/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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.

 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#include "../mixer.h"
#include <sci_memory.h>
#include <dc/sound/sound.h>
#include <stream.h>
#include <sys/queue.h>

#define FEED_MODE_ALIVE 0
#define FEED_MODE_IDLE 1
#define FEED_MODE_DIEING 2
#define FEED_MODE_DEAD 3
#define FEED_MODE_RESTART 4

typedef struct feed_state {
	/* Queue entry. */
	TAILQ_ENTRY(feed_state) entry;

	/* Whether feed is alive or dead. */
	int mode;

	/* Blank gap in frames. */
	int gap;

	/* Stream handle. */
	snd_stream_hnd_t handle;

	/* Feed. */
	sfx_pcm_feed_t *feed;

	/* Timestamp of next frame requested by stream driver. */
	sfx_timestamp_t time;
} feed_state_t;

TAILQ_HEAD(feed_list, feed_state) feeds;

/* Buffer size in samples. */
#define BUF_SIZE 0x4000

static char buf[BUF_SIZE * 2];

static feed_state_t *
find_feed_state(snd_stream_hnd_t hnd) {
	feed_state_t *state;
	TAILQ_FOREACH(state, &feeds, entry) {
		if (state->handle == hnd)
			return state;
	}

	return NULL;
}

static void
query_timestamp(feed_state_t *state) {
	sfx_pcm_feed_t *feed = state->feed;

	if (feed->get_timestamp) {
		sfx_timestamp_t stamp;
		int val = feed->get_timestamp(feed, &stamp);

		switch (val) {
		case PCM_FEED_TIMESTAMP:
			state->gap = sfx_timestamp_frame_diff(stamp, state->time);

			if (state->gap >= 0)
				state->mode = FEED_MODE_ALIVE;
			else {
				long secs, usecs;

				state->mode = FEED_MODE_RESTART;
				sci_gettime(&secs, &usecs);
				state->time = sfx_new_timestamp(secs, usecs, feed->conf.rate);
				state->gap = sfx_timestamp_frame_diff(stamp, state->time);

				if (state->gap < 0)
					state->gap = 0;
			}
			break;
		case PCM_FEED_IDLE:
			state->mode = FEED_MODE_IDLE;
			break;
		case PCM_FEED_EMPTY:
			state->mode = FEED_MODE_DIEING;
			state->gap = BUF_SIZE;
		}
	} else {
		state->mode = FEED_MODE_DIEING;
		state->gap = BUF_SIZE;
	}
}

void
U8_to_S16(char *buf, int frames, int stereo) {
	int samples = frames * (stereo ? 2 : 1);
	int i;

	for (i = samples - 1; i >= 0; i--) {
		buf[i * 2 + 1] = (unsigned char) buf[i] - 128;
		buf[i * 2] = 0;
	}
}

static void *
callback(snd_stream_hnd_t hnd, sfx_timestamp_t timestamp, int bytes_req, int *bytes_recv) {
	feed_state_t *state = find_feed_state(hnd);
	sfx_pcm_feed_t *feed;
	int channels, frames_req;
	int frames_recv = 0;

	assert(state);

	state->time = timestamp;
	feed = state->feed;
	channels = feed->conf.stereo == SFX_PCM_MONO ? 1 : 2;
	frames_req = bytes_req / 2 / channels;

	while (frames_req != frames_recv) {
		int frames_left = frames_req - frames_recv;
		char *buf_pos = buf + frames_recv * channels * 2;

		if (state->mode == FEED_MODE_IDLE)
			query_timestamp(state);

		if (state->mode == FEED_MODE_IDLE) {
			memset(buf_pos, 0, frames_left * channels * 2);

			state->time = sfx_timestamp_add(state->time, frames_left);
			break;
		}

		if (state->gap) {
			int frames = state->gap;

			if (frames > frames_left)
				frames = frames_left;

			memset(buf_pos, 0, frames * channels * 2);

			state->gap -= frames;
			frames_recv += frames;
			state->time = sfx_timestamp_add(state->time, frames);
			if (!state->gap && state->mode == FEED_MODE_DIEING) {
				state->mode = FEED_MODE_DEAD;
				break;
			}
		} else {
			int frames = feed->poll(feed, buf_pos, frames_left);

