// Copyright 1998-2019 Epic Games, Inc. All Rights Reserved.

#include "MaterialEditorDetailCustomization.h"
#include "Widgets/Text/STextBlock.h"
#include "Widgets/Input/SEditableText.h"
#include "Widgets/Input/SComboButton.h"
#include "Widgets/Views/SListView.h"
#include "Materials/Material.h"
#include "Materials/MaterialParameterCollection.h"
#include "DetailLayoutBuilder.h"
#include "DetailWidgetRow.h"
#include "DetailCategoryBuilder.h"
#include "Materials/MaterialExpressionScalarParameter.h"
#include "MaterialLayersFunctionsCustomization.h"
#include "PropertyEditorModule.h"
#include "MaterialEditor/MaterialEditorPreviewParameters.h"
#include "Widgets/Input/SButton.h"
#include "MaterialEditor/MaterialEditorInstanceConstant.h"
#include "IDetailGroup.h"
#include "MaterialEditor/DEditorParameterValue.h"
#include "AssetToolsModule.h"
#include "Modules/ModuleManager.h"
#include "Factories/MaterialInstanceConstantFactoryNew.h"
#include "Materials/MaterialInstanceConstant.h"
#include "MaterialEditor/DEditorScalarParameterValue.h"
#include "MaterialEditor/DEditorFontParameterValue.h"
#include "MaterialEditor/DEditorTextureParameterValue.h"
#include "MaterialEditor/DEditorVectorParameterValue.h"
#include "MaterialEditor/DEditorStaticSwitchParameterValue.h"
#include "MaterialEditor/DEditorStaticComponentMaskParameterValue.h"
#include "MaterialPropertyHelpers.h"
#include "MaterialEditor/DEditorMaterialLayersParameterValue.h"
#include "PropertyCustomizationHelpers.h"
#include "Curves/CurveLinearColor.h"
#include "IPropertyUtilities.h"

#define LOCTEXT_NAMESPACE "MaterialEditor"

TSharedRef<IDetailCustomization> FMaterialEditorParameterDetails::MakeInstance(UMaterialEditorPreviewParameters* Material)
{
	return MakeShareable(new FMaterialEditorParameterDetails(Material));
}

FMaterialEditorParameterDetails::FMaterialEditorParameterDetails(UMaterialEditorPreviewParameters* Material)
	: MaterialEditorInstance(Material)
{
}


TOptional<float> FMaterialEditorParameterDetails::OnGetValue(TSharedRef<IPropertyHandle> PropertyHandle)
{
	float Value = 0.0f;
	if (PropertyHandle->GetValue(Value) == FPropertyAccess::Success)
	{
		return TOptional<float>(Value);
	}

	// Value couldn't be accessed. Return an unset value
	return TOptional<float>();
}

void FMaterialEditorParameterDetails::OnValueCommitted(float NewValue, ETextCommit::Type CommitType, TSharedRef<IPropertyHandle> PropertyHandle)
{
	// Try setting as float, if that fails then set as int
	ensure(PropertyHandle->SetValue(NewValue) == FPropertyAccess::Success);
}

void FMaterialEditorParameterDetails::CustomizeDetails(IDetailLayoutBuilder& DetailLayout)
{
	PropertyUtilities = DetailLayout.GetPropertyUtilities();
	// Create a new category for a custom layout for the MIC parameters at the very top
	FName GroupsCategoryName = TEXT("ParameterGroups");
	IDetailCategoryBuilder& GroupsCategory = DetailLayout.EditCategory(GroupsCategoryName, LOCTEXT("MICParamGroupsTitle", "Parameter Groups"));
	TSharedRef<IPropertyHandle> ParameterGroupsProperty = DetailLayout.GetProperty("ParameterGroups");

	CreateGroupsWidget(ParameterGroupsProperty, GroupsCategory);

	DetailLayout.HideProperty("ParameterGroups");

	TArray<UObject*> ExternalObjects;
	ExternalObjects.Add(MaterialEditorInstance->OriginalMaterial);
}


void FMaterialEditorParameterDetails::CreateGroupsWidget(TSharedRef<IPropertyHandle> ParameterGroupsProperty, IDetailCategoryBuilder& GroupsCategory)
{
	check(MaterialEditorInstance);
	bool bShowSaveButtons = false;
	for (int32 GroupIdx = 0; GroupIdx < MaterialEditorInstance->ParameterGroups.Num(); ++GroupIdx)
	{
		FEditorParameterGroup& ParameterGroup = MaterialEditorInstance->ParameterGroups[GroupIdx];
		if (ParameterGroup.GroupAssociation == EMaterialParameterAssociation::GlobalParameter
			&& ParameterGroup.GroupName != FMaterialPropertyHelpers::LayerParamName)
		{
			IDetailGroup& DetailGroup = GroupsCategory.AddGroup(ParameterGroup.GroupName, FText::FromName(ParameterGroup.GroupName), false, true);
			CreateSingleGroupWidget(ParameterGroup, ParameterGroupsProperty->GetChildHandle(GroupIdx), DetailGroup);
			bShowSaveButtons = true;
		}
	}
	if (bShowSaveButtons)
	{
		FOnClicked ChildButtonClicked;
		UObject* LocalEditorInstance = MaterialEditorInstance;
		if (MaterialEditorInstance->OriginalMaterial)
		{
			ChildButtonClicked = FOnClicked::CreateStatic(FMaterialPropertyHelpers::OnClickedSaveNewMaterialInstance,
				ImplicitConv<UMaterialInterface*>(MaterialEditorInstance->OriginalMaterial), LocalEditorInstance);
		}
		if (MaterialEditorInstance->OriginalFunction)
		{
			ChildButtonClicked = FOnClicked::CreateStatic(FMaterialPropertyHelpers::OnClickedSaveNewFunctionInstance,
				ImplicitConv<UMaterialFunctionInterface*>(MaterialEditorInstance->OriginalFunction), ImplicitConv<UMaterialInterface*>(MaterialEditorInstance->PreviewMaterial), LocalEditorInstance);
		}

