#include <stdlib.h>
//#include <string.h>
//#include <stdio.h>
//#include <math.h>
#include "test_02_fnc.h"

unsigned char getpixel(int x, int y, unsigned char * srcD, int width, int height) {
	if (x < 0) {
		x = 0;
	} else if (x >= width) {
		x = width - 1;
	}
	
	if (y < 0) {
		y = 0;
	} else if (y >= height) {
		y = height - 1;
	}
	
	return *(srcD + y * width + x);
}

int imageConvolution(float * dstD, unsigned char * srcD, int width, int height, float * kernel, int size) {
	if (!dstD || !srcD || !kernel) {
		return 0;
	}
	
	for (int y = 0; y < height; y++) {
		for (int x = 0; x < width; x++) {
			short pixel = 0;
			for (int j = 0; j < size; j++) {
				for (int i = 0; i < size; i++) {
					pixel += *(kernel + j * size + i) * getpixel(x + i - size / 2, y + j - size / 2, srcD, width, height);
				}
			}
			*(dstD + y * width + x) = pixel;
		}
	}
	
	return 1;
}

int imageFilterSobel(unsigned char * dstD, unsigned char * srcD, int width, int height) {
	if (!dstD || !srcD) {
		return 0;
	}
	
	const short sobel[3][3] = {{1, 0, -1}, {2, 0, -2}, {1, 0, -1}};
	for (int y = 0; y < height; y++) {
		for (int x = 0; x < width; x++) {
			short pixel_v = 0;
			short pixel_h = 0;
			for (int j = 0; j < 3; j++) {
				for (int i = 0; i < 3; i++) {
					pixel_v += sobel[j][i] * getpixel(x + i - 1, y + j - 1, srcD, width, height);
					pixel_h += sobel[i][j] * getpixel(x + i - 1, y + j - 1, srcD, width, height);
				}
			}
			pixel_h /= 4;
			pixel_v /= 4;
			unsigned short pixel = abs(pixel_h) + abs(pixel_v);
			if (pixel > 255) pixel = 255;	//Orez
			*(dstD + y * width + x) = pixel;
		}
	}
	
	return 1;
}

int uchar_cmp(const void *a, const void *b) {
	const unsigned char *ca = (const unsigned char *) a;
	const unsigned char *cb = (const unsigned char *) b;
	return *ca - *cb;
}

int imageFilterMedian(unsigned char * dstD, unsigned char * srcD, int width, int height, int radius) {
	if (!dstD || !srcD) {
		return 0;
	}
	
	int edge = 2 * radius + 1;
	for (int y = 0; y < height; y++) {
		for (int x = 0; x < width; x++) {
			unsigned char pixels[edge * edge];
			for (int j = 0; j < edge; j++) {
				for (int i = 0; i < edge; i++) {
					pixels[j * edge + i] = getpixel(x + i - edge / 2, y + j - edge / 2, srcD, width, height);
				}
			}
			qsort(&pixels, edge * edge, sizeof(unsigned char), uchar_cmp);
			*(dstD + y * width + x) = pixels[(edge * edge) / 2];
		}
	}
	
	return 1;
}

/*
Stručně popište chování konvoluce na kraji obrazu.
==================================================
Opakuji se krajni pixely.

Proč se tak děje?
=================
Je to nejsnazsi cesta jak "roztahnout" obrazek, aby nedochazelo ke zmenam ve frekvencich.

Jaké znáte druhy konvoluce?
===========================
Diskretni, spojita, kruhova, 1D, 2D, 3D, rychla, ...

Proč se většinou konvoluční jádra normalizují?
==============================================
Aby nebyl vysledny obrazek prilis svetly.
*/