/*
 *  Copyright (C) 2005-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 */

#include "AESinkDARWINTVOS.h"

#include "ServiceBroker.h"
#include "cores/AudioEngine/AESinkFactory.h"
#include "cores/AudioEngine/Sinks/darwin/CoreAudioHelpers.h"
#include "cores/AudioEngine/Utils/AERingBuffer.h"
#include "cores/AudioEngine/Utils/AEUtil.h"
#include "threads/Condition.h"
#include "threads/SystemClock.h"
#include "utils/StringUtils.h"
#include "utils/log.h"
#include "windowing/WinSystem.h"

#include "platform/darwin/DarwinUtils.h"

#include <mutex>
#include <sstream>

#import <AVFoundation/AVAudioSession.h>
#include <AudioToolbox/AudioToolbox.h>
#include <unistd.h>

using namespace std::chrono_literals;

enum CAChannelIndex
{
  CAChannel_PCM_6CHAN = 0,
  CAChannel_PCM_8CHAN = 1,
  CAChannel_PCM_DD5_1 = 2,
};

static enum AEChannel CAChannelMap[3][9] = {
    {AE_CH_FL, AE_CH_FR, AE_CH_LFE, AE_CH_FC, AE_CH_BL, AE_CH_BR, AE_CH_NULL},
    {AE_CH_FL, AE_CH_FR, AE_CH_LFE, AE_CH_FC, AE_CH_SL, AE_CH_SR, AE_CH_BL, AE_CH_BR, AE_CH_NULL},
    {AE_CH_FL, AE_CH_FC, AE_CH_FR, AE_CH_BL, AE_CH_BR, AE_CH_LFE, AE_CH_NULL},
};

static std::string getAudioRoute()
{
  std::string route;
  AVAudioSession* myAudioSession = [AVAudioSession sharedInstance];
  AVAudioSessionRouteDescription* currentRoute = [myAudioSession currentRoute];
  NSString* output = [[currentRoute.outputs firstObject] portType];
  if (output)
    route = [output UTF8String];

  return route;
}

static void dumpAVAudioSessionProperties()
{
  std::string route = getAudioRoute();
  CLog::Log(LOGINFO, "{} audio route = {}", __PRETTY_FUNCTION__, route.empty() ? "NONE" : route);

  AVAudioSession* mySession = [AVAudioSession sharedInstance];

  CLog::Log(LOGINFO, "{} sampleRate {:f}", __PRETTY_FUNCTION__, [mySession sampleRate]);
  CLog::Log(LOGINFO, "{} outputLatency {:f}", __PRETTY_FUNCTION__, [mySession outputLatency]);
  CLog::Log(LOGINFO, "{} IOBufferDuration {:f}", __PRETTY_FUNCTION__, [mySession IOBufferDuration]);
  CLog::Log(LOGINFO, "{} outputNumberOfChannels {}", __PRETTY_FUNCTION__,
            static_cast<long>([mySession outputNumberOfChannels]));
  // maximumOutputNumberOfChannels provides hints to tvOS audio settings
  // if 2, then audio is set to two channel stereo. iOS return this unless hdmi connected
  // if 6, then audio is set to Digital Dolby 5.1 OR hdmi path detected sink can only handle 6 channels.
  // if 8, then audio is set to Best Quality AND hdmi path detected sink can handle 8 channels.
  CLog::Log(LOGINFO, "{} maximumOutputNumberOfChannels {}", __PRETTY_FUNCTION__,
            static_cast<long>([mySession maximumOutputNumberOfChannels]));

  //CDarwinUtils::DumpAudioDescriptions(__PRETTY_FUNCTION__);
}

static bool deactivateAudioSession(int count)
{
  if (--count < 0)
    return false;

  bool rtn = false;
  NSError* err = nullptr;
  // deactvivate the session
  AVAudioSession* mySession = [AVAudioSession sharedInstance];
  if (![mySession setActive:NO error:&err])
  {
    CLog::Log(LOGWARNING, "AVAudioSession setActive NO failed, count {}", count);
    usleep(10 * 1000);
    rtn = deactivateAudioSession(count);
  }
  else
  {
    rtn = true;
  }
  return rtn;
}

static void setAVAudioSessionProperties(NSTimeInterval bufferseconds,
                                        double samplerate,
                                        int channels)
{
  // darwin docs and technotes say,
  // deavtivate the session before changing the values
  AVAudioSession* mySession = [AVAudioSession sharedInstance];

