#include "StarVoice.hpp"
#include "StarFormat.hpp"
#include "StarApplicationController.hpp"
#include "StarTime.hpp"
#include "StarRoot.hpp"
#include "StarLogging.hpp"
#include "opus/include/opus.h"

#include "SDL.h"

constexpr int VOICE_SAMPLE_RATE = 48000;
constexpr int VOICE_FRAME_SIZE = 960;

constexpr int VOICE_MAX_FRAME_SIZE = 6 * VOICE_FRAME_SIZE;
constexpr int VOICE_MAX_PACKET_SIZE = 3 * 1276;

constexpr uint16_t VOICE_VERSION = 1;

namespace Star {

EnumMap<VoiceInputMode> const VoiceInputModeNames{
  {VoiceInputMode::VoiceActivity, "VoiceActivity"},
  {VoiceInputMode::PushToTalk, "PushToTalk"}
};

EnumMap<VoiceChannelMode> const VoiceChannelModeNames{
  {VoiceChannelMode::Mono, "Mono"},
  {VoiceChannelMode::Stereo, "Stereo"}
};

float getAudioChunkLoudness(int16_t* data, size_t samples) {
	if (!samples)
		return 0.f;

	double rms = 0.;
	for (size_t i = 0; i != samples; ++i) {
		float sample = (float)data[i] / 32767.f;
		rms += (double)(sample * sample);
	}

  float fRms = sqrtf((float)(rms / samples));

	if (fRms > 0)
		return std::clamp<float>(20.f * log10f(fRms), -127.f, 0.f);
	else
		return -127.f;
}

float getAudioLoudness(int16_t* data, size_t samples) {
	constexpr size_t CHUNK_SIZE = 50;

	float highest = -127.f;
	for (size_t i = 0; i < samples; i += CHUNK_SIZE) {
		float level = getAudioChunkLoudness(data + i, std::min<size_t>(i + CHUNK_SIZE, samples) - i);
		if (level > highest)
      highest = level;
	}

	return highest;
}

struct VoiceAudioStream {
  // TODO: This should really be a ring buffer instead.
  std::queue<VoiceAudioChunk> chunks{};
  size_t samples = 0;

  Mutex mutex;

  inline int16_t getSample() {
		int16_t sample = 0;
		while (!chunks.empty()) {
			auto& front = chunks.front();
			if (front.exhausted()) {
        chunks.pop();
				continue;
			}
			--samples;
			return front.takeSample();
		}
		return 0;
	}

	void nukeSamples(size_t count) {
		while (!chunks.empty() && count > 0) {
			auto& front = chunks.front();
			if (count >= front.remaining) {
				count -= front.remaining;
				samples -= front.remaining;
        chunks.pop();
			}
			else {
				for (size_t i = 0; i != count; ++i) {
					--samples;
					front.takeSample();
				}
				break;
			}
		}
	}

	inline bool empty() { return chunks.empty(); }

	void take(int16_t* ptr, size_t size) {
    MutexLocker lock(mutex);
	  while (samples > 22050 && !chunks.empty()) {
		  samples -= chunks.front().remaining;
		  chunks.pop();
    }
    chunks.emplace(ptr, size);
		samples += size;
	}
};

Voice::Speaker::Speaker(SpeakerId id)
  : decoderMono  (createDecoder(1), opus_decoder_destroy)
  , decoderStereo(createDecoder(2), opus_decoder_destroy) {
  speakerId = id;
  audioStream = make_shared<VoiceAudioStream>();
}

Voice* Voice::s_singleton;

Voice* Voice::singletonPtr() {
  return s_singleton;
}

Voice& Voice::singleton() {
  if (!s_singleton)
    throw VoiceException("Voice::singleton() called with no Voice instance available");
  else
    return *s_singleton;
}

Voice::Voice(ApplicationControllerPtr appController) : m_encoder(nullptr, opus_encoder_destroy) {
  if (s_singleton)
    throw VoiceException("Singleton Voice has been constructed twice");

  m_clientSpeaker = make_shared<Speaker>(m_speakerId);
  m_inputMode = VoiceInputMode::PushToTalk;
  m_channelMode = VoiceChannelMode::Mono;
  m_applicationController = appController;

  s_singleton = this;
}

Voice::~Voice() {
  save();
	closeDevice();

  s_singleton = nullptr;
}

void Voice::init() {
  resetEncoder();
  if (m_inputEnabled)
    openDevice();
}

void Voice::loadJson(Json const& config) {
  m_enabled      = config.getBool("enabled",         m_enabled);
  m_inputEnabled = config.getBool("inputEnabled",    m_inputEnabled);
  m_deviceName   = config.optQueryString("inputDevice");
  m_threshold    = config.getFloat("threshold", m_threshold);
  m_inputVolume  = config.getFloat("inputVolume", m_inputVolume);
  m_outputVolume = config.getFloat("outputVolume",   m_outputVolume);
  m_inputMode    = VoiceInputModeNames.getLeft(config.getString("inputMode", "PushToTalk"));
  m_channelMode  = VoiceChannelModeNames.getLeft(config.getString("channelMode", "Mono"));
}



