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

#pragma once

#include "CoreMinimal.h"

#include "Algo/Find.h"
#include "Containers/StringView.h"
#include "IAssetRegistry.h"
#include "Misc/PackageName.h"

/* This class has marked all of its functions const and its variables mutable so that CookOnTheFlyServer can use its functions from const functions */
struct FPackageNameCache
{
    bool HasCacheForPackageName(const FName& PackageName) const;

    FString GetCachedStandardFileNameString(const UPackage* Package) const;

    FName GetCachedStandardFileName(const FName& PackageName) const;
    FName GetCachedStandardFileName(const UPackage* Package) const;

    const FName* GetCachedPackageNameFromStandardFileName(const FName& NormalizedFileName, bool bExactMatchRequired = true, FName* FoundFileName = nullptr) const;

    void ClearPackageFileNameCache(IAssetRegistry* InAssetRegistry) const;
    bool ClearPackageFileNameCacheForPackage(const UPackage* Package) const;
    bool ClearPackageFileNameCacheForPackage(const FName& PackageName) const;

    void AppendCacheResults(TArray<TTuple<FName, FString>>&& PackageToStandardFileNames) const;

    bool CalculateCacheData(FName PackageName, FString& OutStandardFilename, FName& OutStandardFileFName) const;

    bool ContainsPackageName(FName PackageName) const;

    void SetAssetRegistry(IAssetRegistry* InAssetRegistry) const;
    IAssetRegistry* GetAssetRegistry() const;

    /** Normalize the given FileName for use in looking up the cached data associated with the FileName. This normalization is equivalent to FPaths::MakeStandardFilename */
    static FName GetStandardFileName(const FName& FileName);
    static FName GetStandardFileName(const FStringView& FileName);

private:
    struct FCachedPackageFilename
    {
        FCachedPackageFilename(FString&& InStandardFilename, FName InStandardFileFName)
            : StandardFileNameString(MoveTemp(InStandardFilename)), StandardFileName(InStandardFileFName)
        {
        }

        FCachedPackageFilename(const FCachedPackageFilename& In) = default;

        FCachedPackageFilename(FCachedPackageFilename&& In)
            : StandardFileNameString(MoveTemp(In.StandardFileNameString)), StandardFileName(In.StandardFileName)
        {
        }

        FString StandardFileNameString;
        FName StandardFileName;
    };

    bool DoesPackageExist(const FName& PackageName, FString* OutFilename) const;
    const FCachedPackageFilename& Cache(const FName& PackageName) const;

    mutable IAssetRegistry* AssetRegistry = nullptr;

    mutable TMap<FName, FCachedPackageFilename> PackageFilenameCache;  // filename cache (only process the string operations once)
    mutable TMap<FName, FName> PackageFilenameToPackageFNameCache;
};

inline FName FPackageNameCache::GetCachedStandardFileName(const FName& PackageName) const
{
    return Cache(PackageName).StandardFileName;
}

inline bool FPackageNameCache::HasCacheForPackageName(const FName& PackageName) const
{
    return PackageFilenameCache.Find(PackageName) != nullptr;
}

inline FString FPackageNameCache::GetCachedStandardFileNameString(const UPackage* Package) const
{
    // check( Package->GetName() == Package->GetFName().ToString() );
    return Cache(Package->GetFName()).StandardFileNameString;
}

inline FName FPackageNameCache::GetCachedStandardFileName(const UPackage* Package) const
{
    // check( Package->GetName() == Package->GetFName().ToString() );
    return Cache(Package->GetFName()).StandardFileName;
}

inline bool FPackageNameCache::ClearPackageFileNameCacheForPackage(const UPackage* Package) const
{
    return ClearPackageFileNameCacheForPackage(Package->GetFName());
}

inline void FPackageNameCache::AppendCacheResults(TArray<TTuple<FName, FString>>&& PackageToStandardFileNames) const
{
    check(IsInGameThread());
    for (auto& Entry: PackageToStandardFileNames)
    {
        FName PackageName         = Entry.Get<0>();
        FString& StandardFilename = Entry.Get<1>();

        FName StandardFileFName(*StandardFilename);
        PackageFilenameToPackageFNameCache.Add(StandardFileFName, PackageName);
        PackageFilenameCache.Emplace(PackageName, FCachedPackageFilename(MoveTemp(StandardFilename), StandardFileFName));
    }
}

inline bool FPackageNameCache::ClearPackageFileNameCacheForPackage(const FName& PackageName) const
{
    check(IsInGameThread());

    return PackageFilenameCache.Remove(PackageName) >= 1;
}

inline bool FPackageNameCache::DoesPackageExist(const FName& PackageName, FString* OutFilename) const
{
    FString PackageNameStr = PackageName.ToString();

    // "/Extra/" packages are editor-generated in-memory packages which don't have a corresponding
    // asset file (yet). However, we still want to cook these packages out, producing cooked
    // asset files for packaged projects.
    if (FPackageName::IsExtraPackage(PackageNameStr))
    {
        if (UPackage* ExtraPackage = FindPackage(/*Outer =*/nullptr, *PackageNameStr))
        {
            if (OutFilename)
            {
                *OutFilename = FPackageName::LongPackageNameToFilename(PackageNameStr, FPackageName::GetAssetPackageExtension());
            }
            return true;
        }
        // else, the cooker could be responding to a NotifyUObjectCreated() event, and the object hasn't
        // been fully constructed yet (missing from the FindObject() list) -- in this case, we've found
        // that the linker loader is creating a dummy object to fill a referencing import slot, not loading
        // the proper object (which means we want to ignore it).
    }

    if (!AssetRegistry)
    {
        return FPackageName::DoesPackageExist(PackageNameStr, NULL, OutFilename, false);
    }

