/*
Copyright (C) 2006 Pedro Felzenszwalb
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/

#ifndef SEGMENT_IMAGE
#define SEGMENT_IMAGE

#include <cstdlib>
#include <image.h>
#include <misc.h>
#include <filter.h>
#include "segment-graph.h"
#include <map>

// random color
rgb random_rgb(){
    rgb c;
    double r;

    c.r = (uchar)random();
    c.g = (uchar)random();
    c.b = (uchar)random();

    return c;
}

// dissimilarity measure between pixels
static inline float diff(image<float> *r, image<float> *g, image<float> *b,
                         int x1, int y1, int x2, int y2) {
    return sqrt(square(imRef(r, x1, y1)-imRef(r, x2, y2)) +
                square(imRef(g, x1, y1)-imRef(g, x2, y2)) +
                square(imRef(b, x1, y1)-imRef(b, x2, y2)));
}

/*
 * Segment an image
 *
 * Returns a color image representing the segmentation.
 *
 * im: image to segment.
 * sigma: to smooth the image.
 * c: constant for treshold function.
 * min_size: minimum component size (enforced by post-processing stage).
 * num_ccs: number of connected components in the segmentation.
 */
image<rgb> *segment_image(image<rgb> *im, float sigma, float c, int min_size,
                          int *num_ccs) {
    int width = im->width();
    int height = im->height();

    image<float> *r = new image<float>(width, height);
    image<float> *g = new image<float>(width, height);
    image<float> *b = new image<float>(width, height);

    // smooth each color channel
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            imRef(r, x, y) = imRef(im, x, y).r;
            imRef(g, x, y) = imRef(im, x, y).g;
            imRef(b, x, y) = imRef(im, x, y).b;
        }
    }
    image<float> *smooth_r = smooth(r, sigma);
    image<float> *smooth_g = smooth(g, sigma);
    image<float> *smooth_b = smooth(b, sigma);
    delete r;
    delete g;
    delete b;

    // build graph
    edge *edges = new edge[width*height*4];
    int num = 0;
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            if (x < width-1) {
                edges[num].a = y * width + x;
                edges[num].b = y * width + (x+1);
                edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y);
                num++;
            }

            if (y < height-1) {
                edges[num].a = y * width + x;
                edges[num].b = (y+1) * width + x;
                edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x, y+1);
                num++;
            }

            if ((x < width-1) && (y < height-1)) {
                edges[num].a = y * width + x;
                edges[num].b = (y+1) * width + (x+1);
                edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y+1);
                num++;
            }

            if ((x < width-1) && (y > 0)) {
                edges[num].a = y * width + x;
                edges[num].b = (y-1) * width + (x+1);
                edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y-1);
                num++;
            }
        }
    }
    delete smooth_r;
    delete smooth_g;
    delete smooth_b;

    // segment
    Universe *u = segment_graph(width*height, num, edges, c);

    // post process small components
    for (int i = 0; i < num; i++) {
        int a = u->find(edges[i].a);
        int b = u->find(edges[i].b);
        if ((a != b) && ((u->size(a) < min_size) || (u->size(b) < min_size)))
            u->join(a, b);
    }
    delete [] edges;
    *num_ccs = u->num_sets();

    image<rgb> *output = new image<rgb>(width, height);


    // pick random colors for each component
    std::map<int, float> average_r;
    std::map<int, float> average_g;
    std::map<int, float> average_b;

    std::map<int, int> nb_pixels;

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int comp = u->find(y * width + x);

            average_r[comp] += imRef(im, x, y).r;
            average_g[comp] += imRef(im, x, y).g;
            average_b[comp] += imRef(im, x, y).b;
            nb_pixels[comp]++;



        }
    }

    std::map<int, rgb> component_colors;
    for( std::map<int, int>::iterator it = nb_pixels.begin() ; it != nb_pixels.end() ; it++ ){
        rgb color;
        int comp = it->first;

        color.r = int(float(average_r[comp])/nb_pixels[comp]);
        color.g = int(float(average_g[comp])/nb_pixels[comp]);
        color.b = int(float(average_b[comp])/nb_pixels[comp]);

        component_colors[comp] = color;
    }

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            int comp = u->find(y * width + x);

            imRef(output, x, y) = component_colors[comp];
        }
    }

    delete u;

    return output;
}

#endif