FReply FDragConnection::DroppedOnNode(FVector2D ScreenPosition, FVector2D GraphPosition)
{
	bool bHandledPinDropOnNode = false;
	UEdGraphNode* HoveredNode = GetHoveredNode();

	if (HoveredNode)
	{
		// Gather any source drag pins
		TArray<UEdGraphPin*> ValidSourcePins;
		ValidateGraphPinList(/*out*/ ValidSourcePins);


		if (ValidSourcePins.Num())
		{
			for (UEdGraphPin* SourcePin : ValidSourcePins)
			{
				// Check for pin drop support
				FText ResponseText;
				if (SourcePin->GetOwningNode() != HoveredNode && SourcePin->GetSchema()->SupportsDropPinOnNode(HoveredNode, SourcePin->PinType, SourcePin->Direction, ResponseText))
				{
					bHandledPinDropOnNode = true;

					// Find which pin name to use and drop the pin on the node
					FString PinName = SourcePin->PinFriendlyName.IsEmpty()? SourcePin->PinName : SourcePin->PinFriendlyName.ToString();

					const FScopedTransaction Transaction( NSLOCTEXT("UnrealEd", "AddInParam", "Add In Parameter" ) );

					UEdGraphPin* EdGraphPin = HoveredNode->GetSchema()->DropPinOnNode(GetHoveredNode(), PinName, SourcePin->PinType, SourcePin->Direction);

					if(EdGraphPin)
					{
						SourcePin->Modify();
						EdGraphPin->Modify();
						SourcePin->GetSchema()->TryCreateConnection(SourcePin, EdGraphPin);
					}
				}

				// If we have not handled the pin drop on node and there is an error message, do not let other actions occur.
				if(!bHandledPinDropOnNode && !ResponseText.IsEmpty())
				{
					bHandledPinDropOnNode = true;
				}
			}
		}
	}
	return bHandledPinDropOnNode? FReply::Handled() : FReply::Unhandled();
}
FReply FKismetVariableDragDropAction::DroppedOnNode(FVector2D ScreenPosition, FVector2D GraphPosition)
{
	UK2Node_Variable* TargetNode = Cast<UK2Node_Variable>(GetHoveredNode());

	if (TargetNode && (VariableName != TargetNode->GetVarName()))
	{
		const FScopedTransaction Transaction( LOCTEXT("ReplacePinVariable", "Replace Pin Variable") );

		UProperty* VariableProperty = GetVariableProperty();

		if(CanVariableBeDropped(VariableProperty, *TargetNode->GetGraph()))
		{
			const FString OldVarName = TargetNode->GetVarNameString();
			const UEdGraphSchema_K2* Schema = Cast<const UEdGraphSchema_K2>(TargetNode->GetSchema());

			TArray<class UEdGraphPin*> BadLinks;
			GetLinksThatWillBreak(TargetNode,VariableProperty,BadLinks);

			// Change the variable name and context
			UBlueprint* DropOnBlueprint = FBlueprintEditorUtils::FindBlueprintForGraph(TargetNode->GetGraph());
			UEdGraphPin* Pin = TargetNode->FindPin(OldVarName);
			DropOnBlueprint->Modify();
			TargetNode->Modify();

			if (Pin != NULL)
			{
				Pin->Modify();
			}

			UEdGraphSchema_K2::ConfigureVarNode(TargetNode, VariableName, VariableSource.Get(), DropOnBlueprint);


			if ((Pin == NULL) || (Pin->LinkedTo.Num() == BadLinks.Num()) || (Schema == NULL))
			{
				TargetNode->GetSchema()->ReconstructNode(*TargetNode);
			}
			else 
			{
				FEdGraphPinType NewPinType;
				Schema->ConvertPropertyToPinType(VariableProperty,NewPinType);

				Pin->PinName = VariableName.ToString();
				Pin->PinType = NewPinType;

