/**
    * 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.processing.morphology;
  
  import java.util.HashSet;
  import java.util.Set;
  
  import org.openimaj.image.FImage;
  import org.openimaj.image.pixel.ConnectedComponent;
  import org.openimaj.image.pixel.Pixel;
  import org.openimaj.image.processing.algorithm.MinFilter;
  import org.openimaj.image.processor.KernelProcessor;
  import org.openimaj.image.processor.connectedcomponent.ConnectedComponentProcessor;
  import org.openimaj.math.geometry.shape.Rectangle;
  
  /**
   * Morphological erosion of connected components and (assumed binary) FImages.
   * See {@link MinFilter} for greyscale erosion.
   *
   * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
   */
  public class Erode implements ConnectedComponentProcessor, KernelProcessor<Float, FImage> {
  	protected StructuringElement element;
  	protected int cx;
  	protected int cy;
  	protected int sw;
  	protected int sh;
  
  	/**
  	 * Construct the erode operator with the given structuring element
  	 *
  	 * @param se
  	 *            the structuring element
  	 */
  	public Erode(StructuringElement se) {
  		this.element = se;
  
  		final int[] sz = se.size();
  		sw = sz[0];
  		sh = sz[1];
  		cx = sw / 2;
  		cy = sh / 2;
  	}
  
  	/**
  	 * Construct the erode operator with a BOX structuring element
  	 */
  	public Erode() {
  		this(StructuringElement.BOX);
  	}
  
  	@Override
  	public void process(ConnectedComponent cc) {
  		// Erode a connected component
  		final Set<Pixel> retain = new HashSet<Pixel>();
  		final Set<Pixel> pixels = cc.getPixels();
  		final int[] se_size = element.size();
  		final Rectangle cc_bb = cc.calculateRegularBoundingBox();
  		for (int j = (int) (cc_bb.y - se_size[1]); j <= cc_bb.y + se_size[1] + cc_bb.height; j++) {
  			for (int i = (int) (cc_bb.x - se_size[0]); i <= cc_bb.x + se_size[0] + cc_bb.width; i++) {
  				final Pixel p = new Pixel(i, j);
  
  				if (element.matches(p, pixels)) {
  					retain.add(p);
  				}
  			}
  		}
  
  		cc.getPixels().retainAll(retain);
  	}
  
  	@Override
 	public int getKernelHeight() {
 		return sh;
 	}
 
 	@Override
 	public int getKernelWidth() {
 		return sw;
 	}
 
 	@Override
 	public Float processKernel(FImage patch) {
 		int count = 0;
 
 		for (final Pixel p : element.positive) {
 			final int px = cx - p.x;
 			final int py = cy - p.y;
 			if (px >= 0 && py >= 0 && px < sw && py < sh && patch.pixels[py][px] == 1)
 				count++;
 		}
 
 		for (final Pixel p : element.negative) {
 			final int px = cx - p.x;
 			final int py = cy - p.y;
 			if (px >= 0 && py >= 0 && px < sw && py < sh && patch.pixels[py][px] == 0)
 				count++;
 		}
 
 		return (count == element.positive.size() + element.negative.size() ? patch.pixels[cy][cx] : 0);
 	}
 
 	/**
 	 * Apply erosion some number of times to an image with the default
 	 * {@link StructuringElement#BOX} element
 	 *
 	 * @param img
 	 *            the image
 	 * @param times
 	 *            the number of times to apply the erosion
 	 */
 	public static void erode(FImage img, int times) {
 		final Erode e = new Erode();
 		for (int i = 0; i < times; i++)
 			img.processInplace(e);
 	}
 }