		FDetailWidgetRow& SaveInstanceRow = GroupsCategory.AddCustomRow(LOCTEXT("SaveInstances", "Save Instances"));
		SaveInstanceRow.ValueContent()
			.HAlign(HAlign_Fill)
			[
				SNew(SHorizontalBox)
				+ SHorizontalBox::Slot()
				.FillWidth(1.0f)
				[
					SNullWidget::NullWidget
				]
				+ SHorizontalBox::Slot()
				.AutoWidth()
				.Padding(2.0f)
				[
					SNew(SButton)
					.ButtonStyle(FEditorStyle::Get(), "FlatButton.Dark")
					.HAlign(HAlign_Center)
					.OnClicked(ChildButtonClicked)
					.ToolTipText(LOCTEXT("SaveToChildInstance", "Save To Child Instance"))
					.Content()
					[
						SNew(SHorizontalBox)
						+ SHorizontalBox::Slot()
						.AutoWidth()
						[
							SNew(STextBlock)
							.Font(FEditorStyle::Get().GetFontStyle("FontAwesome.10"))
							.TextStyle(FEditorStyle::Get(), "NormalText.Important")
							.Text(FText::FromString(FString(TEXT("\xf0c7 \xf149"))) /*fa-filter*/)
						]
						+ SHorizontalBox::Slot()
						.AutoWidth()
						[
							SNew(STextBlock)
							.TextStyle(FEditorStyle::Get(), "NormalText.Important")
							.Text(FText::FromString(FString(TEXT(" Save Child"))) /*fa-filter*/)
						]
					]
				]
			];
	}
	else
	{
		FDetailWidgetRow& NoParameters = GroupsCategory.AddCustomRow(LOCTEXT("NoParameters", "No Parameters"));
		NoParameters.WholeRowContent()
			[
				SNew(STextBlock)
				.Text(LOCTEXT("AddGlobalParameterPrompt", "Add a global parameter to see it here. \nMaterial Attribute Layers parameters are found in the Layer Parameter Preview panel."))
				.AutoWrapText(true)
			];
	}
}


void FMaterialEditorParameterDetails::CreateSingleGroupWidget(FEditorParameterGroup& ParameterGroup, TSharedPtr<IPropertyHandle> ParameterGroupProperty, IDetailGroup& DetailGroup)
{
	TSharedPtr<IPropertyHandle> ParametersArrayProperty = ParameterGroupProperty->GetChildHandle("Parameters");

	// Create a custom widget for each parameter in the group
	for (int32 ParamIdx = 0; ParamIdx < ParameterGroup.Parameters.Num(); ++ParamIdx)
	{
		TSharedPtr<IPropertyHandle> ParameterProperty = ParametersArrayProperty->GetChildHandle(ParamIdx);

		FString ParameterName = ParameterGroup.Parameters[ParamIdx]->ParameterInfo.Name.ToString();

		UDEditorParameterValue* Parameter = ParameterGroup.Parameters[ParamIdx];
		UDEditorFontParameterValue* FontParam = Cast<UDEditorFontParameterValue>(Parameter);
		UDEditorScalarParameterValue* ScalarParam = Cast<UDEditorScalarParameterValue>(Parameter);
		UDEditorStaticComponentMaskParameterValue* CompMaskParam = Cast<UDEditorStaticComponentMaskParameterValue>(Parameter);
		UDEditorStaticSwitchParameterValue* SwitchParam = Cast<UDEditorStaticSwitchParameterValue>(Parameter);
		UDEditorTextureParameterValue* TextureParam = Cast<UDEditorTextureParameterValue>(Parameter);
		UDEditorVectorParameterValue* VectorParam = Cast<UDEditorVectorParameterValue>(Parameter);
		UDEditorMaterialLayersParameterValue* LayersParam = Cast<UDEditorMaterialLayersParameterValue>(Parameter);

		if (VectorParam && VectorParam->bIsUsedAsChannelMask)
		{
			CreateVectorChannelMaskParameterValueWidget(Parameter, ParameterProperty, DetailGroup);
		}
		if (ScalarParam && ScalarParam->AtlasData.bIsUsedAsAtlasPosition)
		{
			CreateScalarAtlasPositionParameterValueWidget(Parameter, ParameterProperty, DetailGroup);
		}
		else if (ScalarParam || SwitchParam || TextureParam || VectorParam || FontParam)
		{
			if (ScalarParam && ScalarParam->SliderMax > ScalarParam->SliderMin)
			{
				TSharedPtr<IPropertyHandle> ParameterValueProperty = ParameterProperty->GetChildHandle("ParameterValue");
				ParameterValueProperty->SetInstanceMetaData("UIMin", FString::Printf(TEXT("%f"), ScalarParam->SliderMin));
				ParameterValueProperty->SetInstanceMetaData("UIMax", FString::Printf(TEXT("%f"), ScalarParam->SliderMax));
			}

