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

#pragma once

#include "CoreMinimal.h"
#include "Serialization/ArchiveUObject.h"
#include "UObject/ObjectResource.h"
#include "UObject/PackageFileSummary.h"

struct FAssetData;
class FPackageDependencyData;

class FPackageReader: public FArchiveUObject
{
public:
    FPackageReader();
    ~FPackageReader();

    enum class EOpenPackageResult : uint8
    {
        Success,
        NoLoader,
        MalformedTag,
        VersionTooOld,
        VersionTooNew,
        CustomVersionMissing,
        CustomVersionInvalid,
    };

    /** Creates a loader for the filename */
    bool OpenPackageFile(const FString& PackageFilename, EOpenPackageResult* OutErrorCode = nullptr);
    bool OpenPackageFile(FArchive* Loader, EOpenPackageResult* OutErrorCode = nullptr);
    bool OpenPackageFile(EOpenPackageResult* OutErrorCode = nullptr);

    /** Reads information from the asset registry data table and converts it to FAssetData */
    bool ReadAssetRegistryData(TArray<FAssetData*>& AssetDataList);

    /** Attempts to get the class name of an object from the thumbnail cache for packages older than VER_UE4_ASSET_REGISTRY_TAGS */
    bool ReadAssetDataFromThumbnailCache(TArray<FAssetData*>& AssetDataList);

    /** Creates asset data reconstructing all the required data from cooked package info */
    bool ReadAssetRegistryDataIfCookedPackage(TArray<FAssetData*>& AssetDataList, TArray<FString>& CookedPackageNamesWithoutAssetData);

    /** Reads information used by the dependency graph */
    bool ReadDependencyData(FPackageDependencyData& OutDependencyData);

    /** Serializers for different package maps */
    bool SerializeNameMap();
    bool SerializeImportMap(TArray<FObjectImport>& OutImportMap);
    bool SerializeExportMap(TArray<FObjectExport>& OutExportMap);
    bool SerializeSoftPackageReferenceList(TArray<FName>& OutSoftPackageReferenceList);
    bool SerializeSearchableNamesMap(FPackageDependencyData& OutDependencyData);
    bool SerializeAssetRegistryDependencyData(FPackageDependencyData& DependencyData);

    /** Returns flags the asset package was saved with */
    uint32 GetPackageFlags() const;

    // Farchive implementation to redirect requests to the Loader
    virtual void Serialize(void* V, int64 Length) override;
    virtual bool Precache(int64 PrecacheOffset, int64 PrecacheSize) override;
    virtual void Seek(int64 InPos) override;
    virtual int64 Tell() override;
    virtual int64 TotalSize() override;
    virtual FArchive& operator<<(FName& Name) override;
    virtual FString GetArchiveName() const override
    {
        return PackageFilename;
    }

private:
    bool StartSerializeSection(int64 Offset);

    FString PackageFilename;
    /* Loader is the interface used to read the bytes from the package's repository. All interpretation of the bytes is done by serializing into *this, which is also an FArchive. */
    FArchive* Loader;
    FPackageFileSummary PackageFileSummary;
    TArray<FName> NameMap;
    int64 PackageFileSize;
    int64 AssetRegistryDependencyDataOffset;
};