D-Net

package eu.dnetlib.utils;

import java.math.RoundingMode;

import java.text.DateFormat;

import java.text.FieldPosition;

import java.text.NumberFormat;

import java.text.ParseException;

import java.text.ParsePosition;

import java.util.Calendar;

import java.util.Date;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**

 * This class implements a date format conforming to RFC-3339.

 * @author thanos@di.uoa.gr

 *

 */

public class RFC3339DateFormat extends DateFormat {

	private static final long serialVersionUID = 1L;

	private final NumberFormat twoDigits;

	private final NumberFormat threeDigits;

	private final NumberFormat fourDigits;

	private final Pattern pattern;

	/**

	 * Construct a new RFC-3339 date format.

	 */

	public RFC3339DateFormat() {

		calendar = Calendar.getInstance();

		twoDigits = NumberFormat.getIntegerInstance();

		twoDigits.setGroupingUsed(false);

		twoDigits.setRoundingMode(RoundingMode.UNNECESSARY);

		twoDigits.setMaximumIntegerDigits(2);

		twoDigits.setMinimumIntegerDigits(2);

		threeDigits = NumberFormat.getIntegerInstance();

		threeDigits.setGroupingUsed(false);

		threeDigits.setRoundingMode(RoundingMode.UNNECESSARY);

		threeDigits.setMaximumIntegerDigits(3);

		threeDigits.setMinimumIntegerDigits(3);

		fourDigits = NumberFormat.getIntegerInstance();

		fourDigits.setGroupingUsed(false);

		fourDigits.setRoundingMode(RoundingMode.UNNECESSARY);

		fourDigits.setMaximumIntegerDigits(4);

		fourDigits.setMinimumIntegerDigits(4);

		pattern = Pattern.compile("^(\\d{4})\\-(\\d{2})\\-(\\d{2})T(\\d{2}):(\\d{2}):(\\d{2})\\.(\\d{3})(Z|\\+(\\d{2}):(\\d{2})|\\-(\\d{2}):(\\d{2}))$");

	}

	@Override

	public StringBuffer format(final Date date, final StringBuffer toAppendTo, final FieldPosition fieldPosition) {

		calendar.setTime(date);

		final int beginIndex = toAppendTo.length();

		toAppendTo.append(fourDigits.format(calendar.get(Calendar.YEAR)));

		toAppendTo.append("-");

		toAppendTo.append(twoDigits.format(calendar.get(Calendar.MONTH) + 1));

		toAppendTo.append("-");

		toAppendTo.append(twoDigits.format(calendar.get(Calendar.DAY_OF_MONTH)));

		toAppendTo.append("T");

		toAppendTo.append(twoDigits.format(calendar.get(Calendar.HOUR_OF_DAY)));

		toAppendTo.append(":");

		toAppendTo.append(twoDigits.format(calendar.get(Calendar.MINUTE)));

		toAppendTo.append(":");

		toAppendTo.append(twoDigits.format(calendar.get(Calendar.SECOND)));

		toAppendTo.append(".");

		toAppendTo.append(threeDigits.format(calendar.get(Calendar.MILLISECOND)));

		final int offset = calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET);

		if (offset == 0)

			toAppendTo.append("Z");

		else {

			toAppendTo.append((offset > 0) ? "+" : "-");

			toAppendTo.append(twoDigits.format(offset / 3600000)); // convert milliseconds to hours

			toAppendTo.append(":");

			toAppendTo.append(twoDigits.format((offset % 3600000) / 60000)); // convert remaining milliseconds to minutes

		}

		switch (fieldPosition.getField()) {

		case DateFormat.YEAR_FIELD:

			fieldPosition.setBeginIndex(beginIndex);

			fieldPosition.setEndIndex(beginIndex + 4);

			break;

		case DateFormat.MONTH_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 5);

			fieldPosition.setEndIndex(beginIndex + 7);

			break;

		case DateFormat.DATE_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 8);

			fieldPosition.setEndIndex(beginIndex + 10);

			break;

		case DateFormat.HOUR_OF_DAY0_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 11);

			fieldPosition.setEndIndex(beginIndex + 13);

			break;

		case DateFormat.MINUTE_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 14);

			fieldPosition.setEndIndex(beginIndex + 16);

			break;

		case DateFormat.SECOND_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 17);

			fieldPosition.setEndIndex(beginIndex + 19);

			break;

		case DateFormat.MILLISECOND_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 20);

			fieldPosition.setEndIndex(beginIndex + 23);

		case DateFormat.TIMEZONE_FIELD:

			fieldPosition.setBeginIndex(beginIndex + 23);

			fieldPosition.setEndIndex(toAppendTo.length());

		}

		return toAppendTo;

	}

	@Override

	public Date parse(final String source, final ParsePosition parsePosition) {

		Matcher matcher = pattern.matcher(source.substring(parsePosition.getIndex()));

		if (!matcher.matches()) {

			parsePosition.setErrorIndex(parsePosition.getIndex());

			return null;

		}

		try {

			calendar.set(Calendar.YEAR, fourDigits.parse(matcher.group(1)).intValue());

			calendar.set(Calendar.MONTH, twoDigits.parse(matcher.group(2)).intValue() - 1);

			calendar.set(Calendar.DAY_OF_MONTH, twoDigits.parse(matcher.group(3)).intValue());

			calendar.set(Calendar.HOUR_OF_DAY, twoDigits.parse(matcher.group(4)).intValue());

			calendar.set(Calendar.MINUTE, twoDigits.parse(matcher.group(5)).intValue());

			calendar.set(Calendar.SECOND, twoDigits.parse(matcher.group(6)).intValue());

			calendar.set(Calendar.MILLISECOND, threeDigits.parse(matcher.group(7)).intValue());

			if (matcher.group(8).equals("Z"))

				calendar.set(Calendar.ZONE_OFFSET, 0);

			else if (matcher.group(8).startsWith("+"))

				calendar.set(Calendar.ZONE_OFFSET, (twoDigits.parse(matcher.group(9)).intValue() * 60 + twoDigits.parse(matcher.group(10)).intValue()) * 60000);

			else if (matcher.group(8).startsWith("-"))

				calendar.set(Calendar.ZONE_OFFSET, -((twoDigits.parse(matcher.group(11)).intValue() * 60 + twoDigits.parse(matcher.group(12)).intValue()) * 60000));

			calendar.set(Calendar.DST_OFFSET, 0);

			parsePosition.setIndex(parsePosition.getIndex() + matcher.group(0).length());

			return new Date(calendar.getTimeInMillis());

		} catch (ParseException e) {

			parsePosition.setErrorIndex(parsePosition.getIndex() + e.getErrorOffset());

			return null;

		}

	}

}