			CreateParameterValueWidget(Parameter, ParameterProperty, DetailGroup);
		}
		else if (LayersParam)
		{
		}
		else if (CompMaskParam)
		{
			CreateMaskParameterValueWidget(Parameter, ParameterProperty, DetailGroup);
		}
		else
		{
			// Unsupported parameter type
			check(false);
		}
	}
}


void FMaterialEditorParameterDetails::CreateParameterValueWidget(UDEditorParameterValue* Parameter, TSharedPtr<IPropertyHandle> ParameterProperty, IDetailGroup& DetailGroup)
{
	TSharedPtr<IPropertyHandle> ParameterValueProperty = ParameterProperty->GetChildHandle("ParameterValue");

	if (ParameterValueProperty->IsValidHandle())
	{

		IDetailPropertyRow& PropertyRow = DetailGroup.AddPropertyRow(ParameterValueProperty.ToSharedRef());
		PropertyRow
			.DisplayName(FText::FromName(Parameter->ParameterInfo.Name))
			.ToolTip(GetParameterExpressionDescription(Parameter));
	}
}

void FMaterialEditorParameterDetails::CreateMaskParameterValueWidget(UDEditorParameterValue* Parameter, TSharedPtr<IPropertyHandle> ParameterProperty, IDetailGroup& DetailGroup)
{
	TSharedPtr<IPropertyHandle> ParameterValueProperty = ParameterProperty->GetChildHandle("ParameterValue");
	TSharedPtr<IPropertyHandle> RMaskProperty = ParameterValueProperty->GetChildHandle("R");
	TSharedPtr<IPropertyHandle> GMaskProperty = ParameterValueProperty->GetChildHandle("G");
	TSharedPtr<IPropertyHandle> BMaskProperty = ParameterValueProperty->GetChildHandle("B");
	TSharedPtr<IPropertyHandle> AMaskProperty = ParameterValueProperty->GetChildHandle("A");

	if (ParameterValueProperty->IsValidHandle())
	{
		IDetailPropertyRow& PropertyRow = DetailGroup.AddPropertyRow(ParameterValueProperty.ToSharedRef());
		const FText ParameterName = FText::FromName(Parameter->ParameterInfo.Name);

		FDetailWidgetRow& CustomWidget = PropertyRow.CustomWidget();
		CustomWidget
			.FilterString(ParameterName)
			.NameContent()
			[
				SNew(STextBlock)
				.Text(ParameterName)
				.ToolTipText(GetParameterExpressionDescription(Parameter))
				.Font(FEditorStyle::GetFontStyle(TEXT("PropertyWindow.NormalFont")))
			]
			.ValueContent()
			.MaxDesiredWidth(200.0f)
			[
				SNew(SHorizontalBox)
				+ SHorizontalBox::Slot()
				.FillWidth(1.0f)
				[
					SNew(SHorizontalBox)
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.AutoWidth()
					[
						RMaskProperty->CreatePropertyNameWidget(FText::GetEmpty(), FText::GetEmpty(), false)
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.AutoWidth()
					[
						RMaskProperty->CreatePropertyValueWidget()
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.Padding(FMargin(10.0f, 0.0f, 0.0f, 0.0f))
					.AutoWidth()
					[
						GMaskProperty->CreatePropertyNameWidget(FText::GetEmpty(), FText::GetEmpty(), false)
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.AutoWidth()
					[
						GMaskProperty->CreatePropertyValueWidget()
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.Padding(FMargin(10.0f, 0.0f, 0.0f, 0.0f))
					.AutoWidth()
					[
						BMaskProperty->CreatePropertyNameWidget(FText::GetEmpty(), FText::GetEmpty(), false)
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.AutoWidth()
					[
						BMaskProperty->CreatePropertyValueWidget()
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.Padding(FMargin(10.0f, 0.0f, 0.0f, 0.0f))
					.AutoWidth()
					[
						AMaskProperty->CreatePropertyNameWidget(FText::GetEmpty(), FText::GetEmpty(), false)
					]
					+ SHorizontalBox::Slot()
					.HAlign(HAlign_Left)
					.AutoWidth()
					[
						AMaskProperty->CreatePropertyValueWidget()
					]
				]
			];
	}
}

void FMaterialEditorParameterDetails::CreateVectorChannelMaskParameterValueWidget(UDEditorParameterValue* Parameter, TSharedPtr<IPropertyHandle> ParameterProperty, IDetailGroup& DetailGroup)
{
	TSharedPtr<IPropertyHandle> ParameterValueProperty = ParameterProperty->GetChildHandle("ParameterValue");

	if (ParameterValueProperty->IsValidHandle())
	{
		TAttribute<bool> IsParamEnabled = TAttribute<bool>::Create(TAttribute<bool>::FGetter::CreateStatic(&FMaterialPropertyHelpers::IsOverriddenExpression, Parameter));

