RFC3339Date.java

/*
 * Copyright (c) 2015 Jonas Kalderstam.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.nononsenseapps.notepad.util;

// package org.doubango.imsdroid.utils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class RFC3339Date {
	public static java.util.Date parseRFC3339Date(String datestring) {
		if (datestring == null || datestring.isEmpty()) {
			return null;
		}
		
		Date d = new Date();

		// if there is no time zone, we don't need to do any special parsing.
		if (datestring.endsWith("Z")) {
			try {
				SimpleDateFormat s = new SimpleDateFormat(
						"yyyy-MM-dd'T'HH:mm:ss'Z'"); // spec for RFC3339
				s.setCalendar(Calendar.getInstance(TimeZone.getTimeZone("UTC")));
				d = s.parse(datestring);
			}
			catch (ParseException pe) {// try again with optional
													// decimals
				SimpleDateFormat s = new SimpleDateFormat(
						"yyyy-MM-dd'T'HH:mm:ss.SSSSSS'Z'");// spec for RFC3339
															// (with fractional
															// seconds)
				s.setCalendar(Calendar.getInstance(TimeZone.getTimeZone("UTC")));
				s.setLenient(true);
				try {
					d = s.parse(datestring);
				}
				catch (ParseException e) {
					return null;
				}
			}
			return d;
		}

		// step one, split off the timezone.
//		String firstpart = datestring.substring(0, datestring.lastIndexOf('-'));
//		String secondpart = datestring.substring(datestring.lastIndexOf('-'));
//
//		// step two, remove the colon from the timezone offset
//		secondpart = secondpart.substring(0, secondpart.indexOf(':'))
//				+ secondpart.substring(secondpart.indexOf(':') + 1);
//		datestring = firstpart + secondpart;
		SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
		// spec for RFC3339
		s.setCalendar(Calendar.getInstance(TimeZone.getTimeZone("UTC")));

		try {
			d = s.parse(datestring);
		}
		catch (java.text.ParseException pe) {// try again with optional decimals
			s = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSSSSZ");
			s.setCalendar(Calendar.getInstance(TimeZone.getTimeZone("UTC")));
			// spec for RFC3339(with fractional seconds)
			s.setLenient(true);
			try {
				d = s.parse(datestring);
			}
			catch (ParseException e) {
				return null;
			}
		}

		return d;
	}
	
	/**
	 * Given a UTC date (2013-02-21), and a local time(13:23), will combine them
	 * into 2013-02-21T13:23 local time.
	 * 
	 * DateString should be in RFC3339.
	 * If time is null, defaults to 23:59
	 */
	public static Long combineDateAndTime(final String datestring, final Long time) {
		final java.util.Date d = parseRFC3339Date(datestring);
		if (d == null) {
			return null;
		}
		// UTC
		final Calendar utc = GregorianCalendar.getInstance(TimeZone.getTimeZone("UTC"));
		utc.setTime(d);
		utc.set(Calendar.HOUR_OF_DAY, 0);
		utc.set(Calendar.MINUTE, 0);
		
		// Local date
		final Calendar local = GregorianCalendar.getInstance();
		local.set(Calendar.YEAR, utc.get(Calendar.YEAR));
		local.set(Calendar.MONTH, utc.get(Calendar.MONTH));
		local.set(Calendar.DAY_OF_MONTH, utc.get(Calendar.DAY_OF_MONTH));
		// Default to 23:59
		local.set(Calendar.MINUTE, 59);
		local.set(Calendar.HOUR_OF_DAY, 23);
		
		// Time
		if (time == null) {
			return local.getTimeInMillis();
		}
		
		final Calendar localTime = GregorianCalendar.getInstance();
		localTime.setTimeInMillis(time);

		local.set(Calendar.MINUTE, localTime.get(Calendar.MINUTE));
		local.set(Calendar.HOUR_OF_DAY, localTime.get(Calendar.HOUR_OF_DAY));
	
		return local.getTimeInMillis();
	}
	
	public static String asRFC3339(final Long time) {
		if (time == null)
			return null;
		return asRFC3339(new Date(time));
	}
	
	/**
	 * For GTasks syncing. Given a date and time, say 2013-02-21T13:34.
	 * Will return 2013-02-21T00:00Z.
	 */
	public static String asRFC3339ZuluDate(final Long time) {
		if (time == null)
			return null;
		
		// Local time calendar
		Calendar cal = GregorianCalendar.getInstance();
		cal.setTimeInMillis(time);
		
		// Extract the date
		return new StringBuilder(String.format("%d", cal.get(Calendar.YEAR)))
		.append("-").append(String.format("%02d", (1 + cal.get(Calendar.MONTH))))
		.append("-").append(String.format("%02d", cal.get(Calendar.DAY_OF_MONTH)))
		.append("T00:00:00Z")
		
		.toString();
	}

	private static String asRFC3339(final java.util.Date date) {
		if (date == null)
			return null;
		final SimpleDateFormat s = new SimpleDateFormat(
				"yyyy-MM-dd'T'HH:mm:ssZ");// spec for RFC3339
		return s.format(date);
	}
}