Json Voice::saveJson() const {
  return JsonObject{
    {"enabled",      m_enabled},
    {"inputEnabled", m_inputEnabled},
    {"inputDevice",  m_deviceName ? *m_deviceName : Json()},
    {"threshold",    m_threshold},
    {"inputVolume",  m_inputVolume},
    {"outputVolume", m_outputVolume},
    {"inputMode",    VoiceInputModeNames.getRight(m_inputMode)},
    {"channelMode",  VoiceChannelModeNames.getRight(m_channelMode)},
    {"version",      1}
  };
}

void Voice::save() const {
  if (Root* root = Root::singletonPtr()) {
    if (auto config = root->configuration())
      config->set("voice", saveJson());
  }
}

void Voice::scheduleSave() {
  if (!m_nextSaveTime)
		m_nextSaveTime = Time::monotonicMilliseconds() + 2000;
}

Voice::SpeakerPtr Voice::setLocalSpeaker(SpeakerId speakerId) {
  if (m_speakers.contains(m_speakerId))
    m_speakers.remove(m_speakerId);

  m_clientSpeaker->speakerId = m_speakerId = speakerId;
  return m_speakers.insert(m_speakerId, m_clientSpeaker).first->second;
}

Voice::SpeakerPtr Voice::speaker(SpeakerId speakerId) {
  if (m_speakerId == speakerId)
    return m_clientSpeaker;
  else {
    if (SpeakerPtr const* ptr = m_speakers.ptr(speakerId))
      return *ptr;
    else
      return m_speakers.emplace(speakerId, make_shared<Speaker>(speakerId)).first->second;
  }
}

void Voice::readAudioData(uint8_t* stream, int len) {
	auto now = Time::monotonicMilliseconds();
	if (!m_encoder || m_inputMode == VoiceInputMode::PushToTalk && now > m_lastInputTime)
		return;

	// Stop encoding if 2048 bytes have been encoded and not taken by the game thread yet
	if (m_encodedChunksLength > 2048)
		return;

	size_t samples = len / 2;
	float decibels = getAudioLoudness((int16_t*)stream, samples);
	m_clientSpeaker->decibelLevel = decibels;

	bool active = true;

	if (m_inputMode == VoiceInputMode::VoiceActivity) {
		bool aboveThreshold = decibels > m_threshold;
		if (aboveThreshold)
			m_lastThresholdTime = now;
		active = now - m_lastThresholdTime < 50; 
	}

	if (active) {
		m_capturedChunksFrames += samples / m_deviceChannels;
		auto data = (opus_int16*)malloc(len);
		memcpy(data, stream, len);
		m_capturedChunks.emplace(data, samples); // takes ownership
	}
	else { // Clear out any residual data so they don't manifest at the start of the next encode, whenever that is
		while (!m_capturedChunks.empty())
			m_capturedChunks.pop();

		m_capturedChunksFrames = 0;
	}

	while (m_capturedChunksFrames >= VOICE_FRAME_SIZE) {
		size_t samplesToTake = VOICE_FRAME_SIZE * (size_t)m_deviceChannels;
		std::vector<opus_int16> takenSamples;
		takenSamples.reserve(samplesToTake);

		while (!m_capturedChunks.empty()) {
			auto& front = m_capturedChunks.front();
			if (front.exhausted())
				m_capturedChunks.pop();
			else {
				samplesToTake -= front.takeSamples(takenSamples, samplesToTake);
			  if (samplesToTake == 0)
				  break;
			}
		}
		m_capturedChunksFrames -= VOICE_FRAME_SIZE;

		float vol = m_inputVolume;
		if (m_inputVolume != 1.0f) {
			for (size_t i = 0; i != takenSamples.size(); ++i)
				takenSamples[i] *= m_inputVolume;
		}
		ByteArray encodedData(VOICE_MAX_FRAME_SIZE, 0);
		opus_int32 encodedSize = opus_encode(m_encoder.get(), takenSamples.data(), VOICE_FRAME_SIZE, (unsigned char*)encodedData.ptr(), encodedData.size());
		if (encodedSize == 1)
			continue;
		else if (encodedSize < 0)
			Logger::error("Voice: Opus encode error {}", opus_strerror(encodedSize));
		else {
			encodedData.resize(encodedSize);
			MutexLocker lock(m_captureMutex);
			m_encodedChunks.emplace_back(move(encodedData)); // reset takes ownership of data buffer
			m_encodedChunksLength += encodedSize;
			Logger::info("Voice: encoded Opus chunk {} bytes big", encodedSize);
		}

