/* ===========================================
   
   filename:  mergesort.c      
   revision:  February 22, 2006

   1.  C Program to sort a data file containing one
   positive integer on each line. 
   
   Usage:

      mergesort [-f foo.txt]

   where "foo.txt" is a text file with one positive
   integer on each line.

   The program will then sort the lines in "foo.txt"
   and write the output file "new_foo.txt".

   2.  The command line specification of the input file
   is optional.  The default is "random_ints.txt".
   So the default output file is "new_random_ints.txt".

   ========================================== */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "combinatorics.h"

#define MAX_NO_INTS 2000
#define DEFAULT_NO_INTS 100

int main(int argc, char *argv[]) {

  int n = DEFAULT_NO_INTS;
  int i,j,k; 
  int i1,i2, i3; 
  int j1,j2, j3; 
  int no_lines_read = 0;

  char mychar;

  errno_t err;

  int *s;
  int *temp_s;

  char input_filename[100]="random_ints.txt";
  char output_filename[100] = "new_";

  FILE *input_file;
  FILE *output_file;

  // Open file for reading

  for (i = 1; i < argc; i++) {
    if (argv[i][0]== '-') {
      mychar = argv[i][1];
      switch (mychar) {
        case 'n':
          n = atoi(argv[i+1]);
          if (n > MAX_NO_INTS) {
            printf("\nNumber of points is greater than ");
            printf("%d. Exiting.\n",MAX_NO_INTS);
            exit(1);
          }
          break;
        case 'f':
          err = strncpy_s(input_filename,100,argv[i+1],100);
          break;
        default:
          printf("Unrecognized command line option: -%c.\n", mychar);
          printf("Usage: %s [-n filename]\n",argv[0]);
          exit(1);
          break;
      }
    }
  }
  err = strcat_s(output_filename,100,input_filename);

  if ((err  = fopen_s(&input_file, input_filename, "r" )) !=0 ) {
    printf("\nThe input file %s was not opened.  Exiting.\n",input_filename);
    exit(1);
  }

  if ((err  = fopen_s(&output_file, output_filename, "w" )) !=0 ) {
    printf("\nThe output file %s was not opened.  Exiting.\n",output_filename);
    exit(1);
  }

  s = (int *)malloc((n+5)*sizeof(int));
  
  if (s == NULL) {
    printf("\nUnable to allocate memory for sequence s.\n");
    exit(1);
  }

  j1 = 0;

  while(!feof(input_file)) {
    fscanf_s(input_file, "%d\n", &s[j1]);  
    j1++;
  }
  
  j1--;

  sort_segment(s,0,j1);

  for (j2 = 0; j2 <= j1; j2++) {
    fprintf(output_file, "%d\n", s[j2]);
  }

  if (fclose(input_file) != 0) {
    printf("\nError closing input file. Exiting.\n");
    exit(1);
  }
  if (fclose(output_file) != 0) {
    printf("\nError closing output file. Exiting.\n");
    exit(1);
  }
  else {
    printf("\nThe input file \"%s\" was successfully closed.\n", input_filename);
    printf("\nThe output file \"%s\" was successfully\n", output_filename);
    printf("written and closed.\n");
  }
  free(s);
  return(0);
}