#include <random>
#include <cstdio>
#include "pipewire/pipewire.h"
#include "spa/param/audio/format-utils.h"

struct local_data {
	pw_main_loop* loop;
	pw_stream* stream;

	std::mt19937 gen;
	std::normal_distribution<float> nd{0, 0.3};
};

void on_process(local_data* ld) {
	pw_buffer *b;
	spa_buffer *buf;
	if((b = pw_stream_dequeue_buffer(ld->stream)) == NULL) {
		pw_log_warn("No buffers left!");
		return;
	}

	buf = b->buffer;

	float* dst;
	if((dst = (float*)buf->datas[0].data) == NULL) {
		return;
	}

	int n_frames = buf->datas[0].maxsize / sizeof(float);
	if(b->requested) {
		n_frames = SPA_MIN(b->requested, n_frames);
	}

	for(int i = 0; i < n_frames; ++i) {
		*dst++ = ld->nd(ld->gen);
	}

	buf->datas[0].chunk->offset = 0;
	buf->datas[0].chunk->stride = sizeof(float);
	buf->datas[0].chunk->size = n_frames * sizeof(float);

	pw_stream_queue_buffer(ld->stream, b);
}

const struct pw_stream_events stream_events {
	PW_VERSION_STREAM_EVENTS,
	.process = (void(*)(void*))on_process,
};

int main(int argc, char** argv) {
	// We do NOT seed the MT engine -> the time series will be predictable!
	local_data bookkeep{nullptr,nullptr,};

	pw_init(&argc, &argv);
	bookkeep.loop = pw_main_loop_new(NULL);

	bookkeep.stream = pw_stream_new_simple(
		pw_main_loop_get_loop(bookkeep.loop),
		"audio-src",
		pw_properties_new(
			PW_KEY_MEDIA_TYPE, "Audio",
			PW_KEY_MEDIA_CATEGORY, "Playback",
			PW_KEY_MEDIA_ROLE, "Test",
			NULL),
		&stream_events,
		&bookkeep);

	const spa_pod* params[1];
	uint8_t buffer[1024];
	spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));

	auto audio_info = SPA_AUDIO_INFO_RAW_INIT(
			.format = SPA_AUDIO_FORMAT_F32_LE,
			.rate = 44100,
			.channels = 1,);

	params[0] = spa_format_audio_raw_build(&b, SPA_PARAM_EnumFormat,&audio_info);

	pw_stream_connect(bookkeep.stream,
		PW_DIRECTION_OUTPUT,
		PW_ID_ANY,
		(pw_stream_flags)(PW_STREAM_FLAG_AUTOCONNECT |
		PW_STREAM_FLAG_MAP_BUFFERS |
		PW_STREAM_FLAG_RT_PROCESS),
		params, 1);

	pw_main_loop_run(bookkeep.loop);

	pw_stream_destroy(bookkeep.stream);
	pw_main_loop_destroy(bookkeep.loop);
	return 0;
}