		IDetailPropertyRow& PropertyRow = DetailGroup.AddPropertyRow(ParameterValueProperty.ToSharedRef());
		const FText ParameterName = FText::FromName(Parameter->ParameterInfo.Name);

		FOnGetPropertyComboBoxStrings GetMaskStrings = FOnGetPropertyComboBoxStrings::CreateStatic(&FMaterialPropertyHelpers::GetVectorChannelMaskComboBoxStrings);
		FOnGetPropertyComboBoxValue GetMaskValue = FOnGetPropertyComboBoxValue::CreateStatic(&FMaterialPropertyHelpers::GetVectorChannelMaskValue, Parameter);
		FOnPropertyComboBoxValueSelected SetMaskValue = FOnPropertyComboBoxValueSelected::CreateStatic(&FMaterialPropertyHelpers::SetVectorChannelMaskValue, ParameterValueProperty, Parameter, (UObject*)MaterialEditorInstance);

		FDetailWidgetRow& CustomWidget = PropertyRow.CustomWidget();
		CustomWidget
		.FilterString(ParameterName)
		.NameContent()
		[
			SNew(STextBlock)
			.Text(ParameterName)
			.ToolTipText(FMaterialPropertyHelpers::GetParameterExpressionDescription(Parameter, MaterialEditorInstance))
			.Font(FEditorStyle::GetFontStyle(TEXT("PropertyWindow.NormalFont")))
		]
		.ValueContent()
		.MaxDesiredWidth(200.0f)
		[
			SNew(SHorizontalBox)
			+ SHorizontalBox::Slot()
			.FillWidth(1.0f)
			[
				SNew(SHorizontalBox)
				+ SHorizontalBox::Slot()
				.HAlign(HAlign_Left)
				.AutoWidth()
				[
					PropertyCustomizationHelpers::MakePropertyComboBox(ParameterValueProperty, GetMaskStrings, GetMaskValue, SetMaskValue)
				]
			]
		];
	}
}

void FMaterialEditorParameterDetails::CreateScalarAtlasPositionParameterValueWidget(class UDEditorParameterValue* Parameter, TSharedPtr<IPropertyHandle> ParameterProperty, IDetailGroup& DetailGroup)
{
	TSharedPtr<IPropertyHandle> ParameterValueProperty = ParameterProperty->GetChildHandle("ParameterValue");

	if (ParameterValueProperty->IsValidHandle())
	{
		TAttribute<bool> IsParamEnabled = TAttribute<bool>::Create(TAttribute<bool>::FGetter::CreateStatic(&FMaterialPropertyHelpers::IsOverriddenExpression, Parameter));

		IDetailPropertyRow& PropertyRow = DetailGroup.AddPropertyRow(ParameterValueProperty.ToSharedRef());
	
		const FText ParameterName = FText::FromName(Parameter->ParameterInfo.Name);
		UDEditorScalarParameterValue* AtlasParameter = Cast<UDEditorScalarParameterValue>(Parameter);

		FDetailWidgetRow& CustomWidget = PropertyRow.CustomWidget();
		CustomWidget
			.FilterString(ParameterName)
			.NameContent()
			[
				SNew(STextBlock)
				.Text(ParameterName)
				.ToolTipText(FMaterialPropertyHelpers::GetParameterExpressionDescription(Parameter, MaterialEditorInstance))
				.Font(FEditorStyle::GetFontStyle(TEXT("PropertyWindow.NormalFont")))
			]
			.ValueContent()
			.HAlign(HAlign_Fill)
			.MaxDesiredWidth(400.0f)
			[
				SNew(SObjectPropertyEntryBox)
				.ObjectPath(this, &FMaterialEditorParameterDetails::GetCurvePath, AtlasParameter)
				.AllowedClass(UCurveLinearColor::StaticClass())
				.NewAssetFactories(TArray<UFactory*>())
				.DisplayThumbnail(true)
				.ThumbnailPool(PropertyUtilities.Pin()->GetThumbnailPool())
				.OnShouldSetAsset(FOnShouldSetAsset::CreateStatic(&FMaterialPropertyHelpers::OnShouldSetCurveAsset, AtlasParameter->AtlasData.Atlas))
				.OnObjectChanged(FOnSetObject::CreateStatic(&FMaterialPropertyHelpers::SetPositionFromCurveAsset, AtlasParameter->AtlasData.Atlas, AtlasParameter, ParameterProperty, (UObject*)MaterialEditorInstance))
				.DisplayCompactSize(true)
			];
	}
}

FString FMaterialEditorParameterDetails::GetCurvePath(UDEditorScalarParameterValue* Parameter) const
{
	FString Path = Parameter->AtlasData.Curve->GetPathName();
	return Path;
}

