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//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later
// version.
//
// This library 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 Lesser General Public License for more
// details.
//
// You should have received a copy of the GNU Lesser General
// Public License along with this library; if not, write to the
//
// Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330,
// Boston, MA
// 02111-1307 USA
//
// The Initial Developer of the Original Code is Charles W. Rapp.
// Portions created by Charles W. Rapp are
// Copyright 2013, 2016. Charles W. Rapp
// All Rights Reserved.
//

package net.sf.eBusx.io;

import java.io.File;
import java.io.Serializable;
import net.sf.eBus.messages.EFieldInfo;
import net.sf.eBus.messages.ENotificationMessage;

/**
 * Used to transmit a Java {@link java.nio.file.WatchEvent}
 * asynchronously to all interested listeners. The message
 * subject is the file or directory path. The message contains
 * the how the file changed (created, modified, or deleted), the
 * file modification timestamp (in Java millisecond epoch time),
 * and the file length in byte.
 *
 * @author Charles Rapp
 */

@EFieldInfo(fields={"file",
                    "eventType",
                    "lastModified",
                    "length"})
public final class EFileNotification
    extends ENotificationMessage
    implements Serializable
{
//---------------------------------------------------------------
// Member methods.
//

    //-----------------------------------------------------------
    // Constructors.
    //

    /**
     * Creates a new file notification instance for the given
     * parameters.
     * @param subject the notification subject.
     * @param file the event applies to this file.
     * @param eventType {@code file} was either created,
     * modified, or deleted.
     * @param modifyTime the file modify time. Will be
     * {@code null} when {@code eventType} is
     * {@link EventType#DELETE}.
     * @param length the file length. Will be zero for a delete
     * event type.
     */
    /* package */ EFileNotification(final String subject,
                                    final File file,
                                    final EventType eventType,
                                    final long modifyTime,
                                    final long length)
    {
        this (subject,
              System.currentTimeMillis(),
              file,
              eventType,
              modifyTime,
              length);
    } // end of EFileNotification(...)

    /**
     * Creates a new file notification instance from the
     * de-serialized parameters.
     * @param subject the notification subject.
     * @param timestamp the message timestamp.
     * @param file the event applies to this file.
     * @param eventType {@code file} was either created,
     * modified, or deleted.
     * @param modifyTime the file modify time. Will be
     * {@code null} when {@code eventType} is
     * {@link EventType#DELETE}.
     * @param length the file length. Will be zero for a delete
     * event type.
     */
    public  EFileNotification(final String subject,
                              final long timestamp,
                              final File file,
                              final EventType eventType,
                              final long modifyTime,
                              final long length)
    {
        super (subject, timestamp);

        this.file = file;
        this.eventType = eventType;
        this.lastModified = modifyTime;
        this.length = length;
    } // end of EFileNotification(...)

    //
    // end of Constructors.
    //-----------------------------------------------------------

//---------------------------------------------------------------
// Enums.
//

    /**
     * The watched file was either created, modified, or deleted.
     */
    public enum EventType
    {
    //-----------------------------------------------------------
    // Member methods.
    //

        /**
         * The file was newly created.
         */
        CREATE,

        /**
         * The file was modified.
         */
        MODIFY,

        /**
         * The file event was deleted. The file
         * {@link #lastModified last modify timestamp} and
         * {@link #length} will be zero.
         */
        DELETE
    } // end of enum EventType

//---------------------------------------------------------------
// Member data.
//

    /**
     * The notification applies to this file instance.
     */
    public final File file;

    /**
     * This notification signifies that either the file or
     * directory was created, modified, or deleted.
     */
    public final EventType eventType;

    /**
     * The date and time when the {@link #file} was last
     * modified. Will be zero if {@link #eventType} is
     * {@link EventType#DELETE}.
     */
    public final long lastModified;

    /**
     * {@link #file} length in bytes. Will be zero if
     * {@link #eventType} is {@link EventType#DELETE}.
     */
    public final long length;

    //-----------------------------------------------------------
    // Constants.
    //

    /**
     * Serialization version identifier.
     */
    private static final long serialVersionUID = 0x060100L;
} // end of class EFileNotification