/**
 * 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.image.pixel.statistics;

import java.util.Arrays;

import org.apache.commons.math.DimensionMismatchException;
import org.apache.commons.math.stat.descriptive.MultivariateSummaryStatistics;
import org.openimaj.image.FImage;
import org.openimaj.image.pixel.sampling.FLineSampler;
import org.openimaj.math.geometry.line.Line2d;
import org.openimaj.math.geometry.point.Point2d;
import org.openimaj.math.geometry.point.Point2dImpl;
import org.openimaj.math.util.FloatArrayStatsUtils;
import org.openimaj.util.array.ArrayUtils;

import Jama.Matrix;

/**
 * An {@link FStatisticalPixelProfileModel} is a statistical model of pixels
 * from an {@link FImage} sampled along a line.
 * 
 * The model allows for various sampling strategies (see {@link FLineSampler})
 * and uses the mean and covariance as its internal state.
 * 
 * The model is updateable, but does not hold on to previously seen samples to
 * reduce memory usage.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
@SuppressWarnings("deprecation")
public class FStatisticalPixelProfileModel implements PixelProfileModel<FImage> {
        private MultivariateSummaryStatistics statistics;
        private int nsamples;
        private FLineSampler sampler;

        private double[] mean;
        private Matrix invCovar;

        /**
         * Construct a new {@link FStatisticalPixelProfileModel} with the given
         * number of samples per line, and the given sampling strategy.
         * 
         * @param nsamples
         *            number of samples
         * @param sampler
         *            line sampling strategy
         */
        public FStatisticalPixelProfileModel(int nsamples, FLineSampler sampler) {
                this.nsamples = nsamples;
                this.statistics = new MultivariateSummaryStatistics(nsamples, true);
                this.sampler = sampler;
        }

        private float[] normaliseSamples(float[] samples) {
                final float sum = FloatArrayStatsUtils.sum(samples);

                for (int i = 0; i < samples.length; i++) {
                        samples[i] /= sum;
                }

                return samples;
        }

        @Override
        public void updateModel(FImage image, Line2d line) {
                final float[] samples = normaliseSamples(sampler.extractSamples(line, image, nsamples));
                try {
                        statistics.addValue(ArrayUtils.convertToDouble(samples));
                } catch (final DimensionMismatchException e) {
                        throw new RuntimeException(e);
                }

                invCovar = null;
                mean = null;
        }

        /**
         * @return the mean of the model
         */
        public double[] getMean() {
                if (mean == null) {
                        mean = statistics.getMean();
                        invCovar = new Matrix(statistics.getCovariance().getData()).inverse();
                }

                return mean;
        }

        /**
         * @return the covariance of the model
         */
        public Matrix getCovariance() {
                if (mean == null) {
                        mean = statistics.getMean();
                        invCovar = new Matrix(statistics.getCovariance().getData()).inverse();
                }
                return new Matrix(statistics.getCovariance().getData());
        }

        /**
         * @return the inverse of the covariance matrix
         */
        public Matrix getInverseCovariance() {
                if (mean == null) {
                        mean = statistics.getMean();
                        invCovar = new Matrix(statistics.getCovariance().getData()).inverse();
                }
                return invCovar;
        }

        /**
         * Compute the Mahalanobis distance of the given vector to the internal
         * model. The vector must have the same size as the number of samples given
         * during construction.
         * 
         * @param vector
         *            the vector
         * @return the computed Mahalanobis distance
         */
        public float computeMahalanobis(float[] vector) {
                if (mean == null) {
                        mean = statistics.getMean();
                        try {
                                invCovar = new Matrix(statistics.getCovariance().getData()).inverse();
                        } catch (final RuntimeException e) {
                                invCovar = Matrix.identity(nsamples, nsamples);
                        }
                }

                final double[] meanCentered = new double[mean.length];
                for (int i = 0; i < mean.length; i++) {
                        meanCentered[i] = vector[i] - mean[i];
                }

                final Matrix mct = new Matrix(new double[][] { meanCentered });
                final Matrix mc = mct.transpose();

                final Matrix dist = mct.times(invCovar).times(mc);

                return (float) dist.get(0, 0);
        }

        /**
         * Compute the Mahalanobis distance of a vector of samples extracted along a
         * line in the given image to the internal model.
         * 
         * @param image
         *            the image to sample
         * @param line
         *            the line to sample along
         * @return the computed Mahalanobis distance
         */
        public float computeMahalanobis(FImage image, Line2d line) {
                final float[] samples = normaliseSamples(sampler.extractSamples(line, image, nsamples));
                return computeMahalanobis(samples);
        }