  // need to fetch maximumOutputNumberOfChannels when active
  NSInteger maxchannels = [mySession maximumOutputNumberOfChannels];

  NSError* err = nil;
  // deactvivate the session
  if (!deactivateAudioSession(10))
    CLog::Log(LOGWARNING, "AVAudioSession setActive NO failed: {}", static_cast<long>(err.code));

  // change the number of channels
  if (channels > maxchannels)
    channels = static_cast<UInt32>(maxchannels);
  err = nil;
  [mySession setPreferredOutputNumberOfChannels:channels error:&err];
  if (err != nil)
    CLog::Log(LOGWARNING, "{} setPreferredOutputNumberOfChannels failed", __PRETTY_FUNCTION__);

  // change the sameple rate
  err = nil;
  [mySession setPreferredSampleRate:samplerate error:&err];
  if (err != nil)
    CLog::Log(LOGWARNING, "{} setPreferredSampleRate failed", __PRETTY_FUNCTION__);

  // change the i/o buffer duration
  err = nil;
  [mySession setPreferredIOBufferDuration:bufferseconds error:&err];
  if (err != nil)
    CLog::Log(LOGWARNING, "{} setPreferredIOBufferDuration failed", __PRETTY_FUNCTION__);

  // reactivate the session
  err = nil;
  if (![mySession setActive:YES error:&err])
    CLog::Log(LOGWARNING, "AVAudioSession setActive YES failed: {}", static_cast<long>(err.code));

  // check that we got the samperate what we asked for
  if (samplerate != [mySession sampleRate])
    CLog::Log(LOGWARNING, "sampleRate does not match: asked {:f}, is {:f}", samplerate,
              [mySession sampleRate]);

  // check that we got the number of channels what we asked for
  if (channels != [mySession outputNumberOfChannels])
    CLog::Log(LOGWARNING, "number of channels do not match: asked {}, is {}", channels,
              static_cast<long>([mySession outputNumberOfChannels]));
}

#pragma mark - SineWaveGenerator
/***************************************************************************************/
/***************************************************************************************/
#if DO_440HZ_TONE_TEST
static void SineWaveGeneratorInitWithFrequency(SineWaveGenerator* ctx,
                                               double frequency,
                                               double samplerate)
{
  // Given:
  //   frequency in cycles per second
  //   2*PI radians per sine wave cycle
  //   sample rate in samples per second
  //
  // Then:
  //   cycles     radians     seconds     radians
  //   ------  *  -------  *  -------  =  -------
  //   second      cycle      sample      sample
  ctx->currentPhase = 0.0;
  ctx->phaseIncrement = frequency * 2 * M_PI / samplerate;
}

static int16_t SineWaveGeneratorNextSampleInt16(SineWaveGenerator* ctx)
{
  int16_t sample = INT16_MAX * sinf(ctx->currentPhase);

  ctx->currentPhase += ctx->phaseIncrement;
  // Keep the value between 0 and 2*M_PI
  while (ctx->currentPhase > 2 * M_PI)
    ctx->currentPhase -= 2 * M_PI;

  return sample / 4;
}
static float SineWaveGeneratorNextSampleFloat(SineWaveGenerator* ctx)
{
  float sample = MAXFLOAT * sinf(ctx->currentPhase);

  ctx->currentPhase += ctx->phaseIncrement;
  // Keep the value between 0 and 2*M_PI
  while (ctx->currentPhase > 2 * M_PI)
    ctx->currentPhase -= 2 * M_PI;

  return sample / 4;
}
#endif

#pragma mark - CAAudioUnitSink
/***************************************************************************************/
/***************************************************************************************/
class CAAudioUnitSink
{
public:
  CAAudioUnitSink();
  ~CAAudioUnitSink();

  bool open(AudioStreamBasicDescription outputFormat, size_t buffer_size);
  bool close();
  bool activate();
  bool deactivate();
  void updatedelay(AEDelayStatus& status);
  double buffertime();
  unsigned int sampletrate() { return m_outputFormat.mSampleRate; };
  unsigned int write(uint8_t* data, unsigned int frames, unsigned int framesize);
  void drain();

private:
  bool setupAudio();

