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

#pragma once

#include "CoreMinimal.h"

namespace Insights
{

class ITableCellValueSorter;

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

class FBaseTreeNode;

/** Type definition for shared pointers to instances of FBaseTreeNode. */
typedef TSharedPtr<class FBaseTreeNode> FBaseTreeNodePtr;

/** Type definition for shared references to instances of FBaseTreeNode. */
typedef TSharedRef<class FBaseTreeNode> FBaseTreeNodeRef;

/** Type definition for shared references to const instances of FBaseTreeNode. */
typedef TSharedRef<const class FBaseTreeNode> FBaseTreeNodeRefConst;

/** Type definition for weak references to instances of FBaseTreeNode. */
typedef TWeakPtr<class FBaseTreeNode> FBaseTreeNodeWeak;

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

class FBaseTreeNode: public TSharedFromThis<FBaseTreeNode>
{
public:
    /** Initialization constructor for the node. */
    FBaseTreeNode(const FName InName, bool bInIsGroup)
        : DefaultSortOrder(0), Name(InName), bIsGroup(bInIsGroup), bIsExpanded(false)
    {
    }

    virtual ~FBaseTreeNode()
    {
    }

    virtual const FName& GetTypeName() const = 0;

    uint32 GetDefaultSortOrder() const { return DefaultSortOrder; }
    void SetDefaultSortOrder(uint32 Order) { DefaultSortOrder = Order; }

    /**
     * @return a name of this node.
     */
    const FName& GetName() const
    {
        return Name;
    }

    /**
     * @return a name of this node to display in tree view. Ex.: group nodes may include additional info, like the number of visible/total children.
     */
    virtual const FText GetDisplayName() const;

    /**
     * @return true, if this node is a group node.
     */
    bool IsGroup() const
    {
        return bIsGroup;
    }

    /**
     * @return a const reference to the child nodes of this group.
     */
    FORCEINLINE_DEBUGGABLE const TArray<FBaseTreeNodePtr>& GetChildren() const
    {
        return Children;
    }

    /**
     * @return a const reference to the child nodes that should be visible to the UI based on filtering.
     */
    FORCEINLINE_DEBUGGABLE const TArray<FBaseTreeNodePtr>& GetFilteredChildren() const
    {
        return FilteredChildren;
    }

    /**
     * @return a weak reference to the group of this node, may be invalid.
     */
    FBaseTreeNodeWeak GetGroupPtr() const
    {
        return GroupPtr;
    }

    /**
     * @return a name of the group node that this node belongs to.
     */
    const FName& GetGroupName() const
    {
        return GroupPtr.Pin()->GetName();
    }

    virtual bool IsFiltered() const
    {
        return false;
    }

    void SortChildrenAscending(const ITableCellValueSorter& Sorter);
    void SortChildrenDescending(const ITableCellValueSorter& Sorter);

    /** Adds specified child to the children and sets group for it. */
    FORCEINLINE_DEBUGGABLE void AddChildAndSetGroupPtr(const FBaseTreeNodePtr& ChildPtr)
    {
        ChildPtr->GroupPtr = AsShared();
        Children.Add(ChildPtr);
    }

    /** Clears children. */
    void ClearChildren()
    {
        for (FBaseTreeNodePtr& NodePtr: Children)
        {
            NodePtr->GroupPtr = nullptr;
        }
        Children.Reset();
    }

    /** Adds specified child to the filtered children. */
    FORCEINLINE_DEBUGGABLE void AddFilteredChild(const FBaseTreeNodePtr& ChildPtr)
    {
        FilteredChildren.Add(ChildPtr);
    }

    /** Clears filtered children. */
    void ClearFilteredChildren()
    {
        FilteredChildren.Reset();
    }

    bool IsExpanded() const { return bIsExpanded; }
    void SetExpansion(bool bOnOff) { bIsExpanded = bOnOff; }

protected:
    /**
     * @return a reference to the child nodes of this group.
     */
    FORCEINLINE_DEBUGGABLE TArray<FBaseTreeNodePtr>& GetChildrenMutable()
    {
        return Children;
    }

private:
    /** The default sort order. Index used to optimize sorting. */
    int32 DefaultSortOrder;

    /** The name of this node. */
    const FName Name;

    /** Children of this node. */
    TArray<FBaseTreeNodePtr> Children;

    /** Filtered children of this node. */
    TArray<FBaseTreeNodePtr> FilteredChildren;

    /** A weak pointer to the group/parent of this node. */
    FBaseTreeNodeWeak GroupPtr;

    /** If this node is a group node or not. */
    bool bIsGroup;

    /** Whether this group node should be expanded or not. */
    bool bIsExpanded;
};

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

}  // namespace Insights