SnapshotSubsystem.h

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// Fill out your copyright notice in the Description page of Project Settings.
 
#pragma once
 
#include "CK_UE.h"
#include "Command/CommandBase.h"
#include "Engine/GameInstance.h"
#include "Engine/World.h"
#include "Subsystems/GameInstanceSubsystem.h"
#include "Templates/UnrealTypeTraits.h"
#include "SnapshotSubsystem.generated.h"
 
 
UCLASS()
class CK_UE_API USnapshotSubsystem : public UGameInstanceSubsystem
{
    GENERATED_BODY()
 
public:
    USnapshotSubsystem();
 
    virtual void Deinitialize() override;
 
public:
    bool ProcessCommand(UCommandBase* Command);
    void RecordCommand(UCommandBase* Command);
    void MarkRollbackPoint(FName RollbackPointID);
    bool RollbackTo(FName RollbackPointID);
    void ResetCommands();
 
#if WITH_EDITOR
    void PrintCommandStack();
#endif
 
public:
    template <typename TCommandType, typename TInitializeCommand>
    TCommandType* ProcessNewCommand(TInitializeCommand InitializeCommand);
 
    template <typename TCommandType, typename TInitializeCommand>
    static TCommandType* ProcessNewCommand(UObject* WorldContextObject, TInitializeCommand InitializeCommand);
 
public:
    FORCEINLINE bool IsRollingBack() const
    {
        return RollbackDepth > 0;
    }
 
private:
    UPROPERTY(Transient)
    TArray<TObjectPtr<UCommandBase>> CommandStack;
 
private:
    TMap<FName, int32> RollbackPointByID;
    int32 RollbackDepth = 0;
};
 
 
template <typename TCommandType, typename TInitializeCommand>
TCommandType* USnapshotSubsystem::ProcessNewCommand(TInitializeCommand InitializeCommand)
{
    static_assert(TIsDerivedFrom<TCommandType, UCommandBase>::Value, "TCommandType must derive from UCommandBase.");
 
    if (IsRollingBack())
    {
        return nullptr;
    }
 
    TCommandType* Command = NewObject<TCommandType>(this);
 
    if (Command == nullptr)
    {
        return nullptr;
    }
 
    InitializeCommand(Command);
 
    if (ProcessCommand(Command) == false)
    {
        return nullptr;
    }
    else
    {
        return Command;
    }
}
 
 
template <typename TCommandType, typename TInitializeCommand>
TCommandType* USnapshotSubsystem::ProcessNewCommand(UObject* WorldContextObject, TInitializeCommand InitializeCommand)
{
    static_assert(TIsDerivedFrom<TCommandType, UCommandBase>::Value, "TCommandType must derive from UCommandBase.");
    
    if (WorldContextObject == nullptr)
    {
        return nullptr;
    }
 
    UGameInstance* GameInstance = Cast<UGameInstance>(WorldContextObject);
 
    if (GameInstance == nullptr)
    {
        UWorld* World = WorldContextObject->GetWorld();
        GameInstance = World ? World->GetGameInstance() : nullptr;
        check(GameInstance);
    }
 
    USnapshotSubsystem* SnapshotSubsystem = GameInstance->GetSubsystem<USnapshotSubsystem>();
 
    if (SnapshotSubsystem == nullptr)
    {
        LOG_ERROR(LogCK, "%s를 가져올 수 없습니다. ", NAMEOF(USnapshotSubsystem));
        return nullptr;
    }
    else
    {
        return SnapshotSubsystem->ProcessNewCommand<TCommandType>(InitializeCommand);
    }
}