FText FMaterialEditorParameterDetails::GetParameterExpressionDescription(UDEditorParameterValue* Parameter) const
{
	if (MaterialEditorInstance && MaterialEditorInstance->OriginalMaterial)
	{
		UMaterial* BaseMaterial = MaterialEditorInstance->OriginalMaterial->GetMaterial();
		if (BaseMaterial)
		{
			UMaterialExpression* MaterialExpression = BaseMaterial->FindExpressionByGUID<UMaterialExpression>(Parameter->ExpressionId);

			if (MaterialExpression)
			{
				return FText::FromString(MaterialExpression->Desc);
			}
		}
	}
	return FText::GetEmpty();
}

TSharedRef<IDetailCustomization> FMaterialExpressionParameterDetails::MakeInstance(FOnCollectParameterGroups InCollectGroupsDelegate)
{
	return MakeShareable( new FMaterialExpressionParameterDetails(InCollectGroupsDelegate) );
}

FMaterialExpressionParameterDetails::FMaterialExpressionParameterDetails(FOnCollectParameterGroups InCollectGroupsDelegate)
	: CollectGroupsDelegate(InCollectGroupsDelegate)
{
}

FMaterialExpressionParameterDetails::FMaterialExpressionParameterDetails()
{
}

void FMaterialExpressionParameterDetails::CustomizeDetails( IDetailLayoutBuilder& DetailLayout )
{
	// for expression parameters all their properties are in one category based on their class name.
	FName DefaultCategory = NAME_None;
	IDetailCategoryBuilder& Category = DetailLayout.EditCategory( DefaultCategory );

	TArray< TWeakObjectPtr<UObject> > Objects;
	DetailLayout.GetObjectsBeingCustomized(Objects);

	DefaultValueHandles.Reset();
	ScalarParameterObjects.Reset();

	for (const auto& WeakObjectPtr : Objects)
	{
		UObject* Object = WeakObjectPtr.Get();

		UMaterialExpressionScalarParameter* ScalarParameter = Cast<UMaterialExpressionScalarParameter>(Object);

		if (ScalarParameter)
		{
			// Store these for OnSliderMinMaxEdited
			ScalarParameterObjects.Emplace(WeakObjectPtr);
			DefaultValueHandles.Emplace(DetailLayout.GetProperty("DefaultValue", UMaterialExpressionScalarParameter::StaticClass()));

			TSharedPtr<IPropertyHandle> SliderMinHandle = DetailLayout.GetProperty("SliderMin", UMaterialExpressionScalarParameter::StaticClass());

			if (SliderMinHandle.IsValid() && SliderMinHandle->IsValidHandle())
			{
				// Setup a callback when SliderMin changes to update the DefaultValue slider
				FSimpleDelegate OnSliderMinMaxEditedDelegate = FSimpleDelegate::CreateSP(this, &FMaterialExpressionParameterDetails::OnSliderMinMaxEdited);
				SliderMinHandle->SetOnPropertyValueChanged(OnSliderMinMaxEditedDelegate);
			}

			TSharedPtr<IPropertyHandle> SliderMaxHandle = DetailLayout.GetProperty("SliderMax", UMaterialExpressionScalarParameter::StaticClass());

			if (SliderMaxHandle.IsValid() && SliderMaxHandle->IsValidHandle())
			{
				FSimpleDelegate OnSliderMinMaxEditedDelegate = FSimpleDelegate::CreateSP(this, &FMaterialExpressionParameterDetails::OnSliderMinMaxEdited);
				SliderMaxHandle->SetOnPropertyValueChanged(OnSliderMinMaxEditedDelegate);
			}

			OnSliderMinMaxEdited();
		}
	}

	check(ScalarParameterObjects.Num() == DefaultValueHandles.Num());
	
	Category.AddProperty("ParameterName");

	const FName MaterialExpressionCategory = TEXT("MaterialExpression");
	IDetailCategoryBuilder& ExpressionCategory = DetailLayout.EditCategory(MaterialExpressionCategory);

	// Get a handle to the property we are about to edit
	GroupPropertyHandle = DetailLayout.GetProperty( "Group" );

	TSharedPtr<SComboButton> NewComboButton;
	TSharedPtr<SEditableText> NewEditBox;
	TSharedPtr<SListView<TSharedPtr<FString>>> NewListView;

	if (GroupPropertyHandle->IsValidHandle())
	{
		GroupPropertyHandle->MarkHiddenByCustomization();

		PopulateGroups();	

		ExpressionCategory.AddCustomRow(GroupPropertyHandle->GetPropertyDisplayName())
			.NameContent()
			[
				SNew(STextBlock)
				.Text(GroupPropertyHandle->GetPropertyDisplayName())
				.Font(IDetailLayoutBuilder::GetDetailFont())
			]
			.ValueContent()
			[
				SAssignNew(NewComboButton, SComboButton)
				.ContentPadding(FMargin(2.0f, 2.0f))
				.ButtonContent()
				[
					SAssignNew(NewEditBox, SEditableText)
					.Text(this, &FMaterialExpressionParameterDetails::OnGetText)
					.OnTextCommitted(this, &FMaterialExpressionParameterDetails::OnTextCommitted)
				]
				.MenuContent()
				[
					SNew(SVerticalBox)
					+ SVerticalBox::Slot()
					.AutoHeight()
					.MaxHeight(400.0f)
					[
						SAssignNew(NewListView, SListView<TSharedPtr<FString>>)
						.ListItemsSource(&GroupsSource)
						.OnGenerateRow(this, &FMaterialExpressionParameterDetails::MakeDetailsGroupViewWidget)
						.OnSelectionChanged(this, &FMaterialExpressionParameterDetails::OnSelectionChanged)
					]
				]
			];

