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

#pragma once

#include "CoreMinimal.h"
#include "Misc/Attribute.h"
#include "GameFramework/Actor.h"
#include "Input/Reply.h"
#include "Widgets/SWidget.h"
#include "Widgets/SNullWidget.h"
#include "Widgets/DeclarativeSyntaxSupport.h"
#include "Widgets/SCompoundWidget.h"
#include "BlueprintUtilities.h"
#include "Framework/Commands/InputChord.h"
#include "Framework/Commands/UICommandList.h"
#include "Engine/LevelStreaming.h"

class UEdGraph;
struct FNotificationInfo;
struct Rect;
class FMenuBuilder;
class FAssetEditorToolkit;

DECLARE_DELEGATE_ThreeParams(FOnNodeTextCommitted, const FText&, ETextCommit::Type, UEdGraphNode*);
DECLARE_DELEGATE_RetVal_ThreeParams(bool, FOnNodeVerifyTextCommit, const FText&, UEdGraphNode*, FText&);
DECLARE_MULTICAST_DELEGATE(FOnGraphContentMenuDismissed);

typedef TSet<class UObject*> FGraphPanelSelectionSet;

/** Info about how to draw the graph */
struct FGraphAppearanceInfo
{
    FGraphAppearanceInfo()
        : CornerImage(NULL), InstructionFade(1.f)
    {
    }

    /** Image to draw in corner of graph */
    const FSlateBrush* CornerImage;
    /** Text to write in corner of graph */
    FText CornerText;
    /** If set, will be used as override for PIE notify text */
    FText PIENotifyText;
    /** If set, will be used as override for read only text */
    FText ReadOnlyText;
    /** Text to display if the graph is empty (to guide the user on what to do) */
    FText InstructionText;
    /** Allows graphs to nicely fade instruction text (or completely hide it). */
    TAttribute<float> InstructionFade;
};

/** Struct used to return info about action menu */
struct FActionMenuContent
{
    explicit FActionMenuContent(TSharedRef<SWidget> InContent, TSharedPtr<SWidget> InWidgetToFocus = TSharedPtr<SWidget>())
        : Content(InContent), WidgetToFocus(InWidgetToFocus)
    {
    }

    FActionMenuContent()
        : Content(SNullWidget::NullWidget)
    {
    }

    TSharedRef<SWidget> Content;
    TSharedPtr<SWidget> WidgetToFocus;
    FOnGraphContentMenuDismissed OnMenuDismissed;
};

/**
 * Interface and wrapper for GraphEditor widgets.
 * Gracefully handles the GraphEditorModule being unloaded.
 */
class SGraphEditor: public SCompoundWidget
{
public:
    DECLARE_DELEGATE_OneParam(FOnSelectionChanged, const FGraphPanelSelectionSet&)

        DECLARE_DELEGATE_OneParam(FOnFocused, const TSharedRef<SGraphEditor>&);

    DECLARE_DELEGATE_ThreeParams(FOnDropActor, const TArray<TWeakObjectPtr<class AActor>>&, class UEdGraph*, const FVector2D&);

    DECLARE_DELEGATE_ThreeParams(FOnDropStreamingLevel, const TArray<TWeakObjectPtr<class ULevelStreaming>>&, class UEdGraph*, const FVector2D&);

    DECLARE_DELEGATE(FActionMenuClosed);

    DECLARE_DELEGATE_RetVal_FiveParams(FActionMenuContent, FOnCreateActionMenu, UEdGraph*, const FVector2D&, const TArray<UEdGraphPin*>&, bool, FActionMenuClosed);

    DECLARE_DELEGATE_RetVal_FiveParams(FActionMenuContent, FOnCreateNodeOrPinMenu, UEdGraph*, const UEdGraphNode*, const UEdGraphPin*, FMenuBuilder*, bool);

    DECLARE_DELEGATE_RetVal_TwoParams(FReply, FOnSpawnNodeByShortcut, FInputChord, const FVector2D&);

    DECLARE_DELEGATE(FOnNodeSpawnedByKeymap);

    DECLARE_DELEGATE_TwoParams(FOnDisallowedPinConnection, const UEdGraphPin*, const UEdGraphPin*);

