integration/Plugins/BlueprintMCP/Source/BlueprintMCP/Private/Handlers/UMCPHandler_CreateStructAsset.h

#pragma once

#include "CoreMinimal.h"
#include "MCPHandler.h"
#include "MCPAssetFinder.h"
#include "MCPUtils.h"
#include "StructUtils/UserDefinedStruct.h"
#include "Engine/UserDefinedEnum.h"
#include "Kismet2/BlueprintEditorUtils.h"
#include "UserDefinedStructure/UserDefinedStructEditorData.h"
#include "Kismet2/EnumEditorUtils.h"
#include "AssetRegistry/AssetRegistryModule.h"
#include "AssetRegistry/IAssetRegistry.h"
#include "AssetToolsModule.h"
#include "IAssetTools.h"
#include "Factories/StructureFactory.h"
#include "Factories/EnumFactory.h"
#include "UMCPHandler_CreateStructAsset.generated.h"


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

USTRUCT()
struct FStructPropertyEntry
{
	GENERATED_BODY()

	UPROPERTY()
	FString Name;

	UPROPERTY()
	FString Type;
};

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

public:
	UPROPERTY(meta=(Description="Full package path for the new struct (e.g. '/Game/DataTypes/S_MyStruct')"))
	FString AssetPath;

	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. "
			"Optionally add initial properties via the 'properties' array (each element needs 'name' and 'type').");
	}

	virtual void Handle(const FJsonObject* Json, FJsonObject* Result) override
	{
    	FString PackagePath, AssetName;
    	if (!MCPUtils::SplitAssetPath(AssetPath, PackagePath, AssetName))
    	{
    		return MCPUtils::MakeErrorJson(Result, TEXT("assetPath must be a full path (e.g. '/Game/DataTypes/S_MyStruct')"));
    	}

    	// Check if asset already exists
    	FAssetRegistryModule& ARM = FModuleManager::LoadModuleChecked<FAssetRegistryModule>("AssetRegistry");
    	FAssetData ExistingAsset = ARM.Get().GetAssetByObjectPath(FSoftObjectPath(AssetPath + TEXT(".") + AssetName));
    	if (ExistingAsset.IsValid())
    	{
    		return MCPUtils::MakeErrorJson(Result, FString::Printf(TEXT("Asset already exists at '%s'"), *AssetPath));
    	}

    	// Create the struct using the AssetTools factory
    	FAssetToolsModule& AssetToolsModule = FModuleManager::LoadModuleChecked<FAssetToolsModule>("AssetTools");
    	IAssetTools& AssetTools = AssetToolsModule.Get();

    	UStructureFactory* Factory = NewObject<UStructureFactory>();
    	UObject* NewAsset = AssetTools.CreateAsset(AssetName, PackagePath, UUserDefinedStruct::StaticClass(), Factory);

    	if (!NewAsset)
    	{
    		return MCPUtils::MakeErrorJson(Result, TEXT("Failed to create UserDefinedStruct asset"));
    	}

    	UUserDefinedStruct* NewStruct = Cast<UUserDefinedStruct>(NewAsset);
    	if (!NewStruct)
    	{
    		return MCPUtils::MakeErrorJson(Result, TEXT("Created asset is not a UserDefinedStruct"));
    	}

    	// 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;
    		FString TypeError;
    		if (!MCPUtils::ResolveTypeFromString(Entry.Type, PinType, TypeError))
    		{
    			UE_LOG(LogTemp, Warning, TEXT("BlueprintMCP: Could not resolve type '%s' for property '%s': %s"), *Entry.Type, *Entry.Name, *TypeError);
    			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);
    		}

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

    	// Save
    	bool bSaved = MCPUtils::SaveGenericPackage(NewStruct);

    	Result->SetStringField(TEXT("assetName"), AssetName);
    	Result->SetNumberField(TEXT("propertiesAdded"), PropsAdded);
    	Result->SetBoolField(TEXT("saved"), bSaved);
	}
};