		ExpressionCategory.AddProperty("SortPriority");
	}

	GroupComboButton = NewComboButton;
	GroupEditBox = NewEditBox;
	GroupListView = NewListView;
}

void FMaterialExpressionParameterDetails::PopulateGroups()
{
	TArray<FString> Groups;
	CollectGroupsDelegate.ExecuteIfBound(&Groups);
	Groups.Sort([&](const FString& A, const FString& B) {
		return A.ToLower() < B.ToLower();
	});

	GroupsSource.Empty();
	for (int32 GroupIdx = 0; GroupIdx < Groups.Num(); ++GroupIdx)
	{
		GroupsSource.Add(MakeShareable(new FString(Groups[GroupIdx])));
	}
}

TSharedRef< ITableRow > FMaterialExpressionParameterDetails::MakeDetailsGroupViewWidget( TSharedPtr<FString> Item, const TSharedRef< STableViewBase >& OwnerTable )
{
	return SNew(STableRow<TSharedPtr<FString>>, OwnerTable)
		[
			SNew(STextBlock) .Text(FText::FromString(*Item.Get()))
		];
}

void FMaterialExpressionParameterDetails::OnSelectionChanged( TSharedPtr<FString> ProposedSelection, ESelectInfo::Type /*SelectInfo*/ )
{
	if (ProposedSelection.IsValid())
	{
		GroupPropertyHandle->SetValue(*ProposedSelection.Get());
		GroupListView.Pin()->ClearSelection();
		GroupComboButton.Pin()->SetIsOpen(false);
	}
}

void FMaterialExpressionParameterDetails::OnTextCommitted( const FText& InText, ETextCommit::Type /*CommitInfo*/)
{
	GroupPropertyHandle->SetValue(InText.ToString());
	PopulateGroups();
}

FString FMaterialExpressionParameterDetails::OnGetString() const
{
	FString OutText;
	if (GroupPropertyHandle->GetValue(OutText) == FPropertyAccess::MultipleValues)
	{
		return LOCTEXT("MultipleValues", "Multiple Values").ToString();
	}
	return OutText;
}

FText FMaterialExpressionParameterDetails::OnGetText() const
{
	FString NewString = OnGetString();
	return FText::FromString(NewString);
}

void FMaterialExpressionParameterDetails::OnSliderMinMaxEdited()
{
	check(ScalarParameterObjects.Num() == DefaultValueHandles.Num());
	for (int32 Index = 0; Index < ScalarParameterObjects.Num(); Index++)
	{
		UMaterialExpressionScalarParameter* ScalarParameter = Cast<UMaterialExpressionScalarParameter>(ScalarParameterObjects[Index].Get());

		if (ScalarParameter && DefaultValueHandles[Index].IsValid() && DefaultValueHandles[Index]->IsValidHandle())
		{
			if (ScalarParameter->SliderMax > ScalarParameter->SliderMin)
			{
				// Update the values that SPropertyEditorNumeric reads
				// Unfortuantly there is no way to recreate the widget to actually update the UI with these new values
				DefaultValueHandles[Index]->SetInstanceMetaData("UIMin", FString::Printf(TEXT("%f"), ScalarParameter->SliderMin));
				DefaultValueHandles[Index]->SetInstanceMetaData("UIMax", FString::Printf(TEXT("%f"), ScalarParameter->SliderMax));
			}
			else
			{
				DefaultValueHandles[Index]->SetInstanceMetaData("UIMin", TEXT(""));
				DefaultValueHandles[Index]->SetInstanceMetaData("UIMax", TEXT(""));
			}
		}
	}
}

TSharedRef<IDetailCustomization> FMaterialExpressionCollectionParameterDetails::MakeInstance()
{
	return MakeShareable( new FMaterialExpressionCollectionParameterDetails() );
}

FMaterialExpressionCollectionParameterDetails::FMaterialExpressionCollectionParameterDetails()
{
}

FText FMaterialExpressionCollectionParameterDetails::GetToolTipText() const
{
	if (ParametersSource.Num() == 1)
	{
		return LOCTEXT("SpecifyCollection", "Specify a Collection to get parameter options");
	}
	else
	{
		return LOCTEXT("ChooseParameter", "Choose a parameter from the collection");
	}
}

FText FMaterialExpressionCollectionParameterDetails::GetParameterNameString() const
{
	FString CurrentParameterName;

