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

#pragma once

#include "CoreMinimal.h"
#include "Serialization/ArchiveUObject.h"
#include "Serialization/ArchiveObjectGraph.h"

// DEPRECATED: This class is out of date and misses many GC references, replace with FReferenceChainSearch
class FArchiveTraceRoute: public FArchiveUObject
{
    /**
     * Simple container struct for grouping two FObjectGraphNodes together.
     */
    struct FRouteLink
    {
        /**
         * Constructor
         */
        FRouteLink(FObjectGraphNode* InParent = NULL, FObjectGraphNode* InChild = NULL)
            : LinkParent(InParent), LinkChild(InChild)
        {}

        /**
         * The node corresponding to the "referencing" object.
         */
        FObjectGraphNode* LinkParent;

        /**
         * The node corresponding to the "referenced" object.
         */
        FObjectGraphNode* LinkChild;
    };

public:
    UE_DEPRECATED(4.23, "This function is out of date and misses many GC references, replace with FReferenceChainSearch")
    static COREUOBJECT_API TMap<UObject*, FProperty*> FindShortestRootPath(UObject* Object, bool bIncludeTransients, EObjectFlags KeepFlags);

    /**
     * Retuns path to root created by e.g. FindShortestRootPath via a string.
     *
     * @param TargetObject	object marking one end of the route
     * @param Route			route to print to log.
     * @param String of root path
     */
    static COREUOBJECT_API FString PrintRootPath(const TMap<UObject*, FProperty*>& Route, const UObject* TargetObject);

    /**
     * Returns the name of the Archive.  Useful for getting the name of the package a struct or object
     * is in when a loading error occurs.
     *
     * This is overridden for the specific Archive Types
     **/
    virtual FString GetArchiveName() const { return TEXT("FArchiveTraceRoute"); }

    /**
     * Serializes the objects in the specified set; any objects encountered during serialization
     * of an object are added to the object set and processed until no new objects are added.
     *
     * @param	Objects		the original set of objects to serialize; the original set will be preserved.
     */
    void GenerateObjectGraph(TSparseArray<UObject*>& Objects);

    /**
     * Recursively iterates over the referencing objects for the specified node, marking each with
     * the current Depth value.  Stops once it reaches a route root.
     *
     * @param	ObjectNode	the node to evaluate.
     */
    void CalculateReferenceDepthsForNode(FObjectGraphNode* ObjectNode);

    /**
     * Searches through the objects referenced by CurrentNode for a record with a Depth lower than LowestDepth.
     *
     * @param	CurrentNode		the node containing the list of referenced objects that will be searched.
     * @param	LowestDepth		the current number of links we are from the target object.
     * @param	ClosestLink		if a trace route record is found with a lower depth value than LowestDepth, the link is saved to this value.
     *
     * @return	true if a closer link was discovered; false if no links were closer than lowest depth, or if we've reached the target object.
     */
    bool FindClosestLink(FObjectGraphNode* CurrentNode, int32& LowestDepth, FRouteLink& ClosestLink);

private:
    FArchiveTraceRoute(UObject* TargetObject, TMap<UObject*, FTraceRouteRecord>& InRoutes, bool bShouldIncludeTransients, EObjectFlags KeepFlags);
    ~FArchiveTraceRoute();

    /** Handles serialization of UObject references */
    FArchive& operator<<(class UObject*& Obj);

    /** A complete graph of all references between all objects in memory */
    TMap<UObject*, FObjectGraphNode*> ObjectGraph;

    /**
     * The object currently being serialized; used by the overloaded serialization operator to determine the referencing object.
     */
    UObject* CurrentReferencer;

    /** The set of objects encountered while serializing CurrentReferencer */
    TArray<UObject*> ObjectsToSerialize;

    /** the current number of object reference links away from the target object */
    int32 Depth;

    /** true if we should serialize objects marked RF_Transient */
    bool bIncludeTransients;

    /**
     * A bitmask of object flags which indicates which objects should be included in the group of initial objects to be serialized;
     * RF_RootSet will be automatically added to this bitmask, and OBJECTMARK_TagExp will automatically be removed.
     */
    EObjectFlags RequiredFlags;
};