// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"

// Insights
#include "Insights/ViewModels/BaseTimingTrack.h"

////////////////////////////////////////////////////////////////////////////////////////////////////

class TRACEINSIGHTS_API ITimingEventsTrackDrawStateBuilder
{
public:
    typedef TFunctionRef<const FString(float /*AvailableWidth*/)> GetEventNameCallback;

public:
    virtual ~ITimingEventsTrackDrawStateBuilder()                                                                                                                         = default;

    virtual void AddEvent(double InEventStartTime, double InEventEndTime, uint32 InEventDepth, const TCHAR* InEventName, uint64 InEventType = 0, uint32 InEventColor = 0) = 0;
    virtual void AddEvent(double InEventStartTime, double InEventEndTime, uint32 InEventDepth, uint32 InEventColor, GetEventNameCallback InGetEventNameCallback)          = 0;
};

////////////////////////////////////////////////////////////////////////////////////////////////////

class TRACEINSIGHTS_API FTimingEventsTrack: public FBaseTimingTrack
{
    INSIGHTS_DECLARE_RTTI(FTimingEventsTrack, FBaseTimingTrack)

public:
    explicit FTimingEventsTrack();
    explicit FTimingEventsTrack(const FString& InTrackName);
    virtual ~FTimingEventsTrack();

    //////////////////////////////////////////////////
    // FBaseTimingTrack

    virtual void Reset() override;

    virtual void PreUpdate(const ITimingTrackUpdateContext& Context) override;
    virtual void PostUpdate(const ITimingTrackUpdateContext& Context) override;

    virtual void Draw(const ITimingTrackDrawContext& Context) const override;
    virtual void DrawEvent(const ITimingTrackDrawContext& Context, const ITimingEvent& InTimingEvent, EDrawEventMode InDrawMode) const override;

    virtual const TSharedPtr<const ITimingEvent> GetEvent(float InPosX, float InPosY, const FTimingTrackViewport& Viewport) const override;

    virtual TSharedPtr<ITimingEventFilter> GetFilterByEvent(const TSharedPtr<const ITimingEvent> InTimingEvent) const override;

    //////////////////////////////////////////////////

    virtual void BuildDrawState(ITimingEventsTrackDrawStateBuilder& Builder, const ITimingTrackUpdateContext& Context) = 0;
    virtual void BuildFilteredDrawState(ITimingEventsTrackDrawStateBuilder& Builder, const ITimingTrackUpdateContext& Context) {}

protected:
    int32 GetNumLanes() const { return NumLanes; }
    void SetNumLanes(int32 InNumLanes) { NumLanes = InNumLanes; }

    void UpdateTrackHeight(const ITimingTrackUpdateContext& Context);

    void DrawEvents(const ITimingTrackDrawContext& Context, const float OffsetY = 1.0f) const;
    void DrawHeader(const ITimingTrackDrawContext& Context) const;

    void DrawMarkers(const ITimingTrackDrawContext& Context, float LineY, float LineH) const;

    int32 GetHeaderBackgroundLayerId(const ITimingTrackDrawContext& Context) const;
    int32 GetHeaderTextLayerId(const ITimingTrackDrawContext& Context) const;

    virtual const TSharedPtr<const ITimingEvent> GetEvent(double InTime, double SecondsPerPixel, int32 Depth) const;

private:
    int32 NumLanes;  // number of lanes (sub-tracks)
    TSharedRef<struct FTimingEventsTrackDrawState> DrawState;
    TSharedRef<struct FTimingEventsTrackDrawState> FilteredDrawState;

    struct FFilteredDrawStateInfo
    {
        double ViewportStartTime = 0.0;
        double ViewportScaleX    = 0.0;
        double LastBuildDuration = 0.0;
        TWeakPtr<ITimingEventFilter> LastEventFilter;
        uint32 LastFilterChangeNumber = 0;
        uint32 Counter                = 0;
        mutable float Opacity         = 0.0f;
    };
    FFilteredDrawStateInfo FilteredDrawStateInfo;

public:
    static bool bUseDownSampling;  // toggle to enable/disable downsampling, for debugging purposes only
};

////////////////////////////////////////////////////////////////////////////////////////////////////