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

#include "AutoReimport/ContentDirectoryMonitor.h"
#include "HAL/FileManager.h"
#include "Modules/ModuleManager.h"
#include "EditorReimportHandler.h"
#include "Settings/EditorLoadingSavingSettings.h"
#include "Factories/Factory.h"
#include "Factories/SceneImportFactory.h"
#include "EditorFramework/AssetImportData.h"
#include "Editor.h"

#include "AutoReimport/AutoReimportUtilities.h"

#include "AssetRegistryModule.h"
#include "PackageTools.h"
#include "ObjectTools.h"
#include "IAssetTools.h"
#include "AssetToolsModule.h"
#include "AutoReimport/ReimportFeedbackContext.h"
#include "AutoReimport/AssetSourceFilenameCache.h"

#define LOCTEXT_NAMESPACE "ContentDirectoryMonitor"

bool IsAssetDirty(UObject* Asset)
{
    UPackage* Package = Asset ? Asset->GetOutermost() : nullptr;
    return Package ? Package->IsDirty() : false;
}

/** Generate a config from the specified options, to pass to FFileCache on construction */
DirectoryWatcher::FFileCacheConfig GenerateFileCacheConfig(const FString& InPath, const DirectoryWatcher::FMatchRules& InMatchRules, const FString& InMountedContentPath)
{
    FString Directory         = FPaths::ConvertRelativePathToFull(InPath);

    const FString& HashString = InMountedContentPath.IsEmpty() ? Directory : InMountedContentPath;
    const uint32 CRC          = FCrc::MemCrc32(*HashString, HashString.Len() * sizeof(TCHAR));
    FString CacheFilename     = FPaths::ConvertRelativePathToFull(FPaths::ProjectIntermediateDir()) / TEXT("ReimportCache") / FString::Printf(TEXT("%u.bin"), CRC);

    DirectoryWatcher::FFileCacheConfig Config(Directory, MoveTemp(CacheFilename));
    Config.Rules = InMatchRules;
    // We always store paths inside content folders relative to the folder
    Config.PathType                   = DirectoryWatcher::EPathType::Relative;

    Config.bDetectChangesSinceLastRun = GetDefault<UEditorLoadingSavingSettings>()->bDetectChangesOnStartup;

    // It's safe to assume the asset registry is not re-loadable
    IAssetRegistry* Registry = &FModuleManager::LoadModuleChecked<FAssetRegistryModule>(AssetRegistryConstants::ModuleName).Get();
    Config.CustomChangeLogic = [Directory, Registry](const DirectoryWatcher::FImmutableString& InRelativePath, const DirectoryWatcher::FFileData& FileData) -> TOptional<bool>
    {
        int32 TotalNumReferencingAssets = 0;

        TArray<FAssetData> Assets       = FAssetSourceFilenameCache::Get().GetAssetsPertainingToFile(*Registry, Directory / InRelativePath.Get());

        if (Assets.Num() == 0)
        {
            return TOptional<bool>();
        }

        // We need to consider this as a changed file if the hash doesn't match any asset imported from that file
        for (FAssetData& Asset: Assets)
        {
            TOptional<FAssetImportInfo> Info = FAssetSourceFilenameCache::ExtractAssetImportInfo(Asset);

            // Check if the source file that this asset last imported was the same as the one we're going to reimport.
            // If it is, there's no reason to auto-reimport it
            if (Info.IsSet() && Info->SourceFiles.Num() == 1)
            {
                if (Info->SourceFiles[0].FileHash != FileData.FileHash)
                {
                    return true;
                }
            }
        }

        return TOptional<bool>();
    };

    // We only detect changes for when the file *contents* have changed (not its timestamp)
    Config
        .DetectMoves(true)
        .DetectChangesFor(DirectoryWatcher::FFileCacheConfig::Timestamp, false)
        .DetectChangesFor(DirectoryWatcher::FFileCacheConfig::FileHash, true);

    return Config;
}

FContentDirectoryMonitor::FContentDirectoryMonitor(const FString& InDirectory, const DirectoryWatcher::FMatchRules& InMatchRules, const FString& InMountedContentPath)
    : Cache(GenerateFileCacheConfig(InDirectory, InMatchRules, InMountedContentPath)), MountedContentPath(InMountedContentPath), LastSaveTime(0)
{
    Registry = &FModuleManager::LoadModuleChecked<FAssetRegistryModule>(AssetRegistryConstants::ModuleName).Get();
}

void FContentDirectoryMonitor::Destroy()
{
    Cache.Destroy();
}

void FContentDirectoryMonitor::IgnoreNewFile(const FString& Filename)
{
    Cache.IgnoreNewFile(Filename);
}

void FContentDirectoryMonitor::IgnoreFileModification(const FString& Filename)
{
    Cache.IgnoreFileModification(Filename);
}

void FContentDirectoryMonitor::IgnoreMovedFile(const FString& SrcFilename, const FString& DstFilename)
{
    Cache.IgnoreMovedFile(SrcFilename, DstFilename);
}

void FContentDirectoryMonitor::IgnoreDeletedFile(const FString& Filename)
{
    Cache.IgnoreDeletedFile(Filename);
}

void FContentDirectoryMonitor::Tick()
{
    Cache.Tick();

