/*******************************************************************************
 * Copyright (c) 2004, 2013 Tasktop Technologies and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Tasktop Technologies - initial API and implementation
 *     Wind River Systems - Extracted from o.e.mylyn.commons and adapted for Target Explorer
 *******************************************************************************/

package org.eclipse.tcf.te.runtime.notifications;

import java.util.Date;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.IAdaptable;

/**
 * A notification. Each notification has an associated <code>eventId</code> that identifies the type of the
 * notification.
 *
 * @author Rob Elves
 * @author Mik Kersten
 * @author Steffen Pingel
 */
public abstract class AbstractNotification implements Comparable<AbstractNotification>, IAdaptable {

	private final String eventId;

	/**
	 * Constructor
	 *
	 * @param eventId The event id. Must not be <code>null</code>.
	 */
	public AbstractNotification(String eventId) {
		Assert.isNotNull(eventId);
		this.eventId = eventId;
	}

	/* (non-Javadoc)
	 * @see java.lang.Comparable#compareTo(java.lang.Object)
	 */
	@Override
    public int compareTo(AbstractNotification o) {
		if (o == null) {
			return 1;
		}
		return compare(getDate(), o.getDate());
	}

	/**
	 * Compares <code>o1</code> and <code>o2</code>.
	 *
	 * @return a negative integer, 0, or a positive, if o1 is less than o2, o1 equals o2 or o1 is more than o2; null is
	 *         considered less than any value
	 */
	private static <T> int compare(Comparable<T> o1, T o2) {
		if (o1 == null) {
			return (o2 != null) ? 1 : 0;
		} else if (o2 == null) {
			return -1;
		}
		return o1.compareTo(o2);
	}

	/**
	 * Returns the event id.
	 *
	 * @return The event id.
	 */
	public final String getEventId() {
		return eventId;
	}

	public abstract Date getDate();

	public abstract String getDescription();

	public abstract String getLabel();

	/**
	 * Returns a token that identifies correlated notifications, e.g. all notifications resulting from a refresh
	 * operation. Returns <code>null</code> by default.
	 *
	 * @return any object; null, if no token is specified
	 */
	public Object getToken() {
		return null;
	}

}