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

#include "Components/ScrollBar.h"
#include "UObject/EditorObjectVersion.h"
#include "Styling/UMGCoreStyle.h"

#define LOCTEXT_NAMESPACE "UMG"

/////////////////////////////////////////////////////
// UScrollBar

namespace
{
	static FScrollBarStyle* DefaultScrollBarStyle = nullptr;
}

#if WITH_EDITOR
static FScrollBarStyle* EditorScrollBarStyle = nullptr;
#endif 

UScrollBar::UScrollBar(const FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)
{
	bIsVariable = false;

	bAlwaysShowScrollbar = true;
	bAlwaysShowScrollbarTrack = true;
	Orientation = Orient_Vertical;
	Thickness = FVector2D(16.0f, 16.0f);
	Padding = FMargin(2.0f);

	if (DefaultScrollBarStyle == nullptr)
	{
		DefaultScrollBarStyle = new FScrollBarStyle(FUMGCoreStyle::Get().GetWidgetStyle<FScrollBarStyle>("Scrollbar"));

		// Unlink UMG default colors.
		DefaultScrollBarStyle->UnlinkColors();
	}
	
	WidgetStyle = *DefaultScrollBarStyle;

#if WITH_EDITOR 
	if (EditorScrollBarStyle == nullptr)
	{
		EditorScrollBarStyle = new FScrollBarStyle(FCoreStyle::Get().GetWidgetStyle<FScrollBarStyle>("Scrollbar"));

		// Unlink UMG Editor colors from the editor settings colors.
		EditorScrollBarStyle->UnlinkColors();
	}

	if (IsEditorWidget())
	{
		WidgetStyle = *EditorScrollBarStyle;

		// The CDO isn't an editor widget and thus won't use the editor style, call post edit change to mark difference from CDO
		PostEditChange();
	}
#endif // WITH_EDITOR
}

void UScrollBar::ReleaseSlateResources(bool bReleaseChildren)
{
	Super::ReleaseSlateResources(bReleaseChildren);

	MyScrollBar.Reset();
}

TSharedRef<SWidget> UScrollBar::RebuildWidget()
{
	MyScrollBar = SNew(SScrollBar)
		.Style(&WidgetStyle)
		.AlwaysShowScrollbar(bAlwaysShowScrollbar)
		.AlwaysShowScrollbarTrack(bAlwaysShowScrollbarTrack)
		.Orientation(Orientation)
		.Thickness(Thickness)
		.Padding(Padding);

	//SLATE_EVENT(FOnUserScrolled, OnUserScrolled)

	return MyScrollBar.ToSharedRef();
}

void UScrollBar::SynchronizeProperties()
{
	Super::SynchronizeProperties();

	//MyScrollBar->SetScrollOffset(DesiredScrollOffset);
}

void UScrollBar::SetState(float InOffsetFraction, float InThumbSizeFraction)
{
	if ( MyScrollBar.IsValid() )
	{
		MyScrollBar->SetState(InOffsetFraction, InThumbSizeFraction);
	}
}

#if WITH_EDITORONLY_DATA

void UScrollBar::Serialize(FArchive& Ar)
{
	Ar.UsingCustomVersion(FEditorObjectVersion::GUID);

	const bool bDeprecateThickness = Ar.IsLoading() && Ar.CustomVer(FEditorObjectVersion::GUID) < FEditorObjectVersion::ScrollBarThicknessChange;
	if (bDeprecateThickness)
	{
		// Set Thickness property to previous default value.
		Thickness.Set(12.0f, 12.0f);
	}

	Super::Serialize(Ar);

	if (bDeprecateThickness)
	{
		// Implicit padding of 2 was removed, so Thickness value must be incremented by 4.
		Thickness += FVector2D(4.0f, 4.0f);
	}
}

#endif // if WITH_EDITORONLY_DATA

#if WITH_EDITOR

const FText UScrollBar::GetPaletteCategory()
{
	return LOCTEXT("Primitive", "Primitive");
}

#endif

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

#undef LOCTEXT_NAMESPACE