/**************************************************************************/
/*  audio_stream_polyphonic.cpp                                           */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/* Permission is hereby granted, free of charge, to any person obtaining  */
/* a copy of this software and associated documentation files (the        */
/* "Software"), to deal in the Software without restriction, including    */
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#include "audio_stream_polyphonic.h"
#include "scene/main/scene_tree.h"

Ref<AudioStreamPlayback> AudioStreamPolyphonic::instantiate_playback() {
	Ref<AudioStreamPlaybackPolyphonic> playback;
	playback.instantiate();
	playback->streams.resize(polyphony);
	return playback;
}

String AudioStreamPolyphonic::get_stream_name() const {
	return "AudioStreamPolyphonic";
}

bool AudioStreamPolyphonic::is_monophonic() const {
	return true; // This avoids stream players to instantiate more than one of these.
}

void AudioStreamPolyphonic::set_polyphony(int p_voices) {
	ERR_FAIL_COND(p_voices < 0 || p_voices > 128);
	polyphony = p_voices;
}
int AudioStreamPolyphonic::get_polyphony() const {
	return polyphony;
}

void AudioStreamPolyphonic::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_polyphony", "voices"), &AudioStreamPolyphonic::set_polyphony);
	ClassDB::bind_method(D_METHOD("get_polyphony"), &AudioStreamPolyphonic::get_polyphony);

	ADD_PROPERTY(PropertyInfo(Variant::INT, "polyphony", PROPERTY_HINT_RANGE, "1,128,1"), "set_polyphony", "get_polyphony");
}

AudioStreamPolyphonic::AudioStreamPolyphonic() {
}

////////////////////////

void AudioStreamPlaybackPolyphonic::start(double p_from_pos) {
	if (active) {
		stop();
	}

	active = true;
}

void AudioStreamPlaybackPolyphonic::stop() {
	if (!active) {
		return;
	}

	bool locked = false;
	for (Stream &s : streams) {
		if (s.active.is_set()) {
			// Need locking because something may still be mixing.
			locked = true;
			AudioServer::get_singleton()->lock();
		}
		s.active.clear();
		s.finalizing.clear();
		s.finish_request.clear();
		s.stream_playback.unref();
		s.stream.unref();
	}
	if (locked) {
		AudioServer::get_singleton()->unlock();
	}

	active = false;
}

bool AudioStreamPlaybackPolyphonic::is_playing() const {
	return active;
}

int AudioStreamPlaybackPolyphonic::get_loop_count() const {
	return 0;
}

double AudioStreamPlaybackPolyphonic::get_playback_position() const {
	return 0;
}
void AudioStreamPlaybackPolyphonic::seek(double p_time) {
	// Ignored.
}

void AudioStreamPlaybackPolyphonic::tag_used_streams() {
	for (Stream &s : streams) {
		if (s.active.is_set()) {
			s.stream_playback->tag_used_streams();
		}
	}
}

int AudioStreamPlaybackPolyphonic::mix(AudioFrame *p_buffer, float p_rate_scale, int p_frames) {
	if (!active) {
		return 0;
	}

	// Pre-clear buffer.
	for (int i = 0; i < p_frames; i++) {
		p_buffer[i] = AudioFrame(0, 0);
	}

	for (Stream &s : streams) {
		if (!s.active.is_set()) {
			continue;
		}

		float volume_db = s.volume_db; // Copy because it can be overriden at any time.
		float next_volume = Math::db_to_linear(volume_db);
		s.prev_volume_db = volume_db;

		if (s.finish_request.is_set()) {
			if (s.pending_play.is_set()) {
				// Did not get the chance to play, was finalized too soon.
				s.active.clear();
				s.finalizing.set();
				continue;
			}
			next_volume = 0;
		}

		if (s.pending_play.is_set()) {
			s.stream_playback->start(s.play_offset);
			s.pending_play.clear();
		}
		float prev_volume = Math::db_to_linear(s.prev_volume_db);

		float volume_inc = (next_volume - prev_volume) / float(p_frames);

		int todo = p_frames;
		int offset = 0;
		float volume = prev_volume;

		while (todo) {
			int to_mix = MIN(todo, int(INTERNAL_BUFFER_LEN));
			int mixed = s.stream_playback->mix(internal_buffer, s.pitch_scale, to_mix);

			for (int i = 0; i < to_mix; i++) {
				p_buffer[offset + i] += internal_buffer[i] * volume;
				volume += volume_inc;
			}

			if (mixed < to_mix) {
				// Stream is done.
				s.active.clear();
				s.finalizing.set();
				break;
			}

			todo -= to_mix;
			offset += to_mix;
		}

		if (s.finish_request.is_set()) {
			s.active.clear();
			s.finalizing.set();
		}
	}

	return p_frames;
}

void AudioStreamPlaybackPolyphonic::_check_finalized_streams() {
	if (!active) {
		return;
	}

	for (Stream &s : streams) {
		if (!s.active.is_set() && s.finalizing.is_set()) {
			s.stream_playback.unref();
			s.stream.unref();
			s.finalizing.clear();
			s.finish_request.clear();
		}
	}
}

