/*************************************************************************
 * Author: Eduardo M. Fleury - talkto (at) eduardofleury.com             *
 * Site  : http://eduardofleury.com                                      *
 * Desc. : Example 3 from post: http://blog.eduardofleury.com/?p=16      *
 *                                                                       *
 *************************************************************************
 *                                                                       *
 * This program is free software: you can redistribute it and/or modify  *
 * it under the terms of the GNU General Public License as published by  *
 * the Free Software Foundation, either version 3 of the License, or     *
 * (at your option) any later version.                                   *
 *                                                                       *
 * This program is distributed in the hope that it will be useful,       *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 * GNU General Public License for more details.                          *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *                                                                       *
 *************************************************************************/

#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <unistd.h>
#include <poll.h>
#include <termios.h>
#include <time.h>

#define VMIN_VALUE 0
#define VTIME_VALUE 50

int main() {

  int our_opt = 0;                 /* Our secret number    */
  char user_opt = 0;               /* User guess           */
  
  int bytes_read = 0;              /* Number of bytes read */

  struct termios tios, orig_tios;  /* terminal settings    */

  
  /* Seed random number gen */
  srandom(time(0));
  
  /* Get our number */
  our_opt = random() % 10;
  
  /**********************************************************************/
  /* Ok, that's what we're here for... Lets play with terminal settings */
  /**********************************************************************/

  /* Get current terminal settings */
  if (tcgetattr(0, &orig_tios)){
    printf("Error getting current terminal settings\n");
    return 3;
  }

  /* Copy that to "tios" and play with it */
  tios = orig_tios;
  
  /* We want to disable the canonical mode */
  tios.c_lflag &= ~ICANON;

  /* And make sure ECHO is enabled */
  tios.c_lflag |= ECHO;

  /* Set timeout */
  tios.c_cc[VMIN] = VMIN_VALUE;
  tios.c_cc[VTIME] = VTIME_VALUE;
  
  /* Apply our settings */
  if (tcsetattr(0, TCSANOW, &tios)){
    printf("Error applying terminal settings\n");
    return 3;
  }

  /* Check whether our settings were correctly applied */
  if (tcgetattr(0, &tios)){
    tcsetattr(0, TCSANOW, &orig_tios);
    printf("Error while asserting terminal settings\n");
    return 3;
  }

  if ( (tios.c_lflag & ICANON)         || !(tios.c_lflag & ECHO) ||
       (tios.c_cc[VMIN] != VMIN_VALUE) ||  (tios.c_cc[VTIME] != VTIME_VALUE) ) {
    tcsetattr(0, TCSANOW, &orig_tios);
    printf("Could not apply all terminal settings\n");
    return 3;
  }

  
  printf("Choose a number [0-9]: ");
  fflush(stdout);

  bytes_read = read(0, &user_opt, 1);

  if (!bytes_read) {
    /* We got a timeout */
    tcsetattr(0, TCSANOW, &orig_tios);
    printf("\nSorry, time is up.\n");
    return 2;
  }
  else if (bytes_read < 0){
    tcsetattr(0, TCSANOW, &orig_tios);
    printf("\nRead() error\n");
    return 3;
  }

  /* Restore terminal settings */
  tcsetattr(0, TCSANOW, &orig_tios);

  user_opt -= 48;

  if (user_opt == our_opt){
    printf("\nCool, you just won a helluva car!\n");
    return 0;
  }
  
  printf("\nThe right answer is %d. Take a walk, alright?\n", our_opt);
  return 1;

}