/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   *  Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   *  Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *
 *   *  Neither the name of the University of Southampton nor the names of its
 *      contributors may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.video;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.openimaj.image.Image;

/**
 * A video backed by a image files on disk. Each image file is a single frame.
 * 
 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 * @author David Dupplaw (dpd@ecs.soton.ac.uk)
 * 
 * @param <T>
 *            the image type of the frames
 */
public abstract class FileBackedVideo<T extends Image<?, T>> extends Video<T> {
        private List<File> files;
        private T heldCurrentFrame;
        private int heldCurrentFrameIndex = -1;
        private boolean loop;
        private double fps = 30;

        /**
         * Construct the video from the provided files. Assumes a frame rate of 30
         * FPS
         * 
         * @param files
         *            the image files
         */
        public FileBackedVideo(List<File> files) {
                this.files = files;
                this.fps = 30;
                this.loop = false;
        }

        /**
         * Construct the video from the provided files.
         * 
         * @param files
         *            the image files
         * @param fps
         *            the frame rate
         */
        public FileBackedVideo(List<File> files, double fps) {
                this.files = files;
                this.fps = fps;
                this.loop = false;
        }

        /**
         * Construct videos from numbered files using the given format string and
         * indices. The format string should contain a single %d substitution.
         * 
         * @param filenameFormat
         *            format string
         * @param start
         *            starting index (inclusive)
         * @param stop
         *            stop index (exclusive)
         */
        public FileBackedVideo(String filenameFormat, int start, int stop) {
                this(getFilesList(filenameFormat, start, stop));
        }

        @Override
        public synchronized T getNextFrame() {
                final T frame = getCurrentFrame();
                incrementFrame();
                return frame;
        }

        private void incrementFrame() {
                if (this.currentFrame + 1 < this.files.size() || loop) {
                        this.currentFrame++;
                }
        }

        @Override
        public boolean hasNextFrame() {
                return loop || this.getCurrentFrameIndex() + 1 < this.files.size();
        }

        @Override
        public T getCurrentFrame() {
                try {
                        if (this.currentFrame != heldCurrentFrameIndex) {
                                this.heldCurrentFrame = loadImage(files.get(currentFrame % this.files.size()));
                                this.heldCurrentFrameIndex = currentFrame;
                        }
                } catch (final IOException e) {
                        this.heldCurrentFrameIndex = currentFrame;
                        this.heldCurrentFrame = null;
                }
                return this.heldCurrentFrame;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.video.Video#getWidth()
         */
        @Override
        public int getWidth()
        {
                return getCurrentFrame().getWidth();
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.video.Video#getHeight()
         */
        @Override
        public int getHeight()
        {
                return getCurrentFrame().getHeight();
        }

        protected abstract T loadImage(File f) throws IOException;

        @Override
        public long countFrames() {
                return this.files.size();
        }

        @Override
        public void reset()
        {
                this.currentFrame = 0;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.video.Video#getTimeStamp()
         */
        @Override
        public long getTimeStamp()
        {
                return (long) (getCurrentFrameIndex() / this.fps) * 1000;
        }

        /**
         * {@inheritDoc}
         * 
         * @see org.openimaj.video.Video#getFPS()
         */
        @Override
        public double getFPS()
        {
                return fps;
        }

        /**
         * Get a list of numbered files using the given format string and indices.
         * The format string should contain a single %d substitution.
         * 
         * @param filenameFormat
         *            format string
         * @param start
         *            starting index (inclusive)
         * @param stop
         *            stop index (exclusive)
         * 
         * @return list of files
         */
        public static List<File> getFilesList(String filenameFormat, int start, int stop) {
                final List<File> files = new ArrayList<File>();

                for (int i = start; i < stop; i++) {
                        files.add(new File(String.format(filenameFormat, i)));
                }

                return files;
        }
}