				//break bad links
				for(TArray<class UEdGraphPin*>::TIterator OtherPinIt(BadLinks);OtherPinIt;)
				{
					Pin->BreakLinkTo(*OtherPinIt);
				}
			}

			return FReply::Handled();
		}
	}
	return FReply::Unhandled();
}
UEdGraph* FGraphEditorDragDropAction::GetHoveredGraph() const
{
	// Note: We always want to report a graph even when hovering over a node or pin;
	// the same is not true for nodes when hovering over a pin (at least right now)
	if (HoveredGraph.IsValid())
	{
		return HoveredGraph->GetGraphObj();
	}
	else if (UEdGraphNode* Node = GetHoveredNode())
	{
		return Node->GetGraph();
	}
	else if (UEdGraphPin* Pin = GetHoveredPin())
	{
		return Pin->GetOwningNode()->GetGraph();
	}
	
	return NULL;
}
void FDragConnection::HoverTargetChanged()
{
	TArray<FPinConnectionResponse> UniqueMessages;

	if (UEdGraphPin* TargetPinObj = GetHoveredPin())
	{
		TArray<UEdGraphPin*> ValidSourcePins;
		ValidateGraphPinList(/*out*/ ValidSourcePins);

		// Check the schema for connection responses
		for (UEdGraphPin* StartingPinObj : ValidSourcePins)
		{
			if (TargetPinObj != StartingPinObj)
			{
				// The Graph object in which the pins reside.
				UEdGraph* GraphObj = StartingPinObj->GetOwningNode()->GetGraph();

				// Determine what the schema thinks about the wiring action
				const FPinConnectionResponse Response = GraphObj->GetSchema()->CanCreateConnection( StartingPinObj, TargetPinObj );

				if (Response.Response == ECanCreateConnectionResponse::CONNECT_RESPONSE_DISALLOW)
				{
					 TSharedPtr<SGraphNode> NodeWidget = TargetPinObj->GetOwningNode()->NodeWidget.Pin();
					 if (NodeWidget.IsValid())
					 {
						 NodeWidget->NotifyDisallowedPinConnection(StartingPinObj, TargetPinObj);
					 }
				}

				UniqueMessages.AddUnique(Response);
			}
		}
	}
	else if(UEdGraphNode* TargetNodeObj = GetHoveredNode())
	{
		TArray<UEdGraphPin*> ValidSourcePins;
		ValidateGraphPinList(/*out*/ ValidSourcePins);

		// Check the schema for connection responses
		for (UEdGraphPin* StartingPinObj : ValidSourcePins)
		{
			FPinConnectionResponse Response;
			FText ResponseText;
			if (StartingPinObj->GetOwningNode() != TargetNodeObj && StartingPinObj->GetSchema()->SupportsDropPinOnNode(TargetNodeObj, StartingPinObj->PinType, StartingPinObj->Direction, ResponseText))
			{
				Response.Response = ECanCreateConnectionResponse::CONNECT_RESPONSE_MAKE;
			}
			else
			{
				Response.Response = ECanCreateConnectionResponse::CONNECT_RESPONSE_DISALLOW;
			}
			
			// Do not display an error if there is no message
			if (!ResponseText.IsEmpty())
			{
				Response.Message = ResponseText;
				UniqueMessages.AddUnique(Response);
			}
		}
	}

	// Let the user know the status of dropping now
	if (UniqueMessages.Num() == 0)
	{
		// Display the place a new node icon, we're not over a valid pin
		SetSimpleFeedbackMessage(
			FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.NewNode")),
			FLinearColor::White,
			NSLOCTEXT("GraphEditor.Feedback", "PlaceNewNode", "Place a new node."));
	}
	else
	{
		// Take the unique responses and create visual feedback for it
		TSharedRef<SVerticalBox> FeedbackBox = SNew(SVerticalBox);
		for (auto ResponseIt = UniqueMessages.CreateConstIterator(); ResponseIt; ++ResponseIt)
		{
			// Determine the icon
			const FSlateBrush* StatusSymbol = NULL;

			switch (ResponseIt->Response)
			{
			case CONNECT_RESPONSE_MAKE:
			case CONNECT_RESPONSE_BREAK_OTHERS_A:
			case CONNECT_RESPONSE_BREAK_OTHERS_B:
			case CONNECT_RESPONSE_BREAK_OTHERS_AB:
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OK"));
				break;

			case CONNECT_RESPONSE_MAKE_WITH_CONVERSION_NODE:
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.ViaCast"));
				break;

			case CONNECT_RESPONSE_DISALLOW:
			default:
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				break;
			}

