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

import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

/**
 *
 * @brief Sample code showing how to segment overlapping objects using Laplacian filtering, in addition to Watershed
 * and Distance Transformation
 *
 */
class ImageSegmentation {
    public void run(String[] args) {
        //! [load_image]
        // Load the image
        String filename = args.length > 0 ? args[0] : "../data/cards.png";
        Mat srcOriginal = Imgcodecs.imread(filename);
        if (srcOriginal.empty()) {
            System.err.println("Cannot read image: " + filename);
            System.exit(0);
        }

        // Show source image
        HighGui.imshow("Source Image", srcOriginal);
        //! [load_image]

        //! [black_bg]
        // Change the background from white to black, since that will help later to
        // extract
        // better results during the use of Distance Transform
        Mat src = srcOriginal.clone();
        byte[] srcData = new byte[(int) (src.total() * src.channels())];
        src.get(0, 0, srcData);
        for (int i = 0; i < src.rows(); i++) {
            for (int j = 0; j < src.cols(); j++) {
                if (srcData[(i * src.cols() + j) * 3] == (byte) 255 && srcData[(i * src.cols() + j) * 3 + 1] == (byte) 255
                        && srcData[(i * src.cols() + j) * 3 + 2] == (byte) 255) {
                    srcData[(i * src.cols() + j) * 3] = 0;
                    srcData[(i * src.cols() + j) * 3 + 1] = 0;
                    srcData[(i * src.cols() + j) * 3 + 2] = 0;
                }
            }
        }
        src.put(0, 0, srcData);

        // Show output image
        HighGui.imshow("Black Background Image", src);
        //! [black_bg]

        //! [sharp]
        // Create a kernel that we will use to sharpen our image
        Mat kernel = new Mat(3, 3, CvType.CV_32F);
        // an approximation of second derivative, a quite strong kernel
        float[] kernelData = new float[(int) (kernel.total() * kernel.channels())];
        kernelData[0] = 1; kernelData[1] = 1; kernelData[2] = 1;
        kernelData[3] = 1; kernelData[4] = -8; kernelData[5] = 1;
        kernelData[6] = 1; kernelData[7] = 1; kernelData[8] = 1;
        kernel.put(0, 0, kernelData);

        // do the laplacian filtering as it is
        // well, we need to convert everything in something more deeper then CV_8U
        // because the kernel has some negative values,
        // and we can expect in general to have a Laplacian image with negative values
        // BUT a 8bits unsigned int (the one we are working with) can contain values
        // from 0 to 255
        // so the possible negative number will be truncated
        Mat imgLaplacian = new Mat();
        Imgproc.filter2D(src, imgLaplacian, CvType.CV_32F, kernel);
        Mat sharp = new Mat();
        src.convertTo(sharp, CvType.CV_32F);
        Mat imgResult = new Mat();
        Core.subtract(sharp, imgLaplacian, imgResult);

        // convert back to 8bits gray scale
        imgResult.convertTo(imgResult, CvType.CV_8UC3);
        imgLaplacian.convertTo(imgLaplacian, CvType.CV_8UC3);

        // imshow( "Laplace Filtered Image", imgLaplacian );
        HighGui.imshow("New Sharped Image", imgResult);
        //! [sharp]

        //! [bin]
        // Create binary image from source image
        Mat bw = new Mat();
        Imgproc.cvtColor(imgResult, bw, Imgproc.COLOR_BGR2GRAY);
        Imgproc.threshold(bw, bw, 40, 255, Imgproc.THRESH_BINARY | Imgproc.THRESH_OTSU);
        HighGui.imshow("Binary Image", bw);
        //! [bin]

        //! [dist]
        // Perform the distance transform algorithm
        Mat dist = new Mat();
        Imgproc.distanceTransform(bw, dist, Imgproc.DIST_L2, 3);

        // Normalize the distance image for range = {0.0, 1.0}
        // so we can visualize and threshold it
        Core.normalize(dist, dist, 0, 1., Core.NORM_MINMAX);
        Mat distDisplayScaled = dist.mul(dist, 255);
        Mat distDisplay = new Mat();
        distDisplayScaled.convertTo(distDisplay, CvType.CV_8U);
        HighGui.imshow("Distance Transform Image", distDisplay);
        //! [dist]

