/*
Copyright (C) 2014 by Leonhard Oelke <leonhard@in-verted.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.

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, see <http://www.gnu.org/licenses/>.
*/

#include <util/bmem.h>
#include <util/threading.h>

#include <pulse/mainloop.h>
#include <pulse/context.h>
#include <pulse/introspect.h>
#include <pulse/stream.h>
#include <pulse/error.h>

#include <obs.h>

#define PULSE_DATA(voidptr) struct pulse_data *data = voidptr;

/*
 * delay in usecs before starting to record, this eliminates problems with
 * pulse audio sending weird data/timestamps when the stream is connected
 * 
 * for more information see:
 * github.com/MaartenBaert/ssr/blob/master/src/AV/Input/PulseAudioInput.cpp
 */
const uint64_t pulse_start_delay = 100000;

struct pulse_data {
	pthread_t thread;
	event_t event;
	obs_source_t source;
	
	uint32_t frames;
	uint32_t samples_per_sec;
	uint32_t channels;
	enum speaker_layout speakers;
	
	pa_mainloop *mainloop;
	pa_context *context;
	pa_stream *stream;
};

/*
 * Create a new pulse audio main loop and connect to the server
 * 
 * Returns a negative value on error
 */
static int pulse_connect(struct pulse_data *data)
{
	data->mainloop = pa_mainloop_new();
	if (!data->mainloop) {
		blog(LOG_ERROR, "Unable to create main loop");
		return -1;
	}
	
	data->context = pa_context_new(
		pa_mainloop_get_api(data->mainloop), "OBS Studio");
	if (!data->context) {
		blog(LOG_ERROR, "Unable to create context");
		return -1;
	}
	
	int status = pa_context_connect(
		data->context, NULL, PA_CONTEXT_NOAUTOSPAWN, NULL);
	if (status < 0) {
		blog(LOG_ERROR, "Unable to connect! Status: %d", status);
		return -1;
	}
	
	// wait until connected
	for (;;) {
		pa_mainloop_iterate(data->mainloop, 0, NULL);
		pa_context_state_t state = pa_context_get_state(data->context);
		if (state == PA_CONTEXT_READY) {
			blog(LOG_DEBUG, "Context ready");
			break;
		}
		if (!PA_CONTEXT_IS_GOOD(state)) {
			blog(LOG_ERROR, "Connection attempt failed");
			return -1;
		}
	}
	
	return 0;
}

/*
 * Disconnect from the pulse audio server and destroy the main loop
 */
static void pulse_disconnect(struct pulse_data *data)
{
	if (data->context) {
		pa_context_disconnect(data->context);
		pa_context_unref(data->context);
	}
	
	if (data->mainloop)
		pa_mainloop_free(data->mainloop);
}

/*
 * Create a new pulse audio stream and connect to it
 * 
 * Return a negative value on error
 */
static int pulse_connect_stream(struct pulse_data *data)
{
	pa_sample_spec spec;
	spec.format = PA_SAMPLE_U8;
	spec.rate = data->samples_per_sec;
	spec.channels = data->channels;
	
	pa_buffer_attr attr;
	attr.fragsize = data->frames * spec.channels;
	attr.maxlength = (uint32_t) -1;
	attr.minreq = (uint32_t) -1;
	attr.prebuf = (uint32_t) -1;
	attr.tlength = (uint32_t) -1;
	
	data->stream = pa_stream_new(
		data->context, "OBS Audio Input", &spec, NULL);
	if (!data->stream) {
		blog(LOG_ERROR, "Unable to create stream");
		return -1;
	}
	pa_stream_flags_t flags =
		PA_STREAM_INTERPOLATE_TIMING
		| PA_STREAM_AUTO_TIMING_UPDATE
		| PA_STREAM_ADJUST_LATENCY;
	if (pa_stream_connect_record(data->stream, NULL, &attr, flags) < 0) {
		blog(LOG_ERROR, "Unable to connect to stream");
		return -1;
	}
	
	for (;;) {
		pa_mainloop_iterate(data->mainloop, 0, NULL);
		pa_stream_state_t state = pa_stream_get_state(data->stream);
		if (state == PA_STREAM_READY) {
			blog(LOG_DEBUG, "Stream ready");
			break;
		}
		if (!PA_STREAM_IS_GOOD(state)) {
			blog(LOG_ERROR, "Stream connection failed");
			return -1;
		}
	}
	
	return 0;
}

/*
 * Disconnect from the pulse audio stream
 */
static void pulse_diconnect_stream(struct pulse_data *data)
{
	if (data->stream) {
		pa_stream_disconnect(data->stream);
		pa_stream_unref(data->stream);
	}
}