	FPropertyAccess::Result Result = ParameterNamePropertyHandle->GetValue(CurrentParameterName);
	if( Result == FPropertyAccess::MultipleValues )
	{
		return NSLOCTEXT("PropertyEditor", "MultipleValues", "Multiple Values");
	}

	return FText::FromString(CurrentParameterName);
}

bool FMaterialExpressionCollectionParameterDetails::IsParameterNameComboEnabled() const
{
	UMaterialParameterCollection* Collection = nullptr;
	
	if (CollectionPropertyHandle->IsValidHandle())
	{
		UObject* CollectionObject = nullptr;
		verify(CollectionPropertyHandle->GetValue(CollectionObject) == FPropertyAccess::Success);
		Collection = Cast<UMaterialParameterCollection>(CollectionObject);
	}

	return Collection != nullptr;
}

void FMaterialExpressionCollectionParameterDetails::OnCollectionChanged()
{
	PopulateParameters();
}

void FMaterialExpressionCollectionParameterDetails::CustomizeDetails( IDetailLayoutBuilder& DetailLayout )
{
	// for expression parameters all their properties are in one category based on their class name.
	FName DefaultCategory = NAME_None;
	IDetailCategoryBuilder& Category = DetailLayout.EditCategory( DefaultCategory );

	// Get a handle to the property we are about to edit
	ParameterNamePropertyHandle = DetailLayout.GetProperty( "ParameterName" );
	check(ParameterNamePropertyHandle.IsValid());
	CollectionPropertyHandle = DetailLayout.GetProperty( "Collection" );
	check(CollectionPropertyHandle.IsValid());

	// Register a changed callback on the collection property since we need to update the PropertyName vertical box when it changes
	FSimpleDelegate OnCollectionChangedDelegate = FSimpleDelegate::CreateSP( this, &FMaterialExpressionCollectionParameterDetails::OnCollectionChanged );
	CollectionPropertyHandle->SetOnPropertyValueChanged( OnCollectionChangedDelegate );

	ParameterNamePropertyHandle->MarkHiddenByCustomization();
	CollectionPropertyHandle->MarkHiddenByCustomization();

	PopulateParameters();

	TSharedPtr<SComboButton> NewComboButton;
	TSharedPtr<SListView<TSharedPtr<FString>>> NewListView;

	// This isn't strictly speaking customized, but we need it to appear before the "Parameter Name" property, 
	// so we manually add it and set MarkHiddenByCustomization on it to avoid it being automatically added
	Category.AddProperty(CollectionPropertyHandle);

	Category.AddCustomRow( ParameterNamePropertyHandle->GetPropertyDisplayName() )
	.NameContent()
	[
		SNew( STextBlock )
		.Text( ParameterNamePropertyHandle->GetPropertyDisplayName() )
		.Font( IDetailLayoutBuilder::GetDetailFont() )
	]
	.ValueContent()
	[
		SAssignNew(NewComboButton, SComboButton)
		.IsEnabled(this, &FMaterialExpressionCollectionParameterDetails::IsParameterNameComboEnabled)
		.ContentPadding(0)
		.ButtonContent()
		[
			SNew(STextBlock)
			.Text(this, &FMaterialExpressionCollectionParameterDetails::GetParameterNameString )
		]
		.MenuContent()
		[
			SNew(SVerticalBox)
			+SVerticalBox::Slot()
			.AutoHeight()
			.MaxHeight(400.0f)
			[
				SAssignNew(NewListView, SListView<TSharedPtr<FString>>)
				.ListItemsSource(&ParametersSource)
				.OnGenerateRow(this, &FMaterialExpressionCollectionParameterDetails::MakeDetailsGroupViewWidget)
				.OnSelectionChanged(this, &FMaterialExpressionCollectionParameterDetails::OnSelectionChanged)
			]
		]
	];

	ParameterComboButton = NewComboButton;
	ParameterListView = NewListView;

	NewComboButton->SetToolTipText(GetToolTipText());
}

void FMaterialExpressionCollectionParameterDetails::PopulateParameters()
{
	UMaterialParameterCollection* Collection = nullptr;
	
	if (CollectionPropertyHandle->IsValidHandle())
	{
		UObject* CollectionObject = nullptr;
		verify(CollectionPropertyHandle->GetValue(CollectionObject) == FPropertyAccess::Success);
		Collection = Cast<UMaterialParameterCollection>(CollectionObject);
	}

	ParametersSource.Empty();

	if (Collection)
	{
		for (int32 ParameterIndex = 0; ParameterIndex < Collection->ScalarParameters.Num(); ++ParameterIndex)
		{
			ParametersSource.Add(MakeShareable(new FString(Collection->ScalarParameters[ParameterIndex].ParameterName.ToString())));
		}

		for (int32 ParameterIndex = 0; ParameterIndex < Collection->VectorParameters.Num(); ++ParameterIndex)
		{
			ParametersSource.Add(MakeShareable(new FString(Collection->VectorParameters[ParameterIndex].ParameterName.ToString())));
		}
	}

	if (ParametersSource.Num() == 0)
	{
		ParametersSource.Add(MakeShareable(new FString(LOCTEXT("NoParameter", "None").ToString())));
	}
}