    // Immediately resolve any changes that we should not consider
    const FDateTime Threshold                                                   = FDateTime::UtcNow() - FTimespan::FromSeconds(GetDefault<UEditorLoadingSavingSettings>()->AutoReimportThreshold);

    TArray<DirectoryWatcher::FUpdateCacheTransaction> InsignificantTransactions = Cache.FilterOutstandingChanges([=](const DirectoryWatcher::FUpdateCacheTransaction& Transaction, const FDateTime& TimeOfChange)
                                                                                                                 {
                                                                                                                     return TimeOfChange <= Threshold && !ShouldConsiderChange(Transaction);
                                                                                                                 });

    for (DirectoryWatcher::FUpdateCacheTransaction& Transaction: InsignificantTransactions)
    {
        Cache.CompleteTransaction(MoveTemp(Transaction));
    }

    const double Now = FPlatformTime::Seconds();
    if (Now - LastSaveTime > ResaveIntervalS)
    {
        LastSaveTime = Now;
        Cache.WriteCache();
    }
}

bool FContentDirectoryMonitor::ShouldConsiderChange(const DirectoryWatcher::FUpdateCacheTransaction& Transaction) const
{
    // If the file was removed, and nothing references it, there's nothing else to do
    if (Transaction.Action == DirectoryWatcher::EFileAction::Removed && FAssetSourceFilenameCache::Get().GetAssetsPertainingToFile(*Registry, Cache.GetDirectory() / Transaction.Filename.Get()).Num() == 0)
    {
        return false;
    }
    return true;
}

int32 FContentDirectoryMonitor::GetNumUnprocessedChanges() const
{
    const FDateTime Threshold = FDateTime::UtcNow() - FTimespan::FromSeconds(GetDefault<UEditorLoadingSavingSettings>()->AutoReimportThreshold);

    int32 Total               = 0;

    // Get all the changes that have happend beyond our import threshold
    Cache.IterateOutstandingChanges([=, &Total](const DirectoryWatcher::FUpdateCacheTransaction& Transaction, const FDateTime& TimeOfChange)
                                    {
                                        if (TimeOfChange <= Threshold && ShouldConsiderChange(Transaction))
                                        {
                                            ++Total;
                                        }
                                        return true;
                                    });

    return Total;
}

void FContentDirectoryMonitor::IterateUnprocessedChanges(TFunctionRef<bool(const DirectoryWatcher::FUpdateCacheTransaction&, const FDateTime&)> InIter) const
{
    Cache.IterateOutstandingChanges(InIter);
}

int32 FContentDirectoryMonitor::StartProcessing()
{
    // We only process things that haven't changed for a given threshold
    auto& FileManager         = IFileManager::Get();
    const FDateTime Threshold = FDateTime::UtcNow() - FTimespan::FromSeconds(GetDefault<UEditorLoadingSavingSettings>()->AutoReimportThreshold);

    // Get all the changes that have happend beyond our import threshold
    auto OutstandingChanges = Cache.FilterOutstandingChanges([=](const DirectoryWatcher::FUpdateCacheTransaction& Transaction, const FDateTime& TimeOfChange)
                                                             {
                                                                 return TimeOfChange <= Threshold && ShouldConsiderChange(Transaction);
                                                             });

    if (OutstandingChanges.Num() == 0)
    {
        return 0;
    }

    const auto* Settings = GetDefault<UEditorLoadingSavingSettings>();
    for (auto& Transaction: OutstandingChanges)
    {
        switch (Transaction.Action)
        {
            case DirectoryWatcher::EFileAction::Added:
                if (Settings->bAutoCreateAssets && !MountedContentPath.IsEmpty())
                {
                    AddedFiles.Emplace(MoveTemp(Transaction));
                }
                else
                {
                    Cache.CompleteTransaction(MoveTemp(Transaction));
                }
                break;

