// Copyright Epic Games, Inc. All Rights Reserved.

#include "MetasoundEnvelopeFollowerNode.h"

#include "MetasoundAudioBuffer.h"
#include "MetasoundExecutableOperator.h"
#include "MetasoundFacade.h"
#include "MetasoundNodeRegistrationMacro.h"
#include "MetasoundDataTypeRegistrationMacro.h"
#include "MetasoundOperatorSettings.h"
#include "MetasoundPrimitives.h"
#include "MetasoundStandardNodesNames.h"
#include "MetasoundTrigger.h"
#include "MetasoundTime.h"
#include "MetasoundVertex.h"
#include "DSP/EnvelopeFollower.h"

#define LOCTEXT_NAMESPACE "MetasoundStandardNodes_EnvelopeFollower"

namespace Metasound
{
	namespace EnvelopeFollower
	{
		static const TCHAR* InParamNameAudioInput = TEXT("In");
		static const TCHAR* InParamNameAttackTime = TEXT("Attack Time");
		static const TCHAR* InParamNameReleaseTime = TEXT("Release Time");
		static const TCHAR* OutParamNameEnvelope = TEXT("Envelope");
	}

	class FEnvelopeFollowerOperator : public TExecutableOperator<FEnvelopeFollowerOperator>
	{
	public:

		static const FNodeClassMetadata& GetNodeInfo();
		static const FVertexInterface& GetVertexInterface();
		static TUniquePtr<IOperator> CreateOperator(const FCreateOperatorParams& InParams, FBuildErrorArray& OutErrors);

		FEnvelopeFollowerOperator(const FOperatorSettings& InSettings, 
			const FAudioBufferReadRef& InAudioInput, 
			const FTimeReadRef& InAttackTime, 
			const FTimeReadRef& InReleaseTime);

		virtual FDataReferenceCollection GetInputs() const override;
		virtual FDataReferenceCollection GetOutputs() const override;
		void Execute();

	private:
		// The input audio buffer
		FAudioBufferReadRef AudioInput;

		// The amount of attack time
		FTimeReadRef AttackTime;

		// The amount of release time
		FTimeReadRef ReleaseTime;

		// The audio output
		FFloatWriteRef EnvelopeOutput;

		// The envelope follower DSP object
		Audio::FEnvelopeFollower EnvelopeFollower;

		double PrevAttackTime = 0.0;
		double PrevReleaseTime = 0.0;
	};

	FEnvelopeFollowerOperator::FEnvelopeFollowerOperator(const FOperatorSettings& InSettings, 
		const FAudioBufferReadRef& InAudioInput, 
		const FTimeReadRef& InAttackTime,
		const FTimeReadRef& InReleaseTime)
		: AudioInput(InAudioInput)
		, AttackTime(InAttackTime)
		, ReleaseTime(InReleaseTime)
		, EnvelopeOutput(FFloatWriteRef::CreateNew(0.0f))
	{
		PrevAttackTime = FMath::Max(FTime::ToMilliseconds(*AttackTime), 0.0);
		PrevReleaseTime = FMath::Max(FTime::ToMilliseconds(*ReleaseTime), 0.0);

		EnvelopeFollower.Init(InSettings.GetSampleRate(), PrevAttackTime, PrevReleaseTime);
	}

	FDataReferenceCollection FEnvelopeFollowerOperator::GetInputs() const
	{
		FDataReferenceCollection InputDataReferences;
		InputDataReferences.AddDataReadReference(EnvelopeFollower::InParamNameAudioInput, AudioInput);
		InputDataReferences.AddDataReadReference(EnvelopeFollower::InParamNameAttackTime, AttackTime);
		InputDataReferences.AddDataReadReference(EnvelopeFollower::InParamNameReleaseTime, ReleaseTime);

		return InputDataReferences;
	}

	FDataReferenceCollection FEnvelopeFollowerOperator::GetOutputs() const
	{
		FDataReferenceCollection OutputDataReferences;
		OutputDataReferences.AddDataReadReference(EnvelopeFollower::OutParamNameEnvelope, EnvelopeOutput);
		return OutputDataReferences;
	}

	void FEnvelopeFollowerOperator::Execute()
	{
		// Check for any input changes
		double CurrentAttackTime = FMath::Max(FTime::ToMilliseconds(*AttackTime), 0.0);
		if (!FMath::IsNearlyEqual(CurrentAttackTime, PrevAttackTime))
		{
			PrevAttackTime = CurrentAttackTime;
			EnvelopeFollower.SetAttackTime(CurrentAttackTime);
		}

		double CurrentReleaseTime = FMath::Max(FTime::ToMilliseconds(*ReleaseTime), 0.0);
		if (!FMath::IsNearlyEqual(CurrentReleaseTime, PrevReleaseTime))
		{
			PrevReleaseTime = CurrentReleaseTime;
			EnvelopeFollower.SetReleaseTime(CurrentReleaseTime);
		}

