/*
 * Project : Embedding SWI-Prolog in a C program.
 *
 * Author : Lens Stephane Ulg
 * Date   : 10/2009
 *
 * Sort a list.
 *
 */

#include <stdio.h>
#include <pl/SWI-Prolog.h>

#define MAX_STRING_SIZE 32


void pl_put_list_nstrings(term_t, int, char (*)[MAX_STRING_SIZE]);



int main(int argc, char *argv[])
{
  int i, j, res;
  char list[10][MAX_STRING_SIZE];
  char *sortedListWrited;

  /* Initialise Prolog */
  if ( !PL_initialise(argc, argv) )
    PL_halt(1);

  /* Get the 10 strings to sort */
  printf("Sort 10 strings (Rem : Max %i chars for a string)\n\n",
         MAX_STRING_SIZE);
  for (i = 0; i < 10; i++)
    {
      printf("Next string to sort : ");
      if( !fgets(list[i], MAX_STRING_SIZE, stdin) )
        PL_halt(1);

      for (j = 0; j < MAX_STRING_SIZE; j++)
        if (list[i][j] == '\n')
          {
            list[i][j] = '\0';
            break;
          }
    }

  /* Define terms to use with Prolog */
  term_t h0 = PL_new_term_refs(2);
  term_t h1 = h0 + 1;

  /* Transform the list of strings to Prolog term */
  pl_put_list_nstrings(h0, 10, list);

  /* Call the predicate */
  res = PL_call_predicate(NULL, PL_Q_NORMAL,
                          PL_predicate("msort", 2, "user"), h0);
  if (res != 1)
    {
      fprintf(stderr, "Error with the predicate !\n");
      PL_halt(1);
      return(1);
    }

  /* Print the sorted list */
  printf("\nSorted List :\n\n");
  PL_get_chars(h1, &sortedListWrited, CVT_WRITE);
  printf("%s\n\n",sortedListWrited);

  /* Stop Prolog */
  PL_halt(0);           /* Stop Prolog */
  return 0;
}



/* Put a list of n strings to prolog atom */
void pl_put_list_nstrings(term_t l, int n, char (*words)[MAX_STRING_SIZE])
{
  fid_t fid = PL_open_foreign_frame();

  term_t a = PL_new_term_ref();

  PL_put_nil(l);
  while(n--)
    {
      PL_put_atom_chars(a, words[n]);
      PL_cons_list(l, a, l);
    }

  PL_close_foreign_frame(fid);
}