  // callbacks
  static OSStatus renderCallback(void* inRefCon,
                                 AudioUnitRenderActionFlags* ioActionFlags,
                                 const AudioTimeStamp* inTimeStamp,
                                 UInt32 inOutputBusNumber,
                                 UInt32 inNumberFrames,
                                 AudioBufferList* ioData);

  bool m_setup;
  bool m_activated = false;
  AudioUnit m_audioUnit;
  AudioStreamBasicDescription m_outputFormat;
  AERingBuffer* m_buffer = nullptr;

  Float32 m_totalLatency;
  Float32 m_inputLatency;
  Float32 m_outputLatency;
  Float32 m_bufferDuration;

  unsigned int m_sampleRate;
  unsigned int m_frameSize;

  std::atomic<bool> m_started;

  CAESpinSection m_render_section;
  std::atomic<int64_t> m_render_timestamp;
};

CAAudioUnitSink::CAAudioUnitSink() : m_started(false), m_render_timestamp(0)
{
}

CAAudioUnitSink::~CAAudioUnitSink()
{
  close();
}

bool CAAudioUnitSink::open(AudioStreamBasicDescription outputFormat, size_t buffer_size)
{
  m_setup = false;
  m_outputFormat = outputFormat;
  m_outputLatency = 0.0;
  m_bufferDuration = 0.0;
  m_sampleRate = static_cast<unsigned int>(outputFormat.mSampleRate);
  m_frameSize = outputFormat.mChannelsPerFrame * outputFormat.mBitsPerChannel / 8;

  m_buffer = new AERingBuffer(buffer_size);

  return setupAudio();
}

bool CAAudioUnitSink::close()
{
  deactivate();
  delete m_buffer;
  m_buffer = NULL;

  m_started = false;
  return true;
}

bool CAAudioUnitSink::activate()
{
  if (!m_activated)
  {
    if (setupAudio())
    {
      AudioOutputUnitStart(m_audioUnit);
      m_activated = true;
    }
  }

  return m_activated;
}

bool CAAudioUnitSink::deactivate()
{
  if (m_activated)
  {
    AudioUnitReset(m_audioUnit, kAudioUnitScope_Global, 0);

    // this is a delayed call, the OS will block here
    // until the autio unit actually is stopped.
    AudioOutputUnitStop(m_audioUnit);

    // detach the render callback on the unit
    AURenderCallbackStruct callbackStruct = {};
    AudioUnitSetProperty(m_audioUnit, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Input,
                         0, &callbackStruct, sizeof(callbackStruct));

    AudioUnitUninitialize(m_audioUnit);
    AudioComponentInstanceDispose(m_audioUnit), m_audioUnit = nullptr;

    m_setup = false;
    m_activated = false;
  }

  return m_activated;
}

void CAAudioUnitSink::updatedelay(AEDelayStatus& status)
{
  // return the number of audio frames in buffer, in seconds
  // use internal framesize, once written,
  // bytes in buffer are owned by CAAudioUnitSink.
  unsigned int size;
  CAESpinLock lock(m_render_section);
  do
  {
    status.tick = m_render_timestamp;
    status.delay = 0;
    if (m_buffer)
      size = m_buffer->GetReadSize();
    else
      size = 0;
  } while (lock.retry());

  // bytes to seconds
  status.delay += static_cast<double>(size) / static_cast<double>(m_frameSize) /
                  static_cast<double>(m_sampleRate);
  // add in hw delay and total latency (in seconds)
  status.delay += static_cast<double>(m_totalLatency);
}

double CAAudioUnitSink::buffertime()
{
  // return the number of audio frames for the total buffer size, in seconds
  // use internal framesize, buffer is owned by CAAudioUnitSink.
  double buffertime;
  buffertime =
      static_cast<double>(m_buffer->GetMaxSize()) / static_cast<double>(m_frameSize * m_sampleRate);
  return buffertime;
}

