// Copyright 2017 ~ 2022 Critical Failure Studio Ltd. All rights reserved.

#pragma once

#include "SEditorViewport.h"

#include "PaperZDToolViewportClient.h"

#include "Animation/CurveSequence.h"

#include "Framework/MarqueeRect.h"

class FPaintArgs;
class FSlateWindowElementList;
struct Rect;

struct FPaperZDToolMarqueeOperation
{
	FPaperZDToolMarqueeOperation()
	: Operation(Add)
	{
	}

	enum Type
	{
		/** Holding down Ctrl toggles affected nodes */
		Toggle,
		/** Holding down Shift adds to the selection */
		Add,
		/** When nothing is pressed, marquee replaces selection */
		Replace
	} Operation;

	bool IsValid() const
	{
		return Rect.IsValid();
	}

	void Start(const FVector2D& InStartLocation, FPaperZDToolMarqueeOperation::Type InOperationType)
	{
		Rect = FMarqueeRect(InStartLocation);
		Operation = InOperationType;
	}

	void End()
	{
		Rect = FMarqueeRect();
	}

	/** Given a mouse event, figure out what the marquee selection should do based on the state of Shift and Ctrl keys */
	static FPaperZDToolMarqueeOperation::Type OperationTypeFromMouseEvent(const FPointerEvent& MouseEvent)
	{
		if (MouseEvent.IsControlDown())
		{
			return FPaperZDToolMarqueeOperation::Toggle;
		}
		else if (MouseEvent.IsShiftDown())
		{
			return FPaperZDToolMarqueeOperation::Add;
		}
		else
		{
			return FPaperZDToolMarqueeOperation::Replace;
		}
	}

public:
	/** The marquee rectangle being dragged by the user */
	FMarqueeRect Rect;

	/** Nodes that will be selected or unselected by the current marquee operation */
	TSet<class UObject*> AffectedNodes;
};

class SPaperZDToolViewport : public SEditorViewport
{
public:
    DECLARE_DELEGATE_TwoParams(FOnSelectionChanged, FPaperZDToolMarqueeOperation /*MarqueeAction*/, bool /*bPreview*/);
public:
    SLATE_BEGIN_ARGS(SPaperZDToolViewport) {}
        SLATE_EVENT(FOnSelectionChanged, OnSelectionChanged);
    SLATE_END_ARGS()

    /** Destructor */
    ~SPaperZDToolViewport();

    // SWidget interface
    virtual void Tick(const FGeometry& AllottedGeometry, const double InCurrentTime, const float InDeltaTime) 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 FReply OnMouseWheel(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;
    virtual FCursorReply OnCursorQuery(const FGeometry& MyGeometry, const FPointerEvent& CursorEvent) const override;
    virtual int32 OnPaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled) const override;
    // End of SWidget interface

    void Construct(const FArguments& InArgs, TSharedRef<class FPaperZDToolViewportClient> InViewportClient);

    float GetZoomAmount() const;
    FText GetZoomText() const;
    FSlateColor GetZoomTextColorAndOpacity() const;
    FVector2D GetViewOffset() const;

protected:

    // SEditorViewport interface
    virtual TSharedRef<FEditorViewportClient> MakeEditorViewportClient() override;
    // End of SEditorViewport interface

    int32 FindNearestZoomLevel(float InZoomAmount, bool bRoundDown) const;
    FVector2D ComputeEdgePanAmount(const FGeometry& MyGeometry, const FVector2D& TargetPosition);
    void UpdateViewOffset(const FGeometry& MyGeometry, const FVector2D& TargetPosition);
    void RequestDeferredPan(const FVector2D& UpdatePosition);
    FVector2D GraphCoordToPanelCoord(const FVector2D& GraphSpaceCoordinate) const;
    FVector2D PanelCoordToGraphCoord(const FVector2D& PanelSpaceCoordinate) const;
    FSlateRect PanelRectToGraphRect(const FSlateRect& PanelSpaceRect) const;
    virtual bool OnHandleLeftMouseRelease(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) { return false; }

    void PaintSoftwareCursor(const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 DrawLayerId) const;

    virtual FText GetTitleText() const;

protected:
    /** The position within the graph at which the user is looking */
    FVector2D ViewOffset;

    /** How zoomed in/out we are. e.g. 0.25f results in quarter-sized nodes. */
    int32 ZoomLevel;

    /** Previous Zoom Level */
    int32 PreviousZoomLevel;

    /** Are we panning the view at the moment? */
    bool bIsPanning;

    /** The total distance that the mouse has been dragged while down */
    float TotalMouseDelta;

    /** A pending marquee operation if it's active */
    FPaperZDToolMarqueeOperation Marquee;

    /** Curve that handles fading the 'Zoom +X' text */
    FCurveSequence ZoomLevelFade;

    /** Position to pan to */
    FVector2D DeferredPanPosition;

    /** true if pending request for deferred panning */
    bool bRequestDeferredPan;

    /**	The current position of the software cursor */
    FVector2D SoftwareCursorPosition;

    /**	Whether the software cursor should be drawn */
    bool bShowSoftwareCursor;

    /** Level viewport client */
    TSharedPtr<class FPaperZDToolViewportClient> ViewportClient;

    // Selection changed delegate
    FOnSelectionChanged OnSelectionChanged;
};