#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include "util/versie.h"


static void usage(FILE *f) {
  fprintf(f,
      "Gebruik: rij [-hV] [EERSTE] [STAP] LAATSTE\n"
      "\n"
      "Druk getallen van EERSTE t/m LAATSTE af, in stappen van STAP.\n"
      "\n"
      "  -h    Toon deze hulptekst\n"
      "  -V    Toon versienummer\n");
}

// Returns pointer to argument array containing the file names
static char** parse_options(int argc, char **argv) {
  int opt;
  while ((opt = getopt(argc, argv, "hV")) != -1) {
    switch (opt) {
      case 'h':
        usage(stdout);
        exit(0);

      case 'V':
        drukkedoos_print_versie(stdout, "rij");
        exit(0);

      case '?':
        fprintf(stderr, "Ongeldige optie: -%c\n", optopt);
        usage(stderr);
        exit(1);
    }
  }

  return argv + optind;
}

int entry_rij(int argc, char **argv) {
  char **args = parse_options(argc, argv);

  // Use 'long long' because that's what strtoll() parses
  long long argnums[3], nnums = 0;
  while (*args && nnums < 3) {
    char *endp;
    errno = 0;
    argnums[nnums++] = strtoll(*args, &endp, 10);
    if (errno == ERANGE) {
      fprintf(stderr, "rij: Getal te groot: %s\n", *args);
      return 1;
    }
    if (!**args || *endp) {
      fprintf(stderr, "rij: Ongeldig getal '%s'\n", *args);
      return 1;
    }
    args++;
  }

  if (nnums == 0) {
    fprintf(stderr, "rij: Missend argument\n");
    return 1;
  }

  if (nnums == 3 && *args) {
    fprintf(stderr, "rij: Teveel argumenten\n");
    return 1;
  }

  long long start, step, end;
  switch (nnums) {
    case 1: start = step = 1; end = argnums[0]; break;
    case 2: start = argnums[0]; step = 1; end = argnums[1]; break;
    case 3: start = argnums[0]; step = argnums[1]; end = argnums[2]; break;
  }

  const long long safeend = end == LLONG_MAX ? LLONG_MAX - 1 : end;

  for (long long i = start; i <= safeend; i += step) {
    printf("%lld\n", i);
  }

  if (end == LLONG_MAX) printf("%lld\n", LLONG_MAX);

  return 0;
}