    /** Info about events occurring in/on the graph */
    struct FGraphEditorEvents
    {
        /** Called when selection changes */
        FOnSelectionChanged OnSelectionChanged;
        /** Called when a node is double clicked */
        FSingleNodeEvent OnNodeDoubleClicked;
        /* Called when focus moves to graph */
        FOnFocused OnFocused;
        /* Called when an actor is dropped on graph */
        FOnDropActor OnDropActor;
        /* Called when a streaming level is dropped on graph */
        FOnDropStreamingLevel OnDropStreamingLevel;
        /** Called when text is being committed on the graph to verify */
        FOnNodeVerifyTextCommit OnVerifyTextCommit;
        /** Called when text is committed on the graph */
        FOnNodeTextCommitted OnTextCommitted;
        /** Called to create context menu for right clicking in empty area */
        FOnCreateActionMenu OnCreateActionMenu;
        /** Called to create context menu for right clicking a node or pin, same parameters as GetContextMenuActions on schema */
        FOnCreateNodeOrPinMenu OnCreateNodeOrPinMenu;
        /** Called to spawn a node in the graph using a shortcut */
        FOnSpawnNodeByShortcut OnSpawnNodeByShortcut;
        /** Called when a keymap spawns a node */
        FOnNodeSpawnedByKeymap OnNodeSpawnedByKeymap;
        /** Called when the user generates a warning tooltip because a connection was invalid */
        FOnDisallowedPinConnection OnDisallowedPinConnection;
    };

    SLATE_BEGIN_ARGS(SGraphEditor)
        : _AdditionalCommands(static_cast<FUICommandList*>(NULL)), _IsEditable(true), _DisplayAsReadOnly(false), _IsEmpty(false), _GraphToEdit(NULL), _GraphToDiff(NULL), _AutoExpandActionMenu(false), _ShowGraphStateOverlay(true)
    {}

    SLATE_ARGUMENT(TSharedPtr<FUICommandList>, AdditionalCommands)
    SLATE_ATTRIBUTE(bool, IsEditable)
    SLATE_ATTRIBUTE(bool, DisplayAsReadOnly)
    SLATE_ATTRIBUTE(bool, IsEmpty)
    SLATE_ARGUMENT(TSharedPtr<SWidget>, TitleBar)
    SLATE_ATTRIBUTE(FGraphAppearanceInfo, Appearance)
    SLATE_EVENT(FEdGraphEvent, OnGraphModuleReloaded)
    SLATE_ARGUMENT(UEdGraph*, GraphToEdit)
    SLATE_ARGUMENT(UEdGraph*, GraphToDiff)
    SLATE_ARGUMENT(FGraphEditorEvents, GraphEvents)
    SLATE_ARGUMENT(bool, AutoExpandActionMenu)
    SLATE_ARGUMENT(TWeakPtr<FAssetEditorToolkit>, AssetEditorToolkit)
    SLATE_EVENT(FSimpleDelegate, OnNavigateHistoryBack)
    SLATE_EVENT(FSimpleDelegate, OnNavigateHistoryForward)

    /** Show overlay elements for the graph state such as the PIE and read-only borders and text */
    SLATE_ATTRIBUTE(bool, ShowGraphStateOverlay)
    SLATE_END_ARGS()

    /**
     * Loads the GraphEditorModule and constructs a GraphEditor as a child of this widget.
     *
     * @param InArgs   Declaration params from which to construct the widget.
     */
    UNREALED_API void Construct(const FArguments& InArgs);

    /** @return The current graph being edited */
    UEdGraph* GetCurrentGraph() const
    {
        return EdGraphObj;
    }

    virtual FVector2D GetPasteLocation() const
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetPasteLocation();
        }
        else
        {
            return FVector2D::ZeroVector;
        }
    }

    /* Set new viewer location and optionally set the current bookmark */
    virtual void SetViewLocation(const FVector2D& Location, float ZoomAmount, const FGuid& BookmarkId = FGuid())
    {
        if (Implementation.IsValid())
        {
            Implementation->SetViewLocation(Location, ZoomAmount, BookmarkId);
        }
    }

    /**
     * Gets the view location of the graph
     *
     * @param OutLocation		Will have the current view location
     * @param OutZoomAmount		Will have the current zoom amount
     */
    virtual void GetViewLocation(FVector2D& OutLocation, float& OutZoomAmount)
    {
        if (Implementation.IsValid())
        {
            Implementation->GetViewLocation(OutLocation, OutZoomAmount);
        }
    }

    /**
     * Gets the current graph view bookmark
     *
     * @param OutBookmarkId		Will have the current bookmark ID
     */
    virtual void GetViewBookmark(FGuid& OutBookmarkId)
    {
        if (Implementation.IsValid())
        {
            Implementation->GetViewBookmark(OutBookmarkId);
        }
    }

