/******************************************************************************
 * Laborator 01 - Zaklady pocitacove grafiky - IZG
 * ihulik@fit.vutbr.cz
 *
 * $Id: $
 *
 * Popis: Hlavicky funkci pro funkce studentu
 *
 * Opravy a modifikace:
 * - ibobak@fit.vutbr.cz, orderedDithering
 */

#include "student.h"
#include "globals.h"

#include <time.h>

const int M[] = {
    0, 204, 51, 255,
    68, 136, 187, 119,
    34, 238, 17, 221,
    170, 102, 153, 85
};

const int M_SIDE = 4;

/******************************************************************************
 ******************************************************************************
 Funkce vraci pixel z pozice x, y. Je nutne hlidat frame_bufferu, pokud
 je dana souradnice mimo hranice, funkce vraci barvu (0, 0, 0).
 Ukol za 0.25 bodu */
S_RGBA getPixel(int x, int y)
{
    int offset = y * width + x;
    S_RGBA color = frame_buffer[offset];

    if (x < 0 || x > width || y < 0 || y > height) {
        color = COLOR_BLACK; //vraci barvu (0, 0, 0)
    } else {
        color = frame_buffer[offset];
    }

    return color;
}
/******************************************************************************
 ******************************************************************************
 Funkce vlozi pixel na pozici x, y. Je nutne hlidat frame_bufferu, pokud
 je dana souradnice mimo hranice, funkce neprovadi zadnou zmenu.
 Ukol za 0.25 bodu */
void putPixel(int x, int y, S_RGBA color)
{
    // width: x
    // height: y
    int offset = y * width + x;
    if (x < 0 || x > width || y < 0 || y > height) {
        frame_buffer[offset] = COLOR_BLACK; //vraci barvu (0, 0, 0)
    } else {
        frame_buffer[offset] = color;
    }
}
/******************************************************************************
 ******************************************************************************
 Funkce prevadi obrazek na odstiny sedi. Vyuziva funkce GetPixel a PutPixel.
 Ukol za 0.5 bodu */
void grayScale()
{
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x)
        {
            S_RGBA pixel = getPixel(x, y);

            int intensity =  0.299 * pixel.red    \
                            + 0.587 * pixel.green \
                            + 0.114 * pixel.blue;

            S_RGBA ret_pixel = { intensity, intensity, intensity };
            putPixel(x, y, ret_pixel);

            // if (intensity > 127) {
            //  putPixel(x, y, COLOR_BLACK);
            // } else {
            //  putPixel(x, y, COLOR_WHITE);
            // }
        }
    }
}

/******************************************************************************
 ******************************************************************************
 Funkce prevadi obrazek na cernobily pomoci algoritmu maticoveho rozptyleni.
 Ukol za 1 bod */

void orderedDithering()
{
    grayScale();

    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x)
        {
            S_RGBA pixel = getPixel(x, y);

            int i = x % M_SIDE;
            int j = y % M_SIDE;

            if (pixel.red < M[j*M_SIDE+i]) {
                putPixel(x, y, COLOR_BLACK);
            }
            else
                putPixel(x, y, COLOR_WHITE);
        }
    }
}


/******************************************************************************
 ******************************************************************************
 Funkce prevadi obrazek na cernobily pomoci algoritmu distribuce chyby.
 Ukol za 1 bod */
void errorDistribution()
{
    // todo
}

/******************************************************************************
 ******************************************************************************
 Funkce prevadi obrazek na cernobily pomoci metody prahovani.
 Demonstracni funkce */
void thresholding(int Threshold)
{
    /* Prevedeme obrazek na grayscale */
    grayScale();

    /* Projdeme vsechny pixely obrazku */
    for (int y = 0; y < height; ++y)
        for (int x = 0; x < width; ++x)
        {
            /* Nacteme soucasnou barvu */
            S_RGBA color = getPixel(x, y);

            /* Porovname hodnotu cervene barevne slozky s prahem.
               Muzeme vyuzit jakoukoli slozku (R, G, B), protoze
               obrazek je sedotonovy, takze R=G=B */
            if (color.red > Threshold)
                putPixel(x, y, COLOR_WHITE);
            else
                putPixel(x, y, COLOR_BLACK);
        }
}

/******************************************************************************
 ******************************************************************************
 Funkce prevadi obrazek na cernobily pomoci nahodneho rozptyleni.
 Vyuziva funkce GetPixel, PutPixel a GrayScale.
 Demonstracni funkce. */
void randomDithering()
{
    /* Prevedeme obrazek na grayscale */
    grayScale();

    /* Inicializace generatoru pseudonahodnych cisel */
    srand((unsigned int)time(NULL));

    /* Projdeme vsechny pixely obrazku */
    for (int y = 0; y < height; ++y)
        for (int x = 0; x < width; ++x)
        {
            /* Nacteme soucasnou barvu */
            S_RGBA color = getPixel(x, y);

            /* Porovname hodnotu cervene barevne slozky s nahodnym prahem.
               Muzeme vyuzit jakoukoli slozku (R, G, B), protoze
               obrazek je sedotonovy, takze R=G=B */
            if (color.red > rand()%255)
            {
                putPixel(x, y, COLOR_WHITE);
            }
            else
                putPixel(x, y, COLOR_BLACK);
        }
}
/*****************************************************************************/
/*****************************************************************************/