CCriticalSection mutex;
XbmcThreads::ConditionVariable condVar;

unsigned int CAAudioUnitSink::write(uint8_t* data, unsigned int frames, unsigned int framesize)
{
  // use the passed in framesize instead of internal,
  // writes are relative to AE formats. once written,
  // CAAudioUnitSink owns them.
  if (m_buffer->GetWriteSize() < frames * framesize)
  { // no space to write - wait for a bit
    std::unique_lock<CCriticalSection> lock(mutex);
    auto timeout = std::chrono::milliseconds(900 * frames / m_sampleRate);
    if (!m_started)
      timeout = 4500ms;

    // we are using a timer here for being sure for timeouts
    // condvar can be woken spuriously as signaled
    XbmcThreads::EndTime<> timer(timeout);
    condVar.wait(mutex, timeout);
    if (!m_started && timer.IsTimePast())
    {
      CLog::Log(LOGERROR, "{} engine didn't start in {} ms!", __FUNCTION__, timeout.count());
      return INT_MAX;
    }
  }

  unsigned int write_frames = std::min(frames, m_buffer->GetWriteSize() / framesize);
  if (write_frames)
    m_buffer->Write(data, write_frames * framesize);

  return write_frames;
}

void CAAudioUnitSink::drain()
{
  unsigned int bytes = m_buffer->GetReadSize();
  unsigned int totalBytes = bytes;
  int maxNumTimeouts = 3;
  auto timeout = std::chrono::milliseconds(static_cast<int>(buffertime()));

  while (bytes && maxNumTimeouts > 0)
  {
    std::unique_lock<CCriticalSection> lock(mutex);
    XbmcThreads::EndTime<> timer(timeout);
    condVar.wait(mutex, timeout);

    bytes = m_buffer->GetReadSize();
    // if we timeout and do not consume bytes,
    // decrease maxNumTimeouts and try again.
    if (timer.IsTimePast() && bytes == totalBytes)
      maxNumTimeouts--;
    totalBytes = bytes;
  }
}

bool CAAudioUnitSink::setupAudio()
{
  if (m_setup && m_audioUnit)
    return true;

  // Audio Unit Setup
  // Describe a default output unit.
  AudioComponentDescription description = {};
  description.componentType = kAudioUnitType_Output;
  description.componentSubType = kAudioUnitSubType_RemoteIO;
  description.componentManufacturer = kAudioUnitManufacturer_Apple;

  // Get component
  AudioComponent component;
  component = AudioComponentFindNext(nullptr, &description);
  OSStatus status = AudioComponentInstanceNew(component, &m_audioUnit);
  if (status != noErr)
  {
    CLog::Log(LOGERROR, "{} error creating audioUnit (error: {})", __PRETTY_FUNCTION__,
              static_cast<int>(status));
    return false;
  }

  // set the hw buffer size (in seconds), this affects the number of samples
  // that get rendered every time the audio callback is fired.
  double samplerate = m_outputFormat.mSampleRate;
  int channels = m_outputFormat.mChannelsPerFrame;
  NSTimeInterval bufferseconds =
      1024 * m_outputFormat.mChannelsPerFrame / m_outputFormat.mSampleRate;
  CLog::Log(LOGINFO, "{} setting channels {}", __PRETTY_FUNCTION__, channels);
  CLog::Log(LOGINFO, "{} setting samplerate {:f}", __PRETTY_FUNCTION__, samplerate);
  CLog::Log(LOGINFO, "{} setting buffer duration to {:f}", __PRETTY_FUNCTION__, bufferseconds);
  setAVAudioSessionProperties(bufferseconds, samplerate, channels);

