/* 
 * Copyright (c) 2017 Kris Occhipint.
 * http://filmsbykris.com 
 *
 * Detects if Volume Buttons are being pressed on SADES USB Headphones
 *
 * 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, version 3.
 *
 * 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 <stdlib.h>
#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <linux/input.h>

#include <string.h>
#include <stdio.h>

int main(void){

  //get input device
  const char *dev = "/dev/input/by-id/usb-C-Media_Electronics_Inc._USB_Audio_Device-event-if03";
  struct input_event ev;
  ssize_t n;
  int fd;

  //open device for reading
  fd = open(dev, O_RDONLY);
  //exit on error opening device
  if (fd == -1) {
    fprintf(stderr, "Cannot open %s: %s.\n", dev, strerror(errno));
    return -1;
  }
  while (1) {
    n = read(fd, &ev, sizeof ev);
    if (ev.value == 1){
      if ((int)ev.code == 115){
        printf("Volume Up\n");
      }else if ((int)ev.code == 114){
        printf("Volume Down\n");
      }
    }
  }

  return 0;
}