#include "header.h"

/* comparison function needed for quicksort -- sorts
 * backwards */
int
compare (const void * a, const void * b) {
  struct dfreq *a1, *b1;
  a1 = (struct dfreq *) a;
  b1 = (struct dfreq *) b;
  return (b1->count - a1->count);
}

/* zero the multi-dim array before main logic */
int 
zero (long arr[SIZE][SIZE]) {
  int i, j;
  for (i = 0; i < SIZE; i++) {
    for (j = 0; j < SIZE; j++) {
      arr[i][j] = 0;
    }
  }
  return 0;
}

/* move multi-dimensional array data to a dfreq array */
int
transfer (long arr[SIZE][SIZE]) {
  int i, j, k;
  /* transfer multi-dim array data to struct array */
  k = 0;
  for (int i = 0; i < SIZE; i++) {
    for (int j = 0; j < SIZE; j++) {
      pd[k].code1 = i;
      pd[k].code2 = j;
      pd[k].count = arr[i][j];
      k++;
    }
  }

  return 0;
}

int
main (int argc, char *argv[]) {
  long array[SIZE][SIZE];
  FILE *fp;
  int i, sqrsize = SIZE*SIZE;
  unsigned char   uc[NMax+1]; // TODO: why NMax + 1 ?
  char Format[20]; // store formating info for scanf
  sprintf(Format, "%%%dc", NMax);

  clock_t	start, stop;
  start = clock();
  zero(array);

  /* file reading logic! */
  fp = fopen(argv[1], "r");

  /* In order to change the number of characters being read
   * at once through fscanf, I have made the following logic
   * execute once and then start looping if there are more
   * characters in the file.  The initial case is different
   * than the following cases because there is no clast to
   * deal with. 
   */
  int c1, c2, clast, nchar; // current character ascii values
  /* open file for reading, send data to multi-dim array */
  if (fscanf(fp, Format, uc) > 0) {
    nchar = strlen(uc);
    clast = uc[nchar-1];
    c1 = uc[0];
    for (i = 1; i < nchar; i++) {
      c2 = uc[i];
      array[c1][c2]++;
      c1 = c2;
    }
  }

  while (fscanf(fp, Format, uc) > 0) {
    nchar = strlen(uc); // store number of chars taken this loop
    c1 = uc[0];
    array[clast][c1]++; // add character pairs between fscans
    clast = uc[nchar-1]; // store last char from this loop
    for (i = 1; i < nchar; i++) {
      c2 = uc[i];
      array[c1][c2]++;
      c1 = c2;
    }
  }

  fclose(fp);

  transfer(array);

  qsort (pd, sqrsize, sizeof(struct dfreq), compare);

  /* print NOut most frequent dipthongs */
  for (i = 0; i < NOut; i++) {
    int c1 = pd[i].code1;
    int c2 = pd[i].code2;

    if (isprint(c1) && isprint(c2)) {
      printf("(%3d,%3d)  %c%c  %d\n",
        c1, c2, c1, c2, pd[i].count);
    }
    else {
      printf("(%3d,%3d)      %d\n",
        c1, c2, pd[i].count);
    }
  }

  stop = clock();
  printf("\nElapsed time = %g Seconds\n", 
    (stop-start)/((float) CLOCKS_PER_SEC));

  return 0;
}