// Catalano Imaging Library
// The Catalano Framework
//
// Copyright © Diego Catalano, 2012-2016
// diego.catalano at live.com
//
//
//    This library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU Lesser General Public
//    License as published by the Free Software Foundation; either
//    version 2.1 of the License, or (at your option) any later version.
//
//    This library is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//    Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//

package Catalano.Imaging.Concurrent.Filters;

import Catalano.Imaging.Concurrent.Share;
import Catalano.Imaging.FastBitmap;
import Catalano.Imaging.IApplyInPlace;
import Catalano.Imaging.Tools.IntegralImage;

/**
 * Adaptive thresholding using the integral image.
 * @author Diego Catalano
 */
public class BradleyLocalThreshold implements IApplyInPlace{
    
    private int windowSize = 41;
    private float pixelBrightnessDifferenceLimit = 0.15f;
    private IntegralImage im;

    /**
     * Initialize a new instance of the BradleyLocalThreshold class.
     */
    public BradleyLocalThreshold() {}
    
    /**
     * Initialize a new instance of the BradleyLocalThreshold class.
     * @param windowSize Window size to calculate average value of pixels for.
     */
    public BradleyLocalThreshold(int windowSize) {
        this.windowSize = windowSize;
    }
    
    /**
     * Initialize a new instance of the BradleyLocalThreshold class.
     * @param windowSize Window size to calculate average value of pixels for.
     * @param pixelBrightnessDiff Brightness difference limit between processing pixel and average value across neighbors.
     */
    public BradleyLocalThreshold(int windowSize, float pixelBrightnessDiff) {
        this.windowSize = windowSize;
    }

    /**
     * Window size to calculate average value of pixels for.
     * @return Window size.
     */
    public int getWindowSize() {
        return windowSize;
    }

    /**
     * Window size to calculate average value of pixels for.
     * @param windowSize Window size.
     */
    public void setWindowSize(int windowSize) {
        this.windowSize = windowSize;
    }

    /**
     * Brightness difference limit between processing pixel and average value across neighbors.
     * @return Brightness difference.
     */
    public float getPixelBrightnessDifferenceLimit() {
        return pixelBrightnessDifferenceLimit;
    }

    /**
     * Brightness difference limit between processing pixel and average value across neighbors.
     * @param pixelBrightnessDifferenceLimit Brightness difference.
     */
    public void setPixelBrightnessDifferenceLimit(float pixelBrightnessDifferenceLimit) {
        this.pixelBrightnessDifferenceLimit = pixelBrightnessDifferenceLimit;
    }

    @Override
    public void applyInPlace(FastBitmap fastBitmap) {
        Parallel(fastBitmap);
    }
    
    private void Parallel(FastBitmap fastBitmap){
        
        im = IntegralImage.FromFastBitmap(fastBitmap);
        
        int cores = Runtime.getRuntime().availableProcessors();
        
        Thread[] t = new Thread[cores];
        int part = fastBitmap.getHeight() / cores;
        
        int startX = 0;
        for (int i = 0; i < cores; i++) {
            t[i] = new Thread(new Run(new Share(fastBitmap, startX, startX + part)));
            t[i].start();
            startX += part;
        }
        
        try {
            
            for (int i = 0; i < cores; i++) {
                t[i].join();
            }
            
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    
    private class Run implements Runnable {

        private Share share;
        
        public Run(Share obj) {
            this.share = obj;
        }

        @Override
        public void run() {
            
            int widthM1  = share.fastBitmap.getWidth() - 1;
            int heightM1 = share.endHeight - 1;

            int radius = windowSize / 2;

            float avgBrightnessPart = 1.0f - pixelBrightnessDifferenceLimit;

            for (int x = share.startX; x < share.endHeight; x++) {

                    int x1 = x - radius;
                    int x2 = x + radius;

                    if ( x1 < 0 )
                        x1 = 0;
                    if ( x2 > heightM1 )
                        x2 = heightM1;

                for (int y = 0; y < share.fastBitmap.getWidth(); y++) {
                        int y1 = y - radius;
                        int y2 = y + radius;

                        if ( y1 < 0 )
                            y1 = 0;
                        if ( y2 > widthM1 )
                            y2 = widthM1;


                        int gray = share.fastBitmap.getGray(x, y) < (int)(im.getRectangleMeanUnsafe(x1, y1, x2, y2) * avgBrightnessPart) ? 0 : 255;
                        share.fastBitmap.setGray(x, y, gray);
                }
            }
        }
    }
}