#pragma once

#include "CoreMinimal.h"
#include "Subsystems/GameInstanceSubsystem.h"
#include "Tickable.h"
#include "IronsPerformanceSubsystem.generated.h"

// UE telemetry only. A negative value means that no valid measurement is available.
struct UEADAPTER_API FIronsPerformanceSnapshot
{
    double Fps=-1,FrameMs=-1,GameMs=-1,RenderMs=-1,RhiMs=-1,GpuMs=-1;
    int32 Samples=0;
    uint64 Revision=0;
};

class UEADAPTER_API FIronsPerformanceWindow
{
    struct FSample { double End=0,Seconds=0,Game=-1,Render=-1,Rhi=-1,Gpu=-1; };
    TArray<FSample> Samples;
public:
    void Reset();
    void Add(double End,double Seconds,double Game,double Render,double Rhi,double Gpu);
    FIronsPerformanceSnapshot Read(double Now) const;
};

UCLASS()
class UEADAPTER_API UIronsPerformanceSubsystem : public UGameInstanceSubsystem, public FTickableGameObject
{
    GENERATED_BODY()
    FIronsPerformanceWindow Window;
    FIronsPerformanceSnapshot Snapshot,Raw;
    TWeakObjectPtr<UWorld> SampleWorld;
    double LastSampleTime=0,LastPublishTime=0;
    uint64 LastFrame=MAX_uint64;
    bool bInitialized=false;
public:
    virtual void Initialize(FSubsystemCollectionBase& Collection) override;
    virtual void Deinitialize() override;
    virtual void Tick(float DeltaTime) override;
    virtual TStatId GetStatId() const override;
    virtual bool IsTickable() const override;
    virtual bool IsTickableWhenPaused() const override { return true; }
    virtual UWorld* GetTickableGameObjectWorld() const override;
    const FIronsPerformanceSnapshot& GetSnapshot() const { return Snapshot; }
    const FIronsPerformanceSnapshot& GetRawSample() const { return Raw; }
};