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

/*=============================================================================
        LinkerManager.h: Unreal object linker manager
=============================================================================*/

#pragma once

#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "Misc/CoreMisc.h"
#include "Misc/ScopeLock.h"
#include "HAL/ThreadSafeBool.h"

class FLinkerManager: private FSelfRegisteringExec
{
public:
    FLinkerManager();
    ~FLinkerManager();

    static FLinkerManager& Get();

    FORCEINLINE void GetLoaders(TSet<FLinkerLoad*>& OutLoaders)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&ObjectLoadersCritical);
#endif
        OutLoaders = ObjectLoaders;
    }

    FORCEINLINE void GetLoadersAndEmpty(TSet<FLinkerLoad*>& OutLoaders)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&ObjectLoadersCritical);
#endif
        OutLoaders = MoveTemp(ObjectLoaders);
        check(ObjectLoaders.Num() == 0);
    }

    FORCEINLINE void AddLoader(FLinkerLoad* LinkerLoad)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&ObjectLoadersCritical);
#endif
        ObjectLoaders.Add(LinkerLoad);
    }

    FORCEINLINE void RemoveLoaderFromObjectLoadersAndLoadersWithNewImports(FLinkerLoad* LinkerLoad)
    {
        {
#if THREADSAFE_UOBJECTS
            FScopeLock ObjectLoadersLock(&ObjectLoadersCritical);
#endif
            ObjectLoaders.Remove(LinkerLoad);
        }
        {
#if THREADSAFE_UOBJECTS
            FScopeLock ObjectLoadersLock(&LoadersWithNewImportsCritical);
#endif
            LoadersWithNewImports.Remove(LinkerLoad);
        }
    }

    FORCEINLINE void GetLoadersWithNewImportsAndEmpty(TSet<FLinkerLoad*>& OutLoaders)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&LoadersWithNewImportsCritical);
#endif
        OutLoaders = MoveTemp(LoadersWithNewImports);
    }

    FORCEINLINE void AddLoaderWithNewImports(FLinkerLoad* LinkerLoad)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&LoadersWithNewImportsCritical);
#endif
        LoadersWithNewImports.Add(LinkerLoad);
    }

    FORCEINLINE void GetLoadersWithForcedExportsAndEmpty(TSet<FLinkerLoad*>& OutLoaders)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&LoadersWithForcedExportsCritical);
#endif
        OutLoaders = MoveTemp(LoadersWithForcedExports);
    }

    FORCEINLINE void AddLoaderWithForcedExports(FLinkerLoad* LinkerLoad)
    {
#if THREADSAFE_UOBJECTS
        FScopeLock ObjectLoadersLock(&LoadersWithForcedExportsCritical);
#endif
        LoadersWithForcedExports.Add(LinkerLoad);
    }

#if !UE_BUILD_SHIPPING && !UE_BUILD_TEST
    FORCEINLINE void AddLiveLinker(FLinkerLoad* Linker)
    {
        FScopeLock LiveLinkersLock(&LiveLinkersCritical);
        LiveLinkers.Add(Linker);
    }

    FORCEINLINE void RemoveLiveLinker(FLinkerLoad* Linker)
    {
        FScopeLock LiveLinkersLock(&LiveLinkersCritical);
        LiveLinkers.Remove(Linker);
    }
#endif

    // FSelfRegisteringExec interface
    virtual bool Exec(class UWorld* InWorld, const TCHAR* Cmd, FOutputDevice& Ar) override;

    /** Empty the loaders */
    void ResetLoaders(UObject* InPkg);

    /** Empty the loaders from the specified set */
    void ResetLoaders(const TSet<FLinkerLoad*>& InLinkerLoadSet);

    /** Complete all loading (thumbnails/bulkdata) for the given Package */
    void EnsureLoadingComplete(UPackage* Package);

    /**
     * Dissociates all linker import and forced export object references. This currently needs to
     * happen as the referred objects might be destroyed at any time.
     */
    void DissociateImportsAndForcedExports();

    /** Deletes all linkers that finished loading */
    void DeleteLinkers();

    /** Adds a linker to deferred cleanup list */
    void RemoveLinker(FLinkerLoad* Linker);

private:
    /** Map of packages to their open linkers **/
    TSet<FLinkerLoad*> ObjectLoaders;
#if THREADSAFE_UOBJECTS
    FCriticalSection ObjectLoadersCritical;
#endif

    /** List of loaders that have new imports **/
    TSet<FLinkerLoad*> LoadersWithNewImports;
#if THREADSAFE_UOBJECTS
    FCriticalSection LoadersWithNewImportsCritical;
#endif
#if !UE_BUILD_SHIPPING && !UE_BUILD_TEST
    /** List of all the existing linker loaders **/
    FCriticalSection LiveLinkersCritical;
    TArray<FLinkerLoad*> LiveLinkers;
#endif

    /** List of loaders that have new imports **/
    TSet<FLinkerLoad*> LoadersWithForcedExports;
#if THREADSAFE_UOBJECTS
    FCriticalSection LoadersWithForcedExportsCritical;
#endif

    /** List of linkers to delete **/
    TSet<FLinkerLoad*> PendingCleanupList;
#if THREADSAFE_UOBJECTS
    FCriticalSection PendingCleanupListCritical;
#endif
    FThreadSafeBool bHasPendingCleanup;
};