            case DirectoryWatcher::EFileAction::Moved:
            case DirectoryWatcher::EFileAction::Modified:
                ModifiedFiles.Emplace(MoveTemp(Transaction));
                break;

            case DirectoryWatcher::EFileAction::Removed:
                if (Settings->bAutoDeleteAssets && !MountedContentPath.IsEmpty())
                {
                    DeletedFiles.Emplace(MoveTemp(Transaction));
                }
                else
                {
                    Cache.CompleteTransaction(MoveTemp(Transaction));
                }
                break;
        }
    }

    return AddedFiles.Num() + ModifiedFiles.Num() + DeletedFiles.Num();
}

UObject* AttemptImport(UClass* InFactoryType, UPackage* Package, FName InName, bool& bCancelled, const FString& FullFilename)
{
    UObject* Asset = nullptr;

    if (UFactory* Factory = NewObject<UFactory>(GetTransientPackage(), InFactoryType))
    {
        Factory->AddToRoot();
        if (Factory->ConfigureProperties())
        {
            if (auto* SupportedClass = Factory->ResolveSupportedClass())
            {
                Asset = Factory->ImportObject(SupportedClass, Package, InName, RF_Public | RF_Standalone, FullFilename, nullptr, bCancelled);
            }
        }
        Factory->RemoveFromRoot();
    }

    return Asset;
}

void FContentDirectoryMonitor::ProcessAdditions(const DirectoryWatcher::FTimeLimit& TimeLimit, TArray<UPackage*>& OutPackagesToSave, const TMap<FString, TArray<UFactory*>>& InFactoriesByExtension, FReimportFeedbackContext& Context)
{
    bool bCancelled = false;
    for (int32 Index = 0; Index < AddedFiles.Num(); ++Index)
    {
        auto& Addition = AddedFiles[Index];

        if (bCancelled)
        {
            // Just update the cache immediately if the user cancelled
            Cache.CompleteTransaction(MoveTemp(Addition));
            Context.MainTask->EnterProgressFrame();
            continue;
        }

        const FString FullFilename = Cache.GetDirectory() + Addition.Filename.Get();

        FString NewAssetName       = ObjectTools::SanitizeObjectName(FPaths::GetBaseFilename(FullFilename));
        FString PackagePath        = UPackageTools::SanitizePackageName(MountedContentPath / FPaths::GetPath(Addition.Filename.Get()) / NewAssetName);

        // Don't create assets for new files if assets already exist for the filename
        auto ExistingReferences = Utils::FindAssetsPertainingToFile(*Registry, FullFilename);
        if (ExistingReferences.Num() != 0)
        {
            // Treat this as a modified file that will attempt to reimport it (if applicable). We don't update the progress for this item until it is processed by ProcessModifications
            ModifiedFiles.Add(MoveTemp(Addition));
            continue;
        }

        // Move the progress on now that we know we're going to process the file
        Context.MainTask->EnterProgressFrame();

        if (FPackageName::DoesPackageExist(*PackagePath))
        {
            // Package already exists, so try and import over the top of it, if it doesn't already have a source file path
            TArray<FAssetData> Assets;
            if (Registry->GetAssetsByPackageName(*PackagePath, Assets) && Assets.Num() == 1)
            {
                if (UObject* ExistingAsset = Assets[0].GetAsset())
                {
                    // We're only eligible for reimport if the existing asset doesn't reference a source file already
                    const bool bEligibleForReimport = !Utils::ExtractSourceFilePaths(ExistingAsset).ContainsByPredicate([&](const FString& In)
                                                                                                                        {
                                                                                                                            return !In.IsEmpty() && In == FullFilename;
                                                                                                                        });

                    if (bEligibleForReimport)
                    {
                        ReimportAssetWithNewSource(ExistingAsset, FullFilename, OutPackagesToSave, Context);
                    }
                }
            }
        }
        else
        {
            UPackage* NewPackage = CreatePackage(*PackagePath);
            if (!ensure(NewPackage))
            {
                Context.AddMessage(EMessageSeverity::Error, FText::Format(LOCTEXT("Error_FailedToCreateAsset", "Failed to create new asset ({0}) for file ({1})."), FText::FromString(NewAssetName), FText::FromString(FullFilename)));
            }
            else
            {
                Context.AddMessage(EMessageSeverity::Info, FText::Format(LOCTEXT("Info_CreatingNewAsset", "Importing new asset {0}."), FText::FromString(PackagePath)));

                // Make sure the destination package is loaded
                NewPackage->FullyLoad();

                UObject* NewAsset = nullptr;

