/* sound volume get/set code based on code from here:
   https://stackoverflow.com/a/7661176/5737011
   https://stackoverflow.com/questions/7657624/get-master-sound-volume-in-c-in-linux/7661176#7661176 */

//#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <alsa/asoundlib.h>
#include "vol-alsa.h"

#define card_name "default"
#define mixer_name "Master"
#define mixer_index 0

/* TODO: figure out what all this means */
extern int alsa_volume(int flags, unsigned int * volume, unsigned char * mute) {
  snd_mixer_t * handle;
  snd_mixer_elem_t * elem;
  snd_mixer_selem_id_t * sid;

  snd_mixer_selem_id_alloca(&sid);
  snd_mixer_selem_id_set_name(sid, mixer_name);
  snd_mixer_selem_id_set_index(sid, mixer_index);

  if(snd_mixer_open(&handle, 0)<0) return -1;
  if(snd_mixer_attach(handle, card_name)<0) { snd_mixer_close(handle); return -2; }
  if(snd_mixer_selem_register(handle, NULL, NULL)<0) { snd_mixer_close(handle); return -3; }
  if(snd_mixer_load(handle)<0) { snd_mixer_close(handle); return -4; }
  if(!(elem = snd_mixer_find_selem(handle, sid))) { snd_mixer_close(handle); return -5; }

  {
    long minv, maxv, vv;
    int i;
    
    snd_mixer_selem_get_playback_volume_range (elem, &minv, &maxv);
//    fprintf(stderr, "Volume range <%i,%i>\n", minv, maxv);

    if(flags & 1) {
      vv = *volume;
      if(vv>1000) vv = 1000;
      vv = (vv*(maxv-minv)+500)/1000 + minv;
      if(snd_mixer_selem_set_playback_volume(elem, 0, vv) < 0) { snd_mixer_close(handle); return -8; }
      if(snd_mixer_selem_set_playback_volume(elem, 1, vv) < 0) { snd_mixer_close(handle); return -9; }
    }
    if(flags & 4) {
      i = !*mute;
      if(snd_mixer_selem_set_playback_switch(elem, 0, i) < 0) { snd_mixer_close(handle); return -8; }
      if(snd_mixer_selem_set_playback_switch(elem, 1, i) < 0) { snd_mixer_close(handle); return -9; }
    }
    if(flags & 2) {
      if(snd_mixer_selem_get_playback_volume(elem, 0, &vv) < 0) { snd_mixer_close(handle); return -6; }
      if(vv<=minv) vv = 0;
      else if(vv>=maxv) vv = 1000;
      else vv = (1000*(vv-minv)+(maxv-minv)/2)/(maxv-minv);
      *volume = vv;
    }
    if(flags & 8) {
      if(snd_mixer_selem_get_playback_switch(elem, 0, &i) < 0) { snd_mixer_close(handle); return -6; }
      *mute = !i;
    }
  }
  snd_mixer_close(handle);
  return 0;
}