/**
 * 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.tools.clusterquantiser.samplebatch;

import gnu.trove.list.array.TIntArrayList;

import java.io.IOException;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Random;

import org.openimaj.data.DataSource;
import org.openimaj.data.RandomData;

/**
 * A batched datasource
 *
 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
 *
 */
public class SampleBatchByteDataSource implements DataSource<byte[]> {
        private int total;
        private List<SampleBatch> batches;
        private int dims;

        private Random seed;

        /**
         * Construct with batches
         *
         * @param batches
         * @throws IOException
         */
        public SampleBatchByteDataSource(List<SampleBatch> batches) throws IOException {
                this.batches = batches;
                this.total = batches.get(batches.size() - 1).getEndIndex();
                this.dims = this.batches.get(0).getStoredSamples(0, 1)[0].length;
                this.seed = new Random();
        }

        /**
         * Set the random seed
         *
         * @param seed
         */
        public void setSeed(long seed) {
                if (seed < 0)
                        this.seed = new Random();
                else
                        this.seed = new Random(seed);
        }

        @Override
        public void getData(int startRow, int stopRow, byte[][] output) {
                int added = 0;
                for (final SampleBatch sb : batches) {
                        try {
                                if (sb.getEndIndex() < startRow)
                                        continue; // Before this range
                                if (sb.getStartIndex() > stopRow)
                                        continue; // After this range
                                // So it must be within this range in some sense, find out where
                                final int startDelta = startRow - sb.getStartIndex();
                                final int stopDelta = stopRow - sb.getStartIndex();

                                final int interestedStart = startDelta < 0 ? 0 : startDelta;
                                final int interestedEnd = stopDelta + sb.getStartIndex() > sb.getEndIndex() ? sb.getEndIndex()
                                                - sb.getStartIndex() : stopDelta;
                                                if (interestedEnd - interestedStart == 0)
                                                        continue;
                                                // System.out.print("\rGetting " + interestedStart + "->" +
                                                // interestedEnd + " from" + sb.sampleSource.getName());
                                                final byte[][] subSamples = sb.getStoredSamples(interestedStart, interestedEnd);

                                                for (int i = 0; i < subSamples.length; i++) {
                                                        System.arraycopy(subSamples[i], 0, output[added + i], 0, subSamples[i].length);
                                                }

                                                added += subSamples.length;
                        } catch (final Exception e) {
                                e.printStackTrace();
                        }
                }
        }

        @Override
        public void getRandomRows(byte[][] output) {
                final int k = output.length;
                System.err.println("Requested random samples: " + k);
                final int[] indices = RandomData.getUniqueRandomInts(k, 0, this.total, seed);
                System.err.println("Array constructed");
                int l = 0;
                final TIntArrayList samplesToLoad = new TIntArrayList();

                final int[] original = indices.clone();
                Arrays.sort(indices);
                int indicesMarker = 0;
                for (int sbIndex = 0; sbIndex < this.batches.size(); sbIndex++) {
                        samplesToLoad.clear();

                        final SampleBatch sb = this.batches.get(sbIndex);
                        for (; indicesMarker < indices.length; indicesMarker++) {
                                final int index = indices[indicesMarker];
                                if (sb.getStartIndex() <= index && sb.getEndIndex() > index) {
                                        samplesToLoad.add(index - sb.getStartIndex());
                                }
                                if (sb.getEndIndex() <= index)
                                        break;
                        }

                        try {
                                if (samplesToLoad.size() == 0)
                                        continue;
                                final byte[][] features = sb.getStoredSamples(samplesToLoad.toArray());
                                for (int i = 0; i < samplesToLoad.size(); i++) {
                                        int j = 0;
                                        for (; j < original.length; j++)
                                                if (original[j] == samplesToLoad.get(i) + sb.getStartIndex())
                                                        break;
                                        System.arraycopy(features[i], 0, output[j], 0, features[i].length);
                                        System.err.printf("\rCreating sample index hashmap %8d/%8d", l++, k);
                                }
                        } catch (final IOException e) {
                                e.printStackTrace();
                        }
                }
                System.err.println();
        }

        @Override
        public int numDimensions() {
                return dims;
        }

        @Override
        public int size() {
                return total;
        }

        @Override
        public byte[] getData(int row) {
                final byte[] data = new byte[dims];

                getData(row, row + 1, new byte[][] { data });

                return data;
        }

        @Override
        public Iterator<byte[]> iterator() {
                throw new UnsupportedOperationException();
        }

        @Override
        public byte[][] createTemporaryArray(int size) {
                return new byte[size][dims];
        }
}