			if (feed->conf.format == SFX_PCM_FORMAT_U8)
				U8_to_S16(buf_pos, frames, feed->conf.stereo != SFX_PCM_MONO);

			frames_recv += frames;
			state->time = sfx_timestamp_add(state->time, frames);

			if (frames < frames_left)
				query_timestamp(state);
		}
	}

	*bytes_recv = bytes_req;
	return buf;
}

static int
mix_init(sfx_pcm_mixer_t *self, sfx_pcm_device_t *device) {
	if (snd_stream_init() < 0) {
		fprintf(stderr, "[dc-mixer] Failed to initialize streaming sound driver\n");
		return SFX_ERROR;
	}

	TAILQ_INIT(&feeds);

	return SFX_OK;
}

static void
mix_subscribe(sfx_pcm_mixer_t *self, sfx_pcm_feed_t *feed) {
	feed_state_t *state = sci_malloc(sizeof(feed_state_t));
	long secs, usecs;

	if ((feed->conf.format != SFX_PCM_FORMAT_S16_LE) &&
	        (feed->conf.format != SFX_PCM_FORMAT_U8)) {
		fprintf(stderr, "[dc-mixer] Unsupported feed format\n");
		feed->destroy(feed);
		return;
	}

	state->handle = snd_stream_alloc(callback, BUF_SIZE);

	if (state->handle == SND_STREAM_INVALID) {
		fprintf(stderr, "[dc-mixer] Failed to allocate stream handle\n");
		feed->destroy(feed);
		return;
	}

	feed->frame_size = SFX_PCM_FRAME_SIZE(feed->conf);
	state->mode = FEED_MODE_ALIVE;
	state->feed = feed;
	state->gap = 0;

	TAILQ_INSERT_TAIL(&feeds, state, entry);

	sci_gettime(&secs, &usecs);
	state->time = sfx_new_timestamp(secs, usecs, feed->conf.rate);
	snd_stream_start(state->handle, feed->conf.rate,
	                 feed->conf.stereo != SFX_PCM_MONO);
}

static void
mix_exit(sfx_pcm_mixer_t *self) {
	snd_stream_shutdown();
}

static int
mix_process(sfx_pcm_mixer_t *self) {
	feed_state_t *state, *state_next;

	TAILQ_FOREACH(state, &feeds, entry) {
		snd_stream_poll(state->handle);
	}

	state = TAILQ_FIRST(&feeds);
	while (state) {
		state_next = TAILQ_NEXT(state, entry);
		if (state->mode == FEED_MODE_DEAD) {
			snd_stream_stop(state->handle);
			snd_stream_destroy(state->handle);
			state->feed->destroy(state->feed);
			TAILQ_REMOVE(&feeds, state, entry);
		} else if (state->mode == FEED_MODE_RESTART) {
			snd_stream_stop(state->handle);
			snd_stream_start(state->handle, state->feed->conf.rate,
			                 state->feed->conf.stereo != SFX_PCM_MONO);
			state->mode = FEED_MODE_ALIVE;
		}
		state = state_next;
	}

	return SFX_OK;
}

static void
mix_pause(sfx_pcm_mixer_t *self) {
}

static void
mix_resume(sfx_pcm_mixer_t *self) {
}

static int
pcm_init(sfx_pcm_device_t *self) {
	return SFX_OK;
}

static void
pcm_exit(sfx_pcm_device_t *self) {
}

sfx_pcm_device_t sfx_pcm_driver_dc = {
	"dc",
	"0.1",

	pcm_init,
	pcm_exit,
	NULL,
	NULL,
	NULL,

	{0, 0, 0},
	0,
	NULL,
	NULL
};

sfx_pcm_mixer_t sfx_pcm_mixer_dc = {
	"dc",
	"0.1",

	mix_init,
	mix_exit,
	mix_subscribe,
	mix_pause,
	mix_resume,
	mix_process,

	0,
	0,
	NULL,
	NULL,
	NULL
};