    /** Check if node title is visible with optional flag to ensure it is */
    virtual bool IsNodeTitleVisible(const class UEdGraphNode* Node, bool bRequestRename)
    {
        bool bResult = false;
        if (Implementation.IsValid())
        {
            bResult = Implementation->IsNodeTitleVisible(Node, bRequestRename);
        }
        return bResult;
    }

    /* Lock two graph editors together */
    virtual void LockToGraphEditor(TWeakPtr<SGraphEditor> Other)
    {
        if (Implementation.IsValid())
        {
            Implementation->LockToGraphEditor(Other);
        }
    }

    /* Unlock two graph editors from each other */
    virtual void UnlockFromGraphEditor(TWeakPtr<SGraphEditor> Other)
    {
        if (Implementation.IsValid())
        {
            Implementation->UnlockFromGraphEditor(Other);
        }
    }

    /** Bring the specified node into view */
    virtual void JumpToNode(const class UEdGraphNode* JumpToMe, bool bRequestRename = false, bool bSelectNode = true)
    {
        if (Implementation.IsValid())
        {
            Implementation->JumpToNode(JumpToMe, bRequestRename, bSelectNode);
        }
    }

    /** Bring the specified pin into view */
    virtual void JumpToPin(const class UEdGraphPin* JumpToMe)
    {
        if (Implementation.IsValid())
        {
            Implementation->JumpToPin(JumpToMe);
        }
    }

    /** Pin visibility modes */
    enum EPinVisibility
    {
        Pin_Show,
        Pin_HideNoConnection,
        Pin_HideNoConnectionNoDefault
    };

    /*Set the pin visibility mode*/
    virtual void SetPinVisibility(EPinVisibility InVisibility)
    {
        if (Implementation.IsValid())
        {
            Implementation->SetPinVisibility(InVisibility);
        }
    }

    /** Register an active timer on the graph editor. */
    virtual TSharedRef<FActiveTimerHandle> RegisterActiveTimer(float TickPeriod, FWidgetActiveTimerDelegate TickFunction)
    {
        if (Implementation.IsValid())
        {
            return Implementation->RegisterActiveTimer(TickPeriod, TickFunction);
        }
        return TSharedPtr<FActiveTimerHandle>().ToSharedRef();
    }

    /** @return a reference to the list of selected graph nodes */
    virtual const FGraphPanelSelectionSet& GetSelectedNodes() const
    {
        static FGraphPanelSelectionSet NoSelection;

        if (Implementation.IsValid())
        {
            return Implementation->GetSelectedNodes();
        }
        else
        {
            return NoSelection;
        }
    }

    /** Clear the selection */
    virtual void ClearSelectionSet()
    {
        if (Implementation.IsValid())
        {
            Implementation->ClearSelectionSet();
        }
    }

    /** Set the selection status of a node */
    virtual void SetNodeSelection(UEdGraphNode* Node, bool bSelect)
    {
        if (Implementation.IsValid())
        {
            Implementation->SetNodeSelection(Node, bSelect);
        }
    }

    /** Select all nodes */
    virtual void SelectAllNodes()
    {
        if (Implementation.IsValid())
        {
            Implementation->SelectAllNodes();
        }
    }

    virtual class UEdGraphPin* GetGraphPinForMenu()
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetGraphPinForMenu();
        }
        else
        {
            return NULL;
        }
    }

    virtual class UEdGraphNode* GetGraphNodeForMenu()
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetGraphNodeForMenu();
        }
        else
        {
            return NULL;
        }
    }

    // Zooms out to fit either all nodes or only the selected ones
    virtual void ZoomToFit(bool bOnlySelection)
    {
        if (Implementation.IsValid())
        {
            return Implementation->ZoomToFit(bOnlySelection);
        }
    }

    /** Get Bounds for selected nodes, false if nothing selected*/
    virtual bool GetBoundsForSelectedNodes(class FSlateRect& Rect, float Padding)
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetBoundsForSelectedNodes(Rect, Padding);
        }
        return false;
    }

    /** Get Bounds for the specified node, returns false on failure */
    virtual bool GetBoundsForNode(const UEdGraphNode* InNode, class FSlateRect& Rect, float Padding) const
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetBoundsForNode(InNode, Rect, Padding);
        }
        return false;
    }

    virtual void StraightenConnections()
    {
        if (Implementation.IsValid())
        {
            return Implementation->StraightenConnections();
        }
    }

    virtual void StraightenConnections(UEdGraphPin* SourcePin, UEdGraphPin* PinToAlign = nullptr) const
    {
        if (Implementation.IsValid())
        {
            return Implementation->StraightenConnections(SourcePin, PinToAlign);
        }
    }

    virtual void RefreshNode(UEdGraphNode& Node)
    {
        if (Implementation.IsValid())
        {
            return Implementation->RefreshNode(Node);
        }
    }

