#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include "global.h"
 
typedef enum
{
  NONE,
  FIND,
  HIDE
} stegit_mode_t;
 
static void sighandler(int signum)
{
#ifdef DEBUG
  (void) printf("signal %d received\n", signum);
#endif
  error = 1;
}
 
static void usage(void)
{
  (void) fprintf(stderr, "Usage: %s -f | -h [-o <filename>]\n", me);
  (void) fprintf(stderr, "  -f\t\t\tfind mode\n");
  (void) fprintf(stderr, "  -h\t\t\thide mode\n");
  (void) fprintf(stderr, "  [-o <filename>]\toutput filename\n");
  (void) exit(EXIT_FAILURE);
}
 
static void hide(FILE *in, FILE *out)
{
  int ch;
  char *word;
  int insertdot, wordcount = 0;
 
  (void) srandom(time(NULL) * getpid());
  insertdot = 5 + (int)(11.0 * (random() / (RAND_MAX + 1.0)));
  while(!error && (ch = getc(in)) != EOF && ch != '\n')
  {
    if (ch < 0 || ch >= (sizeof(charmap) / sizeof(charmap[0])))
      continue;
 
    word = charmap[ch];
    if (word == NULL)
      continue;
 
    if (wordcount > 0 && putc(' ', out) == EOF)
    {
      (void) printferr("Error while writing to output");
      return;
    }
 
    if (fputs(word, out) == EOF)
    {
      (void) printferr("Error while writing to output");
      return;
    }
 
    ++wordcount;
 
    if (insertdot <= wordcount)
    {
      if (putc('.', out) == EOF)
      {
        (void) printferr("Error while writing to output");
        return;
      }
      insertdot = wordcount + 5 + (int)(11.0 * (random() / (RAND_MAX + 1.0)));
    }
  }
 
  if (!error && wordcount > 0 && putc('\n', out) == EOF)
  {
    (void) printferr("Error while writing to output");
    return;
  }
}
 
static char lookup(char *str)
{
  int i;
  char *str2;
 
  for(i = 0; !error && i < sizeof(charmap) / sizeof(charmap[0]); ++i)
  {
    str2 = charmap[i];
    if (str2 == NULL)
      continue;
    if (strcmp(str2, str) == 0)
      return i;
  }
  return -1;
}
 
static void find(FILE *in, FILE *out)
{
  char buf[80]; /* increase that for more speed */
  size_t bufsize = sizeof(buf) / sizeof(buf[0]);
  size_t read, off = 0;
  char ch, *sep = " .\r\n", *word, *brkt;
  int wordcount = 0;
 
  buf[0] = '\0';
  while(!error && !ferror(in))
  {
    off = strlen(buf);
    if (off >= bufsize - 1)
    {
      errno = 0;
      (void) printferr("Unable to read input words. buffer is too small.");
      return;
    }
 
    read = fread(buf + off, sizeof(buf[0]), bufsize - off - 1, in);
    if (ferror(in))
    {
      (void) printferr("Error while reading from output");
      return;
    }
    buf[read + off] = '\0';
 
    for(word = strtok_r(buf, sep, &brkt);
        !error && word;
        word = strtok_r(NULL, sep, &brkt))
    {
      ch = lookup(word);
      if (ch >= 0)
      {
        if (putc(ch, out) == EOF)
        {
          (void) printferr("Error while writing to output");
          return;
        }
 
        ++wordcount;
        buf[0] = '\0';
        continue;
      }
 
      if (brkt == NULL)
        (void) strcpy(buf, word);
    }
 
    if (read < bufsize - off - 1 || read == 0)
      break;
  }
 
  if (!error && wordcount && putc('\n', out) == EOF)
  {
    (void) printferr("Error while writing to output");
    return;
  }
}
 
int main(int argc, char *argv[])
{
  int opt;
  char *outfile = NULL;
  FILE *fp = NULL;
  struct sigaction new_action, old_action;
  stegit_mode_t mode = NONE;
 
  me = argv[0];
 
  /* install signal handler */
  new_action.sa_handler = sighandler;
  sigemptyset(&new_action.sa_mask);
  new_action.sa_flags = 0; /* to avoid restart of blocking syscalls */
  INSTALL_SIGNAL(SIGINT,   new_action, old_action)
  INSTALL_SIGNAL(SIGQUIT,  new_action, old_action)
  INSTALL_SIGNAL(SIGTERM,  new_action, old_action)
 
  while ((opt = getopt(argc, argv, "fho:")) != -1)
  {
    switch(opt)
    {
      case 'f':
        if (mode != NONE)
          (void) usage();
        mode = FIND;
        break;
      case 'h':
        if (mode != NONE)
          (void) usage();
        mode = HIDE;
        break;
      case 'o':
        outfile = optarg;
        break;
      default:
        (void) usage();
        break;
    }
  }
 
  if (mode == NONE || (mode == FIND && outfile != NULL))
    (void) usage();
 
#ifdef DEBUG
  (void) printf("mode=%s outfile=%s\n", (mode == FIND) ? "FIND" : "HIDE", outfile);
#endif
 
  if (mode == HIDE)
  {
    if (!error && outfile != NULL && (fp = fopen(outfile, "w")) == NULL)
      (void) bailout("%s", outfile);
    if (!error)
      (void) hide(stdin, (fp != NULL) ? fp : stdout);
  }
  else
  {
    if (!error)
      (void) find(stdin, stdout);
  }
 
  if (fp != NULL)
    (void) fclose(fp);
 
  return (error) ? 1 : 0;
}