/*
 * audio.c
 *
 * Moo like a cow
 *
 * (c) 2008-2009 Thomas White <taw@bitwiz.org.uk>
 *
 * This file is part of OpenMooCow - accelerometer moobox simulator
 *
 * OpenMooCow 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.
 *
 * OpenMooCow 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 OpenMooCow.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/* SDL's headers don't like this. Grr. */
//#ifdef HAVE_CONFIG_H
//#include <config.h>
//#endif

#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <SDL.h>
#include <SDL_audio.h>
#include <alsa/asoundlib.h>
#include <math.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <assert.h>

#include "types.h"
#include "audio.h"

static AudioContext *audio_context = NULL;


void audio_trigger_moo()
{
	AudioContext *a = audio_context;

	if ( a->mootex != 0 ) {
		printf("Mootex says 'no'\n");
		return;
	}

	if ( a == NULL ) {
		/* Try to open the audio again */
		printf("Trying to open the audio again...\n");
		audio_setup();
		a = audio_context;
		if ( a == NULL ) return;
	}

	/* Prevent another moo, until we're done */
	a->mootex = 1;

	printf("Moo!\n");

	/* Switch from "setup" to "prepare" mode, reading for writing data */
	snd_pcm_prepare(a->alsa_handle);
	/* Start the moo */
	a->moo_pos = 0;
}


static void *audio_alsa_work(void *data)
{
	AudioContext *a = data;

	while ( !a->finished ) {

		int ret;
		snd_pcm_uframes_t tp;

		if ( a->moo_pos >= a->moo_len ) {
			usleep(1000);
			continue;
		}

		/* Play the full number of frames, or the number of frames
		 * remaining to be played - whichever is the lowest */
		if ( a->moo_len - a->moo_pos > a->alsa_frames ) {
			tp = a->alsa_frames;
		} else {
			tp = a->moo_len - a->moo_pos;
		}

		ret = snd_pcm_writei(a->alsa_handle, a->moo_buf+a->moo_pos, tp);

		if (ret == -EPIPE) {
			fprintf(stderr, "ALSA buffer underrun\n");
			snd_pcm_prepare(a->alsa_handle);
		} else if (ret < 0) {
			fprintf(stderr, "ALSA write error: %s\n",
				        snd_strerror(ret));
		} else if (ret != (int)tp) {
			fprintf(stderr, "ALSA short write, %d frames\n", ret);
		} else {

			/* Successful write */
			a->moo_pos += ret;

			if ( a->moo_pos == a->moo_len ) {

				/* We have finished writing.  Now sleep
				 * until the hardware has caught up. */
				snd_pcm_hwsync(a->alsa_handle);
				//while ( snd_pcm_avail(a->alsa_handle) >= 0 ) {
				//	usleep(1000);
				//}

				/* Drop back to "setup" state */
				snd_pcm_drop(a->alsa_handle);

				/* Not it's safe to moo again */
				a->mootex = 0;

			}

		}

	}

	snd_pcm_drain(a->alsa_handle);
	snd_pcm_close(a->alsa_handle);

	return NULL;
}

static int audio_open_alsa(AudioContext *a)
{
	int ret;
	snd_pcm_t *handle;
	snd_pcm_hw_params_t *params;
	unsigned int val;
	snd_pcm_uframes_t frames;
	int dir;

	ret = snd_pcm_open(&handle, "default",
                         SND_PCM_STREAM_PLAYBACK, 0);
	if ( ret < 0 ) {
		fprintf(stderr, "Couldn't open audio: %s\n", snd_strerror(ret));
		return FALSE;
	}

	snd_pcm_hw_params_alloca(&params);
	snd_pcm_hw_params_any(handle, params);
	snd_pcm_hw_params_set_access(handle, params,
                                     SND_PCM_ACCESS_RW_INTERLEAVED);
	snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);
	snd_pcm_hw_params_set_channels(handle, params, 1); /* One channel */
	val = 44100;	/* 44.1 kHz */
	snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);
	frames = 32;
	snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);
	ret = snd_pcm_hw_params(handle, params);
	if ( ret < 0 ) {
		fprintf(stderr, "Couldn't set parameters: %s\n",
		                 snd_strerror(ret));
		return FALSE;
	}

	/* Get the actual period size */
	snd_pcm_hw_params_get_period_size(params, &frames, &dir);
	a->alsa_frames = frames;

	a->alsa_handle = handle;
	a->finished = 0;
	a->alsa_thread = g_thread_create(audio_alsa_work, a, TRUE, NULL);

	return TRUE;
}


/* Audio initial setup */
void audio_setup()
{
	SDL_AudioSpec wave;
	Uint8 *data;
	Uint32 dlen;
	SDL_AudioCVT cvt;
	AudioContext *a;

	/* Create audio context */
	a = malloc(sizeof(AudioContext));
	assert(a != NULL);
	a->mootex = 1;		/* Not ready yet */
	audio_context = a;

	if ( audio_open_alsa(a) ) {
		printf("Using ALSA for audio.\n");
	} else {
		exit(1);
	}

	if ( SDL_LoadWAV(DATADIR"/openmoocow/moo.wav", &wave, &data, &dlen)
								== NULL ) {
		fprintf(stderr, "Couldn't load moo sound: %s\n",
				SDL_GetError());
		goto out;
	}
	SDL_BuildAudioCVT(&cvt, wave.format, wave.channels, wave.freq,
				AUDIO_S16, 1, 44100);
	cvt.buf = malloc(dlen*cvt.len_mult);
	if ( cvt.buf == NULL ) {
		fprintf(stderr, "Not enough memory to convert audio \n");
		goto out;
	}
	memcpy(cvt.buf, data, dlen);
	cvt.len = dlen;
	SDL_ConvertAudio(&cvt);
	SDL_FreeWAV(data);

	a->moo_len = cvt.len_cvt/2 - 2;	/* Convert bytes to samples */
	a->moo_pos = a->moo_len;	/* Play nothing to start with */
	a->moo_buf = (Sint16 *)cvt.buf;

out:
	a->mootex = 0;		/* Ready now */
}

void audio_shutdown()
{
	AudioContext *a = audio_context;

	if ( a == NULL ) return;

	a->finished = 1;

	/* Now this can be freed */
	free(a);
}