// Copyright IHY. Vertical Partition Streaming plugin (editor module).
//
// Installs the runtime->editor bridge so the volume's CallInEditor buttons and the
// vp.* build console commands reach UVerticalPartitionBuilder. Also implements the
// editor-only chunk preview.
#include "Modules/ModuleManager.h"
#include "VerticalPartitionVolume.h"
#include "VerticalPartitionBuilder.h"
#include "VerticalPartitionDescriptor.h"
#include "VerticalPartitionStatics.h"
#include "VerticalPartitionLog.h"
#include "Engine/World.h"
#include "Engine/Engine.h"
#include "Engine/StaticMesh.h"
#include "Engine/StaticMeshActor.h"
#include "Components/StaticMeshComponent.h"
#include "DrawDebugHelpers.h"
#include "EngineUtils.h"
#include "Misc/PackageName.h"
#include "UObject/Package.h"

static const FName VPPreviewTag(TEXT("VPHLODPreview"));

#if WITH_EDITOR
#include "Editor.h"
#endif

namespace
{
	void LogReport(const FVerticalPartitionBuildReport& R, const TCHAR* Title)
	{
		UE_LOG(LogVerticalPartition, Log, TEXT("[VP] %s: scanned=%d inside=%d excluded=%d cells=%d empty=%d warn=%d err=%d largest=%s(%d)"),
			Title, R.TotalActorsScanned, R.ActorsInsideVolume, R.ActorsExcluded, R.GeneratedCells, R.EmptyCells,
			R.WarningCount, R.ErrorCount, *R.LargestCell.ToString(), R.LargestCellActorCount);

		if (GEngine)
		{
			GEngine->AddOnScreenDebugMessage(-1, 8.f, FColor::Cyan,
				FString::Printf(TEXT("VP %s: %d cells, %d warnings, %d errors"), Title, R.GeneratedCells, R.WarningCount, R.ErrorCount));
		}
		for (const FVerticalPartitionWarning& W : R.Warnings)
		{
			UE_LOG(LogVerticalPartition, Warning, TEXT("[VP]   WARN [%s] %s"), *UVerticalPartitionStatics::WarningTypeToString(W.Type), *W.Message);
		}
		for (const FVerticalPartitionError& E : R.Errors)
		{
			UE_LOG(LogVerticalPartition, Error, TEXT("[VP]   ERR  [%s] %s"), *UVerticalPartitionStatics::WarningTypeToString(E.Type), *E.Message);
		}
	}

	// Persistent coloured cell boxes. GREEN = cell has a baked HLOD proxy, ORANGE = cell
	// has streamed actors but no proxy (it will just hide when far), GREY = empty Z slice.
	void PreviewChunks(AVerticalPartitionVolume* Volume)
	{
#if WITH_EDITOR
		if (!Volume || !GEditor) { return; }
		UWorld* World = GEditor->GetEditorWorldContext().World();
		if (!World) { return; }

		const FVerticalPartitionSettings& S = Volume->Settings;
		const FBox Bounds = Volume->GetVolumeBounds();
		UVerticalPartitionDescriptor* Desc = Volume->Descriptor.LoadSynchronous();

		FlushPersistentDebugLines(World);
		DrawDebugBox(World, Bounds.GetCenter(), Bounds.GetExtent(), FColor::Cyan, true, -1.f, 0, 30.f);

		const int32 NumZ = UVerticalPartitionStatics::GetNumZCells(Bounds, S);
		int32 CellsWithHLOD = 0;
		for (int32 Z = 0; Z < NumZ; ++Z)
		{
			const FVerticalCellId Id(0, 0, Z);
			const FBox CB = UVerticalPartitionStatics::GetCellBounds(Id, Bounds, S);

