/*
        AUTOMATICALLY GENERATED BY jTemp FROM
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*/
/**
 * 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 package org.openimaj.knn.pq;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.openimaj.citation.annotation.Reference;
import org.openimaj.citation.annotation.ReferenceType;
import org.openimaj.knn.ShortNearestNeighbours;
import org.openimaj.util.pair.IntFloatPair;
import org.openimaj.util.queue.BoundedPriorityQueue;
/**
 * Nearest-neighbours using Asymmetric Distance Computation (ADC) on Product
 * Quantised vectors. In ADC, only the database points are quantised. The
 * queries themselves are not quantised. The overall distance is computed as the
 * summed distance of each subvector of the query to each corresponding
 * centroids of each database vector.
 * <p>
 * For efficiency, the distance of each sub-vector of a query is computed to
 * every centroid (for the sub-vector under consideration) only once, and is
 * then cached for the lookup during the computation of the distance to each
 * database vector.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
@Reference(
                type = ReferenceType.Article,
                author = { "Jegou, Herve", "Douze, Matthijs", "Schmid, Cordelia" },
                title = "Product Quantization for Nearest Neighbor Search",
                year = "2011",
                journal = "IEEE Trans. Pattern Anal. Mach. Intell.",
                pages = { "117", "", "128" },
                url = "http://dx.doi.org/10.1109/TPAMI.2010.57",
                month = "January",
                number = "1",
                publisher = "IEEE Computer Society",
                volume = "33",
                customData = {
                                "issn", "0162-8828",
                                "numpages", "12",
                                "doi", "10.1109/TPAMI.2010.57",
                                "acmid", "1916695",
                                "address", "Washington, DC, USA",
                                "keywords", "High-dimensional indexing, High-dimensional indexing, image indexing, very large databases, approximate search., approximate search., image indexing, very large databases"
                })
public class ShortADCNearestNeighbours extends ShortNearestNeighbours {
        protected final ShortProductQuantiser pq;
        protected final int ndims;
        protected final byte[][] data;

        /**
         * Construct the ADC with the given quantiser and data points.
         * 
         * @param pq
         *            the Product Quantiser
         * @param dataPoints
         *            the data points to index
         */
        public ShortADCNearestNeighbours(ShortProductQuantiser pq, short[][] dataPoints) {
                this.pq = pq;
                this.ndims = dataPoints[0].length;

                this.data = new byte[dataPoints.length][];
                for (int i = 0; i < dataPoints.length; i++) {
                        data[i] = pq.quantise(dataPoints[i]);
                }
        }

    /**
         * Construct the ADC with the given quantiser and pre-quantised data .
         * 
         * @param pq
         *            the Product Quantiser
         * @param pqData
         *            the pre-quantised data (i.e. vectors already quantised with
         *            the given pq)
         * @param ndims
         *            the dimensionality of the indexed data
         */
        public ShortADCNearestNeighbours(ShortProductQuantiser pq, byte[][] pqData, int ndims) {
                this.ndims = ndims;
                this.pq = pq;
                this.data = pqData;
        }

        @Override
        public void searchNN(final short [][] qus, int [] indices, float [] distances) {
                final int N = qus.length;
                
                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(1, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(2);
                list.add(new IntFloatPair());
                list.add(new IntFloatPair());
                
                for (int n=0; n < N; ++n) {
                        List<IntFloatPair> result = search(qus[n], queue, list);
                        
                        final IntFloatPair p = result.get(0);
                        indices[n] = p.first;
                        distances[n] = p.second;
                }
        }

        @Override
        public void searchKNN(final short [][] qus, int K, int [][] indices, float [][] distances) {
                // Fix for when the user asks for too many points.
                K = Math.min(K, data.length);

                final int N = qus.length;

                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(K, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(K + 1);
                for (int i = 0; i < K + 1; i++) {
                        list.add(new IntFloatPair());
                }

        // search on each query
                for (int n = 0; n < N; ++n) {
                        List<IntFloatPair> result = search(qus[n], queue, list);
                        