AudioStreamPlaybackPolyphonic::ID AudioStreamPlaybackPolyphonic::play_stream(const Ref<AudioStream> &p_stream, float p_from_offset, float p_volume_db, float p_pitch_scale) {
	ERR_FAIL_COND_V(p_stream.is_null(), INVALID_ID);
	for (uint32_t i = 0; i < streams.size(); i++) {
		if (!streams[i].active.is_set() && !streams[i].finish_request.is_set() && !streams[i].finalizing.is_set()) {
			// Can use this stream, as it's not active.
			streams[i].stream = p_stream;
			streams[i].stream_playback = streams[i].stream->instantiate_playback();
			streams[i].play_offset = p_from_offset;
			streams[i].volume_db = p_volume_db;
			streams[i].prev_volume_db = p_volume_db;
			streams[i].pitch_scale = p_pitch_scale;
			streams[i].id = id_counter++;
			streams[i].pending_play.set();
			streams[i].active.set();
			return (ID(i) << INDEX_SHIFT) | ID(streams[i].id);
		}
	}

	return INVALID_ID;
}

AudioStreamPlaybackPolyphonic::Stream *AudioStreamPlaybackPolyphonic::_find_stream(int64_t p_id) {
	uint32_t index = p_id >> INDEX_SHIFT;
	if (index >= streams.size()) {
		return nullptr;
	}
	if (!streams[index].active.is_set()) {
		return nullptr; // Not active, no longer exists.
	}
	int64_t id = p_id & ID_MASK;
	if (streams[index].id != id) {
		return nullptr;
	}
	return &streams[index];
}

void AudioStreamPlaybackPolyphonic::set_stream_volume(ID p_stream_id, float p_volume_db) {
	Stream *s = _find_stream(p_stream_id);
	if (!s) {
		return;
	}
	s->volume_db = p_volume_db;
}

void AudioStreamPlaybackPolyphonic::set_stream_pitch_scale(ID p_stream_id, float p_pitch_scale) {
	Stream *s = _find_stream(p_stream_id);
	if (!s) {
		return;
	}
	s->pitch_scale = p_pitch_scale;
}

bool AudioStreamPlaybackPolyphonic::is_stream_playing(ID p_stream_id) const {
	return const_cast<AudioStreamPlaybackPolyphonic *>(this)->_find_stream(p_stream_id) != nullptr;
}

void AudioStreamPlaybackPolyphonic::stop_stream(ID p_stream_id) {
	Stream *s = _find_stream(p_stream_id);
	if (!s) {
		return;
	}
	s->finish_request.set();
}

void AudioStreamPlaybackPolyphonic::_bind_methods() {
	ClassDB::bind_method(D_METHOD("play_stream", "stream", "from_offset", "volume_db", "pitch_scale"), &AudioStreamPlaybackPolyphonic::play_stream, DEFVAL(0), DEFVAL(0), DEFVAL(1.0));
	ClassDB::bind_method(D_METHOD("set_stream_volume", "stream", "volume_db"), &AudioStreamPlaybackPolyphonic::set_stream_volume);
	ClassDB::bind_method(D_METHOD("set_stream_pitch_scale", "stream", "pitch_scale"), &AudioStreamPlaybackPolyphonic::set_stream_pitch_scale);
	ClassDB::bind_method(D_METHOD("is_stream_playing", "stream"), &AudioStreamPlaybackPolyphonic::is_stream_playing);
	ClassDB::bind_method(D_METHOD("stop_stream", "stream"), &AudioStreamPlaybackPolyphonic::stop_stream);

	BIND_CONSTANT(INVALID_ID);
}

AudioStreamPlaybackPolyphonic::AudioStreamPlaybackPolyphonic() {
	SceneTree::get_singleton()->connect(SNAME("process_frame"), callable_mp(this, &AudioStreamPlaybackPolyphonic::_check_finalized_streams));
}