/**
 * 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.workinprogress.featlearn;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Random;

import org.openimaj.data.dataset.Dataset;
import org.openimaj.image.FImage;
import org.openimaj.image.Image;
import org.openimaj.image.ImageUtilities;
import org.openimaj.image.MBFImage;
import org.openimaj.image.annotation.evaluation.datasets.Caltech101;

import com.google.common.collect.Lists;

public class RandomPatchSampler<IMAGE extends Image<?, IMAGE>> implements Iterable<IMAGE> {
        long seed = 0;
        int nsamples;
        int height;
        int width;
        Dataset<IMAGE> ds;

        public RandomPatchSampler(Dataset<IMAGE> data, int width, int height, int nsamples) {
                this.ds = data;
                this.width = width;
                this.height = height;
                this.nsamples = nsamples;
        }

        public List<IMAGE> getPatches() {
                return Lists.newArrayList(this);
        }

        @Override
        public Iterator<IMAGE> iterator() {
                return new Iterator<IMAGE>() {
                        Random rng = new Random(seed);
                        int i = 0;

                        @Override
                        public boolean hasNext() {
                                return i < nsamples;
                        }

                        @Override
                        public IMAGE next() {
                                i++;
                                return getRandomPatch(ds.getRandomInstance());
                        }

                        @Override
                        public void remove() {
                                throw new UnsupportedOperationException();
                        }

                        private IMAGE getRandomPatch(IMAGE instance) {
                                final int x = rng.nextInt(instance.getWidth() - width - 1);
                                final int y = rng.nextInt(instance.getHeight() - height - 1);

                                return instance.extractROI(x, y, width, height);
                        }
                };
        }

        public static List<FImage> loadPatches(File file) throws IOException {
                final List<FImage> list = new ArrayList<FImage>();

                DataInputStream dis = null;
                try {
                        dis = new DataInputStream(new BufferedInputStream(new
                                        FileInputStream(file)));
                        final int width = dis.readInt();
                        final int height = dis.readInt();
                        final int nsamples = dis.readInt();

                        for (int i = 0; i < nsamples; i++) {
                                final FImage image = new FImage(width, height);
                                for (int y = 0; y < height; y++) {
                                        for (int x = 0; x < width; x++) {
                                                image.pixels[y][x] = dis.readFloat();
                                        }
                                }
                                list.add(image);
                        }
                } finally {
                        if (dis != null) {
                                try {
                                        dis.close();
                                } catch (final IOException e1) {
                                }
                        }
                }

                return list;
        }

        // public void save(File file) throws IOException {
        // DataOutputStream dos = null;
        // try {
        // dos = new DataOutputStream(new FileOutputStream(file));
        // dos.writeInt(this.width);
        // dos.writeInt(this.height);
        // dos.writeInt(this.nsamples);
        //
        // for (final FImage image : this) {
        // for (int y = 0; y < height; y++) {
        // for (int x = 0; x < width; x++) {
        // dos.writeFloat(image.pixels[y][x]);
        // }
        // }
        // }
        // } finally {
        // if (dos != null) {
        // try {
        // dos.close();
        // } catch (final IOException e1) {
        // }
        // }
        // }
        // }

        public static void main(String[] args) throws IOException {
                final RandomPatchSampler<MBFImage> ps = new RandomPatchSampler<MBFImage>(
                                Caltech101.getImages(ImageUtilities.MBFIMAGE_READER), 28, 28, 70000);

                final File TRAINING = new File("/Users/jon/Data/caltech101-patches/training/");
                final File TESTING = new File("/Users/jon/Data/caltech101-patches/testing/");

                TRAINING.mkdirs();
                TESTING.mkdirs();

                int i = 0;
                for (final MBFImage patch : ps) {
                        System.out.println(i);
                        if (i < 60000) {
                                ImageUtilities.write(patch, new File(TRAINING, i + ".png"));
                        } else {
                                ImageUtilities.write(patch, new File(TESTING, (i - 60000) + ".png"));
                        }
                        i++;
                }
        }
}