/**
 * 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.objectdetection;

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

import org.openimaj.image.FImage;
import org.openimaj.image.Image;
import org.openimaj.image.processing.resize.ResizeProcessor;
import org.openimaj.image.processing.transform.ProjectionProcessor;
import org.openimaj.image.processor.SinglebandImageProcessor;
import org.openimaj.math.geometry.shape.Rectangle;
import org.openimaj.math.geometry.shape.Shape;
import org.openimaj.math.geometry.transforms.TransformUtilities;

import Jama.Matrix;

/**
 * An {@link ObjectDetector} that wraps another {@link ObjectDetector} and
 * performs rotation simulations on the images it passes to the internal
 * detector. This allows a non rotation invariant detector to be able to detect
 * rotated objects.
 * <p>
 * This implementation allows the input image to be scaled in order to reduce
 * computational complexity, and control over the simulated angles.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 * 
 * @param <IMAGE>
 *            Type of image in which the detection happens
 * @param <PIXEL>
 *            Type of pixel of the image in which the detection happens
 * @param <DETECTED_OBJECT>
 *            The type of object emitted by the inner detector
 */
public class RotationSimulationObjectDetector<IMAGE extends Image<PIXEL, IMAGE> & SinglebandImageProcessor.Processable<Float, FImage, IMAGE>, PIXEL, DETECTED_OBJECT>
                implements
                ObjectDetector<IMAGE, TransformedDetection<DETECTED_OBJECT>>
{
        private ObjectDetector<IMAGE, DETECTED_OBJECT> detector;
        private Rectangle roi;
        private float scalefactor = 1f;
        private float[] simulationAngles;

        /**
         * Construct with the given inner detector and number of rotations.
         * Simulations will occur every 360/numRotations degrees.
         * 
         * @param detector
         *            the internal detector
         * @param numRotations
         *            the number of rotations
         */
        public RotationSimulationObjectDetector(ObjectDetector<IMAGE, DETECTED_OBJECT> detector, int numRotations) {
                this.detector = detector;
                this.simulationAngles = computeAngles(numRotations);
        }

        /**
         * Construct with the given inner detector, number of rotations and scale
         * factor. Simulations will occur every 360/numRotations degrees.
         * 
         * @param detector
         *            the internal detector
         * @param numRotations
         *            the number of rotations
         * @param scalefactor
         *            the amount by which to scale the input image prior to passing
         *            to the inner detector
         */
        public RotationSimulationObjectDetector(ObjectDetector<IMAGE, DETECTED_OBJECT> detector, int numRotations,
                        float scalefactor)
        {
                this(detector, numRotations);
                this.scalefactor = scalefactor;
        }

        /**
         * Construct with the given inner detector, simulation angles and scale
         * factor. Simulations will occur every 360/numRotations degrees.
         * 
         * @param detector
         *            the internal detector
         * @param simulationAngles
         *            the rotation angles to simulate
         * @param scalefactor
         *            the amount by which to scale the input image prior to passing
         *            to the inner detector
         */
        public RotationSimulationObjectDetector(ObjectDetector<IMAGE, DETECTED_OBJECT> detector, float[] simulationAngles,
                        float scalefactor)
        {
                this.detector = detector;
                this.simulationAngles = simulationAngles;
                this.scalefactor = scalefactor;
        }

        private float[] computeAngles(int numRotations) {
                final float[] angles = new float[numRotations];

                for (int i = 1; i < numRotations; i++) {
                        angles[i] = (float) (2 * i * Math.PI / numRotations);
                }

                return angles;
        }

        @Override
        public List<TransformedDetection<DETECTED_OBJECT>> detect(IMAGE image) {
                final List<TransformedDetection<DETECTED_OBJECT>> results = new ArrayList<TransformedDetection<DETECTED_OBJECT>>();

                Matrix scale;

                if (scalefactor != 1) {
                        image = image.process(new ResizeProcessor(scalefactor));
                        scale = TransformUtilities.scaleMatrix(scalefactor, scalefactor);
                } else {
                        scale = Matrix.identity(3, 3);
                }

                for (final float angle : simulationAngles) {
                        if (angle == 0) {
                                detectObjects(image, scale, results);
                        } else {
                                final Matrix matrix = TransformUtilities.rotationMatrix(angle);
                                final IMAGE rimg = ProjectionProcessor.project(image, matrix);

                                final Rectangle actualBounds = image.getBounds();
                                final Shape transformedActualBounds = actualBounds.transform(matrix);
                                final double tminX = transformedActualBounds.minX();
                                final double tminY = transformedActualBounds.minY();

                                final int minc = (int) Math.floor(tminX);
                                final int minr = (int) Math.floor(tminY);

                                matrix.set(0, 2, -minc);
                                matrix.set(1, 2, -minr);

                                detectObjects(rimg, matrix.times(scale), results);
                        }
                }

                return results;
        }

        private void detectObjects(IMAGE image, Matrix transform, List<TransformedDetection<DETECTED_OBJECT>> results) {
                if (this.roi != null) {
                        final Rectangle troi = roi.transform(transform).calculateRegularBoundingBox();
                        detector.setROI(troi);
                }

                final List<DETECTED_OBJECT> detections = detector.detect(image);

                if (detections == null)
                        return;

                for (final DETECTED_OBJECT o : detections) {
                        results.add(new TransformedDetection<DETECTED_OBJECT>(o, transform.inverse()));
                }
        }

        @Override
        public void setROI(Rectangle roi) {
                this.roi = roi;
        }

        /**
         * Get the internal detector
         * 
         * @return the internal detector
         */
        public ObjectDetector<IMAGE, DETECTED_OBJECT> getInnerDetector() {
                return detector;
        }
}