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

#pragma once

#include "CoreMinimal.h"
#include "Fonts/FontMeasure.h"
#include "Framework/Application/SlateApplication.h"
#include "Rendering/DrawElements.h"

#define MAKE_PAINT_GEOMETRY_PT(Geometry, X, Y)       Geometry.ToPaintGeometry(FSlateLayoutTransform(1.0f, FVector2D(X, Y)))
#define MAKE_PAINT_GEOMETRY_RC(Geometry, X, Y, W, H) Geometry.ToPaintGeometry(FVector2D(W, H), FSlateLayoutTransform(1.0f, FVector2D(X, Y)))

struct FGeometry;
class FSlateRect;
class WidgetStyle;
enum class ESlateDrawEffect : uint8;
class FSlateWindowElementList;

/**
 * Holds current state provided by OnPaint function, used to simplify drawing.
 */
struct TRACEINSIGHTS_API FDrawContext
{
    FDrawContext(const FGeometry& InGeometry,
                 const FSlateRect& InCullingRect,
                 const FWidgetStyle& InWidgetStyle,
                 const ESlateDrawEffect InDrawEffects,
                 FSlateWindowElementList& InOutElementList,
                 int32& InOutLayerId)
        : Geometry(InGeometry), CullingRect(InCullingRect), WidgetStyle(InWidgetStyle), DrawEffects(InDrawEffects), ElementList(InOutElementList), LayerId(InOutLayerId)
    {}

    /**
     * Non-copyable
     */
    FDrawContext(const FDrawContext&)            = delete;
    FDrawContext& operator=(const FDrawContext&) = delete;

    inline void DrawBox(const float X, const float Y, const float W, const float H, const FSlateBrush* Brush, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeBox(ElementList, LayerId, MAKE_PAINT_GEOMETRY_RC(Geometry, X, Y, W, H), Brush, DrawEffects, Color);
    }

    inline void DrawBox(const int32 InLayer, const float X, const float Y, const float W, const float H, const FSlateBrush* Brush, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeBox(ElementList, InLayer, MAKE_PAINT_GEOMETRY_RC(Geometry, X, Y, W, H), Brush, DrawEffects, Color);
    }

    inline void DrawRotatedBox(const float X, const float Y, const float W, const float H, const FSlateBrush* Brush, const FLinearColor& Color, float Angle, TOptional<FVector2D> RotationPoint) const
    {
        FSlateDrawElement::MakeRotatedBox(ElementList, LayerId, MAKE_PAINT_GEOMETRY_RC(Geometry, X, Y, W, H), Brush, DrawEffects, Angle, RotationPoint, FSlateDrawElement::RelativeToElement, Color);
    }

    inline void DrawText(const float X, const float Y, const FString& Text, const FSlateFontInfo& Font, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeText(ElementList, LayerId, MAKE_PAINT_GEOMETRY_PT(Geometry, X, Y), Text, Font, DrawEffects, Color);
    }

    inline void DrawText(const int32 InLayer, const float X, const float Y, const FString& Text, const FSlateFontInfo& Font, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeText(ElementList, InLayer, MAKE_PAINT_GEOMETRY_PT(Geometry, X, Y), Text, Font, DrawEffects, Color);
    }

    inline void DrawText(const float X, const float Y, const FString& Text, const int32 StartIndex, const int32 EndIndex, const FSlateFontInfo& Font, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeText(ElementList, LayerId, MAKE_PAINT_GEOMETRY_PT(Geometry, X, Y), Text, StartIndex, EndIndex, Font, DrawEffects, Color);
    }

    inline void DrawText(const int32 InLayer, const float X, const float Y, const FString& Text, const int32 StartIndex, const int32 EndIndex, const FSlateFontInfo& Font, const FLinearColor& Color) const
    {
        FSlateDrawElement::MakeText(ElementList, InLayer, MAKE_PAINT_GEOMETRY_PT(Geometry, X, Y), Text, StartIndex, EndIndex, Font, DrawEffects, Color);
    }

    inline void DrawTextAligned(EHorizontalAlignment HAlign, const float X, const float Y, const FString& Text, const FSlateFontInfo& Font, const FLinearColor& Color) const
    {
        const TSharedRef<FSlateFontMeasure> FontMeasureService = FSlateApplication::Get().GetRenderer()->GetFontMeasureService();
        const float TextWidth                                  = FontMeasureService->Measure(Text, Font).X;
        float TextX                                            = X;
        if (HAlign == HAlign_Right)
        {
            TextX -= TextWidth;
        }
        else if (HAlign == HAlign_Center)
        {
            TextX -= TextWidth / 2;
        }
        FSlateDrawElement::MakeText(ElementList, LayerId, MAKE_PAINT_GEOMETRY_PT(Geometry, TextX, Y), Text, Font, DrawEffects, Color);
    }

    // inline void IncrementLayer() const { ++LayerId; }

    // Accessors
    const FGeometry& Geometry;
    const FSlateRect& CullingRect;
    const FWidgetStyle& WidgetStyle;
    const ESlateDrawEffect DrawEffects;

    FSlateWindowElementList& ElementList;
    int32& LayerId;
};