			int32 Actors = 0;
			bool bHasCell = false;
			bool bHasHLOD = false;
			if (Desc)
			{
				for (const FVerticalCellDescriptor& CD : Desc->Cells)
				{
					if (CD.CellId.Z == Z)
					{
						bHasCell = true;
						Actors += CD.ActorCount;
						if (CD.HLODProxyAsset.IsValid()) { bHasHLOD = true; }
					}
				}
			}
			if (bHasHLOD) { ++CellsWithHLOD; }

			const FColor Color = !bHasCell ? FColor(90, 90, 90)
				: (bHasHLOD ? FColor(40, 200, 80) : FColor(235, 140, 30));
			DrawDebugBox(World, CB.GetCenter(), CB.GetExtent(), Color, true, -1.f, 0, 12.f);

			const FString Label = bHasCell
				? FString::Printf(TEXT("Z%d  %s  actors:%d"), Z, bHasHLOD ? TEXT("[HLOD]") : TEXT("[no-HLOD]"), Actors)
				: FString::Printf(TEXT("Z%d  (empty/persistent)"), Z);
			DrawDebugString(World, CB.GetCenter(), Label, nullptr, Color, -1.f, true);
		}

		UE_LOG(LogVerticalPartition, Log, TEXT("[VP] Preview: %d Z cells (%s). GREEN=HLOD proxy, ORANGE=streamed/no-proxy, GREY=empty. %d cells have a proxy. Use 'Clear Preview' to remove."),
			NumZ, Desc ? TEXT("from descriptor") : TEXT("no descriptor yet — Build first for HLOD colours"), CellsWithHLOD);
#endif
	}

	int32 ClearPreviewActors(UWorld* World)
	{
		int32 Removed = 0;
#if WITH_EDITOR
		if (!World) { return 0; }
		for (TActorIterator<AStaticMeshActor> It(World); It; ++It)
		{
			if (It->ActorHasTag(VPPreviewTag))
			{
				It->Destroy();
				++Removed;
			}
		}
#endif
		return Removed;
	}

	void ClearPreview(AVerticalPartitionVolume* Volume)
	{
#if WITH_EDITOR
		if (!GEditor) { return; }
		UWorld* World = GEditor->GetEditorWorldContext().World();
		if (!World) { return; }
		FlushPersistentDebugLines(World);
		const int32 Removed = ClearPreviewActors(World);
		UE_LOG(LogVerticalPartition, Log, TEXT("[VP] Preview cleared (%d HLOD preview actors removed)."), Removed);
#endif
	}

	// Spawn the baked proxy meshes as temporary editor actors so the HLOD geometry is
	// directly visible in the viewport. They sit exactly over the source (pivot-at-zero),
	// so hide the real decor to compare. Tagged + transient; removed by Clear Preview.
	void SpawnHLODPreview(AVerticalPartitionVolume* Volume)
	{
#if WITH_EDITOR
		if (!Volume || !GEditor) { return; }
		UWorld* World = GEditor->GetEditorWorldContext().World();
		if (!World) { return; }

		UVerticalPartitionDescriptor* Desc = Volume->Descriptor.LoadSynchronous();
		if (!Desc)
		{
			UE_LOG(LogVerticalPartition, Warning, TEXT("[VP] SpawnHLODPreview: no descriptor — run Build first."));
			return;
		}

		ClearPreviewActors(World);

		int32 Spawned = 0;
		for (const FVerticalCellDescriptor& CD : Desc->Cells)
		{
			if (!CD.HLODProxyAsset.IsValid()) { continue; }
			UStaticMesh* Mesh = Cast<UStaticMesh>(CD.HLODProxyAsset.TryLoad());
			if (!Mesh) { continue; }

			FActorSpawnParameters Params;
			Params.ObjectFlags |= RF_Transient;
			Params.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AlwaysSpawn;
			AStaticMeshActor* Actor = World->SpawnActor<AStaticMeshActor>(FVector::ZeroVector, FRotator::ZeroRotator, Params);
			if (!Actor) { continue; }

