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

struct BitMap {

	short int Signature;
	int FileSize;
	short int Reserved1;
	short int Reserved2;
	int Offset;

	int HeaderSize;
	int Width;
	int Height;
	short int Planes;
	short int BitsPerPixel;
	int Compression;
	int ImageSize;
	int XPixelsPerMeter;
	int YPixelsPerMeter;
	int ColorsInColorTable;
	int ImportantColorCount;

	char *rest;


	char *ColorTable;

	char *GAP1;
	struct Pix*PixelArray;



};

struct Pix {
	char R;
	char G;
	char B;


};

/*void PixOne (char r0, char g0, char b0, struct Pix p){
		p.R=r0;
		p.G=g0;
		p.B=b0;
	};*/

struct Pix getPix (int x, int y, struct BitMap bm)
{
    //struct Pix p;

	return bm.PixelArray [(bm.Height - y - 1)*bm.Width*3 + x];

}

void setPix (int x, int y, struct BitMap bm, struct Pix p)
{
    	y = bm.Height - y - 1;
		bm.PixelArray [y*bm.Width*3 + x].R = p.R;
    	(bm.PixelArray [y*bm.Width*3 + x]).G = p.G;
    	(bm.PixelArray [y*bm.Width*3 + x]).B = p.B;
}

struct BitMap readBitMap(FILE *BMPFile) {
	struct BitMap x;

	fread(&x.Signature,2,1,BMPFile);
	fread(&x.FileSize,4,1,BMPFile);
	fread(&x.Reserved1,2,1,BMPFile);
	fread(&x.Reserved2,2,1,BMPFile);
	fread(&x.Offset,4,1,BMPFile);

	fread(&x.HeaderSize,4,1,BMPFile);
	fread(&x.Width,4,1,BMPFile);
	fread(&x.Height,4,1,BMPFile);
	fread(&x.Planes,2,1,BMPFile);
	fread(&x.BitsPerPixel,2,1,BMPFile);
	fread(&x.Compression,4,1,BMPFile);
	fread(&x.ImageSize,4,1,BMPFile);
	fread(&x.XPixelsPerMeter,4,1,BMPFile);
	fread(&x.YPixelsPerMeter,4,1,BMPFile);
	fread(&x.ColorsInColorTable,4,1,BMPFile);
	fread(&x.ImportantColorCount,4,1,BMPFile);

	x.rest = (char*) malloc(x.HeaderSize-40);

    //printf("%d%n",x.ImageSize);

    //printf("%d%n",(x.Width*3+2)*x.Height);
	fread(x.rest,x.HeaderSize-40,1,BMPFile);


    x.ColorTable = (char*) malloc(x.ColorsInColorTable*4);

    fread(x.ColorTable,x.ColorsInColorTable*4,1,BMPFile);

    x.GAP1 = (char*) malloc(x.Offset-x.HeaderSize-14-x.ColorsInColorTable*4);

	fread(x.GAP1,x.Offset-x.HeaderSize-14-x.ColorsInColorTable*4,1,BMPFile);

    int JunkBytes = 0;

    if ((4-(x.Width*3)%4) !=4)
    JunkBytes = 4-(x.Width*3)%4;

	fseek(BMPFile, x.Offset, SEEK_SET);
	x.PixelArray = (struct Pix*) malloc(x.Width*x.Height*3);
    int i;
	for (i = 0; i < x.Height; i++){
	fread(x.PixelArray+3*x.Width*i,3,x.Width,BMPFile);
	fseek(BMPFile,JunkBytes,SEEK_CUR);
    }
	return x;

}

void writeBitMap(FILE *BMPFile,struct BitMap bm) {

	fwrite(&bm.Signature,2,1,BMPFile);
	fwrite(&bm.FileSize,4,1,BMPFile);
	fwrite(&bm.Reserved1,2,1,BMPFile);
	fwrite(&bm.Reserved2,2,1,BMPFile);
	fwrite(&bm.Offset,4,1,BMPFile);

	fwrite(&bm.HeaderSize,4,1,BMPFile);
	fwrite(&bm.Width,4,1,BMPFile);
	fwrite(&bm.Height,4,1,BMPFile);
	fwrite(&bm.Planes,2,1,BMPFile);
	fwrite(&bm.BitsPerPixel,2,1,BMPFile);
	fwrite(&bm.Compression,4,1,BMPFile);
	fwrite(&bm.ImageSize,4,1,BMPFile);
	fwrite(&bm.XPixelsPerMeter,4,1,BMPFile);
	fwrite(&bm.YPixelsPerMeter,4,1,BMPFile);
	fwrite(&bm.ColorsInColorTable,4,1,BMPFile);
	fwrite(&bm.ImportantColorCount,4,1,BMPFile);
	fwrite(bm.rest,bm.HeaderSize-40,1,BMPFile);



	fwrite(bm.ColorTable,bm.ColorsInColorTable*4,1,BMPFile);



	fwrite(bm.GAP1,bm.Offset-bm.HeaderSize-14-bm.ColorsInColorTable*4,1,BMPFile);

	int JunkBytes = 0;

    if ((4-(bm.Width*3)%4) !=4)
    JunkBytes = 4-(bm.Width*3)%4;
    fseek(BMPFile, bm.Offset, SEEK_SET);
	int i;
	for (i = 0; i < bm.Height; i++){
	fwrite(bm.PixelArray+3*bm.Width*i,3,bm.Width,BMPFile);

	int x=0;

	int j=0;
	for (j = 0; j<JunkBytes;j++)
	fwrite(&x,1,1,BMPFile);
    }




}




int main(void) {

	if (sizeof(int)!=4) {
	printf ("error");
	}

	else {
		struct BitMap x;

		FILE *f;
		FILE *f1;
		f = fopen("mapa.bmp","rb");

		if(f!= NULL) {
		x = readBitMap(f);

		fclose(f);
	}

	else {
		printf ("bad file");

	}
		    struct Pix p;
	    p = getPix (6,6,x);
		setPix(0,13,x,p);

		f1 = fopen("mapa.bmp","wb");
		writeBitMap(f1,x);

		fclose(f1);

	}

	return 0;
}