  // Get the real output samplerate, the requested might not available
  Float64 realisedSampleRate = [[AVAudioSession sharedInstance] sampleRate];
  if (m_outputFormat.mSampleRate != realisedSampleRate)
  {
    CLog::Log(LOGINFO,
              "{} couldn't set requested samplerate {}, AudioUnit will resample to {} instead",
              __PRETTY_FUNCTION__, static_cast<int>(m_outputFormat.mSampleRate),
              static_cast<int>(realisedSampleRate));
    // if we don't want AudioUnit to resample - but instead let activeae resample -
    // reflect the realised samplerate to the output format here
    // well maybe it is handy in the future - as of writing this
    // AudioUnit was about 6 times faster then activeae ;)
    //m_outputFormat.mSampleRate = realisedSampleRate;
    //m_sampleRate = realisedSampleRate;
  }

  // Set the output stream format
  UInt32 ioDataSize = sizeof(AudioStreamBasicDescription);
  status = AudioUnitSetProperty(m_audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input,
                                0, &m_outputFormat, ioDataSize);
  if (status != noErr)
  {
    CLog::Log(LOGERROR, "{} error setting stream format on audioUnit (error: {})",
              __PRETTY_FUNCTION__, static_cast<int>(status));
    return false;
  }

  // Attach a render callback on the unit
  AURenderCallbackStruct callbackStruct = {};
  callbackStruct.inputProc = renderCallback;
  callbackStruct.inputProcRefCon = this;
  status = AudioUnitSetProperty(m_audioUnit, kAudioUnitProperty_SetRenderCallback,
                                kAudioUnitScope_Input, 0, &callbackStruct, sizeof(callbackStruct));
  if (status != noErr)
  {
    CLog::Log(LOGERROR, "{} error setting render callback for AudioUnit (error: {})",
              __PRETTY_FUNCTION__, static_cast<int>(status));
    return false;
  }

  status = AudioUnitInitialize(m_audioUnit);
  if (status != noErr)
  {
    CLog::Log(LOGERROR, "{} error initializing AudioUnit (error: {})", __PRETTY_FUNCTION__,
              static_cast<int>(status));
    return false;
  }

  AVAudioSession* mySession = [AVAudioSession sharedInstance];
  m_inputLatency = [mySession inputLatency];
  m_outputLatency = [mySession outputLatency];
  m_bufferDuration = [mySession IOBufferDuration];
  m_totalLatency = m_outputLatency + m_bufferDuration;
  CLog::Log(LOGINFO, "{} total latency = {:f}", __PRETTY_FUNCTION__, m_totalLatency);

  m_setup = true;
  std::string formatString;
  CLog::Log(LOGINFO, "{} setup audio format: {}", __PRETTY_FUNCTION__,
            StreamDescriptionToString(m_outputFormat, formatString));

  dumpAVAudioSessionProperties();

  return m_setup;
}

inline void LogLevel(unsigned int got, unsigned int wanted)
{
  static unsigned int lastReported = INT_MAX;
  if (got != wanted)
  {
    if (got != lastReported)
    {
      CLog::Log(LOGWARNING, "DARWINIOS: {}flow ({} vs {} bytes)", got > wanted ? "over" : "under",
                got, wanted);
      lastReported = got;
    }
  }
  else
    lastReported = INT_MAX; // indicate we were good at least once
}

OSStatus CAAudioUnitSink::renderCallback(void* inRefCon,
                                         AudioUnitRenderActionFlags* ioActionFlags,
                                         const AudioTimeStamp* inTimeStamp,
                                         UInt32 inOutputBusNumber,
                                         UInt32 inNumberFrames,
                                         AudioBufferList* ioData)
{
  CAAudioUnitSink* sink = (CAAudioUnitSink*)inRefCon;

  sink->m_render_section.enter();
  sink->m_started = true;

  for (unsigned int i = 0; i < ioData->mNumberBuffers; i++)
  {
    unsigned int wanted = ioData->mBuffers[i].mDataByteSize;
    unsigned int bytes = std::min(sink->m_buffer->GetReadSize(), wanted);
    sink->m_buffer->Read(static_cast<unsigned char*>(ioData->mBuffers[i].mData), bytes);
    LogLevel(bytes, wanted);