    // Invoked to let this widget know that the GraphEditor module has been reloaded
    UNREALED_API void OnModuleReloaded();

    // Invoked to let this widget know that the GraphEditor module is being unloaded.
    UNREALED_API void OnModuleUnloading();

    UNREALED_API void NotifyPrePropertyChange(const FString& PropertyName);
    UNREALED_API void NotifyPostPropertyChange(const FPropertyChangedEvent& PropertyChangeEvent, const FString& PropertyName);

    /** Invoked when the Graph being edited changes in some way. */
    virtual void NotifyGraphChanged()
    {
        if (Implementation.IsValid())
        {
            Implementation->NotifyGraphChanged();
        }
    }

    /* Get the title bar if there is one */
    virtual TSharedPtr<SWidget> GetTitleBar() const
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetTitleBar();
        }
        return TSharedPtr<SWidget>();
    }

    /** Show notification on graph */
    virtual void AddNotification(FNotificationInfo& Info, bool bSuccess)
    {
        if (Implementation.IsValid())
        {
            Implementation->AddNotification(Info, bSuccess);
        }
    }

    /** Capture keyboard */
    virtual void CaptureKeyboard()
    {
        if (Implementation.IsValid())
        {
            Implementation->CaptureKeyboard();
        }
    }

    /** Sets the current node, pin and connection factory. */
    virtual void SetNodeFactory(const TSharedRef<class FGraphNodeFactory>& NewNodeFactory)
    {
        if (Implementation.IsValid())
        {
            Implementation->SetNodeFactory(NewNodeFactory);
        }
    }

    /** Common methods for MaterialEditor and BlueprintEditor's focusing related nodes feature */
    UNREALED_API void ResetAllNodesUnrelatedStates();

    UNREALED_API void FocusCommentNodes(TArray<UEdGraphNode*>& CommentNodes, TArray<UEdGraphNode*>& RelatedNodes);

    virtual void OnAlignTop()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignTop();
        }
    }

    virtual void OnAlignMiddle()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignMiddle();
        }
    }

    virtual void OnAlignBottom()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignBottom();
        }
    }

    virtual void OnAlignLeft()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignLeft();
        }
    }

    virtual void OnAlignCenter()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignCenter();
        }
    }

    virtual void OnAlignRight()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnAlignRight();
        }
    }

    virtual void OnStraightenConnections()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnStraightenConnections();
        }
    }

    virtual void OnDistributeNodesH()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnDistributeNodesH();
        }
    }

    virtual void OnDistributeNodesV()
    {
        if (Implementation.IsValid())
        {
            Implementation->OnDistributeNodesV();
        }
    }

    virtual int32 GetNumberOfSelectedNodes() const
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetNumberOfSelectedNodes();
        }
        return 0;
    }

    /** Returns the currently selected node if there is a single node selected (if there are multiple nodes selected or none selected, it will return nullptr) */
    virtual UEdGraphNode* GetSingleSelectedNode() const
    {
        if (Implementation.IsValid())
        {
            return Implementation->GetSingleSelectedNode();
        }
        return nullptr;
    }

    // Returns the first graph editor that is viewing the specified graph
    UNREALED_API static TSharedPtr<SGraphEditor> FindGraphEditorForGraph(const UEdGraph* Graph);

protected:
    /** Invoked when the underlying Graph is being changed. */
    virtual void OnGraphChanged(const struct FEdGraphEditAction& InAction)
    {
        if (Implementation.IsValid())
        {
            Implementation->OnGraphChanged(InAction);
        }
    }

private:
    static void RegisterGraphEditor(const TSharedRef<SGraphEditor>& InGraphEditor);

    void ConstructImplementation(const FArguments& InArgs);

protected:
    /** The Graph we are currently editing */
    UEdGraph* EdGraphObj;

    TWeakPtr<FAssetEditorToolkit> AssetEditorToolkit;

private:
    /** The actual implementation of the GraphEditor */
    TSharedPtr<SGraphEditor> Implementation;

    /** Active GraphEditor wrappers; we will notify these about the module being unloaded so they can handle it gracefully. */
    UNREALED_API static TArray<TWeakPtr<SGraphEditor>> AllInstances;

    // This callback is triggered whenever the graph module is reloaded
    FEdGraphEvent OnGraphModuleReloadedCallback;

    // The graph editor module needs to access AllInstances, but no-one else should be able to
    friend class FGraphEditorModule;
};