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

#include "ThumbnailRendering/FontThumbnailRenderer.h"
#include "Fonts/SlateFontInfo.h"
#include "Fonts/FontCache.h"
#include "Framework/Application/SlateApplication.h"
#include "Engine/Font.h"
#include "CanvasItem.h"
#include "Engine/Texture2D.h"
#include "CanvasTypes.h"

UFontThumbnailRenderer::UFontThumbnailRenderer(const FObjectInitializer& ObjectInitializer)
    : Super(ObjectInitializer)
{
}

void UFontThumbnailRenderer::GetThumbnailSize(UObject* Object, float Zoom, uint32& OutWidth, uint32& OutHeight) const
{
    UFont* const Font = Cast<UFont>(Object);

    if (Font)
    {
        switch (Font->FontCacheType)
        {
            case EFontCacheType::Offline:
                if (Font->Textures.Num() > 0 && Font->Textures[0])
                {
                    // Get the texture interface for the font text
                    UTexture2D* const Tex = Font->Textures[0];
                    OutWidth              = FMath::TruncToInt(Zoom * (float)Tex->GetSurfaceWidth());
                    OutHeight             = FMath::TruncToInt(Zoom * (float)Tex->GetSurfaceHeight());
                    return;
                }
                break;

            case EFontCacheType::Runtime:
                if (Font->CompositeFont.DefaultTypeface.Fonts.Num() > 0)
                {
                    OutWidth = OutHeight = Zoom * 256.0f;
                }
                break;

            default:
                break;
        };
    }

    OutWidth = OutHeight = 0;
}

void UFontThumbnailRenderer::Draw(UObject* Object, int32 X, int32 Y, uint32 Width, uint32 Height, FRenderTarget*, FCanvas* Canvas, bool bAdditionalViewFamily)
{
    UFont* const Font = Cast<UFont>(Object);

    if (Font)
    {
        switch (Font->FontCacheType)
        {
            case EFontCacheType::Offline:
                if (Font->Textures.Num() > 0 && Font->Textures[0])
                {
                    FCanvasTileItem TileItem(FVector2D(X, Y), Font->Textures[0]->Resource, FLinearColor::White);
                    TileItem.BlendMode = (Font->ImportOptions.bUseDistanceFieldAlpha) ? SE_BLEND_TranslucentDistanceField : SE_BLEND_Translucent;
                    Canvas->DrawItem(TileItem);
                }
                break;

            case EFontCacheType::Runtime:
                if (Font->CompositeFont.DefaultTypeface.Fonts.Num() > 0)
                {
                    static const int32 FontSize                              = 28;
                    static const float FontScale                             = 1.0f;

                    const FString FontName                                   = Object->GetName();
                    const TextBiDi::ETextDirection FontNameBaseTextDirection = TextBiDi::ComputeBaseDirection(FontName);

                    TSharedRef<FSlateFontCache> FontCache                    = FSlateApplication::Get().GetRenderer()->GetFontCache();

                    // Draw the object name using each of the default fonts
                    FVector2D CurPos(X, Y);
                    for (const FTypefaceEntry& TypefaceEntry: Font->CompositeFont.DefaultTypeface.Fonts)
                    {
                        FSlateFontInfo FontInfo(Font, FontSize, TypefaceEntry.Name);
                        FShapedGlyphSequenceRef FontNameShapedText = FontCache->ShapeBidirectionalText(FontName, FontInfo, FontScale, FontNameBaseTextDirection, ETextShapingMethod::Auto);

                        FVector2D TextDrawPos                      = CurPos;
                        if (FontNameBaseTextDirection == TextBiDi::ETextDirection::RightToLeft)
                        {
                            TextDrawPos.X = Width - CurPos.X - FontNameShapedText->GetMeasuredWidth();
                        }

                        FCanvasShapedTextItem TextItem(TextDrawPos, FontNameShapedText, FLinearColor::White);
                        Canvas->DrawItem(TextItem);

                        CurPos.Y += FontNameShapedText->GetMaxTextHeight();
                    }
                }
                break;

            default:
                break;
        };
    }
}