/*
 * Copyright 2002-2008 Guillaume Cottenceau, 2015 Aleksander Denisiuk
 *
 * This software may be freely redistributed under the terms
 * of the X11 license.
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>

#define PNG_DEBUG 3
#include <png.h>


#define OUT_FILE "initials.png"
#define WIDTH 600
#define HEIGHT 600
#define COLOR_TYPE PNG_COLOR_TYPE_RGB
#define BIT_DEPTH 8


void abort_(const char * s, ...)
{
	va_list args;
	va_start(args, s);
	vfprintf(stderr, s, args);
	fprintf(stderr, "\n");
	va_end(args);
	abort();
}

int x, y;

int width, height;
png_byte color_type;
png_byte bit_depth;

png_structp png_ptr;
png_infop info_ptr;
int number_of_passes;
png_bytep * row_pointers;

void create_png_file()
{
	width = WIDTH;
	height = HEIGHT;
        bit_depth = BIT_DEPTH;
        color_type = COLOR_TYPE;

	row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height);
	for (y=0; y<height; y++)
		row_pointers[y] = (png_byte*) malloc(width*bit_depth*3);


}


void write_png_file(char* file_name)
{
	/* create file */
	FILE *fp = fopen(file_name, "wb");
	if (!fp)
		abort_("[write_png_file] File %s could not be opened for writing", file_name);


	/* initialize stuff */
	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

	if (!png_ptr)
		abort_("[write_png_file] png_create_write_struct failed");

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr)
		abort_("[write_png_file] png_create_info_struct failed");

	if (setjmp(png_jmpbuf(png_ptr)))
		abort_("[write_png_file] Error during init_io");

	png_init_io(png_ptr, fp);


	/* write header */
	if (setjmp(png_jmpbuf(png_ptr)))
		abort_("[write_png_file] Error during writing header");

	png_set_IHDR(png_ptr, info_ptr, width, height,
		     bit_depth, color_type, PNG_INTERLACE_NONE,
		     PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

	png_write_info(png_ptr, info_ptr);


	/* write bytes */
	if (setjmp(png_jmpbuf(png_ptr)))
		abort_("[write_png_file] Error during writing bytes");

	png_write_image(png_ptr, row_pointers);


	/* end write */
	if (setjmp(png_jmpbuf(png_ptr)))
		abort_("[write_png_file] Error during end of write");

	png_write_end(png_ptr, NULL);

        /* cleanup heap allocation */
	for (y=0; y<height; y++)
		free(row_pointers[y]);
	free(row_pointers);

        fclose(fp);
}

void write_pixel(int x, int y, png_byte cr, png_byte cg, png_byte cb)
{
    png_byte* row = row_pointers[y];
    png_byte* ptr = &(row[x*3]);
    ptr[0] = cr;
    ptr[1] = cg;
    ptr[2] = cb;

}

void bresenham(int i1, int j1, int i2, int j2, png_byte cr, png_byte cg, png_byte cb)
{
    int m, b, j, P, i;

    if(i2>i1 && j2 >= j1 && j2-j1<=i2-i1){
        printf("przypadek 1 \n");
        m = 2*(j2-j1);
        b = 0;
        write_pixel(i1, j1, cr, cg, cb);
        j = j1;
        P = i2-i1;
        for(i=i1+1; i<=i2;i++){
            b = b+m;
            if(b>P){
                j = j+1;
                b = b-2*P;
            }
            write_pixel(i,j,cr,cg,cb);
        }
    }


    else if(i2>i1 && -j2 >= -j1 && -j2+j1<=i2-i1){
        printf("przypadek 2 \n");
        m = 2*(-j2+j1);
        b = 0;
        write_pixel(i1, j1, cr, cg, cb);
        j = j1;
        P = i2-i1;
        for(i=i1+1; i<=i2;i++){
            b = b+m;
            if(b>P){
                j = j-1;
                b = b-2*P;
            }
            write_pixel(i,j,cr,cg,cb);
        }
    }
else if(j2>j1 && i2 >= i1 && i2-i1<=j2-j1){
    printf("przypadek 3\n");
    m = 2*(i2-i1);
    b = 0;
    write_pixel(i1, j1, cr, cg, cb);
    i = i1;
    P = j2-j1;
    for(j=j1+1; j<=j2; j++){
        b = b+m;
        if(b>P){
            i = i+1;
            b = b-2*P;
        }
        write_pixel(i,j,cr,cg,cb);
    }
}
else if(-j2 > -j1 && i2 >= i1 && i2-i1<= -j2+j1){
    printf("przypadek 4\n");
    m = 2*(i2-i1);
    b = 0;
    write_pixel(i1, j1, cr, cg, cb);
    i = i1;
    P = -j2+j1;
    for(j=j1-1; j>=j2; j--){
        b = b+m;
        if(b>P){
            i = i+1;
            b = b-2*P;
        }
        write_pixel(i,j,cr,cg,cb);
    }
}
    else{
        printf("Nigdy tego nie zobacze\n");
    }
}


void draw_ellipse(int xc, int yc, int a, int b,
                  png_byte cr, png_byte cg, png_byte cb)
{
    int i = 0;
    int j = b;

    int a2 = a * a;
    int b2 = b * b;

    int f = 4*b2 - 4*a2*b + a2;


    void plot4(int x, int y) {
        write_pixel(xc + x, yc + y, cr, cg, cb);
        write_pixel(xc - x, yc + y, cr, cg, cb);
        write_pixel(xc + x, yc - y, cr, cg, cb);
        write_pixel(xc - x, yc - y, cr, cg, cb);
    }

    plot4(i, j);

    while (b2 * i < a2 * j) {
        if (f > 0) {
            f = f + 8*b2*i - 8*a2*j + 12*b2 + 8*a2;
            j = j - 1;
        } else {
            f = f + 8*b2*i + 12*b2;
        }
        i = i + 1;
        plot4(i, j);
    }
}

void process_file(void)
{
    for (y=0; y<height; y++) {
        png_byte* row = row_pointers[y];
        for (x=0; x<width; x++) {
            png_byte* ptr = &(row[x*3]);
            ptr[0] = 0;
            ptr[1] = ptr[2] = 255;
        }
    }

    bresenham(150, 200, 150, 400, 0, 0, 0);


    draw_ellipse(200, 260, 50, 40, 0, 0, 0);


    draw_ellipse(200, 340, 50, 40, 0, 0, 0);



    bresenham(300, 200, 330, 400, 0, 0, 0);
    bresenham(330, 400, 360, 300, 0, 0, 0);
    bresenham(360, 300, 390, 400, 0, 0, 0);
    bresenham(390, 400, 420, 200, 0, 0, 0);

    draw_ellipse(300, 300, 220, 220, 255, 0, 0);
}


int main(int argc, char **argv)
{
	create_png_file();
	process_file();
	write_png_file(OUT_FILE);

        return 0;
}