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

#pragma once

#include "Components/Widget.h"
#include "Framework/Views/TreeFilterHandler.h"
#include "Misc/TextFilter.h"
#include "Framework/SlateDelegates.h"
#include "UObject/ObjectPtr.h"
#include "WidgetBlueprint.h"
#include "Widgets/SCompoundWidget.h"

#include "SReadOnlyHierarchyView.generated.h"

class ITableRow;
class SSearchBox;
class STableViewBase;

template <typename ItemType> class STreeView;
template <typename ItemType> class TreeFilterHandler;
template <typename ItemType> class TTextFilter;

UENUM()
enum class ERootSelectionMode : uint8
{
	/** The Root Widget is not selectable */
	Disabled,

	/** The Root Widget is selectable and will show it's name as the display text */
	Enabled,

	/** The Root Widget is selectable and it will show Self as the display text */
	Self
};

class UMGEDITOR_API SReadOnlyHierarchyView : public SCompoundWidget
{
private:

	struct FItem
	{
		FItem(const UWidget* InWidget) : Widget(InWidget) {}
		FItem(const UWidgetBlueprint* InWidgetBlueprint) : WidgetBlueprint(InWidgetBlueprint) {}

		TWeakObjectPtr<const UWidget> Widget;
		TWeakObjectPtr<const UWidgetBlueprint> WidgetBlueprint;

		TArray<TSharedPtr<FItem>> Children;
	};

public:

	using FOnSelectionChanged = typename TSlateDelegates<FName>::FOnSelectionChanged;

	SLATE_BEGIN_ARGS(SReadOnlyHierarchyView) {}
		SLATE_ARGUMENT_DEFAULT(bool, ShowSearch) = true;
		SLATE_ARGUMENT_DEFAULT(ERootSelectionMode, RootSelectionMode) = ERootSelectionMode::Enabled;
		SLATE_ARGUMENT_DEFAULT(ESelectionMode::Type, SelectionMode) = ESelectionMode::Single;
		SLATE_EVENT(FOnSelectionChanged, OnSelectionChanged)
		SLATE_ARGUMENT(TArray<FName>, ShowOnly)
		SLATE_ARGUMENT_DEFAULT(bool, ExpandAll) = true;
	SLATE_END_ARGS()

	virtual ~SReadOnlyHierarchyView();

	void Construct(const FArguments& InArgs, const UWidgetBlueprint* WidgetBlueprint);
	void Refresh();

	void SetSelectedWidget(FName WidgetName);
	void SetRawFilterText(const FText& Text);

	TArray<FName> GetSelectedWidgets() const;
	void ClearSelection();

private:

	TSharedRef<ITableRow> GenerateRow(TSharedPtr<FItem> Item, const TSharedRef<STableViewBase>& OwnerTable) const;

	void GetItemChildren(TSharedPtr<FItem> Item, TArray<TSharedPtr<FItem>>& OutChildren) const;
	FText GetItemText(TSharedPtr<FItem> Item) const;
	const FSlateBrush* GetIconBrush(TSharedPtr<FItem> Item) const;
	FText GetIconToolTipText(TSharedPtr<FItem> Item) const;
	FText GetWidgetToolTipText(TSharedPtr<FItem> Item) const;
	void GetFilterStringsForItem(TSharedPtr<FItem> Item, TArray<FString>& OutStrings) const;
	TSharedPtr<FItem> FindItem(const TArray<TSharedPtr<FItem>>& RootItems, FName Name) const;
	void OnSelectionChanged(TSharedPtr<FItem> Selected, ESelectInfo::Type SelectionType);

	void RebuildTree();
	void BuildWidgetChildren(const UWidget* Widget, TSharedPtr<FItem> Parent);

	void SetItemExpansionRecursive(TSharedPtr<FItem> Item, bool bShouldBeExpanded);
	void ExpandAll();

	FName GetItemName(const TSharedPtr<FItem>& Item) const;

private:

	TWeakObjectPtr<const UWidgetBlueprint> WidgetBlueprint;
	TArray<FName> ShowOnly;

	TArray<TSharedPtr<FItem>> RootWidgets;
	TArray<TSharedPtr<FItem>> FilteredRootWidgets;

	ERootSelectionMode RootSelectionMode;

	FOnSelectionChanged OnSelectionChangedDelegate;

	TSharedPtr<SSearchBox> SearchBox;

	using FTextFilter = TTextFilter<TSharedPtr<FItem>>;
	TSharedPtr<FTextFilter> SearchFilter;
	using FTreeFilterHandler = TreeFilterHandler<TSharedPtr<FItem>>;
	TSharedPtr<FTreeFilterHandler> FilterHandler;

	TSharedPtr<STreeView<TSharedPtr<FItem>>> TreeView;

	bool bExpandAll;
};