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

#pragma once

#include "CoreMinimal.h"
#include "Input/CursorReply.h"
#include "Input/Reply.h"
#include "Layout/Geometry.h"
#include "Rendering/RenderingCommon.h"
#include "Widgets/DeclarativeSyntaxSupport.h"
#include "Widgets/SCompoundWidget.h"

// Insights
#include "Insights/Common/FixedCircularBuffer.h"
#include "Insights/ViewModels/FrameTrackHelper.h"
#include "Insights/ViewModels/FrameTrackViewport.h"

class SScrollBar;

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

struct FFrameTrackSampleRef
{
    TSharedPtr<FFrameTrackSeries> Series;
    TSharedPtr<FFrameTrackSample> Sample;

    FFrameTrackSampleRef()
        : Series(), Sample()
    {
    }

    FFrameTrackSampleRef(TSharedPtr<FFrameTrackSeries> InSeries, TSharedPtr<FFrameTrackSample> InSample)
        : Series(InSeries), Sample(InSample)
    {
    }

    FFrameTrackSampleRef(const FFrameTrackSampleRef& Other)
        : Series(Other.Series), Sample(Other.Sample)
    {
    }

    FFrameTrackSampleRef& operator=(const FFrameTrackSampleRef& Other)
    {
        Series = Other.Series;
        Sample = Other.Sample;
        return *this;
    }

    void Reset()
    {
        Series.Reset();
        Sample.Reset();
    }

    bool IsValid() const
    {
        return Series.IsValid() && Sample.IsValid();
    }

    bool Equals(const FFrameTrackSampleRef& Other) const
    {
        return Series == Other.Series && ((Sample == Other.Sample) || (Sample.IsValid() && Other.Sample.IsValid() && Sample->Equals(*Other.Sample)));
    }

    static bool AreEquals(const FFrameTrackSampleRef& A, const FFrameTrackSampleRef& B)
    {
        return A.Equals(B);
    }
};

////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 * Widget used to present frames data in a bar track.
 */
class SFrameTrack: public SCompoundWidget
{
public:
    /** Number of pixels. */
    static constexpr float MOUSE_SNAP_DISTANCE = 2.0f;

    enum class ECursorType
    {
        Default,
        Arrow,
        Hand,
    };

public:
    /** Default constructor. */
    SFrameTrack();

    /** Virtual destructor. */
    virtual ~SFrameTrack();

    /** Resets internal widget's data to the default one. */
    void Reset();

    SLATE_BEGIN_ARGS(SFrameTrack)
    {
        _Clipping = EWidgetClipping::ClipToBounds;
    }
    SLATE_END_ARGS()

    /**
     * Construct this widget
     * @param InArgs The declaration data for this widget
     */
    void Construct(const FArguments& InArgs);

    /**
     * Ticks this widget. Override in derived classes, but always call the parent implementation.
     * @param  AllottedGeometry The space allotted for this widget
     * @param  InCurrentTime  Current absolute real time
     * @param  InDeltaTime  Real time passed since last tick
     */
    virtual void Tick(const FGeometry& AllottedGeometry, const double InCurrentTime, const float InDeltaTime) override;

    virtual int32 OnPaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled) const override;

    virtual FReply OnMouseButtonDown(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual FReply OnMouseButtonUp(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual FReply OnMouseMove(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual void OnMouseEnter(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual void OnMouseLeave(const FPointerEvent& MouseEvent) override;
    virtual FReply OnMouseWheel(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual FReply OnMouseButtonDoubleClick(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

    virtual FCursorReply OnCursorQuery(const FGeometry& MyGeometry, const FPointerEvent& CursorEvent) const override;

protected:
    TSharedRef<FFrameTrackSeries> FindOrAddSeries(int32 FrameType);
    TSharedPtr<FFrameTrackSeries> FindSeries(int32 FrameType) const;
    void UpdateState();

    void DrawHorizontalAxisGrid(FDrawContext& DrawContext, const FSlateBrush* Brush, const FSlateFontInfo& Font) const;
    void DrawVerticalAxisGrid(FDrawContext& DrawContext, const FSlateBrush* Brush, const FSlateFontInfo& Font) const;

    FFrameTrackSampleRef GetSampleAtMousePosition(float X, float Y);
    void SelectFrameAtMousePosition(float X, float Y);

    void ShowContextMenu(const FPointerEvent& MouseEvent);

    void ContextMenu_ShowGameFrames_Execute();
    bool ContextMenu_ShowGameFrames_CanExecute();
    bool ContextMenu_ShowGameFrames_IsChecked();

    void ContextMenu_ShowRenderingFrames_Execute();
    bool ContextMenu_ShowRenderingFrames_CanExecute();
    bool ContextMenu_ShowRenderingFrames_IsChecked();

    void ContextMenu_AutoZoom_Execute();
    bool ContextMenu_AutoZoom_CanExecute();
    bool ContextMenu_AutoZoom_IsChecked();
    void AutoZoom();

    /** Binds our UI commands to delegates. */
    void BindCommands();

    /**
     * Called when the user scrolls the horizontal scrollbar.
     * @param ScrollOffset Scroll offset as a fraction between 0 and 1.
     */
    void HorizontalScrollBar_OnUserScrolled(float ScrollOffset);
    void UpdateHorizontalScrollBar();

    void ZoomHorizontally(const float Delta, const float X);

protected:
    /** The track's viewport. Encapsulates info about position and scale. */
    FFrameTrackViewport Viewport;
    bool bIsViewportDirty;

    /** Cached info for all frame series. */
    TMap<int32, TSharedPtr<FFrameTrackSeries>> SeriesMap;
    TArray<int32> SeriesOrder;

    bool bIsStateDirty;

    bool bShowGameFrames;
    bool bShowRenderingFrames;
    bool bIsAutoZoomEnabled;
    float AutoZoomViewportPos;
    float AutoZoomViewportScale;
    float AutoZoomViewportSize;

    uint64 AnalysisSyncNextTimestamp;

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

    TSharedPtr<SScrollBar> HorizontalScrollBar;

    //////////////////////////////////////////////////
    // Panning and Zooming behaviors

    /** The current mouse position. */
    FVector2D MousePosition;

    /** Mouse position during the call on mouse button down. */
    FVector2D MousePositionOnButtonDown;
    float ViewportPosXOnButtonDown;

    /** Mouse position during the call on mouse button up. */
    FVector2D MousePositionOnButtonUp;

    bool bIsLMB_Pressed;
    bool bIsRMB_Pressed;

    /** True, if the user is currently interactively scrolling the view (ex.: by holding the left mouse button and dragging). */
    bool bIsScrolling;

    //////////////////////////////////////////////////
    // Selection

    FFrameTrackSampleRef HoveredSample;

    float TooltipDesiredOpacity;
    mutable float TooltipOpacity;

    //////////////////////////////////////////////////
    // Misc

    FGeometry ThisGeometry;

    /** Cursor type. */
    ECursorType CursorType;

    // Debug stats
    int32 NumUpdatedFrames;
    TFixedCircularBuffer<uint64, 32> UpdateDurationHistory;
    mutable TFixedCircularBuffer<uint64, 32> DrawDurationHistory;
    mutable TFixedCircularBuffer<uint64, 32> OnPaintDurationHistory;
    mutable uint64 LastOnPaintTime;
};