// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.

#pragma once

class UEditorTutorial;

DECLARE_DELEGATE_ThreeParams(FOnLaunchTutorial, UEditorTutorial* /** InTutorialToLaunch */, bool /* bRestart */, TWeakPtr<SWindow> /* InFromWindow */)

/** Abstract base class for list entries in the tutorial menu */
struct ITutorialListEntry
{
	/** Generate content for a tree entry */
	virtual TSharedRef<ITableRow> OnGenerateTutorialRow(const TSharedRef<STableViewBase>& OwnerTable) const = 0;

	/** Whether this entry passes the current filter criteria */
	virtual bool PassesFilter(const FString& InCategoryFilter, const FString& InFilter) const = 0;
};

class FTutorialListEntry_Category;

/**
 * The widget which holds all available tutorials
 */
class STutorialsBrowser : public SCompoundWidget
{
	SLATE_BEGIN_ARGS( STutorialsBrowser ) {}

	SLATE_ARGUMENT(FSimpleDelegate, OnClosed)
	SLATE_ARGUMENT(FOnLaunchTutorial, OnLaunchTutorial)
	SLATE_ARGUMENT(TWeakPtr<SWindow>, ParentWindow)

	SLATE_END_ARGS()

	void Construct(const FArguments& Args);

	/** Set the current filter string. Filters are used to only show the specifed category of tutorials (e.g. only Blueprint tutorials) */
	void SetFilter(const FString& InFilter);

protected:
	/** Handle generating a table row in the browser */
	TSharedRef<ITableRow> OnGenerateTutorialRow(TSharedPtr<ITutorialListEntry> InItem, const TSharedRef<STableViewBase>& OwnerTable) const;

	/** Reload all tutorials that we know about */
	void ReloadTutorials();

	/** Handle closing the browser */
	FReply OnCloseButtonClicked();

	/** Handle traversing back up the browser hierarchy */
	FReply OnBackButtonClicked();

	/** Handle whether the back button can be clicked */
	bool IsBackButtonEnabled() const;

	/** Handle back button color - used to dim the button when disabled */
	FSlateColor GetBackButtonColor() const;

	/** Delegate handler fired when a tutorial is selected form the browser */
	void OnTutorialSelected(UEditorTutorial* InTutorial, bool bRestart);

	/** Delegate handler fired when a category is selected form the browser */
	void OnCategorySelected(const FString& InCategory);

	/** Filter displayed tutorials - regenerates the displayed items */
	void FilterTutorials();

	/** Rebuild the displayed categories */
	TSharedPtr<FTutorialListEntry_Category> RebuildCategories();

	/** Rebuild the displayed tutorials */
	void RebuildTutorials(TSharedPtr<FTutorialListEntry_Category> InRootCategory);

	/** Recursive helper function used to find a category given the current NavigationFilter */
	TSharedPtr<FTutorialListEntry_Category> FindCategory_Recursive(TSharedPtr<FTutorialListEntry_Category> InCategory) const;

	/** Handle rebuilding the browser display when the filter text changes */
	void OnSearchTextChanged(const FText& InText);

	/** Supplies the text to display in the filter box */
	FText GetSearchText() const;

private:

	/** Root entry of the tutorials tree */
	TSharedPtr<FTutorialListEntry_Category> RootEntry;

	/** Current filtered entries */
	TArray<TSharedPtr<ITutorialListEntry>> FilteredEntries;

	/** List of tutorials widget */
	TSharedPtr<SListView<TSharedPtr<ITutorialListEntry>>> TutorialList;

	/** Delegate fired when the close button is clicked */
	FSimpleDelegate OnClosed;

	/** Delegate fired when a tutorial is selected */
	FOnLaunchTutorial OnLaunchTutorial;

	/** Current search string */
	FText SearchFilter;

	/** Current category navigation string */
	FString NavigationFilter;

	/** Static category filter for this browser */
	FString CategoryFilter;

	/** Cached current category */
	TWeakPtr<FTutorialListEntry_Category> CurrentCategoryPtr;

	/** Parent window of this browser */
	TWeakPtr<SWindow> ParentWindow;
};