			// Add a new message row
			FeedbackBox->AddSlot()
			.AutoHeight()
			[
				SNew(SHorizontalBox)
				+SHorizontalBox::Slot()
				.AutoWidth()
				.Padding(3.0f)
				[
					SNew(SImage) .Image( StatusSymbol )
				]
				+SHorizontalBox::Slot()
				.AutoWidth()
				.VAlign(VAlign_Center)
				[
					SNew(STextBlock) .Text( ResponseIt->Message )
				]
			];
		}

		SetFeedbackMessage(FeedbackBox);
	}
}
void FKismetVariableDragDropAction::HoverTargetChanged()
{
	UProperty* VariableProperty = GetVariableProperty();
	if (VariableProperty == nullptr)
	{
		return;
	}

	FString VariableString = VariableName.ToString();

	// Icon/text to draw on tooltip
	FSlateColor IconColor = FLinearColor::White;
	const FSlateBrush* StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
	FText Message = LOCTEXT("InvalidDropTarget", "Invalid drop target!");

	UEdGraphPin* PinUnderCursor = GetHoveredPin();

	bool bCanMakeSetter = true;
	bool bBadSchema = false;
	bool bBadGraph = false;
	UEdGraph* HoveredGraph = GetHoveredGraph();
	if (HoveredGraph)
	{
		if (Cast<const UEdGraphSchema_K2>(HoveredGraph->GetSchema()) == NULL)
		{
			bBadSchema = true;
		}
		else if(!CanVariableBeDropped(VariableProperty, *HoveredGraph))
		{
			bBadGraph = true;
		}

		UStruct* Outer = CastChecked<UStruct>(VariableProperty->GetOuter());

		FNodeConstructionParams NewNodeParams;
		NewNodeParams.VariableName = VariableName;
		const UBlueprint* DropOnBlueprint = FBlueprintEditorUtils::FindBlueprintForGraph(HoveredGraph);
		NewNodeParams.Graph = HoveredGraph;
		NewNodeParams.VariableSource = Outer;
		
		bCanMakeSetter = CanExecuteMakeSetter(NewNodeParams, VariableProperty);
	}

	UEdGraphNode* VarNodeUnderCursor = Cast<UK2Node_Variable>(GetHoveredNode());

	if (bBadSchema)
	{
		StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
		Message = LOCTEXT("CannotCreateInThisSchema", "Cannot access variables in this type of graph");
	}
	else if(bBadGraph)
	{
		FFormatNamedArguments Args;
		Args.Add(TEXT("VariableName"), FText::FromString(VariableString));
		Args.Add(TEXT("Scope"), FText::FromString(HoveredGraph->GetName()));

		StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));

		if(IsFromBlueprint(FBlueprintEditorUtils::FindBlueprintForGraph(HoveredGraph)) && VariableProperty->GetOuter()->IsA(UFunction::StaticClass()))
		{
			Message = FText::Format( LOCTEXT("IncorrectGraphForLocalVariable_Error", "Cannot place local variable '{VariableName}' in external scope '{Scope}'"), Args);
		}
		else
		{
			Message = FText::Format( LOCTEXT("IncorrectGraphForVariable_Error", "Cannot place variable '{VariableName}' in external scope '{Scope}'"), Args);
		}
	}
	else if (PinUnderCursor != NULL)
	{
		FFormatNamedArguments Args;
		Args.Add(TEXT("PinUnderCursor"), FText::FromString(PinUnderCursor->PinName));
		Args.Add(TEXT("VariableName"), FText::FromString(VariableString));

		if(CanVariableBeDropped(VariableProperty, *PinUnderCursor->GetOwningNode()->GetGraph()))
		{
			const UEdGraphSchema_K2* Schema = CastChecked<const UEdGraphSchema_K2>(PinUnderCursor->GetSchema());

			const bool bIsRead = PinUnderCursor->Direction == EGPD_Input;
			const UBlueprint* Blueprint = FBlueprintEditorUtils::FindBlueprintForNode(PinUnderCursor->GetOwningNode());
			const bool bReadOnlyProperty = FBlueprintEditorUtils::IsPropertyReadOnlyInCurrentBlueprint(Blueprint, VariableProperty);
			const bool bCanWriteIfNeeded = bIsRead || !bReadOnlyProperty;

