/***************************************************************************
                            alsa.c  -  description
                             -------------------
    begin                : Sat Mar 01 2003
    copyright            : (C) 2002 by Pete Bernert
    email                : BlackDove@addcom.de
 ***************************************************************************/
/***************************************************************************
 *                                                                         *
 *   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 2 of the License, or     *
 *   (at your option) any later version. See also the license.txt file for *
 *   additional informations.                                              *
 *                                                                         *
 ***************************************************************************/

#include <stdio.h>
#include <string.h>
#define ALSA_PCM_NEW_HW_PARAMS_API
#define ALSA_PCM_NEW_SW_PARAMS_API
#include <alsa/asoundlib.h>
#include "out.h"

static snd_pcm_t *handle = NULL;
static snd_pcm_uframes_t buffer_size;

static void alsa_finish(void);

// SETUP SOUND
static int alsa_init(void)
{
 snd_pcm_hw_params_t *hwparams;
 snd_pcm_status_t *status;
 snd_ctl_t *ctl_handle = NULL;
 snd_ctl_card_info_t *info;
 unsigned int pspeed;
 int pchannels;
 int format;
 unsigned int buffer_time = 100000;
 unsigned int period_time = buffer_time / 4;
 const char *alsa_name = "default";
 const char *name;
 int retval = -1;
 int err;

 name = getenv("ALSA_NAME");
 if (name != NULL)
  alsa_name = name;

 snd_ctl_card_info_alloca(&info);
 if ((err = snd_ctl_open(&ctl_handle, alsa_name, 0)) < 0) {
  printf("control open: %s\n", snd_strerror(err));
 }
 else if ((err = snd_ctl_card_info(ctl_handle, info)) < 0) {
  printf("control info: %s\n", snd_strerror(err));
  snd_ctl_card_info_clear(info);
 }
 if (ctl_handle != NULL)
  snd_ctl_close(ctl_handle);

 name = snd_ctl_card_info_get_name(info);
 if (name != NULL) {
  if (strcasecmp(name, "PulseAudio") == 0) {
    // PulseAudio's ALSA emulation is known to be broken..
    printf("alsa: refusing to run under PulseAudio's emulation\n");
    return -1;
  }
  else {
    printf("alsa: using '%s', set ALSA_NAME to change\n", name);
  }
 }

 pchannels=2;

 pspeed = 44100;
 format = SND_PCM_FORMAT_S16;

 if ((err = snd_pcm_open(&handle, alsa_name, 
                      SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK)) < 0)
  {
   printf("Audio open error: %s\n", snd_strerror(err));
   return -1;
  }

 if((err = snd_pcm_nonblock(handle, 0))<0)
  {
   printf("Can't set blocking moded: %s\n", snd_strerror(err));
   goto out;
  }

 snd_pcm_hw_params_alloca(&hwparams);

 if((err=snd_pcm_hw_params_any(handle, hwparams))<0)
  {
   printf("Broken configuration for this PCM: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_access(handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED))<0)
  {
   printf("Access type not available: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_format(handle, hwparams, format))<0)
  {
   printf("Sample format not available: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_channels(handle, hwparams, pchannels))<0)
  {
   printf("Channels count not available: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_rate_near(handle, hwparams, &pspeed, 0))<0)
  {
   printf("Rate not available: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_buffer_time_near(handle, hwparams, &buffer_time, 0))<0)
  {
   printf("Buffer time error: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params_set_period_time_near(handle, hwparams, &period_time, 0))<0)
  {
   printf("Period time error: %s\n", snd_strerror(err));
   goto out;
  }

 if((err=snd_pcm_hw_params(handle, hwparams))<0)
  {
   printf("Unable to install hw params: %s\n", snd_strerror(err));
   goto out;
  }

 snd_pcm_status_alloca(&status);
 if((err=snd_pcm_status(handle, status))<0)
  {
   printf("Unable to get status: %s\n", snd_strerror(err));
   goto out;
  }

 buffer_size = snd_pcm_status_get_avail(status);
 retval = 0;

out:
 if (retval != 0)
  alsa_finish();
 return retval;
}

// REMOVE SOUND
static void alsa_finish(void)
{
 if(handle != NULL)
  {
   snd_pcm_drop(handle);
   snd_pcm_close(handle);
   handle = NULL;
  }
}

static float alsa_capacity(void) {
 int l;

 if (handle == NULL) return 0;
 if (buffer_size == 0) return 0;

 l = snd_pcm_avail(handle);
 if (l < 0) return 0;

 return (float)l / buffer_size;
}

// GET BYTES BUFFERED
static int alsa_busy(void)
{
 return alsa_capacity() < 0.5;
}

// FEED SOUND DATA
static void alsa_feed(void *pSound, int lBytes)
{
 char sbuf[4096];

 if (handle == NULL) return;

 if (snd_pcm_state(handle) == SND_PCM_STATE_XRUN)
  {
   memset(sbuf, 0, sizeof(sbuf));
   snd_pcm_prepare(handle);
   snd_pcm_writei(handle, sbuf, sizeof(sbuf) / 4);
   snd_pcm_writei(handle, sbuf, sizeof(sbuf) / 4);
   snd_pcm_writei(handle, sbuf, sizeof(sbuf) / 4);
  }
 else
  {
   int l = snd_pcm_avail(handle);
   if (l < lBytes / 4)
    {
     if (l == 0)
      return;

     lBytes = l * 4;
    }
  }

 snd_pcm_writei(handle, pSound, lBytes / 4);
}

void out_register_alsa(struct out_driver *drv)
{
	drv->name = "alsa";
	drv->init = alsa_init;
	drv->finish = alsa_finish;
	drv->busy = alsa_busy;
	drv->feed = alsa_feed;
  drv->capacity = alsa_capacity;
}