			Actor->Tags.Add(VPPreviewTag);
			Actor->SetActorLabel(FString::Printf(TEXT("VP_HLODPreview_Z%d"), CD.CellId.Z));
			if (UStaticMeshComponent* Comp = Actor->GetStaticMeshComponent())
			{
				Comp->SetMobility(EComponentMobility::Movable);
				Comp->SetStaticMesh(Mesh);
				Comp->SetCollisionEnabled(ECollisionEnabled::NoCollision);
			}
			++Spawned;
		}

		UE_LOG(LogVerticalPartition, Log, TEXT("[VP] Spawned %d HLOD proxy preview actors (tag '%s'). Hide your static decor to compare; 'Clear Preview' removes them."),
			Spawned, *VPPreviewTag.ToString());
		if (GEngine)
		{
			GEngine->AddOnScreenDebugMessage(-1, 8.f, FColor::Green, FString::Printf(TEXT("VP: %d HLOD proxy preview actors spawned"), Spawned));
		}
#endif
	}

	void HandleAction(AVerticalPartitionVolume* Volume, EVerticalPartitionAction Action)
	{
		if (!Volume) { return; }
		FVerticalPartitionBuildReport Report;
		switch (Action)
		{
		case EVerticalPartitionAction::Analyze:
			Report = UVerticalPartitionBuilder::AnalyzeCurrentLevel(Volume);
			LogReport(Report, TEXT("Analyze"));
			break;
		case EVerticalPartitionAction::Build:
			UVerticalPartitionBuilder::Build(Volume, Report);
			LogReport(Report, TEXT("Build"));
			break;
		case EVerticalPartitionAction::RebuildChangedCells:
			UVerticalPartitionBuilder::RebuildChangedCells(Volume, Report);
			LogReport(Report, TEXT("Rebuild"));
			break;
		case EVerticalPartitionAction::RebuildHLOD:
			UVerticalPartitionBuilder::RebuildHLOD(Volume, Report);
			LogReport(Report, TEXT("RebuildHLOD"));
			break;
		case EVerticalPartitionAction::Validate:
			Report = UVerticalPartitionBuilder::ValidateCells(Volume);
			LogReport(Report, TEXT("Validate"));
			break;
		case EVerticalPartitionAction::PreviewChunks:
			PreviewChunks(Volume);
			break;
		case EVerticalPartitionAction::SpawnHLODPreview:
			SpawnHLODPreview(Volume);
			break;
		case EVerticalPartitionAction::ClearPreview:
			ClearPreview(Volume);
			break;
		case EVerticalPartitionAction::ClearGenerated:
			UVerticalPartitionBuilder::ClearGenerated(Volume);
			break;
		case EVerticalPartitionAction::Commit:
			UVerticalPartitionBuilder::CommitConversion(Volume, Report);
			LogReport(Report, TEXT("Commit"));
			break;
		case EVerticalPartitionAction::RestoreBackup:
			UVerticalPartitionBuilder::RestoreFromBackup(Volume->GetWorld());
			break;
		case EVerticalPartitionAction::DumpReport:
			if (UVerticalPartitionDescriptor* Desc = Volume->Descriptor.LoadSynchronous())
			{
				const FString Map = Volume->GetWorld() ? FPackageName::GetShortName(Volume->GetWorld()->GetOutermost()->GetName()) : TEXT("Map");
				UVerticalPartitionBuilder::DumpReport(Desc->LastReport, Map);
			}
			break;
		}
	}
}

class FVerticalPartitionEditorModule : public IModuleInterface
{
public:
	virtual void StartupModule() override
	{
#if WITH_EDITOR
		FVerticalPartitionEditorBridge::Handler = [](AVerticalPartitionVolume* Volume, EVerticalPartitionAction Action)
		{
			HandleAction(Volume, Action);
		};
#endif
	}

	virtual void ShutdownModule() override
	{
#if WITH_EDITOR
		FVerticalPartitionEditorBridge::Handler = nullptr;
#endif
	}
};

IMPLEMENT_MODULE(FVerticalPartitionEditorModule, VerticalPartitionEditor);