#include  "os.h"
#include  "help.h"

char line[LINE_SIZE + 1];
int main (int argc, char *argv[])
{
  long pos;
  int i, n, lineno, ntopics;
  char *s, *topic;
  help_indx entry;
  FILE *rfp, *wfp;

  if (argc < 2 || argc > 3) {
    printf ("Usage:\tmkindx <file_to_be_indexed> <output_index_filename>\n");
    exit (-1);
  }

  if ((rfp = fopen (argv[1], "rb")) == NULL) {
    fprintf (stderr, "can't open %s for reading\n", argv[1]);
    exit (-1);
  }
  if ((wfp = fopen (argv[2], "wb")) == NULL) {
    fprintf (stderr, "can't open %s for writing\n", argv[2]);
    exit (-1);
  }
  pos = 0L;
  lineno = 0;
  ntopics = 0;
  while (fgets (line, LINE_SIZE, rfp) != NULL) {
    ++lineno;

    n = strlen (line);
    if (line[n - 1] != '\n') {
      fprintf (stderr, "line %d: line too long\n", lineno);
    }
    if (line[0] == '&') {
      ++ntopics;

      if (ntopics > 1) {
        entry.len = (int) (pos - entry.pos);
        if (fwrite (&entry, sizeof (help_indx), 1, wfp) < 1) {
          fprintf (stderr, "error writing %s\n", argv[2]);
          exit (-1);
        }
      }
      for (topic = &line[1];
        (*topic == ' ' || *topic == '\t') && *topic != '\0'; topic++);
      for (i = -1, s = topic; *s != '\n' && *s != '\0'; s++) {
        if (i >= TOPIC_NAME_LEN - 1)
          break;
        if (*s != ' ' || entry.topic[i] != ' ')
          entry.topic[++i] = *s;
      }
      entry.topic[++i] = '\0';
      entry.pos = pos + (long) n;
    }
    pos += n;
  }
  entry.len = (int) (pos - entry.pos);
  if (fwrite (&entry, sizeof (help_indx), 1, wfp) < 1) {
    fprintf (stderr, "error writing %s\n", argv[2]);
    exit (-1);
  }
  fclose (rfp);
  fclose (wfp);

  printf ("%d topics indexed\n", ntopics);
  exit (0);
}