/**
 * 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.analysis.algorithm;

import org.openimaj.image.FImage;
import org.openimaj.image.analyser.ImageAnalyser;
import org.openimaj.math.util.Interpolation;

/**
 * An {@link ImageAnalyser} that can provide interpolate pixel values using a
 * variety of interpolation approaches.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 * 
 */
public class ImageInterpolation implements ImageAnalyser<FImage> {
        /**
         * Interface defining an object capable of performing pixel interpolation
         * 
         * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
         * 
         */
        public static interface Interpolator {
                /**
                 * Interpolate a pixel value
                 * 
                 * @param x
                 *            the x-ordinate
                 * @param y
                 *            the y-ordinate
                 * @param image
                 *            the image
                 * @param workingSpace
                 *            the working space required
                 * @return the interpolated pixel value
                 */
                public float interpolate(float x, float y, FImage image, Object workingSpace);

                /**
                 * Create the working space required for interpolation
                 * 
                 * @return the working space (can be <code>null</code>)
                 */
                public Object createWorkingSpace();
        }

        /**
         * Standard interpolation types.
         * 
         * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
         * 
         */
        public static enum InterpolationType implements Interpolator {
                /**
                 * Nearest neighbour interpolation
                 */
                NEAREST_NEIGHBOUR {
                        @Override
                        public float interpolate(float x, float y, FImage image, Object workingSpace) {
                                x = Math.round(x);
                                y = Math.round(y);

                                if (x < 0 || x >= image.width || y < 0 || y >= image.height)
                                        return 0;

                                return image.pixels[(int) y][(int) x];
                        }

                        @Override
                        public Object createWorkingSpace() {
                                return null;
                        }
                },
                /**
                 * Bilinear interpolation
                 */
                BILINEAR {
                        @Override
                        public float interpolate(float x, float y, FImage image, Object workingSpace) {
                                return image.getPixelInterpNative(x, y, 0);
                        }

                        @Override
                        public Object createWorkingSpace() {
                                return null;
                        }
                },
                /**
                 * Bicubic interpolation
                 */
                BICUBIC {
                        @Override
                        public float interpolate(float x, float y, FImage image, Object workingSpace) {
                                final float[][] working = (float[][]) workingSpace;

                                final int sx = (int) Math.floor(x) - 1;
                                final int sy = (int) Math.floor(y) - 1;
                                final int ex = sx + 3;
                                final int ey = sy + 3;

                                for (int yy = sy, i = 0; yy <= ey; yy++, i++) {
                                        for (int xx = sx, j = 0; xx <= ex; xx++, j++) {
                                                final int px = xx < 0 ? 0 : xx >= image.width ? image.width - 1 : xx;
                                                final int py = yy < 0 ? 0 : yy >= image.height ? image.height - 1 : yy;

                                                working[i][j] = image.pixels[py][px];
                                        }
                                }

                                final float dx = (float) (x - Math.floor(x));
                                final float dy = (float) (y - Math.floor(y));
                                return Interpolation.bicubicInterp(dx, dy, working);
                        }

                        @Override
                        public Object createWorkingSpace() {
                                return new float[4][4];
                        }
                };
        }

        protected Interpolator interpolator;
        protected Object workingSpace;
        protected FImage image;

        /**
         * Default constructor.
         * 
         * @param interpolator
         *            the interpolator to use
         */
        public ImageInterpolation(Interpolator interpolator) {
                this.interpolator = interpolator;
                this.workingSpace = interpolator.createWorkingSpace();
        }

        @Override
        public void analyseImage(FImage image) {
                this.image = image;
        }

        /**
         * Get the interpolated pixel value of the previously analysed image
         * 
         * @param x
         *            the x-ordinate
         * @param y
         *            the y-ordinate
         * @return the interpolated pixel value
         */
        public float getPixelInterpolated(float x, float y) {
                return interpolator.interpolate(x, y, image, workingSpace);
        }
}