	}
}

void Voice::mix(int16_t* buffer, size_t frameCount, unsigned channels) {
	size_t samples = frameCount * channels;
	static std::vector<int16_t> finalMixBuffer{};
	static std::vector<int32_t> voiceMixBuffer{};
	finalMixBuffer.resize(samples);
	voiceMixBuffer.resize(samples);
	int32_t* mixBuf = (int32_t*)memset(voiceMixBuffer.data(), 0, samples * sizeof(int32_t));
	//read into buffer now
	bool mix = false;
	{
		MutexLocker lock(m_activeSpeakersMutex);
		auto it = m_activeSpeakers.begin();
		while (it != m_activeSpeakers.end()) {
			SpeakerPtr const& speaker = *it;
			VoiceAudioStream* audio = speaker->audioStream.get();
			MutexLocker audioLock(audio->mutex);
			if (!audio->empty()) {
				if (!speaker->muted) {
					mix = true;
					auto channelVolumes = speaker->channelVolumes.load();
					for (size_t i = 0; i != samples; ++i)
						mixBuf[i] += (int32_t)(audio->getSample()) * channelVolumes[i % 2];
				}
				else {
					for (size_t i = 0; i != samples; ++i)
						audio->getSample();
				}
				++it;
			}
			else {
				speaker->playing = false;
				it = m_activeSpeakers.erase(it);
			}
		}
	}
	if (mix) {
		int16_t* finBuf = finalMixBuffer.data();

		float vol = m_outputVolume;
		for (size_t i = 0; i != samples; ++i)
			finBuf[i] = (int16_t)clamp<int>(mixBuf[i] * vol, INT16_MIN, INT16_MAX);

		SDL_MixAudioFormat((Uint8*)buffer, (Uint8*)finBuf, AUDIO_S16, samples * sizeof(int16_t), SDL_MIX_MAXVOLUME);
	}
}

void Voice::update(PositionalAttenuationFunction positionalAttenuationFunction) {
  if (positionalAttenuationFunction) {
    for (auto& entry : m_speakers) {
      if (SpeakerPtr& speaker = entry.second) {
        speaker->channelVolumes = {
          positionalAttenuationFunction(0, speaker->position, 1.0f),
          positionalAttenuationFunction(1, speaker->position, 1.0f)
        };
      }
    }
  }

  if (m_nextSaveTime && Time::monotonicMilliseconds() > m_nextSaveTime) {
		m_nextSaveTime = 0;
    save();
  }
}


void Voice::setDeviceName(Maybe<String> deviceName) {
  if (m_deviceName == deviceName)
    return;

  m_deviceName = deviceName;
  if (m_deviceOpen)
    openDevice();
}

int Voice::send(DataStreamBuffer& out, size_t budget) {
	out.setByteOrder(ByteOrder::LittleEndian);
	out.write<uint16_t>(VOICE_VERSION);
	MutexLocker captureLock(m_captureMutex);

	if (m_capturedChunks.empty())
		return 0;

	std::vector<ByteArray> encodedChunks = move(m_encodedChunks);
	size_t encodedChunksLength = m_encodedChunksLength;
	m_encodedChunksLength = 0;
	captureLock.unlock();

	for (auto& chunk : encodedChunks) {
		out.write<uint32_t>(chunk.size());
		out.writeBytes(chunk);
		if ((budget -= min<size_t>(budget, chunk.size())) == 0)
			break;
	}

	m_lastSentTime = Time::monotonicMilliseconds();
	return 1;
}

bool Voice::receive(SpeakerPtr speaker, std::string_view view) {
	if (!speaker || view.empty())
		return false;

	try {
		DataStreamExternalBuffer reader(view.data(), view.size());
		reader.setByteOrder(ByteOrder::LittleEndian);

		if (reader.read<uint16_t>() > VOICE_VERSION)
			return false;

		uint32_t opusLength = 0;
		while (!reader.atEnd()) {
			reader >> opusLength;
			auto opusData = (unsigned char*)reader.ptr() + reader.pos();
			reader.seek(opusLength, IOSeek::Relative);