                // Find a relevant factory for this file
                // @todo import: gmp: show dialog in case of multiple matching factories
                const FString Ext = FPaths::GetExtension(Addition.Filename.Get(), false);
                auto* Factories   = InFactoriesByExtension.Find(Ext);
                if (Factories && Factories->Num() != 0)
                {
                    // Make sure all the scene factory are put at the end of the array. We give priority to asset factory before scene factory
                    TArray<UFactory*> SortFactories;
                    TArray<UFactory*> SceneFactories;
                    for (UFactory* Factory: *Factories)
                    {
                        if (Factory->IsA(USceneImportFactory::StaticClass()))
                        {
                            SceneFactories.Add(Factory);
                        }
                        else
                        {
                            SortFactories.Add(Factory);
                        }
                    }
                    if (SceneFactories.Num() > 0)
                    {
                        SortFactories.Append(SceneFactories);
                    }
                    // Prefer a factory if it explicitly can import. UFactory::FactoryCanImport returns false by default, even if the factory supports the extension, so we can't use it directly.
                    UFactory* const* PreferredFactory = SortFactories.FindByPredicate([&](UFactory* F)
                                                                                      {
                                                                                          return F->FactoryCanImport(FullFilename);
                                                                                      });
                    if (PreferredFactory)
                    {
                        NewAsset = AttemptImport((*PreferredFactory)->GetClass(), NewPackage, *NewAssetName, bCancelled, FullFilename);
                    }
                    // If there was no preferred factory, just try them all until one succeeds
                    else
                        for (UFactory* Factory: SortFactories)
                        {
                            NewAsset = AttemptImport(Factory->GetClass(), NewPackage, *NewAssetName, bCancelled, FullFilename);

                            if (bCancelled || NewAsset)
                            {
                                break;
                            }
                        }
                }

                // Verify if the package still exists after the import (it may have been cleaned up by the factory if the import was canceled).
                NewPackage = FindObject<UPackage>(nullptr, *PackagePath);
                if (NewPackage)
                {
                    // If we didn't create an asset and the package was not cleaned up, unload and delete the package we just created
                    if (!NewAsset)
                    {
                        TArray<UPackage*> Packages;
                        Packages.Add(NewPackage);

                        TGuardValue<bool> SuppressSlowTaskMessages(Context.bSuppressSlowTaskMessages, true);

                        FText ErrorMessage;
                        if (!UPackageTools::UnloadPackages(Packages, ErrorMessage))
                        {
                            Context.AddMessage(EMessageSeverity::Error, FText::Format(LOCTEXT("Error_UnloadingPackage", "There was an error unloading a package: {0}."), ErrorMessage));
                        }

                        // Just add the message to the message log rather than add it to the UI
                        // Factories may opt not to import the file, so we let them report errors if they do
                        Context.GetMessageLog().Message(EMessageSeverity::Info, FText::Format(LOCTEXT("Info_FailedToImportAsset", "Failed to import file {0}."), FText::FromString(FullFilename)));
                    }
                    else if (!bCancelled)
                    {
                        FAssetRegistryModule::AssetCreated(NewAsset);
                        GEditor->BroadcastObjectReimported(NewAsset);

                        OutPackagesToSave.Add(NewPackage);
                    }
                }

                // Refresh the supported class.  Some factories (e.g. FBX) only resolve their type after reading the file
                // ImportAssetType = Factory->ResolveSupportedClass();
                // @todo: analytics?
            }
        }

        // Let the cache know that we've dealt with this change (it will be imported immediately)
        Cache.CompleteTransaction(MoveTemp(Addition));

        if (!bCancelled && TimeLimit.Exceeded())
        {
            // Remove the ones we've processed
            AddedFiles.RemoveAt(0, Index + 1);
            return;
        }
    }

    AddedFiles.Empty();
}

void FContentDirectoryMonitor::ProcessModifications(const DirectoryWatcher::FTimeLimit& TimeLimit, TArray<UPackage*>& OutPackagesToSave, FReimportFeedbackContext& Context)
{
    auto* ReimportManager = FReimportManager::Instance();

    for (int32 Index = 0; Index < ModifiedFiles.Num(); ++Index)
    {
        Context.MainTask->EnterProgressFrame();

        auto& Change               = ModifiedFiles[Index];
        const FString FullFilename = Cache.GetDirectory() + Change.Filename.Get();

