/*
 * Ogg/Opus streaming music support, loosely based on several open source
 * Quake engine based projects with many modifications.
 *
 * Copyright (C) 2012-2013 O.Sezer <sezero@users.sourceforge.net>
 *
 * 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
 *
 */

#include "q_defs.h"

#if USE_CODEC_OPUS
#include "snd_codec.h"
#include "snd_codeci.h"

#include <errno.h>
#include <opusfile.h>

/* CALLBACK FUNCTIONS: */
static int opc_fread(void *f, unsigned char *buf, int size)
{
	int32_t ret;

	if(size < 0)
	{
		errno = EINVAL;
		return -1;
	}

	ret = (int32_t) FS_fread(buf, 1, (size_t)size, (fshandle_t *)f);
	if(ret == 0 && errno != 0)
		ret = -1;
	return ret;
}

static int opc_fseek(void *f, opus_int64 off, int whence)
{
	if(f == NULL) return -1;
	return FS_fseek((fshandle_t *)f, (long)off, whence);
}

static opus_int64 opc_ftell(void *f)
{
	return (opus_int64)FS_ftell(f);
}

static int opc_fclose(void *f)
{
	(void)f;
	return 0; /* we fclose() elsewhere. */
}

static const OpusFileCallbacks opc_qfs =
{
	.read  = opc_fread,
	.seek  = opc_fseek,
	.tell  = opc_ftell,
	.close = opc_fclose,
};

static bool S_OPUS_CodecInitialize(void)
{
	return true;
}

static void S_OPUS_CodecShutdown(void)
{
}

static bool S_OPUS_CodecOpenStream(snd_stream_t *stream)
{
	OggOpusFile *opFile;
	const OpusHead *op_info;
	long numstreams;
	int32_t res;

	opFile = op_open_callbacks(&stream->fh, &opc_qfs, NULL, 0, &res);
	if(!opFile)
	{
		Con_Printf("%s is not a valid Opus file (error %" PRIi32 ").\n",
		           stream->name, res);
		goto fail;
	}

	stream->priv = opFile;

	if(!op_seekable(opFile))
	{
		Con_Printf("Opus stream %s not seekable.\n", stream->name);
		goto fail;
	}

	op_info = op_head(opFile, -1);
	if(!op_info)
	{
		Con_Printf("Unable to get stream information for %s.\n", stream->name);
		goto fail;
	}

	/* FIXME: handle section changes */
	numstreams = op_info->stream_count;
	if(numstreams != 1)
	{
		Con_Printf("More than one (%li) stream in %s\n",
		           numstreams, stream->name);
		goto fail;
	}

	if(op_info->channel_count != 1 && op_info->channel_count != 2)
	{
		Con_Printf("Unsupported number of channels %" PRIi32 " in %s\n",
		           op_info->channel_count, stream->name);
		goto fail;
	}

	/* All Opus audio is coded at 48 kHz, and should also be decoded
	 * at 48 kHz for playback: info->input_sample_rate only tells us
	 * the sampling rate of the original input before opus encoding.
	 * S_RawSamples() shall already downsample this, as necessary.  */
	stream->info.rate = 48000;
	stream->info.channels = op_info->channel_count;
	/* op_read() yields 16-bit output using native endian ordering: */
	stream->info.bits = 16;
	stream->info.width = 2;

	return true;
fail:
	if(opFile)
		op_free(opFile);
	return false;
}

static int32_t S_OPUS_CodecReadStream(snd_stream_t *stream, int32_t bytes, void *buffer)
{
	int32_t section;        /* FIXME: handle section changes */
	int32_t cnt, res, rem;
	opus_int16 *    ptr;

	rem = bytes / stream->info.width;
	if(rem / stream->info.channels <= 0)
		return 0;

	cnt = 0;
	ptr = (opus_int16 *) buffer;
	while(1)
	{
		/* op_read() yields 16-bit output using native endian ordering. returns
		 * the number of samples read per channel on success, or a negative value
		 * on failure. */
		res = op_read((OggOpusFile *)stream->priv, ptr, rem, &section);
		if(res <= 0)
			break;
		cnt += res;
		res *= stream->info.channels;
		rem -= res;
		if(rem <= 0)
			break;
		ptr += res;
	}

	if(res < 0)
		return res;

	cnt *= (stream->info.channels * stream->info.width);
	return cnt;
}

static void S_OPUS_CodecCloseStream(snd_stream_t *stream)
{
	op_free((OggOpusFile *)stream->priv);
	S_CodecUtilClose(&stream);
}

static int32_t S_OPUS_CodecRewindStream(snd_stream_t *stream)
{
	return op_pcm_seek((OggOpusFile *)stream->priv, 0);
}

snd_codec_t opus_codec =
{
	CODECTYPE_OPUS,
	true,   /* always available. */
	"opus",
	S_OPUS_CodecInitialize,
	S_OPUS_CodecShutdown,
	S_OPUS_CodecOpenStream,
	S_OPUS_CodecReadStream,
	S_OPUS_CodecRewindStream,
	S_OPUS_CodecCloseStream,
};

#endif /* USE_CODEC_OPUS */