    if (bytes == 0)
    {
      // Apple iOS docs say kAudioUnitRenderAction_OutputIsSilence provides a hint to
      // the audio unit that there is no audio to process. and you must also explicitly
      // set the buffers contents pointed at by the ioData parameter to 0.
      memset(ioData->mBuffers[i].mData, 0x00, ioData->mBuffers[i].mDataByteSize);
      *ioActionFlags |= kAudioUnitRenderAction_OutputIsSilence;
    }
    else if (bytes < wanted)
    {
      // zero out what we did not copy over (underflow)
      uint8_t* empty = static_cast<uint8_t*>(ioData->mBuffers[i].mData) + bytes;
      memset(empty, 0x00, wanted - bytes);
    }
  }

  sink->m_render_timestamp = inTimeStamp->mHostTime;
  sink->m_render_section.leave();
  // tell the sink we're good for more data
  condVar.notifyAll();

  return noErr;
}

#pragma mark - EnumerateDevices
/***************************************************************************************/
/***************************************************************************************/
static void EnumerateDevices(AEDeviceInfoList& list)
{
  CAEDeviceInfo device;

  device.m_deviceName = "default";
  device.m_displayName = "Default";
  device.m_displayNameExtra = "";

  // if not hdmi,  CAESinkDARWINIOS::Initialize will kick back to 2 channel PCM
  device.m_deviceType = AE_DEVTYPE_HDMI;
  device.m_wantsIECPassthrough = true;

  // Passthrough only working < tvos 11.2??
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_AC3);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_EAC3);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_512);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_1024);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTS_2048);
  device.m_streamTypes.push_back(CAEStreamInfo::STREAM_TYPE_DTSHD_CORE);

  device.m_sampleRates.push_back(44100);
  device.m_sampleRates.push_back(48000);

  device.m_dataFormats.push_back(AE_FMT_RAW);
  device.m_dataFormats.push_back(AE_FMT_S16LE);
  device.m_dataFormats.push_back(AE_FMT_FLOAT);

  // add channel info
  NSInteger maxChannels = [[AVAudioSession sharedInstance] maximumOutputNumberOfChannels];
  if (maxChannels > 6)
    device.m_channels = AE_CH_LAYOUT_7_1;
  else
    device.m_channels = AE_CH_LAYOUT_5_1;

  CLog::Log(LOGDEBUG, "EnumerateDevices:Device({})", device.m_deviceName);

  list.push_back(device);
}

#pragma mark - AEDeviceInfoList
/***************************************************************************************/
/***************************************************************************************/
AEDeviceInfoList CAESinkDARWINTVOS::m_devices;

CAESinkDARWINTVOS::CAESinkDARWINTVOS()
{
}

void CAESinkDARWINTVOS::Register()
{
  AE::AESinkRegEntry reg;
  reg.sinkName = "DARWINTVOS";
  reg.createFunc = CAESinkDARWINTVOS::Create;
  reg.enumerateFunc = CAESinkDARWINTVOS::EnumerateDevicesEx;
  AE::CAESinkFactory::RegisterSink(reg);
}

std::unique_ptr<IAESink> CAESinkDARWINTVOS::Create(std::string& device,
                                                   AEAudioFormat& desiredFormat)
{
  auto sink = std::make_unique<CAESinkDARWINTVOS>();
  if (sink->Initialize(desiredFormat, device))
    return sink;

  return {};
}

bool CAESinkDARWINTVOS::Initialize(AEAudioFormat& format, std::string& device)
{
  std::string route = getAudioRoute();
  // no route, no audio. bail and let AE kick back to NULL device
  if (route.empty())
    return false;

  // no device, bail and let AE kick back to NULL device
  bool found = false;
  std::string devicelower = device;
  StringUtils::ToLower(devicelower);
  for (size_t i = 0; i < m_devices.size(); i++)
  {
    if (devicelower.find(m_devices[i].m_deviceName) != std::string::npos)
    {
      m_info = m_devices[i];
      found = true;
      break;
    }
  }
  if (!found)
    return false;

  AudioStreamBasicDescription audioFormat = {};
  audioFormat.mFormatID = kAudioFormatLinearPCM;

