/*
 * RED5 Open Source Media Server - https://github.com/Red5/ Copyright 2006-2016 by respective authors (see below). All rights reserved. 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.red5.server.api.stream;

/**
 * A play list controller that controls the order of play items.
 *
 * @author The Red5 Project
 * @author Steven Gong (steven.gong@gmail.com)
 */
public interface IPlaylistController {
    /**
     * Get next item to play.
     *
     * @param playlist
     *            The related play list.
     * @param itemIndex
     *            The current item index. -1 indicates to retrieve the first item for play.
     * @return The next item index to play. -1 reaches the end.
     */
    int nextItem(IPlaylist playlist, int itemIndex);

    /**
     * Get previous item to play.
     *
     * @param playlist
     *            The related play list.
     * @param itemIndex
     *            The current item index. IPlaylist.itemSize indicated to retrieve the last item for play.
     * @return The previous item index to play. -1 reaches the beginning.
     */
    int previousItem(IPlaylist playlist, int itemIndex);
}
