// Copyright Epic Games, Inc. All Rights Reserved.
#include "MetasoundOperatorCacheSubsystem.h"

#include "AudioMixerDevice.h"
#include "MetasoundGenerator.h"
#include "MetasoundGeneratorModule.h"
#include "MetasoundOperatorCache.h"
#include "Modules/ModuleManager.h"
#include "Misc/Optional.h"
#include "Sound/SoundGenerator.h"

static TOptional<Metasound::FMetasoundGeneratorInitParams> CreateInitParams(UMetaSoundSource* InMetaSound, const FSoundGeneratorInitParams& InParams)
{
	using namespace Metasound;
	using namespace Metasound::Frontend;
	using namespace Metasound::Engine;
	using namespace Metasound::SourcePrivate;

	if (!ensure(InMetaSound))
	{
		return {}; // InMetaSound was null
	}

	if (ensure(!InMetaSound->IsDynamic()))
	{
		return {}; // we cannot precache dynamic metasounds
	}

	FOperatorSettings InSettings = InMetaSound->GetOperatorSettings(static_cast<FSampleRate>(InParams.SampleRate));
	FMetasoundEnvironment Environment = InMetaSound->CreateEnvironment(InParams);

	FOperatorBuilderSettings BuilderSettings = FOperatorBuilderSettings::GetDefaultSettings();
	// Graph analyzer currently only enabled for preview sounds (but can theoretically be supported for all sounds)
	BuilderSettings.bPopulateInternalDataReferences = InParams.bIsPreviewSound;

	return FMetasoundGeneratorInitParams
	{
		InSettings,
		MoveTemp(BuilderSettings),
		{}, // Graph, retrieved from the FrontEnd Registry in FOperatorPool::BuildAndAddOperator()
		Environment,
		InMetaSound->GetName(),
		InMetaSound->GetOutputAudioChannelOrder(),
		{}, // DefaultParameters
		true, // bBuildSynchronous
		{} // DataChannel
	};
}

bool UMetaSoundCacheSubsystem::ShouldCreateSubsystem(UObject* Outer) const
{
	return !IsRunningDedicatedServer();
}

void UMetaSoundCacheSubsystem::Initialize(FSubsystemCollectionBase& Collection)
{
	using namespace Audio;
	using namespace Metasound;

	BuildParams = MakeUnique<FSoundGeneratorInitParams>();
	const FMixerDevice* MixerDevice = GetMixerDevice();

	if (BuildParams && ensure(MixerDevice))
	{
		BuildParams->AudioDeviceID = GetAudioDeviceHandle().GetDeviceID();
		BuildParams->SampleRate = MixerDevice->GetSampleRate();
		BuildParams->AudioMixerNumOutputFrames = MixerDevice->GetNumOutputFrames();
		BuildParams->NumChannels = MixerDevice->GetNumDeviceChannels();
		BuildParams->NumFramesPerCallback = 0;
		BuildParams->InstanceID = 0;
	}
}

void UMetaSoundCacheSubsystem::Update()
{
#if METASOUND_OPERATORCACHEPROFILER_ENABLED
	using namespace Metasound;
	if (TSharedPtr<FOperatorPool> OperatorPool = FModuleManager::GetModuleChecked<IMetasoundGeneratorModule>("MetasoundGenerator").GetOperatorPool())
	{
		OperatorPool->UpdateHitRateTracker();
	}
#endif // #if METASOUND_OPERATORCACHEPROFILER_ENABLED
}

void UMetaSoundCacheSubsystem::PrecacheMetaSound(UMetaSoundSource* InMetaSound, int32 InNumInstances)
{
	using namespace Audio;
	using namespace Metasound;

	TSharedPtr<FOperatorPool> OperatorPool;
	IMetasoundGeneratorModule* Module = FModuleManager::GetModulePtr<IMetasoundGeneratorModule>("MetasoundGenerator");
	if (ensure(Module))
	{
		OperatorPool = Module->GetOperatorPool();
	}

	const FMixerDevice* MixerDevice = GetMixerDevice();

	if (!ensure(MixerDevice && InMetaSound && BuildParams && OperatorPool))
	{
		return;
	}

	if (!ensure(InNumInstances > 0))
	{
		return;
	}

	InMetaSound->InitResources();
	BuildParams->GraphName = InMetaSound->GetOwningAssetName();

	if (InMetaSound->IsDynamic())
	{
		return;
	}

	TOptional<FMetasoundGeneratorInitParams> InitParams = CreateInitParams(InMetaSound, *BuildParams);
	if (!InitParams.IsSet())
	{
		return;
	}
	

	TUniquePtr<FOperatorBuildData> Data = MakeUnique<FOperatorBuildData>(
		  MoveTemp(InitParams.GetValue())
		, InMetaSound->GetRegistryKey()
		, FSoftObjectPath(InMetaSound->GetOwningAsset())
		, InNumInstances
	);

	OperatorPool->BuildAndAddOperator(MoveTemp(Data));
}