		// Process the audio through the envelope follower
		const float* InputAudio = AudioInput->GetData();
		int32 NumFrames = AudioInput->Num();
		EnvelopeFollower.ProcessAudio(InputAudio, NumFrames);

		// Write the current envelope follower value to the output
		*EnvelopeOutput = EnvelopeFollower.GetCurrentValue();
	}

	const FVertexInterface& FEnvelopeFollowerOperator::GetVertexInterface()
	{
		static const FVertexInterface Interface(
			FInputVertexInterface(
				TInputDataVertexModel<FAudioBuffer>(EnvelopeFollower::InParamNameAudioInput, LOCTEXT("AudioInputToolTT", "Audio input.")),
				TInputDataVertexModel<FTime>(EnvelopeFollower::InParamNameAttackTime, LOCTEXT("AttackTimeTT", "The attack time of the envelope follower."), 0.01f),
				TInputDataVertexModel<FTime>(EnvelopeFollower::InParamNameReleaseTime, LOCTEXT("ReleaseTimeTT", "The release time of the envelope follower."), 0.1f)
			),
			FOutputVertexInterface(
				TOutputDataVertexModel<float>(EnvelopeFollower::OutParamNameEnvelope, LOCTEXT("EnvelopeFollowerOutputTT", "The output envelope value of the audio signal."))
			)
		);

		return Interface;
	}

	const FNodeClassMetadata& FEnvelopeFollowerOperator::GetNodeInfo()
	{
		auto InitNodeInfo = []() -> FNodeClassMetadata
		{
			FNodeClassMetadata Info;
			Info.ClassName = { Metasound::StandardNodes::Namespace, TEXT("Envelope Follower"), TEXT("") };
			Info.MajorVersion = 1;
			Info.MinorVersion = 0;
			Info.DisplayName = LOCTEXT("Metasound_EnvelopeFollowerDisplayName", "Envelope Follower");
			Info.Description = LOCTEXT("Metasound_EnvelopeFollowerDescription", "Outputs an envelope from an input audio signal.");
			Info.Author = PluginAuthor;
			Info.PromptIfMissing = PluginNodeMissingPrompt;
			Info.DefaultInterface = GetVertexInterface();

			return Info;
		};

		static const FNodeClassMetadata Info = InitNodeInfo();

		return Info;
	}

	TUniquePtr<IOperator> FEnvelopeFollowerOperator::CreateOperator(const FCreateOperatorParams& InParams, FBuildErrorArray& OutErrors)
	{
		const FEnvelopeFollowerNode& EnvelopeFollowerNode = static_cast<const FEnvelopeFollowerNode&>(InParams.Node);
		const FDataReferenceCollection& InputCollection = InParams.InputDataReferences;
		const FInputVertexInterface& InputInterface = GetVertexInterface().GetInputInterface();

		FAudioBufferReadRef AudioIn = InputCollection.GetDataReadReferenceOrConstruct<FAudioBuffer>(EnvelopeFollower::InParamNameAudioInput, InParams.OperatorSettings);
		FTimeReadRef AttackTime = InputCollection.GetDataReadReferenceOrConstructWithVertexDefault<FTime>(InputInterface, EnvelopeFollower::InParamNameAttackTime, InParams.OperatorSettings);
		FTimeReadRef ReleaseTime = InputCollection.GetDataReadReferenceOrConstructWithVertexDefault<FTime>(InputInterface, EnvelopeFollower::InParamNameReleaseTime, InParams.OperatorSettings);

		return MakeUnique<FEnvelopeFollowerOperator>(InParams.OperatorSettings, AudioIn, AttackTime, ReleaseTime);
	}

	FEnvelopeFollowerNode::FEnvelopeFollowerNode(const FNodeInitData& InitData)
		: FNodeFacade(InitData.InstanceName, InitData.InstanceID, TFacadeOperatorClass<FEnvelopeFollowerOperator>())
	{
	}

	METASOUND_REGISTER_NODE(FEnvelopeFollowerNode)
}

#undef LOCTEXT_NAMESPACE