TSharedRef< ITableRow > FMaterialExpressionCollectionParameterDetails::MakeDetailsGroupViewWidget( TSharedPtr<FString> Item, const TSharedRef< STableViewBase >& OwnerTable )
{
	return SNew(STableRow<TSharedPtr<FString>>, OwnerTable)
		[
			SNew(STextBlock) .Text(FText::FromString(*Item.Get()))
		];
}

void FMaterialExpressionCollectionParameterDetails::OnSelectionChanged( TSharedPtr<FString> ProposedSelection, ESelectInfo::Type /*SelectInfo*/ )
{
	if (ProposedSelection.IsValid())
	{
		ParameterNamePropertyHandle->SetValue(*ProposedSelection.Get());
		ParameterListView.Pin()->ClearSelection();
		ParameterComboButton.Pin()->SetIsOpen(false);
	}
}

TSharedRef<class IDetailCustomization> FMaterialDetailCustomization::MakeInstance()
{
	return MakeShareable( new FMaterialDetailCustomization );
}

void FMaterialDetailCustomization::CustomizeDetails( IDetailLayoutBuilder& DetailLayout )
{
	TArray<TWeakObjectPtr<UObject> > Objects;
	DetailLayout.GetObjectsBeingCustomized( Objects );

	bool bUIMaterial = true;
	for( TWeakObjectPtr<UObject>& Object : Objects )
	{
		UMaterial* Material = Cast<UMaterial>( Object.Get() );
		if( Material )
		{
			bUIMaterial &= Material->IsUIMaterial();
		}
		else
		{
			// this shouldn't happen but just in case, let all properties through
			bUIMaterial = false;
		}
	}

	if( bUIMaterial )
	{
		DetailLayout.HideCategory( TEXT("TranslucencySelfShadowing") );
		DetailLayout.HideCategory( TEXT("Translucency") );
		DetailLayout.HideCategory( TEXT("Tessellation") );
		DetailLayout.HideCategory( TEXT("PostProcessMaterial") );
		DetailLayout.HideCategory( TEXT("Lightmass") );
		DetailLayout.HideCategory( TEXT("Thumbnail") );
		DetailLayout.HideCategory( TEXT("MaterialInterface") );
		DetailLayout.HideCategory( TEXT("PhysicalMaterial") );
		DetailLayout.HideCategory( TEXT("Usage") );

		// Materail category
		{
			IDetailCategoryBuilder& MaterialCategory = DetailLayout.EditCategory( TEXT("Material") );

			TArray<TSharedRef<IPropertyHandle>> AllProperties;
			MaterialCategory.GetDefaultProperties( AllProperties );

			for( TSharedRef<IPropertyHandle>& PropertyHandle : AllProperties )
			{
				UProperty* Property = PropertyHandle->GetProperty();
				FName PropertyName = Property->GetFName();

				if(		PropertyName != GET_MEMBER_NAME_CHECKED(UMaterial, MaterialDomain) 
					&&	PropertyName != GET_MEMBER_NAME_CHECKED(UMaterial, BlendMode) 
					&&	PropertyName != GET_MEMBER_NAME_CHECKED(UMaterial, OpacityMaskClipValue) 
					&& 	PropertyName != GET_MEMBER_NAME_CHECKED(UMaterial, NumCustomizedUVs) )
				{
					DetailLayout.HideProperty( PropertyHandle );
				}
			}
		}

		// Mobile category
		{
			IDetailCategoryBuilder& MobileCategory = DetailLayout.EditCategory(TEXT("Mobile"));
			
			TArray<TSharedRef<IPropertyHandle>> AllProperties;
			MobileCategory.GetDefaultProperties(AllProperties);

			for (TSharedRef<IPropertyHandle>& PropertyHandle : AllProperties)
			{
				UProperty* Property = PropertyHandle->GetProperty();
				FName PropertyName = Property->GetFName();

				if (PropertyName != GET_MEMBER_NAME_CHECKED(UMaterial, bUseFullPrecision)) 
				{
					DetailLayout.HideProperty(PropertyHandle);
				}
			}
		}
	}
}

TSharedRef<class IDetailCustomization> FMaterialExpressionLayersParameterDetails::MakeInstance(FOnCollectParameterGroups InCollectGroupsDelegate)
{
	return MakeShareable(new FMaterialExpressionLayersParameterDetails(InCollectGroupsDelegate));
}

FMaterialExpressionLayersParameterDetails::FMaterialExpressionLayersParameterDetails(FOnCollectParameterGroups InCollectGroupsDelegate)
{
	CollectGroupsDelegate = InCollectGroupsDelegate;
}

void FMaterialExpressionLayersParameterDetails::CustomizeDetails(IDetailLayoutBuilder& DetailLayout)
{
	FMaterialExpressionParameterDetails::CustomizeDetails(DetailLayout);
	// for expression parameters all their properties are in one category based on their class name.
	FName LayerCategory = FName("Layers");
	IDetailCategoryBuilder& Category = DetailLayout.EditCategory(LayerCategory);
	// Get a handle to the property we are about to edit
	GroupPropertyHandle = DetailLayout.GetProperty("DefaultLayers");
	GroupPropertyHandle->MarkHiddenByCustomization();
	TSharedRef<FMaterialLayersFunctionsCustomization> MaterialLayersFunctionsCustomization = MakeShareable(new FMaterialLayersFunctionsCustomization(GroupPropertyHandle, &DetailLayout));
	Category.AddCustomBuilder(MaterialLayersFunctionsCustomization);
	
}

#undef LOCTEXT_NAMESPACE