    TArray<FAssetData> Assets;
    AssetRegistry->GetAssetsByPackageName(PackageName, Assets, /*bIncludeOnlyDiskAssets =*/true);

    if (Assets.Num() <= 0)
    {
        return false;
    }

    if (OutFilename)
    {
        FName ClassRedirector    = UObjectRedirector::StaticClass()->GetFName();
        bool bContainsMap        = false;
        bool bContainsRedirector = false;
        for (const FAssetData& Asset: Assets)
        {
            bContainsMap        = bContainsMap | ((Asset.PackageFlags & PKG_ContainsMap) != 0);
            bContainsRedirector = bContainsRedirector | (Asset.AssetClass == ClassRedirector);
        }
        if (!bContainsMap && bContainsRedirector)
        {
            // presence of map -> .umap
            // But we can only assume lack of map -> .uasset if we know the type of every object in the package.
            // If we don't, because there was a redirector, we have to check the package on disk
            // TODO: Have the AssetRegistry store the extension of the package so that we don't have to look it up
            // Guessing the extension based on map vs non-map also does not support text assets and maps which have a different extension
            return FPackageName::DoesPackageExist(PackageNameStr, NULL, OutFilename, false);
        }
        const FString& PackageExtension = bContainsMap ? FPackageName::GetMapPackageExtension() : FPackageName::GetAssetPackageExtension();
        *OutFilename                    = FPackageName::LongPackageNameToFilename(PackageNameStr, PackageExtension);
    }

    return true;
}

inline bool FPackageNameCache::CalculateCacheData(FName PackageName, FString& OutStandardFilename, FName& OutStandardFileFName) const
{
    FString FilenameOnDisk;
    if (DoesPackageExist(PackageName, &FilenameOnDisk))
    {
        OutStandardFilename = FPaths::ConvertRelativePathToFull(FilenameOnDisk);

        FPaths::MakeStandardFilename(OutStandardFilename);
        OutStandardFileFName = FName(*OutStandardFilename);
        return true;
    }
    return false;
}

inline bool FPackageNameCache::ContainsPackageName(FName PackageName) const
{
    return PackageFilenameCache.Contains(PackageName);
}
inline IAssetRegistry* FPackageNameCache::GetAssetRegistry() const
{
    return AssetRegistry;
}

inline const FPackageNameCache::FCachedPackageFilename& FPackageNameCache::Cache(const FName& PackageName) const
{
    check(IsInGameThread());

    FCachedPackageFilename* Cached = PackageFilenameCache.Find(PackageName);

    if (Cached != NULL)
    {
        return *Cached;
    }

    // cache all the things, like it's your birthday!

    FString FileNameString;
    FName FileName = NAME_None;

    CalculateCacheData(PackageName, FileNameString, FileName);

    PackageFilenameToPackageFNameCache.Add(FileName, PackageName);

    return PackageFilenameCache.Emplace(PackageName, FCachedPackageFilename(MoveTemp(FileNameString), FileName));
}

inline const FName* FPackageNameCache::GetCachedPackageNameFromStandardFileName(const FName& NormalizedFileName, bool bExactMatchRequired, FName* FoundFileName) const
{
    check(IsInGameThread());
    const FName* Result = PackageFilenameToPackageFNameCache.Find(NormalizedFileName);
    if (Result)
    {
        if (FoundFileName)
        {
            *FoundFileName = NormalizedFileName;
        }
        return Result;
    }

    FName PackageName                = NormalizedFileName;
    FString PotentialLongPackageName = NormalizedFileName.ToString();
    if (!FPackageName::IsValidLongPackageName(PotentialLongPackageName))
    {
        if (!FPackageName::TryConvertFilenameToLongPackageName(PotentialLongPackageName, PotentialLongPackageName))
        {
            return nullptr;
        }
        PackageName = FName(*PotentialLongPackageName);
    }

    const FCachedPackageFilename& CachedFilename = Cache(PackageName);

    if (bExactMatchRequired)
    {
        if (FoundFileName)
        {
            *FoundFileName = NormalizedFileName;
        }
        return PackageFilenameToPackageFNameCache.Find(NormalizedFileName);
    }
    else
    {
        check(FoundFileName != nullptr);
        *FoundFileName = CachedFilename.StandardFileName;
        return PackageFilenameToPackageFNameCache.Find(CachedFilename.StandardFileName);
    }
}

inline void FPackageNameCache::ClearPackageFileNameCache(IAssetRegistry* InAssetRegistry) const
{
    check(IsInGameThread());
    PackageFilenameCache.Empty();
    PackageFilenameToPackageFNameCache.Empty();
    AssetRegistry = InAssetRegistry;
}

inline void FPackageNameCache::SetAssetRegistry(IAssetRegistry* InAssetRegistry) const
{
    AssetRegistry = InAssetRegistry;
}

inline FName FPackageNameCache::GetStandardFileName(const FName& FileName)
{
    return GetStandardFileName(FileName.ToString());
}

inline FName FPackageNameCache::GetStandardFileName(const FStringView& InFileName)
{
    FString FileName(InFileName);
    FPaths::MakeStandardFilename(FileName);
    return FName(FileName);
}