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

typedef int *ROW;

void readFile(char *filename, ROW **image, int *nrows, int *ncols)
{
	FILE *infile;
    char *line= NULL;
    ssize_t read;   
	size_t len=0;
	int i;
    int row, col;
 	int maxpix;
    ROW onerow;

    if ((infile= fopen(filename, "r"))==NULL) {
		  printf("Could not open file\n");
	      exit(0);
	}
    for(i=0; i< 2; i++) {
	    read = getline(&line, &len, infile);
    	printf("%s", line);
    }
	fscanf(infile, "%d %d %d", &(*ncols), &(*nrows), &maxpix);
    printf("Ncols=%d Nrows=%d, Max pixel val=%d\n", *ncols, *nrows, maxpix);

    (*image) = (ROW *)malloc((*nrows)*sizeof(ROW));
    for(i=0; i < *nrows; i++) {
		(*image)[i] = (int *)malloc((*ncols) * sizeof(int));
	}
    for(row=0;row<(*nrows); row++) {
		for(col=0;col<(*ncols); col++) {
           fscanf(infile, "%d",&(*image)[row][col]);
        }
    }
    fclose(infile);

								 
}

void writeFile(char *filename, ROW *image, int nrows, int ncols)
{
    FILE *outfile;
    int row,col;
    outfile=fopen(filename, "w");

    fprintf(outfile, "P2\n#Test PGM file\n%d %d\n255\n", ncols, nrows);
    for(row=0;row<nrows; row++) {
		for(col=0;col<ncols; col++) {
           fprintf(outfile, "%4d",image[row][col]);
           if(col % 10==9) fprintf(outfile, "\n");
           printf("%4d", image[row][col]);
        }
    }

    fclose(outfile);
}

void copyImage(ROW *image, ROW **temp, int nrows, int ncols)
{
    int row, col;
	int i;
    ROW onerow;

    (*temp) = (ROW *)malloc((nrows)*sizeof(ROW));
    for(i=0; i < nrows; i++) {
		(*temp)[i] = (int *)malloc((ncols) * sizeof(int));
	}
}

void horizontalDifferences (ROW *image, ROW **temp, int nrows, int ncols)
{
	int row, col;
       
    for(row=0; row < nrows; row++) {
       (*temp)[row][ncols-1]=0;
       for(col=0; col < (ncols-1); col++)
	   {
       	//	(*temp)[row][col] = ??;
	   }
	}
}       

void verticalDifferences (ROW *image, ROW **temp, int nrows, int ncols)
{
	int row, col;
       
    for(col=0; col < ncols; col++) {
       (*temp)[nrows-1][col]=0;
       for(row=0; row < (nrows-1); row++)
	   {
       	//	(*temp)[row][col] = ??;
	   }
	}
}       

void robertsCross (ROW *image, ROW **temp, int nrows, int ncols)
  //Returns result of applying Roberts' cross operator.
{
	int row, col;

	for(row=0; row< (nrows-1); row++) {
    	(*temp)[row][ncols-1]=0;
      	for(col=0; col<(ncols-1);col++) {
        //	(*temp)[row][col]= ??
		
		}
	}
    for(col=0; col<ncols; col++)
    	(*temp)[nrows-1][col]= 0;
}

void sobel(ROW *image, ROW **temp, int nrows, int ncols)
{
  //Returns result of applying Roberts' cross operator.
	int a,b,c,d,e,f,g,h,i,dx,dy;
	int row, col;
	
    for (row=0; row<(nrows-1); row++) {
    	(*temp)[row][ncols-1]= 0;
      	for(col=0; col< (ncols-1); col++) {
        	if ((row>0) && (col>0)) {
          		a = image[row-1][col-1];
                b = image[row-1][col];
 	          //etc...
		    }
          //  dx = ??;
          //  dy = ??;
          //  (*temp)[row][col] = (int)floor(sqrt(???)));
		}
	}
    for(col=0; col<ncols; col++) {
      	(*temp)[nrows-1][col]=0; 
      	(*temp)[0][col]= 0; 
	}
    for(row=0; row<nrows; row++) {
    	(*temp)[row][ncols-1]=0; 
      	(*temp)[row][0]=0; 
	}
}

int main()
{
   ROW *image;
   ROW *temp;
   int nrows, ncols;
   char *filename="fig1.pgm";
   char *filenameB="fig1Horiz.pgm";
   char *filenameC="fig1Vert.pgm";
   char *filenameD="fig1Roberts.pgm";
   char *filenameE="fig1Sobel.pgm";


   readFile(filename,&image, &nrows, &ncols);
   writeFile(filename, image, nrows, ncols);
   copyImage(image, &temp, nrows, ncols);
   horizontalDifferences(image, &temp, nrows, ncols);	
   writeFile(filenameB, temp, nrows, ncols);
   verticalDifferences(image, &temp, nrows, ncols);	
   writeFile(filenameC, temp, nrows, ncols);
   robertsCross(image, &temp, nrows, ncols);	
   writeFile(filenameD, temp, nrows, ncols);
   sobel(image, &temp, nrows, ncols);	
   writeFile(filenameE, temp, nrows, ncols);

   return 0;
}