        //! [peaks]
        // Threshold to obtain the peaks
        // This will be the markers for the foreground objects
        Imgproc.threshold(dist, dist, .4, 1., Imgproc.THRESH_BINARY);

        // Dilate a bit the dist image
        Mat kernel1 = Mat.ones(3, 3, CvType.CV_8U);
        Imgproc.dilate(dist, dist, kernel1);
        Mat distDisplay2 = new Mat();
        dist.convertTo(distDisplay2, CvType.CV_8U);
        distDisplay2 = distDisplay2.mul(distDisplay2, 255);
        HighGui.imshow("Peaks", distDisplay2);
        //! [peaks]

        //! [seeds]
        // Create the CV_8U version of the distance image
        // It is needed for findContours()
        Mat dist_8u = new Mat();
        dist.convertTo(dist_8u, CvType.CV_8U);

        // Find total markers
        List<MatOfPoint> contours = new ArrayList<>();
        Mat hierarchy = new Mat();
        Imgproc.findContours(dist_8u, contours, hierarchy, Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);

        // Create the marker image for the watershed algorithm
        Mat markers = Mat.zeros(dist.size(), CvType.CV_32S);

        // Draw the foreground markers
        for (int i = 0; i < contours.size(); i++) {
            Imgproc.drawContours(markers, contours, i, new Scalar(i + 1), -1);
        }

        // Draw the background marker
        Imgproc.circle(markers, new Point(5, 5), 3, new Scalar(255, 255, 255), -1);
        Mat markersScaled = markers.mul(markers, 10000);
        Mat markersDisplay = new Mat();
        markersScaled.convertTo(markersDisplay, CvType.CV_8U);
        HighGui.imshow("Markers", markersDisplay);
        //! [seeds]

        //! [watershed]
        // Perform the watershed algorithm
        Imgproc.watershed(imgResult, markers);

        Mat mark = Mat.zeros(markers.size(), CvType.CV_8U);
        markers.convertTo(mark, CvType.CV_8UC1);
        Core.bitwise_not(mark, mark);
        // imshow("Markers_v2", mark); // uncomment this if you want to see how the mark
        // image looks like at that point

        // Generate random colors
        Random rng = new Random(12345);
        List<Scalar> colors = new ArrayList<>(contours.size());
        for (int i = 0; i < contours.size(); i++) {
            int b = rng.nextInt(256);
            int g = rng.nextInt(256);
            int r = rng.nextInt(256);

            colors.add(new Scalar(b, g, r));
        }

        // Create the result image
        Mat dst = Mat.zeros(markers.size(), CvType.CV_8UC3);
        byte[] dstData = new byte[(int) (dst.total() * dst.channels())];
        dst.get(0, 0, dstData);

        // Fill labeled objects with random colors
        int[] markersData = new int[(int) (markers.total() * markers.channels())];
        markers.get(0, 0, markersData);
        for (int i = 0; i < markers.rows(); i++) {
            for (int j = 0; j < markers.cols(); j++) {
                int index = markersData[i * markers.cols() + j];
                if (index > 0 && index <= contours.size()) {
                    dstData[(i * dst.cols() + j) * 3 + 0] = (byte) colors.get(index - 1).val[0];
                    dstData[(i * dst.cols() + j) * 3 + 1] = (byte) colors.get(index - 1).val[1];
                    dstData[(i * dst.cols() + j) * 3 + 2] = (byte) colors.get(index - 1).val[2];
                } else {
                    dstData[(i * dst.cols() + j) * 3 + 0] = 0;
                    dstData[(i * dst.cols() + j) * 3 + 1] = 0;
                    dstData[(i * dst.cols() + j) * 3 + 2] = 0;
                }
            }
        }
        dst.put(0, 0, dstData);

        // Visualize the final image
        HighGui.imshow("Final Result", dst);
        //! [watershed]

        HighGui.waitKey();
        System.exit(0);
    }
}

public class ImageSegmentationDemo {
    public static void main(String[] args) {
        // Load the native OpenCV library
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        new ImageSegmentation().run(args);
    }
}
