#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>

const int maxsize=1000;

int main()
{
    int image1[maxsize][maxsize];
    int image2[maxsize][maxsize];
    int rows, cols;
    int row, col;
    int maxpixel;
    int totallines;
    struct timeval tv;
    struct timezone tz;
    long starttimeSec, starttimeMicro;
    long endtimeSec, endtimeMicro;
    long totalSec, totalMicro;   
    char *line = NULL;
    ssize_t inputline;
    size_t len=0;
    FILE *infile;
    FILE *outfile;

  /*  if ((infile=fopen("ISS-four.pgm", "r")) == NULL) {
        printf("Could not open file\n");
        exit(0);
    }
*/
    if ((outfile=fopen("fig1Test.pgm", "w")) == NULL) {
        printf("Could not open file\n");
        exit(0);
    }

   if ((infile=fopen("fig1.pgm", "r")) == NULL) {
        printf("Could not open file\n");
        exit(0);
    }
    inputline = getline(&line, &len, infile);  // read the format line
    inputline = getline(&line, &len, infile);  // read the comment line
    fscanf(infile,"%d %d", &cols, &rows);
    fscanf(infile,"%d", &maxpixel);
    printf("Rows=%d  Cols=%d  Max pixel value=%d\n", rows, cols, maxpixel);
    totallines = rows*cols;
    printf("Totallines=%d\n", totallines);
    for(row=0; row<rows; row++)
       for(col=0; col<cols; col++)
           fscanf(infile, "%d", &image1[row][col]);
    printf("Starting image processing...\n");
    gettimeofday(&tv, &tz);
    starttimeSec = tv.tv_sec;
    starttimeMicro = tv.tv_usec;
    printf("begin (date_and_time):  %d sec, %d microsec\n", starttimeSec,
                     starttimeMicro);
    for(row=0; row<rows; row++)
        for(col=0; col<cols; col++) {
      /*
            image2[row][col]= image1[row][col] * 1.5;
            if (image2[row][col] > 255)
                image2[row][col] = 255;
      */
    /*  // Horizontal differencing:
      image2[row][col] = abs(image1[row][col+1] - image1[row][col]);
      if (col == cols-1) image2[row][col] = 0;
//   	    Set the pixels in the last column equal to 0
     */
  
   // Robert's cross

    image2[row][col] = abs(image1[row][col-1] - image1[row][col+1]) +
                      abs(image1[row-1][col] - image1[row+1][col]);
     if (row == 0 || row == rows-1 || col == 0 || col == cols-1) image2[row][col] = 0;
  //	   Set the first and last rows and cols to 0
  
	}
    gettimeofday(&tv, &tz);
    endtimeSec = tv.tv_sec;
    endtimeMicro = tv.tv_usec;

    printf("End image processing\n");
    printf("end (date_and_time):  %d sec, %d microsec\n", endtimeSec, 
                        endtimeMicro);

    if (endtimeSec > starttimeSec)
    {
       totalSec = endtimeSec-starttimeSec;
       totalMicro = endtimeMicro + (1000000 - starttimeMicro);
    } else {
       totalSec = 0;
       totalMicro = endtimeMicro - starttimeMicro;
    }
   
    printf("Total time = %d sec, %d microsec\n", totalSec, totalMicro);

    fprintf(outfile,"P2\n");
    fprintf(outfile, "# Test file\n%d %d\n%d\n", cols, rows, maxpixel);
    for(row = 0; row<rows;row++)
        for(col = 0; col<cols; col++)
            fprintf(outfile,"%d\n", image2[row][col]);
    fclose(outfile);

    return 0;
}