/**
 * Copyright 2010 JBoss Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.eclipse.webdav.internal.kernel.utils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * A generic date and time object. It uses UTC as the timezone and US as the locale.
 */

public class DateTime {
	protected SimpleDateFormat dateFormat;
	protected long dateTime;

	protected static final String RFC_1123_PATTERN = "EEE, dd MMM yyyy HH:mm:ss 'GMT'"; //$NON-NLS-1$
	protected static final String RFC_850_PATTERN = "E, dd-MMM-yyyy HH:mm:ss 'GMT'"; //$NON-NLS-1$
	protected static final String ASCTIME_PATTERN = "EEE MMM dd HH:mm:ss yyyy"; //$NON-NLS-1$
	protected static final String ISO_8601_UTC_PATTERN = "yyyy-MM-dd'T'HH:mm:ss'Z'"; //$NON-NLS-1$
	protected static final String ISO_8601_PATTERN = "yyyy-MM-dd'T'HH:mm:ssz"; //$NON-NLS-1$
	protected static final String ISO_8601_UTC_MILLIS_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"; //$NON-NLS-1$
	protected static final String ISO_8601_MILLIS_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSSz"; //$NON-NLS-1$

	public DateTime() {
		this(0);
	}

	/**
	 * Starts this object from a java long format (milliseconds).
	 */
	public DateTime(long date) {
		setDateTime(date);
		dateFormat = new SimpleDateFormat();
		dateFormat.setCalendar(Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.US)); //$NON-NLS-1$
	}

	public boolean after(DateTime other) {
		return getDateTime() > other.getDateTime();
	}

	public boolean before(DateTime other) {
		return getDateTime() < other.getDateTime();
	}

	public boolean equals(DateTime other) {
		return getDateTime() == other.getDateTime();
	}

	/**
	 * Milliseconds since 1 January 1970 0:00 UTC.
	 */
	public long getDateTime() {
		return dateTime;
	}

	public int getMilliseconds() {
		return (int) (getDateTime() % 1000);
	}

	/**
	 * Sets the date and time from a java long format (milliseconds).
	 */
	public void setDateTime(long dateTime) {
		this.dateTime = dateTime;
	}

	/**
	 * Do nothing if date format is not supported
	 */
	public void setDateTime(String date) {
		String[] patterns = {RFC_1123_PATTERN, ISO_8601_UTC_PATTERN, ISO_8601_UTC_MILLIS_PATTERN, ISO_8601_PATTERN, ISO_8601_MILLIS_PATTERN, RFC_850_PATTERN, ASCTIME_PATTERN};
		for (int i = 0; i < patterns.length; i++) {
			if (setDateTime(date, patterns[i]))
				break;
		}
	}

	/**
	 * Do nothing if date format is not supported.
	 */
	protected boolean setDateTime(String date, String pattern) {
		boolean dateChanged = true;
		dateFormat.applyPattern(pattern);
		try {
			setDateTime(dateFormat.parse(date));
		} catch (ParseException e) {
			dateChanged = false;
		}
		return dateChanged;
	}

	public void setDateTime(Date date) {
		dateTime = date.getTime();
	}

	public Date toDate() {
		return new Date(dateTime);
	}

	public String toISO8601() {
		if (getMilliseconds() == 0)
			return toString(ISO_8601_UTC_PATTERN);
		return toString(ISO_8601_UTC_MILLIS_PATTERN);
	}

	public String toRFC1123() {
		return toString(RFC_1123_PATTERN);
	}

	/**
	 * Returns on a RFC 1123 format.
	 */
	public String toString() {
		return toRFC1123();
	}

	protected String toString(String pattern) {
		dateFormat.applyPattern(pattern);
		return dateFormat.format(toDate());
	}
}
