/**
 * 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.image.connectedcomponent.proc;

import java.util.List;

import org.openimaj.feature.DoubleFV;
import org.openimaj.feature.FeatureVectorProvider;
import org.openimaj.image.pixel.ConnectedComponent;
import org.openimaj.image.pixel.ConnectedComponent.ConnectMode;
import org.openimaj.image.pixel.Pixel;
import org.openimaj.image.processor.connectedcomponent.ConnectedComponentProcessor;
import org.openimaj.math.util.Interpolation;

/**
 * Distance-from-centroid descriptor for convex shapes. Sweeps the 
 * edge of the shape over all angles in 0..360 and records the distance
 * from the centroid.
 * 
 * Scale invariance is optionally achieved by normalising the
 * resultant vector to sum to 1.
 * 
 * Rotation invariance is optionally achieved by measuring angles
 * from the dominant orientation of the connected component.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 *
 */
public class BoundaryDistanceDescriptor implements ConnectedComponentProcessor, FeatureVectorProvider<DoubleFV> {
        /**
         * The number of samples
         */
        public final static int DESCRIPTOR_LENGTH = 360;
        
        /**
         * The descriptor vector, measusring distance from centroid per degree
         */
        public double [] descriptor = new double[DESCRIPTOR_LENGTH];
        protected boolean normaliseScale;
        protected boolean normaliseAngle;

        /**
         * Construct the BoundaryDistanceDescriptor with both scale and
         * orientation normalisation enabled
         */
        public BoundaryDistanceDescriptor() {
                this(true, true);
        }
        
        /**
         * Construct the BoundaryDistanceDescriptor with optional scale and
         * orientation invariance.
         * @param normaliseDistance enable scale invariance
         * @param normaliseAngle enable rotation invariance
         */
        public BoundaryDistanceDescriptor(boolean normaliseDistance, boolean normaliseAngle) {
                this.normaliseScale = normaliseDistance;
                this.normaliseAngle = normaliseAngle;
        }

        @Override
        public void process(ConnectedComponent cc) {
                cc = new ConnectedComponent(cc.calculateConvexHull()); //make shape convex
                
                List<Pixel> bound = cc.getInnerBoundary(ConnectMode.CONNECT_8);
                double [] centroid = cc.calculateCentroid();
                double direction = cc.calculateDirection();

                float[] distances = new float[bound.size()];
                float[] angle = new float[bound.size()];
                int count = 0;

                for (int i=0; i<bound.size(); i++) {
                        Pixel p = bound.get(i);
                        double o = p.y - centroid[1];
                        double a = p.x - centroid[0];

                        float dist = (float) Math.sqrt((a*a) + (o*o));
                        distances[i] = dist;

                        if (normaliseAngle) {
                                angle[i] = (float) (direction - Math.atan2(o, a));
                        } else {
                                angle[i] = (float) (Math.atan2(o, a));
                        }
                                        
                        angle[i] = (float) ((angle[i] %= 2.0*Math.PI) >= 0 ? angle[i] : (angle[i] + 2.0*Math.PI));                      
                        angle[i] = (float) (360.0 * angle[i] / (2.0*Math.PI));
                }

                for (int i=0; i<DESCRIPTOR_LENGTH; i++) {
                        int index1 = -1;
                        int index2 = -1;

                        for (int j=0; j<angle.length; j++) {
                                int n = ((j+1 == angle.length) ? 0 : j+1);

                                float aj = angle[j];
                                float an = angle[n];

                                if (an > 350 && aj < 10) if (i<10) an-=360; else aj+=360;
                                if (aj > 350 && an < 10) if (i<10) aj-=360; else an+=360;
                                
                                if (aj==i) {
                                        index1 = j;
                                        index2 = j;
                                        break;
                                } else if (aj<an) {
                                        if (i <= an && i > aj) {
                                                index1 = j;
                                                index2 = n;
                                                break;
                                        }
                                } else {
                                        if (i <= aj && i > an) {
                                                index1 = j;
                                                index2 = n;
                                                break;
                                        }
                                }
                        }

                        
                        descriptor[i] = Interpolation.lerp(i, angle[index1], distances[index1], angle[index2], distances[index2]);
                        count += descriptor[i];
                }
                
                if (normaliseScale) {
                        for (int i=0; i<DESCRIPTOR_LENGTH; i++)
                                descriptor[i] /= count;
                }
        }

        /**
         * Get the feature vector as a double array
         * @return the feature vector
         */
        public double[] getFeatureVectorArray() {
                return descriptor;
        }
        
        @Override
        public DoubleFV getFeatureVector() {
                return new DoubleFV(getFeatureVectorArray());
        }
}