/*
 * Worker thread to get audio data
 * 
 * Will run until signaled
 */
static void *pulse_thread(void *vptr)
{
	PULSE_DATA(vptr);
	
	if (pulse_connect(data) < 0)
		return NULL;
	if (pulse_connect_stream(data) < 0)
		return NULL;
	
	uint64_t skip = 1;
	
	while (event_try(&data->event) == EAGAIN) {
		pa_mainloop_iterate(data->mainloop, 0, NULL);
		
		const void *frames;
		size_t bytes;
		pa_stream_peek(data->stream, &frames, &bytes);
		
		// check if we got data
		if (!bytes) {
			pa_stream_drop(data->stream);
			continue;
		}
		
		uint64_t pa_time;
		if (pa_stream_get_time(data->stream, &pa_time) < 0)
			continue;
		
		// skip the first frames received
		if (skip) {
			// start delay when we receive the first bytes
			if (skip == 1 && bytes)
				skip = pa_time;
			if (skip + pulse_start_delay < pa_time)
				skip = 0;
			pa_stream_drop(data->stream);
			continue;
		}
		
		// get stream latency
		pa_usec_t l_abs;
		int l_sign;
		pa_stream_get_latency(data->stream, &l_abs, &l_sign);
		int64_t latency = (l_sign) ? -(int64_t) l_abs : (int64_t) l_abs;
		
		// push structure
		struct source_audio out;
		out.data[0] = (uint8_t *) frames;
		out.frames = bytes / data->channels;
		out.speakers = data->speakers;
		out.samples_per_sec = data->samples_per_sec;
		out.timestamp = (pa_time - latency) * 1000;
		out.format = AUDIO_FORMAT_U8BIT;
		
		// send data to obs
		obs_source_output_audio(data->source, &out);
		
		// clear pulse audio buffer
		pa_stream_drop(data->stream);
	}
	
	pulse_diconnect_stream(data);
	pulse_disconnect(data);
	
	return NULL;
}

/*
 * Returns the name of the plugin
 */
static const char *pulse_getname(const char *locale)
{
	UNUSED_PARAMETER(locale);
	return "Pulse Audio Input";
}

/*
 * Destroy the plugin object and free all memory
 */
static void pulse_destroy(void *vptr)
{
	PULSE_DATA(vptr);
	
	if (!data)
		return;
	
	if (data->thread) {
		void *ret;
		event_signal(&data->event);
		pthread_join(data->thread, &ret);
	}
	
	event_destroy(&data->event);
	
	bfree(data);
}

/*
 * Create the plugin object
 */
static void *pulse_create(obs_data_t settings, obs_source_t source)
{
	UNUSED_PARAMETER(settings);
	
	struct pulse_data *data = bmalloc(sizeof(struct pulse_data));
	memset(data, 0, sizeof(struct pulse_data));
	
	data->source = source;
	data->frames = 480;
	data->samples_per_sec = 48000;
	data->speakers = SPEAKERS_STEREO;
	data->channels = (data->speakers == SPEAKERS_STEREO) ? 2 : 1;
	
	if (event_init(&data->event, EVENT_TYPE_MANUAL) != 0)
		goto fail;
	if (pthread_create(&data->thread, NULL, pulse_thread, data) != 0)
		goto fail;
	
	return data;
	
fail:
	pulse_destroy(data);
	return NULL;
}

struct obs_source_info pulse_input = {
	.id           = "pulse_input",
	.type         = OBS_SOURCE_TYPE_INPUT,
	.output_flags = OBS_SOURCE_AUDIO,
	.getname      = pulse_getname,
	.create       = pulse_create,
	.destroy      = pulse_destroy
};