);
                    buf.append(':');
                    printNumber(buf,offset%60,2);
                }
                break;
            default:
                throw new InternalError();  // impossible
            }
        }
        
        return buf.toString();
    }
    
    /**
     * Prints an integer as a String. 
     * 
     * @param out
     *      The formatted string will be appended into this buffer.
     * @param number
     *      The integer to be printed. 
     * @param nDigits
     *      The field will be printed by using at least this
     *      number of digits. For example, 5 will be printed as "0005"
     *      if nDigits==4. 
     */
    private void printNumber( StringBuffer out, int number, int nDigits ) {
        String s = String.valueOf(number);
        for( int i=s.length(); i<nDigits; i++ )
            out.append('0');
        out.append(s);
    }

    /**
     * Prints an BigInteger as a String. 
     * 
     * @param out
     *      The formatted string will be appended into this buffer.
     * @param number
     *      The integer to be printed. 
     * @param nDigits
     *      The field will be printed by using at least this
     *      number of digits. For example, 5 will be printed as "0005"
     *      if nDigits==4. 
     */
    private void printNumber( StringBuffer out, BigInteger number, int nDigits) {
        String s = number.toString();
        for( int i=s.length(); i<nDigits; i++ )
            out.append('0');
        out.append(s);
    }

    /**
     * Compute <code>value*signum</code> where value==null is treated as
     * value==0.
     * @return non-null {@link BigInteger}.
     */
    static BigInteger sanitize(Number value, int signum) {
        if (signum == 0 || value == null) {
            return BigInteger.ZERO;
        }
        return (signum <  0)? ((BigInteger)value).negate() : (BigInteger)value;
    }

    /** <p><code>reset()</code> is designed to allow the reuse of existing 
     * <code>XMLGregorianCalendar</code>s thus saving resources associated
     *  with the creation of new <code>XMLGregorianCalendar</code>s.</p>
     */
    public void reset() {
        //PENDING : Implementation of reset method  
    }
}