// Copyright UShaderLab. All Rights Reserved.

#include "MaterialExpressionShaderLabParameterAnchor.h"

#include "MaterialCompiler.h"

UMaterialExpressionShaderLabParameterAnchor::UMaterialExpressionShaderLabParameterAnchor(const FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)
{
}

#if WITH_EDITOR
TArrayView<FExpressionInput*> UMaterialExpressionShaderLabParameterAnchor::GetInputsView()
{
	CachedInputs.Reset(Inputs.Num());
	for (FExpressionInput& Input : Inputs)
	{
		CachedInputs.Add(&Input);
	}
	return CachedInputs;
}

FExpressionInput* UMaterialExpressionShaderLabParameterAnchor::GetInput(int32 InputIndex)
{
	return Inputs.IsValidIndex(InputIndex) ? &Inputs[InputIndex] : nullptr;
}

FName UMaterialExpressionShaderLabParameterAnchor::GetInputName(int32 InputIndex) const
{
	return FName(*FString::Printf(TEXT("Param%d"), InputIndex));
}

int32 UMaterialExpressionShaderLabParameterAnchor::Compile(FMaterialCompiler* Compiler, int32 OutputIndex)
{
	// Compiled in the before-attributes pass. Compiling each input forces its static-switch selector
	// (and the selected `#define`-emitting Custom node) to compile here — emitting `#define <Switch> 0/1`
	// for the current permutation ahead of every body's `#if`. The returned value is unused.
	int32 Last = INDEX_NONE;
	for (FExpressionInput& Input : Inputs)
	{
		if (Input.GetTracedInput().Expression)
		{
			const int32 Code = Input.Compile(Compiler);
			if (Code != INDEX_NONE)
			{
				Last = Code;
			}
		}
	}
	return Last != INDEX_NONE ? Last : Compiler->Constant(0.0f);
}

void UMaterialExpressionShaderLabParameterAnchor::GetCaption(TArray<FString>& OutCaptions) const
{
	OutCaptions.Add(TEXT("ShaderLab Static-Switch Defines / Parameter Anchor"));
}
#endif // WITH_EDITOR