/*

 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.management.remote;

import java.io.IOException;

import java.io.InvalidObjectException;

import java.io.ObjectInputStream;

import java.io.Serializable;

/**

 * <p>Result of a query for buffered notifications.  Notifications in

 * a notification buffer have positive, monotonically increasing

 * sequence numbers.  The result of a notification query contains the

 * following elements:</p>

 *

 * <ul>

 *

 * <li>The sequence number of the earliest notification still in

 * the buffer.

 *

 * <li>The sequence number of the next notification available for

 * querying.  This will be the starting sequence number for the next

 * notification query.

 *

 * <li>An array of (Notification,listenerID) pairs corresponding to

 * the returned notifications and the listeners they correspond to.

 *

 * </ul>

 *

 * <p>It is possible for the <code>nextSequenceNumber</code> to be less

 * than the <code>earliestSequenceNumber</code>.  This signifies that

 * notifications between the two might have been lost.</p>

 *

 * @since 1.5

 */

public class NotificationResult implements Serializable {

    private static final long serialVersionUID = 1191800228721395279L;

    /**

     * <p>Constructs a notification query result.</p>

     *

     * @param earliestSequenceNumber the sequence number of the

     * earliest notification still in the buffer.

     * @param nextSequenceNumber the sequence number of the next

     * notification available for querying.

     * @param targetedNotifications the notifications resulting from

     * the query, and the listeners they correspond to.  This array

     * can be empty.

     *

     * @exception IllegalArgumentException if

     * <code>targetedNotifications</code> is null or if

     * <code>earliestSequenceNumber</code> or

     * <code>nextSequenceNumber</code> is negative.

     */

    public NotificationResult(long earliestSequenceNumber,

                              long nextSequenceNumber,

                              TargetedNotification[] targetedNotifications) {

        validate(targetedNotifications, earliestSequenceNumber, nextSequenceNumber);

        this.earliestSequenceNumber = earliestSequenceNumber;

        this.nextSequenceNumber = nextSequenceNumber;

        this.targetedNotifications = (targetedNotifications.length == 0 ? targetedNotifications : targetedNotifications.clone());

    }

    /**

     * Returns the sequence number of the earliest notification still

     * in the buffer.

     *

     * @return the sequence number of the earliest notification still

     * in the buffer.

     */

    public long getEarliestSequenceNumber() {

        return earliestSequenceNumber;

    }

    /**

     * Returns the sequence number of the next notification available

     * for querying.

     *

     * @return the sequence number of the next notification available

     * for querying.

     */

    public long getNextSequenceNumber() {

        return nextSequenceNumber;

    }

    /**

     * Returns the notifications resulting from the query, and the

     * listeners they correspond to.

     *

     * @return the notifications resulting from the query, and the

     * listeners they correspond to.  This array can be empty.

     */

    public TargetedNotification[] getTargetedNotifications() {

        return targetedNotifications.length == 0 ? targetedNotifications : targetedNotifications.clone();

    }

    /**

     * Returns a string representation of the object.  The result

     * should be a concise but informative representation that is easy

     * for a person to read.

     *

     * @return a string representation of the object.

     */

    public String toString() {

        return "NotificationResult: earliest=" + getEarliestSequenceNumber() +

            "; next=" + getNextSequenceNumber() + "; nnotifs=" +

            getTargetedNotifications().length;

    }

    private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {

        ois.defaultReadObject();

        try {

            validate(

                this.targetedNotifications,

                this.earliestSequenceNumber,

                this.nextSequenceNumber

            );

            this.targetedNotifications = this.targetedNotifications.length == 0 ?

                                            this.targetedNotifications :

                                            this.targetedNotifications.clone();

        } catch (IllegalArgumentException e) {

            throw new InvalidObjectException(e.getMessage());

        }

    }

    private long earliestSequenceNumber;

    private long nextSequenceNumber;

    private TargetedNotification[] targetedNotifications;

    private static void validate(TargetedNotification[] targetedNotifications,

                                 long earliestSequenceNumber,

                                 long nextSequenceNumber)

        throws IllegalArgumentException {

        if (targetedNotifications == null) {

            final String msg = "Notifications null";

            throw new IllegalArgumentException(msg);

        }

        if (earliestSequenceNumber < 0 || nextSequenceNumber < 0)

            throw new IllegalArgumentException("Bad sequence numbers");

        /* We used to check nextSequenceNumber >= earliestSequenceNumber

           here.  But in fact the opposite can legitimately be true if

           notifications have been lost.  */

    }

}