			FEdGraphPinType VariablePinType;
			Schema->ConvertPropertyToPinType(VariableProperty, VariablePinType);
			const bool bTypeMatch = Schema->ArePinTypesCompatible(VariablePinType, PinUnderCursor->PinType);

			Args.Add(TEXT("PinUnderCursor"), FText::FromString(PinUnderCursor->PinName));

			if (bTypeMatch && bCanWriteIfNeeded)
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OK"));

				if (bIsRead)
				{
					Message = FText::Format(LOCTEXT("MakeThisEqualThat_PinEqualVariableName", "Make {PinUnderCursor} = {VariableName}"), Args);
				}
				else
				{
					Message = FText::Format(LOCTEXT("MakeThisEqualThat_VariableNameEqualPin", "Make {VariableName} = {PinUnderCursor}"), Args);
				}
			}
			else
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				if (!bCanWriteIfNeeded)
				{
					Message = FText::Format(LOCTEXT("ReadOnlyVar_Error", "Cannot write to read-only variable '{VariableName}'"), Args);
				}
				else
				{
					Message = FText::Format(LOCTEXT("NotCompatible_Error", "The type of '{VariableName}' is not compatible with {PinUnderCursor}"), Args);
				}
			}
		}
		else
		{
			Args.Add(TEXT("Scope"), FText::FromString(PinUnderCursor->GetOwningNode()->GetGraph()->GetName()));

			StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
			Message = FText::Format( LOCTEXT("IncorrectGraphForPin_Error", "Cannot place local variable '{VariableName}' in external scope '{Scope}'"), Args);
		}
	}
	else if (VarNodeUnderCursor != NULL)
	{
		FFormatNamedArguments Args;
		Args.Add(TEXT("VariableName"), FText::FromString(VariableString));

		if(CanVariableBeDropped(VariableProperty, *VarNodeUnderCursor->GetGraph()))
		{
			const bool bIsRead = VarNodeUnderCursor->IsA(UK2Node_VariableGet::StaticClass());
			const UBlueprint* Blueprint = FBlueprintEditorUtils::FindBlueprintForNode(VarNodeUnderCursor);
			const bool bReadOnlyProperty = FBlueprintEditorUtils::IsPropertyReadOnlyInCurrentBlueprint(Blueprint, VariableProperty);
			const bool bCanWriteIfNeeded = bIsRead || !bReadOnlyProperty;

			if (bCanWriteIfNeeded)
			{
				Args.Add(TEXT("ReadOrWrite"), bIsRead ? LOCTEXT("Read", "read") : LOCTEXT("Write", "write"));
				if(WillBreakLinks(VarNodeUnderCursor, VariableProperty))
				{
					StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OKWarn"));
					Message = FText::Format( LOCTEXT("ChangeNodeToWarnBreakLinks", "Change node to {ReadOrWrite} '{VariableName}', WARNING this will break links!"), Args);
				}
				else
				{
					StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OK"));
					Message = FText::Format( LOCTEXT("ChangeNodeTo", "Change node to {ReadOrWrite} '{VariableName}'"), Args);
				}
			}
			else
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("ReadOnlyVar_Error", "Cannot write to read-only variable '{VariableName}'"), Args);
			}
		}
		else
		{
			Args.Add(TEXT("Scope"), FText::FromString(VarNodeUnderCursor->GetGraph()->GetName()));

			StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
			Message = FText::Format( LOCTEXT("IncorrectGraphForNodeReplace_Error", "Cannot replace node with local variable '{VariableName}' in external scope '{Scope}'"), Args);
		}
	}
	else if (!HoveredCategoryName.IsEmpty())
	{
		// Find Blueprint that made this class and get category of variable
		FText Category;
		UBlueprint* Blueprint;
		
