// Copyright 2026 (c) Jupiter. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "RHIGPUReadback.h"
#include "RHICommandList.h"
#include "Engine/TextureRenderTarget2D.h"
#include "Subsystems/WorldSubsystem.h"
#include "Tickable.h"
#include "CameraCaptureSubSystem.generated.h"


struct FCameraReadbackItem
{
	int32 CameraIndex = INDEX_NONE;
	int32 Width = 0;
	int32 Height = 0;

	TUniquePtr<FRHIGPUTextureReadback> Readback;
};

struct FPendingAtlasCapture
{
	int64 FrameId = 0;
	int32 AtlasW = 0;
	int32 AtlasH = 0;

	TArray<FCameraReadbackItem> Items;
};

class ACameraCaptureActor;


UCLASS()
class CAMERACAPTURE_API UCameraCaptureSubSystem : public UWorldSubsystem, public FTickableGameObject
{
	GENERATED_BODY()

public:

	virtual void Initialize(FSubsystemCollectionBase& Collection) override;
	virtual void Deinitialize() override;
	virtual void OnWorldBeginPlay(UWorld& InWorld) override;

	virtual void Tick(float DeltaTime) override;

	virtual TStatId GetStatId() const override;

	virtual bool IsTickable() const override
	{
		return true;
	}

private:

	void CaptureViewToImageTick();

	// ：发起 Capture + Enqueue GPU Readback
	void BeginCaptureViewToAtlas();

	// 轮询并取回 GPU 数据，再拼图
	void TryResolveCaptureViewAtlas(); 

	void AsyncWriteImageToDisk(TArray<FColor> AtlasPixels, const int32 AtlasW, const int32 AtlasH);

	TArray<TWeakObjectPtr<ACameraCaptureActor>> AllCaptureCameras;

	// 输出的目录
	UPROPERTY()
	FString OutPutDirectoryPath;

	TUniquePtr<FPendingAtlasCapture> PendingAtlasCapture;
	bool bReadbackInFlight = false;

};