#pragma once

#include "CoreMinimal.h"
#include "MCPHandler.h"
#include "MCPFetcher.h"
#include "MCPTypes.h"
#include "MCPUtils.h"
#include "StructUtils/UserDefinedStruct.h"
#include "UserDefinedStructure/UserDefinedStructEditorData.h"
#include "UMCPHandler_AddStructField.generated.h"


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

UCLASS(meta=(Group="Unclassified"))
class UMCPHandler_AddStructField : public UObject, public IMCPHandler
{
	GENERATED_BODY()

public:
	UPROPERTY(meta=(Description="Package path of the struct asset"))
	FString Struct;

	UPROPERTY(meta=(Description="Name for the new field"))
	FString Name;

	UPROPERTY(meta=(Description="Type for the new field (e.g. 'int32', 'FString', 'FVector')"))
	FString Type;

	virtual FString GetDescription() const override
	{
		return TEXT("Add a new field to a UserDefinedStruct asset.");
	}

	virtual void Handle(const FJsonObject* Json, FStringBuilderBase& Result) override
	{
		// Find the struct
		MCPFetcher F(Result);
		UUserDefinedStruct* S = F.Walk(Struct).Cast<UUserDefinedStruct>();
		if (!S) return;

		// Resolve type
		FEdGraphPinType PinType;
		if (!UMCPTypes::TextToType(Type, PinType, Result))
			return;

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

		if (!FStructureEditorUtils::AddVariable(S, PinType))
		{
			Result.Append(TEXT("ERROR: Failed to add field to struct.\n"));
			return;
		}

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

		MCPUtils::SaveGenericPackage(S);
		Result.Appendf(TEXT("Added field: %s %s\n"), *Type, *Name);
	}
};