  // check if are we dealing with raw formats or pcm
  bool passthrough = false;
  switch (format.m_dataFormat)
  {
    case AE_FMT_RAW:
      // this will be selected when AE wants AC3 or DTS or anything other then float
      format.m_dataFormat = AE_FMT_S16LE;
      audioFormat.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
      if (route.find("HDMI") != std::string::npos)
        passthrough = true;
      else
      {
        // this should never happen but we cover it just in case
        // for iOS/tvOS, if we are not hdmi, we cannot do raw
        // so kick back to pcm.
        format.m_dataFormat = AE_FMT_FLOAT;
        audioFormat.mFormatFlags |= kLinearPCMFormatFlagIsFloat;
      }
      break;
    default:
      // AE lies, even when we register formats we can handle,
      // it shoves everything down and it is up to the sink
      // to check/verify and kick back to what the sink supports
      format.m_dataFormat = AE_FMT_FLOAT;
      audioFormat.mFormatFlags |= kLinearPCMFormatFlagIsFloat;
      break;
  }

  // check and correct sample rates to what we support,
  // remember, AE is a lier and we need to check/verify
  // and kick back to what the sink supports
  switch (format.m_sampleRate)
  {
    case 11025:
    case 22050:
    case 44100:
    case 88200:
    case 176400:
      if (route.find("HDMI") != std::string::npos)
        audioFormat.mSampleRate = 48000;
      else
        audioFormat.mSampleRate = 44100;
      break;
    default:
    case 8000:
    case 12000:
    case 16000:
    case 24000:
    case 32000:
    case 48000:
    case 96000:
    case 192000:
    case 384000:
      audioFormat.mSampleRate = 48000;
      break;
  }

  if (passthrough)
  {
    // passthrough is special, PCM encapsulated IEC61937 packets.
    // make sure input and output samplerate match for preventing resampling
    audioFormat.mSampleRate = [[AVAudioSession sharedInstance] sampleRate];
    audioFormat.mFramesPerPacket = 1; // must be 1
    audioFormat.mChannelsPerFrame = 2; // passthrough needs 2 channels
    audioFormat.mBitsPerChannel = 16;
    audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame * (audioFormat.mBitsPerChannel >> 3);
    audioFormat.mBytesPerPacket = audioFormat.mBytesPerFrame * audioFormat.mFramesPerPacket;
    audioFormat.mFormatFlags |= kLinearPCMFormatFlagIsPacked;
  }
  else
  {
    NSInteger maxChannels = [[AVAudioSession sharedInstance] maximumOutputNumberOfChannels];
    audioFormat.mFramesPerPacket = 1; // must be 1

    // tvos supports up to 8 channels
    audioFormat.mChannelsPerFrame = format.m_channelLayout.Count();
    // clamp number of channels to what tvOS reports
    if (maxChannels == 2)
      audioFormat.mChannelsPerFrame = (UInt32)maxChannels;

    audioFormat.mBitsPerChannel = CAEUtil::DataFormatToBits(format.m_dataFormat);
    audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame * (audioFormat.mBitsPerChannel >> 3);
    audioFormat.mBytesPerPacket = audioFormat.mBytesPerFrame * audioFormat.mFramesPerPacket;
    audioFormat.mFormatFlags |= kLinearPCMFormatFlagIsPacked;

    CAEChannelInfo channel_info;
    CAChannelIndex channel_index = CAChannel_PCM_6CHAN;
    if (maxChannels == 6 && format.m_channelLayout.Count() == 6)
    {
      // if 6, then audio is set to Digital Dolby 5.1, need to use DD mapping
      channel_index = CAChannel_PCM_DD5_1;
    }
    else if (format.m_channelLayout.Count() == 5)
    {
      // if 5, then audio is set to Digital Dolby 5.0, need to use DD mapping
      channel_index = CAChannel_PCM_DD5_1;
    }
    else
    {
      if (format.m_channelLayout.Count() > 6)
        channel_index = CAChannel_PCM_8CHAN;
    }
    for (size_t chan = 0; chan < format.m_channelLayout.Count(); ++chan)
    {
      if (chan < maxChannels)
        channel_info += CAChannelMap[channel_index][chan];
    }
    format.m_channelLayout = channel_info;
  }

  std::string formatString;
  CLog::Log(LOGDEBUG, "{}: AudioStreamBasicDescription: {} {}", __PRETTY_FUNCTION__,
            StreamDescriptionToString(audioFormat, formatString),
            passthrough ? "passthrough" : "pcm");

