integration/Plugins/BlueprintMCP/Source/BlueprintMCP/Handlers/Struct_Create.h

#pragma once

#include "CoreMinimal.h"
#include "MCPHandler.h"
#include "MCPAssetFinder.h"
#include "MCPUtils.h"
#include "StructUtils/UserDefinedStruct.h"
#include "Kismet2/BlueprintEditorUtils.h"
#include "UserDefinedStructure/UserDefinedStructEditorData.h"
#include "AssetToolsModule.h"
#include "IAssetTools.h"
#include "Factories/StructureFactory.h"
#include "Struct_Create.generated.h"


// ---------------------------------------------------------------------------
// ---------------------------------------------------------------------------
// ---------------------------------------------------------------------------

USTRUCT()
struct FStructPropertyEntry
{
	GENERATED_BODY()

	UPROPERTY()
	FString Name;

	UPROPERTY()
	FString Type;
};

UCLASS()
class UMCP_Struct_Create : public UObject, public IMCPHandler
{
	GENERATED_BODY()

public:
	UPROPERTY(meta=(Description="Name for the new struct asset"))
	FString Name;

	UPROPERTY(meta=(Description="Package path where the asset will be created (must start with /Game)"))
	FString PackagePath;

	UPROPERTY(meta=(Optional, Description="Array of initial properties, each with 'name' and 'type' fields"))
	FMCPJsonArray Properties;

	virtual FString GetDescription() const override
	{
		return TEXT("Create a new UserDefinedStruct asset with optional initial properties.");
	}

	virtual void Handle(FStringBuilderBase& Result) override
	{
		if (!PackagePath.StartsWith(TEXT("/Game")))
		{
			Result.Append(TEXT("ERROR: PackagePath must start with '/Game'\n"));
			return;
		}

		// Check if an asset with this name already exists.
		MCPAssets<UUserDefinedStruct> ExistCheck;
		if (!ExistCheck.Exact(Name).Errors(Result).EAny().Info()) return;

		// Create the struct using the AssetTools factory.
		IAssetTools& AssetTools = FModuleManager::LoadModuleChecked<FAssetToolsModule>("AssetTools").Get();
		UStructureFactory* Factory = NewObject<UStructureFactory>();
		UObject* NewAsset = AssetTools.CreateAsset(Name, PackagePath, UUserDefinedStruct::StaticClass(), Factory);

		UUserDefinedStruct* NewStruct = Cast<UUserDefinedStruct>(NewAsset);
		if (!NewStruct)
		{
			Result.Appendf(TEXT("ERROR: Failed to create struct '%s' in '%s'\n"), *Name, *PackagePath);
			return;
		}

		// Add properties if specified.
		int32 PropsAdded = 0;
		for (const TSharedPtr<FJsonValue>& PropVal : Properties.Array)
		{
			FStructPropertyEntry Entry;
			if (!MCPUtils::PopulateFromJson(FStructPropertyEntry::StaticStruct(), &Entry, PropVal, Result)) return;
			if (Entry.Name.IsEmpty() || Entry.Type.IsEmpty()) continue;

			FEdGraphPinType PinType;
			if (!MCPUtils::ResolveTypeFromString(Entry.Type, PinType, Result))
				continue;

			// Snapshot existing GUIDs so we can find the newly added one.
			TSet<FGuid> ExistingGuids;
			for (const FStructVariableDescription& Var : FStructureEditorUtils::GetVarDesc(NewStruct))
				ExistingGuids.Add(Var.VarGuid);

			if (!FStructureEditorUtils::AddVariable(NewStruct, PinType))
				continue;

			// Find the new variable by diffing GUID sets.
			for (const FStructVariableDescription& Var : FStructureEditorUtils::GetVarDesc(NewStruct))
			{
				if (!ExistingGuids.Contains(Var.VarGuid))
				{
					FStructureEditorUtils::RenameVariable(NewStruct, Var.VarGuid, Entry.Name);
					break;
				}
			}
			PropsAdded++;
		}

		bool bSaved = MCPUtils::SaveGenericPackage(NewStruct);

		Result.Appendf(TEXT("Created %s\n"), *NewStruct->GetPathName());
		if (PropsAdded > 0)
			Result.Appendf(TEXT("Properties added: %d\n"), PropsAdded);
		if (!bSaved)
			Result.Append(TEXT("WARNING: Package save failed\n"));
	}
};