#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>

/* See http://en.wikipedia.org/wiki/Binary_numeral_system#Decimal for the  */
/* principle of the conversion algorithm used here.                        */

void dec2binstr(int in, char *out, int outlen) {
  char *outend = out + outlen;	/* Initialize a pointer to work the string */
  *outend = '\0';		/* from behind and insert the ASCII 0      */

  while (in) {                  /* Fill wih binary digits from LSB to MSB  */
    outend--;
    switch (in % 2) {
      case 0:
        *outend = '0'; break;
      case 1:
        *outend = '1'; break;
    }
    in = in / 2;
  }

  while (outend > out) {	/* Fill with '0's until beginning of out   */
    outend--;
    *outend = '0';
  }
}

void printhelp(char *callname) {
  printf("USAGE: %s [-s] [-d] [-h]\n", callname);
}

int main(int argc, char *argv[]) {
  int opt_seconds = 0;
  int opt_decimal = 0;
  char inarg;

  while ((inarg = getopt (argc, argv, "sdhv")) != -1)
  switch (inarg) {
    case 's':
      opt_seconds = 1;
      break;
    case 'd':
      opt_decimal = 1;
      break;
    case 'h':
      printhelp(argv[0]);
      return 0;
      break;
    case 'v':
      printf("bintime 0.0.1beta\n");
      return 0;
      break;
    default:
      printhelp(argv[0]);
      return 1;
      break;
  }

  time_t curtime;
  struct tm *timedata;
  curtime = time(0);
  timedata = localtime(&curtime);
  int twelve_hour;

  char bin_hour[5];		/* only four digits for the hour */
  char bin_min[7];
  char bin_sec[7];

  twelve_hour = timedata->tm_hour;
  if (twelve_hour > 12) { twelve_hour -= 12; }

  dec2binstr(twelve_hour, bin_hour, 4);
  dec2binstr(timedata->tm_min, bin_min, 6);
  if (opt_seconds) { dec2binstr(timedata->tm_sec, bin_sec, 6); }

  /* I thought a lot about how to do this and I've decided to rather go *
   * with a bunch of printf(); lines than to do some kind of smartass   *
   * printf("%s  %s\n", bin_min, dec_min) black voodoo thing, because   *
   * that would involve initializing an empty dec_min string and then   *
   * filling it if needed. And since this is C and not Perl, that would *
   * be Shooting Myself In The Foot(tm) big time.                       */

  if (opt_decimal) {
    if (timedata->tm_hour < 10) {
      printf(" %s   (0%ih)\n", bin_hour, timedata->tm_hour); }
    else {
      printf(" %s   (%ih)\n", bin_hour, timedata->tm_hour); }

    if (timedata->tm_min < 10) {
      printf("%s  (0%im)\n", bin_min, timedata->tm_min); }
    else {
      printf("%s  (%im)\n", bin_min, timedata->tm_min); }

    if (opt_seconds) {
      if (timedata->tm_sec < 10) {
        printf("%s  (0%is)\n", bin_sec, timedata->tm_sec); }
      else {
        printf("%s  (%is)\n", bin_sec, timedata->tm_sec); }
    }
  }
  else {			/* Life's much easier without decimal! */
    printf(" %s\n%s\n", bin_hour, bin_min);
    if (opt_seconds) {
      printf("%s\n", bin_sec); }
  }

  return 0;
}