#if DO_440HZ_TONE_TEST
  SineWaveGeneratorInitWithFrequency(&m_SineWaveGenerator, 440.0, audioFormat.mSampleRate);
#endif

  size_t buffer_size;
  switch (format.m_streamInfo.m_type)
  {
    case CAEStreamInfo::STREAM_TYPE_AC3:
      if (!format.m_streamInfo.m_ac3FrameSize)
        format.m_streamInfo.m_ac3FrameSize = 1536;
      format.m_frames = format.m_streamInfo.m_ac3FrameSize;
      buffer_size = format.m_frames * 8;
      break;
    case CAEStreamInfo::STREAM_TYPE_EAC3:
      if (!format.m_streamInfo.m_ac3FrameSize)
        format.m_streamInfo.m_ac3FrameSize = 1536;
      format.m_frames = format.m_streamInfo.m_ac3FrameSize;
      buffer_size = format.m_frames * 8;
      break;
    case CAEStreamInfo::STREAM_TYPE_DTS_512:
    case CAEStreamInfo::STREAM_TYPE_DTSHD_CORE:
      format.m_frames = 512;
      buffer_size = 16384;
      break;
    case CAEStreamInfo::STREAM_TYPE_DTS_1024:
      format.m_frames = 1024;
      buffer_size = 16384;
      break;
    case CAEStreamInfo::STREAM_TYPE_DTS_2048:
      format.m_frames = 2048;
      buffer_size = 16384;
      break;
    default:
      format.m_frames = 1024;
      buffer_size = (512 * audioFormat.mBytesPerFrame) * 8;
      break;
  }
  m_audioSink = new CAAudioUnitSink;
  m_audioSink->open(audioFormat, buffer_size);
  // reset to the realised samplerate
  format.m_sampleRate = m_audioSink->sampletrate();
  format.m_frameSize =
      format.m_channelLayout.Count() * (CAEUtil::DataFormatToBits(format.m_dataFormat) >> 3);

  m_format = format;

  if (!m_audioSink->activate())
    return false;

  return true;
}

void CAESinkDARWINTVOS::Deinitialize()
{
  delete m_audioSink;
  m_audioSink = nullptr;
}

void CAESinkDARWINTVOS::GetDelay(AEDelayStatus& status)
{
  if (m_audioSink)
    m_audioSink->updatedelay(status);
  else
    status.SetDelay(0.0);
}

double CAESinkDARWINTVOS::GetCacheTotal()
{
  if (m_audioSink)
    return m_audioSink->buffertime();
  return 0.0;
}

unsigned int CAESinkDARWINTVOS::AddPackets(uint8_t** data, unsigned int frames, unsigned int offset)
{
  uint8_t* buffer = data[0] + (offset * m_format.m_frameSize);
#if DO_440HZ_TONE_TEST
  if (m_format.m_dataFormat == AE_FMT_FLOAT)
  {
    float* samples = static_cast<float*>(buffer);
    for (unsigned int j = 0; j < frames; j++)
    {
      float sample = SineWaveGeneratorNextSampleFloat(&m_SineWaveGenerator);
      *samples++ = sample;
      *samples++ = sample;
    }
  }
  else
  {
    int16_t* samples = (int16_t*)buffer;
    for (unsigned int j = 0; j < frames; j++)
    {
      int16_t sample = SineWaveGeneratorNextSampleInt16(&m_SineWaveGenerator);
      *samples++ = sample;
      *samples++ = sample;
    }
  }
#endif
  if (m_audioSink)
    return m_audioSink->write(buffer, frames, m_format.m_frameSize);
  return 0;
}

void CAESinkDARWINTVOS::Drain()
{
  if (m_audioSink)
    m_audioSink->drain();
}

bool CAESinkDARWINTVOS::HasVolume()
{
  return false;
}

void CAESinkDARWINTVOS::EnumerateDevicesEx(AEDeviceInfoList& list, bool force)
{
  m_devices.clear();
  EnumerateDevices(m_devices);
  list = m_devices;
}