			int channels = opus_packet_get_nb_channels(opusData);
			if (channels == OPUS_INVALID_PACKET)
				continue;

			bool mono = channels == 1;
			OpusDecoder* decoder = mono ? speaker->decoderMono.get() : speaker->decoderStereo.get();
			int samples = opus_decoder_get_nb_samples(decoder, opusData, opusLength);
			if (samples < 0)
				throw VoiceException(strf("Decoder error: {}", opus_strerror(samples)), false);

			size_t decodeBufferSize = samples * sizeof(opus_int16) * (size_t)channels;
			opus_int16* decodeBuffer = (opus_int16*)malloc(decodeBufferSize);

			int decodedSamples = opus_decode(decoder, opusData, opusLength, decodeBuffer, decodeBufferSize, 0);
			if (decodedSamples < 0) {
				free(decodeBuffer);
				throw VoiceException(strf("Decoder error: {}", opus_strerror(samples)), false);
			}

			Logger::info("Voice: decoded Opus chunk {} bytes big", opusLength);

			static auto getCVT = [](int channels) -> SDL_AudioCVT {
				SDL_AudioCVT cvt;
				SDL_BuildAudioCVT(&cvt, AUDIO_S16SYS, channels, VOICE_SAMPLE_RATE, AUDIO_S16, 2, 44100);
				return cvt;
			};

			//TODO: This isn't the best way to resample to 44100 hz because SDL_ConvertAudio is not for streamed audio.
			static SDL_AudioCVT monoCVT   = getCVT(1);
			static SDL_AudioCVT stereoCVT = getCVT(2);
			SDL_AudioCVT& cvt = mono ? monoCVT : stereoCVT;
			cvt.len = decodedSamples * sizeof(opus_int16) * (size_t)channels;
			cvt.buf = (Uint8*)realloc(decodeBuffer, (size_t)(cvt.len * cvt.len_mult));
			SDL_ConvertAudio(&cvt);

			size_t reSamples = (size_t)cvt.len_cvt / 2;
			speaker->decibelLevel = getAudioLoudness((int16_t*)cvt.buf, reSamples);
			speaker->audioStream->take((opus_int16*)realloc(cvt.buf, cvt.len_cvt), reSamples);
			playSpeaker(speaker, channels);
		}
		return true;
	}
	catch (StarException const& e) {
		Logger::error("Voice: Error receiving voice data for speaker #{} ('{}'): {}", speaker->speakerId, speaker->name, e.what());
		return false;
	}
}

void Voice::setInput(bool input) {
  m_lastInputTime = input ? Time::monotonicMilliseconds() + 1000 : 0;
}

OpusDecoder* Voice::createDecoder(int channels) {
  int error;
  OpusDecoder* decoder = opus_decoder_create(VOICE_SAMPLE_RATE, channels, &error);
  if (error != OPUS_OK)
    throw VoiceException::format("Could not create decoder: {}", opus_strerror(error));
  else
    return decoder;
}

OpusEncoder* Voice::createEncoder(int channels) {
  int error;
  OpusEncoder* encoder = opus_encoder_create(VOICE_SAMPLE_RATE, channels, OPUS_APPLICATION_AUDIO, &error);
  if (error != OPUS_OK)
    throw VoiceException::format("Could not create encoder: {}", opus_strerror(error));
  else
    return encoder;
}

void Voice::resetEncoder() {
  int channels = encoderChannels();
  m_encoder.reset(createEncoder(channels));
  opus_encoder_ctl(m_encoder.get(), OPUS_SET_BITRATE(channels == 2 ? 50000 : 24000));
}

void Voice::openDevice() {
  closeDevice();

  m_applicationController->openAudioInputDevice(
		m_deviceName ? m_deviceName->utf8Ptr() : nullptr,
		VOICE_SAMPLE_RATE,
		m_deviceChannels = encoderChannels(),
		this,
		[](void* userdata, uint8_t* stream, int len) {
      ((Voice*)(userdata))->readAudioData(stream, len);
    }
	);

  m_deviceOpen = true;
}

void Voice::closeDevice() {
  if (!m_deviceOpen)
    return;

  m_applicationController->closeAudioInputDevice();

  m_deviceOpen = false;
}

bool Voice::playSpeaker(SpeakerPtr const& speaker, int channels) {
	unsigned int minSamples = speaker->minimumPlaySamples * channels;
	if (speaker->playing || speaker->audioStream->samples < minSamples)
		return false;

	speaker->playing = true;
	MutexLocker lock(m_activeSpeakersMutex);
	m_activeSpeakers.insert(speaker);
	return true;
}

}