package net.sf.statsvn.util;

 import java.io.File;

 import java.text.DateFormat;

 import java.text.ParseException;

 import java.text.SimpleDateFormat;

 import java.util.Calendar;

 import java.util.Date;

 import java.util.GregorianCalendar;

 import java.util.TimeZone;

 import javax.xml.transform.OutputKeys;

 import javax.xml.transform.Result;

 import javax.xml.transform.Source;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.dom.DOMSource;

 import javax.xml.transform.stream.StreamResult;

 import net.sf.statsvn.output.SvnConfigurationOptions;

 import org.w3c.dom.Document;

 /**

  * 

  * Utilities class to faciliate XML management.

  * 

  * @author Jason Kealey <jkealey@shade.ca>

  * @author Gunter Mussbacher <gunterm@site.uottawa.ca>

  * 

  * @version $Id: XMLUtil.java 351 2008-03-28 18:46:26Z benoitx $

  */

 public final class XMLUtil {

         private static final int ONE_SEC_IN_MILLISECS = 1000;

         private static final int IDOT_POSITION_IFNEG = 20;

         private static final int NORMAL_IDOT_POSITION = 19;

         /**

          * A utility class (only static methods) should be final and have

          * a private constructor.

          */

         private XMLUtil() {

         }

         /**

          * For some reason, can't find this utility method in the java framework.

          * 

          * @param sDateTime

          *            an xsd:dateTime string

          * @return an equivalent java.util.Date

          * @throws ParseException

          */

         public static Date parseXsdDateTime(String sDateTime) throws ParseException {

                 final DateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");

                 int iDotPosition = NORMAL_IDOT_POSITION;

                 if (sDateTime.charAt(0) == '-') {

                         iDotPosition = IDOT_POSITION_IFNEG;

                 }

                 Date result;

                 if (sDateTime.length() <= iDotPosition) {

                         return format.parse(sDateTime + "Z");

                 }

                 String millis = null;

                 char c = sDateTime.charAt(iDotPosition);

                 if (c == '.') {

                         // if datetime has milliseconds, separate them

                         int eoms = iDotPosition + 1;

                         while (Character.isDigit(sDateTime.charAt(eoms))) {

                                 eoms += 1;

                         }

                         millis = sDateTime.substring(iDotPosition, eoms);

                         sDateTime = sDateTime.substring(0, iDotPosition) + sDateTime.substring(eoms);

                         c = sDateTime.charAt(iDotPosition);

                 }

                 if (c == '+' || c == '-') {

                         format.setTimeZone(TimeZone.getTimeZone("GMT" + sDateTime.substring(iDotPosition)));

                         sDateTime = sDateTime.substring(0, iDotPosition) + "Z";

                 } else if (c != 'Z') {

                         throw new ParseException("Illegal timezone specification.", iDotPosition);

                 }

                 result = format.parse(sDateTime);

                 if (millis != null) {

                         result.setTime(result.getTime() + Math.round(Float.parseFloat(millis) * ONE_SEC_IN_MILLISECS));

                 }

                 result = offsetDateFromGMT(result);

                 return result;

         }

         /**

          * This method converts from GMT to local timezone

          * 

          * @param date

          *                 date in GMT timezone

          * @return the date in local timezone

          */

         public static Date offsetDateFromGMT(final Date date) {

                 // Create a calendar - it will default to the current OS timezone.

                 final GregorianCalendar gc = new GregorianCalendar();

                 // Calculate the total offset from GMT

                 final int totalOffset = gc.get(Calendar.ZONE_OFFSET) + gc.get(Calendar.DST_OFFSET);

                 // Calculate the time in GMT

                 final long localTime = date.getTime() + totalOffset;

                 // Create a date using the calculated GMT time

                 final Date localDate = new Date(localTime);

                 return localDate;

         }

         /**

          * This method writes a DOM document to a file

          * 

          * @param doc

          *            DOM document.

          * @param filename

          *            the target file.

          */

         public static void writeXmlFile(final Document doc, final String filename) {

                 try {

                         // Prepare the DOM document for writing

                         final Source source = new DOMSource(doc);

                         // Prepare the output file

                         final File file = new File(filename);

                         final Result result = new StreamResult(file);

                         // Write the DOM document to the file

                         final Transformer xformer = TransformerFactory.newInstance().newTransformer();

                         xformer.setOutputProperty(OutputKeys.INDENT, "yes");

                         xformer.transform(source, result);

                 } catch (final TransformerConfigurationException e) {

                         SvnConfigurationOptions.getTaskLogger().error(e.toString());

                 } catch (final TransformerException e) {

                         SvnConfigurationOptions.getTaskLogger().error(e.toString());

                 }

         }

 }