#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <linux/input.h>

#ifndef GPIO
#define GPIO 4
#endif

#define STRINGIFY(a) #a
#define STRINGIFY_HARDER(a) STRINGIFY(a)
#define GPIO_STR STRINGIFY_HARDER(GPIO)


char *names[KEY_MAX + 1] =
  { "", "", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "-", "=", "",
  "\t", "q", "w", "e", "r", "t", "y", "u", "i", "o", "p", "[", "]", "", "",
    "a", "s", "d", "f", "g",
  "h", "j", "k", "l", ";", "'", "`", "", "\\", "z", "x", "c", "v", "b", "n",
    "m", ",", ".",
  "/"
};

static char *
strcasestr (const char *haystack, const char *needle)
{
  size_t len = strlen (needle);

  for (; *haystack; haystack++)
    {

      if (!strncasecmp (haystack, needle, len))
        return (char *) haystack;

    }

  return NULL;

}

static int
squirt (const char *fn, const char *content)
{
  size_t len = strlen (content);
  int fd = open (fn, O_WRONLY);
  int ret = -1;

  if (fd < 0)
    return ret;

  if (write (fd, content, len) == len)
    ret = 0;

  close (fd);
  return ret;
}

int
open_ykhid (void)
{
#define  MAX_DEV	64
  char name[128];
  unsigned i;
  int fd;

  for (i = 0; i < MAX_DEV; ++i)
    {
      sprintf (name, "/dev/input/event%d", i);
      fd = open (name, O_RDWR);
      if (fd < 0)
        continue;

      ioctl (fd, EVIOCGNAME (sizeof (name)), name);
      name[sizeof (name) - 1] = 0;

      if (strcasestr (name, "yubikey"))
        return fd;

      close (fd);
    }

  return -1;
}



static int
get_string_with_timeout (int fd, struct timeval *tv, char *buf,
                         size_t buf_len)
{
  fd_set rfds;
  struct input_event ev;

  if (buf_len)
    buf_len--;


  FD_ZERO (&rfds);
  for (;;)
    {
      FD_SET (fd, &rfds);

      if (select (fd + 1, &rfds, NULL, NULL, tv) < 1)
        break;

      if (read (fd, &ev, sizeof (struct input_event)) !=
          sizeof (struct input_event))
        continue;

      if (ev.type != EV_KEY)
        continue;

      if (buf_len && ev.code == KEY_ENTER && !ev.value)
        return 0;

      if (!ev.value)
        continue;

// printf("code %d (%s)\n",ev.code,names[ev.code]);

      if (buf_len && names[ev.code][0])
        {
          *(buf++) = names[ev.code][0];
          *buf = 0;
          buf_len--;
        }
    }


  return -1;
}

int
main (int argc, char *argv[])
{
  int fd = open_ykhid ();
  struct timeval tv;
  char ret[128];


  squirt ("/sys/class/gpio/export", GPIO_STR);
  squirt ("/sys/class/gpio/gpio" GPIO_STR "/direction", "out");
  squirt ("/sys/class/gpio/gpio" GPIO_STR "/value", "0");


  tv.tv_sec = 0;
  tv.tv_usec = 100;
  get_string_with_timeout (fd, &tv, NULL, 0);

  squirt ("/sys/class/gpio/gpio" GPIO_STR "/value", "1");


  tv.tv_sec = 2;
  tv.tv_usec = 0;

  get_string_with_timeout (fd, &tv, ret, sizeof (ret));

  squirt ("/sys/class/gpio/gpio" GPIO_STR "/value", "0");

  printf ("Access-Control-Allow-Origin: *\n");
  printf ("Content-Type: text/plain\n\n%s\n", ret);

  return 0;
}