		// Find the Blueprint for this property
		if(Cast<UFunction>(VariableSource.Get()))
		{
			Blueprint = UBlueprint::GetBlueprintFromClass(Cast<UClass>(VariableSource->GetOuter()));
		}
		else
		{
			Blueprint = UBlueprint::GetBlueprintFromClass(Cast<UClass>(VariableSource.Get()));
		}

		if(Blueprint != NULL)
		{
			Category = FBlueprintEditorUtils::GetBlueprintVariableCategory(Blueprint, VariableProperty->GetFName(), GetLocalVariableScope() );
		}

		// See if class is native
		UClass* OuterClass = Cast<UClass>(VariableProperty->GetOuter());
		if(OuterClass || Cast<UFunction>(VariableProperty->GetOuter()))
		{
			const bool bIsNativeVar = (OuterClass && OuterClass->ClassGeneratedBy == NULL);

			FFormatNamedArguments Args;
			Args.Add(TEXT("VariableName"), FText::FromString(VariableString));
			Args.Add(TEXT("HoveredCategoryName"), HoveredCategoryName);

			if (bIsNativeVar)
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("ChangingCatagoryNotThisVar", "Cannot change category for variable '{VariableName}'"), Args );
			}
			else if (Category.EqualTo(HoveredCategoryName))
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("ChangingCatagoryAlreadyIn", "Variable '{VariableName}' is already in category '{HoveredCategoryName}'"), Args );
			}
			else
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OK"));
				Message = FText::Format( LOCTEXT("ChangingCatagoryOk", "Move variable '{VariableName}' to category '{HoveredCategoryName}'"), Args );
			}
		}
	}
	else if (HoveredAction.IsValid())
	{
		if(HoveredAction.Pin()->GetTypeId() == FEdGraphSchemaAction_K2Var::StaticGetTypeId())
		{
			FEdGraphSchemaAction_K2Var* VarAction = (FEdGraphSchemaAction_K2Var*)HoveredAction.Pin().Get();
			FName TargetVarName = VarAction->GetVariableName();

			// Needs to have a valid index to move it (this excludes variables added through other means, like timelines/components
			int32 MoveVarIndex = INDEX_NONE;
			int32 TargetVarIndex = INDEX_NONE;
			UBlueprint* Blueprint = UBlueprint::GetBlueprintFromClass(Cast<UClass>(VariableSource.Get()));
			if(Blueprint != NULL)
			{
				MoveVarIndex = FBlueprintEditorUtils::FindNewVariableIndex(Blueprint, VariableName);
				TargetVarIndex = FBlueprintEditorUtils::FindNewVariableIndex(Blueprint, TargetVarName);
			}

			FFormatNamedArguments Args;
			Args.Add(TEXT("VariableName"), FText::FromString(VariableString));
			Args.Add(TEXT("TargetVarName"), FText::FromName(TargetVarName));

			if(MoveVarIndex == INDEX_NONE)
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("MoveVarDiffClass", "Cannot reorder variable '{VariableName}'."), Args );
			}
			else if(TargetVarIndex == INDEX_NONE)
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("MoveVarOther", "Cannot reorder variable '{VariableName}' before '{TargetVarName}'."), Args );
			}
			else if(VariableName == TargetVarName)
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
				Message = FText::Format( LOCTEXT("MoveVarYourself", "Cannot reorder variable '{VariableName}' before itself."), Args );
			}
			else
			{
				StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.OK"));
				Message = FText::Format( LOCTEXT("MoveVarOK", "Reorder variable '{VariableName}' before '{TargetVarName}'"), Args );
			}
		}
	}
	else if (bAltDrag && !bCanMakeSetter)
	{
		FFormatNamedArguments Args;
		Args.Add(TEXT("VariableName"), FText::FromString(VariableString));

		StatusSymbol = FEditorStyle::GetBrush(TEXT("Graph.ConnectorFeedback.Error"));
		Message = FText::Format(LOCTEXT("CannotPlaceSetter", "Variable '{VariableName}' is readonly, you cannot set this variable."), Args);
	}
	// Draw variable icon
	else
	{
		StatusSymbol = FBlueprintEditor::GetVarIconAndColor(VariableSource.Get(), VariableName, IconColor);
		Message = FText::FromString(VariableString);
	}

	SetSimpleFeedbackMessage(StatusSymbol, IconColor, Message);
}