        /**
         * Extract numSamples samples from the line in the image and then compare
         * this model at each overlapping position starting from the first sample at
         * the beginning of the line.
         * 
         * numSamples must be bigger than the number of samples used to construct
         * the model. In addition, callers are responsible for ensuring the sampling
         * rate between the new samples and the model is equal.
         * 
         * @param image
         *            the image to sample
         * @param line
         *            the line to sample along
         * @param numSamples
         *            the number of samples to make
         * @return an array of the computed Mahalanobis distances at each offset
         */
        public float[] computeMahalanobisWindowed(FImage image, Line2d line, int numSamples) {
                final float[] samples = sampler.extractSamples(line, image, numSamples);
                return computeMahalanobisWindowed(samples);
        }

        @Override
        public Point2d computeNewBest(FImage image, Line2d line, int numSamples) {
                final float[] resp = computeMahalanobisWindowed(image, line, numSamples);

                final int minIdx = ArrayUtils.minIndex(resp);
                final int offset = (numSamples - nsamples) / 2;

                if (resp[offset] == resp[minIdx]) // prefer the centre over another
                                                                                        // value if same response
                        return line.calculateCentroid();

                // the sample line might be different, so we need to measure relative to
                // it...
                line = this.sampler.getSampleLine(line, image, numSamples);

                final float x = line.begin.getX();
                final float y = line.begin.getY();
                final float dxStep = (line.end.getX() - x) / (numSamples - 1);
                final float dyStep = (line.end.getY() - y) / (numSamples - 1);

                return new Point2dImpl(x + (minIdx + offset) * dxStep, y + (minIdx + offset) * dyStep);
        }

        @Override
        public float computeMovementDistance(FImage image, Line2d line, int numSamples, Point2d pt) {
                final Line2d sampleLine = sampler.getSampleLine(line, image, numSamples);

                return (float) (2 * Line2d.distance(sampleLine.calculateCentroid(), pt) / sampleLine.calculateLength());
        }

        /**
         * Compare this model at each overlapping position of the given vector
         * starting from the first sample and return the distance for each overlap.
         * 
         * The length of the vector must be bigger than the number of samples used
         * to construct the model. In addition, callers are responsible for ensuring
         * the sampling rate between the new samples and the model is equal.
         * 
         * @param vector
         *            array of samples
         * @return an array of the computed Mahalanobis distances at each offset
         */
        public float[] computeMahalanobisWindowed(float[] vector) {
                final int maxShift = vector.length - nsamples + 1;

                final float[] responses = new float[maxShift];
                float[] samples = new float[nsamples];
                for (int i = 0; i < maxShift; i++) {
                        System.arraycopy(vector, i, samples, 0, nsamples);
                        samples = normaliseSamples(samples);
                        responses[i] = computeMahalanobis(samples);
                }

                return responses;
        }

        @Override
        public String toString() {
                return "\nPixelProfileModel[\n" +
                                "\tcount = " + statistics.getN() + "\n" +
                                "\tmean = " + Arrays.toString(statistics.getMean()) + "\n" +
                                "\tcovar = " + statistics.getCovariance() + "\n" +
                                "]";
        }

        /**
         * @return the number of samples used along each profile line
         */
        public int getNumberSamples() {
                return nsamples;
        }

        /**
         * @return the sampler used by the model to extract samples along profiles
         */
        public FLineSampler getSampler() {
                return sampler;
        }

        @Override
        public float computeCost(FImage image, Line2d line) {
                return computeMahalanobis(image, line);
        }
}