                        for (int k = 0; k < K; ++k) {
                                final IntFloatPair p = result.get(k);
                                indices[n][k] = p.first;
                                distances[n][k] = p.second;
                        }
                }
        }
        
        @Override
        public void searchNN(final List<short[]> qus, int [] indices, float [] distances) {
                final int N = qus.size();
                
                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(1, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(2);
                list.add(new IntFloatPair());
                list.add(new IntFloatPair());
                
                for (int n=0; n < N; ++n) {
                        List<IntFloatPair> result = search(qus.get(n), queue, list);
                        
                        final IntFloatPair p = result.get(0);
                        indices[n] = p.first;
                        distances[n] = p.second;
                }
        }

        @Override
        public void searchKNN(final List<short[]> qus, int K, int [][] indices, float [][] distances) {
                // Fix for when the user asks for too many points.
                K = Math.min(K, data.length);

                final int N = qus.size();

                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(K, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(K + 1);
                for (int i = 0; i < K + 1; i++) {
                        list.add(new IntFloatPair());
                }

        // search on each query
                for (int n = 0; n < N; ++n) {
                        List<IntFloatPair> result = search(qus.get(n), queue, list);
                        
                        for (int k = 0; k < K; ++k) {
                                final IntFloatPair p = result.get(k);
                                indices[n][k] = p.first;
                                distances[n][k] = p.second;
                        }
                }
        }

    @Override
        public List<IntFloatPair> searchKNN(short[] query, int K) {
                // Fix for when the user asks for too many points.
                K = Math.min(K, data.length);

                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(K, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(K + 1);
                for (int i = 0; i < K + 1; i++) {
                        list.add(new IntFloatPair());
                }

        // search
        return search(query, queue, list);
        }

        @Override
        public IntFloatPair searchNN(final short[] query) {
                final BoundedPriorityQueue<IntFloatPair> queue =
                                new BoundedPriorityQueue<IntFloatPair>(1, IntFloatPair.SECOND_ITEM_ASCENDING_COMPARATOR);

        //prepare working data
                List<IntFloatPair> list = new ArrayList<IntFloatPair>(2);
                list.add(new IntFloatPair());
                list.add(new IntFloatPair());
                
                return search(query, queue, list).get(0);
        }

    private List<IntFloatPair> search(short[] query, BoundedPriorityQueue<IntFloatPair> queue, List<IntFloatPair> results) {
        IntFloatPair wp = null;
        
        // reset all values in the queue to MAX, -1
                for (final IntFloatPair p : results) {
                        p.second = Float.MAX_VALUE;
                        p.first = -1;
                        wp = queue.offerItem(p);
                }

        // perform the search
                computeDistances(query, queue, wp);
                
        return queue.toOrderedListDestructive();
    }
    
    protected void computeDistances(short[] fullQuery, BoundedPriorityQueue<IntFloatPair> queue, IntFloatPair wp) {
                final float[][] distances = new float[pq.assigners.length][];

                for (int j = 0, from = 0; j < this.pq.assigners.length; j++) {
                        final ShortNearestNeighbours nn = this.pq.assigners[j];
                        final int to = nn.numDimensions();
                        final int K = nn.size();

                        final short[][] qus = { Arrays.copyOfRange(fullQuery, from, from + to) };
                        final int[][] idx = new int[1][K];
                        final float[][] dst = new float[1][K];
                        nn.searchKNN(qus, K, idx, dst);

                        distances[j] = new float[K];
                        for (int k = 0; k < K; k++) {
                                distances[j][idx[0][k]] = dst[0][k];
                        }

                        from += to;
                }

                for (int i = 0; i < data.length; i++) {
                        wp.first = i;
                        wp.second = 0;

                        for (int j = 0; j < this.pq.assigners.length; j++) {
                                final int centroid = this.data[i][j] + 128;
                                wp.second += distances[j][centroid];
                        }

                        wp = queue.offerItem(wp);
                }
        }

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

        @Override
        public int size() {
                return data.length;
        }
}