        // Move the asset before reimporting it. We always reimport moved assets to ensure that their import path is up to date
        if (Change.Action == DirectoryWatcher::EFileAction::Moved)
        {
            const FString OldFilename = Cache.GetDirectory() + Change.MovedFromFilename.Get();
            const auto Assets         = Utils::FindAssetsPertainingToFile(*Registry, OldFilename);

            if (Assets.Num() == 1)
            {
                UObject* Asset = Assets[0].GetAsset();
                if (Asset && Utils::ExtractSourceFilePaths(Asset).Num() == 1)
                {
                    UPackage* ExistingPackage  = Asset->GetOutermost();

                    const bool bAssetWasDirty  = IsAssetDirty(Asset);

                    const FString NewAssetName = ObjectTools::SanitizeObjectName(FPaths::GetBaseFilename(Change.Filename.Get()));
                    const FString PackagePath  = UPackageTools::SanitizePackageName(MountedContentPath / FPaths::GetPath(Change.Filename.Get()));
                    const FString FullDestPath = PackagePath / NewAssetName;

                    if (ExistingPackage && ExistingPackage->FileName.ToString() == FullDestPath)
                    {
                        // No need to process this asset - it's already been moved to the right location
                        Cache.CompleteTransaction(MoveTemp(Change));
                        continue;
                    }

                    const FText SrcPathText = FText::FromString(Assets[0].PackageName.ToString()),
                                DstPathText = FText::FromString(FullDestPath);

                    if (FPackageName::DoesPackageExist(*FullDestPath))
                    {
                        Context.AddMessage(EMessageSeverity::Warning, FText::Format(LOCTEXT("MoveWarning_ExistingAsset", "Can't move {0} to {1} - one already exists."), SrcPathText, DstPathText));
                    }
                    else
                    {
                        TArray<FAssetRenameData> RenameData;
                        RenameData.Emplace(Asset, PackagePath, NewAssetName);

                        Context.AddMessage(EMessageSeverity::Info, FText::Format(LOCTEXT("Success_MovedAsset", "Moving asset {0} to {1}."), SrcPathText, DstPathText));

                        FModuleManager::LoadModuleChecked<FAssetToolsModule>("AssetTools").Get().RenameAssetsWithDialog(RenameData);

                        TArray<FString> Filenames;
                        Filenames.Add(FullFilename);

                        // Update the reimport file names
                        FReimportManager::Instance()->UpdateReimportPaths(Asset, Filenames);
                        Asset->MarkPackageDirty();

                        if (!bAssetWasDirty)
                        {
                            if (UPackage* NewPackage = Asset->GetOutermost())
                            {
                                OutPackagesToSave.Add(NewPackage);
                            }
                        }
                    }
                }
            }
        }
        else
        {
            // Modifications or additions are treated the same by this point
            for (const auto& AssetData: Utils::FindAssetsPertainingToFile(*Registry, FullFilename))
            {
                if (UObject* Asset = AssetData.GetAsset())
                {
                    ReimportAsset(Asset, FullFilename, OutPackagesToSave, Context);
                }
            }
        }

        // Let the cache know that we've dealt with this change
        Cache.CompleteTransaction(MoveTemp(Change));

        if (TimeLimit.Exceeded())
        {
            ModifiedFiles.RemoveAt(0, Index + 1);
            return;
        }
    }

    ModifiedFiles.Empty();
}

void FContentDirectoryMonitor::ReimportAssetWithNewSource(UObject* InAsset, const FString& FullFilename, TArray<UPackage*>& OutPackagesToSave, FReimportFeedbackContext& Context)
{
    TArray<FString> Filenames;
    Filenames.Add(FullFilename);
    FReimportManager::Instance()->UpdateReimportPaths(InAsset, Filenames);

    ReimportAsset(InAsset, FullFilename, OutPackagesToSave, Context);
}

void FContentDirectoryMonitor::ReimportAsset(UObject* Asset, const FString& FullFilename, TArray<UPackage*>& OutPackagesToSave, FReimportFeedbackContext& Context)
{
    const bool bAssetWasDirty = IsAssetDirty(Asset);
    if (!FReimportManager::Instance()->Reimport(Asset, false /* Ask for new file */, false /* Show notification */))
    {
        Context.AddMessage(EMessageSeverity::Error, FText::Format(LOCTEXT("Error_FailedToReimportAsset", "Failed to reimport asset {0}."), FText::FromString(Asset->GetName())));
    }
    else
    {
        Context.AddMessage(EMessageSeverity::Info, FText::Format(LOCTEXT("Success_CreatedNewAsset", "Reimported asset {0} from {1}."), FText::FromString(Asset->GetName()), FText::FromString(FullFilename)));
        if (!bAssetWasDirty)
        {
            if (UPackage* NewPackage = Asset->GetOutermost())
            {
                OutPackagesToSave.Add(NewPackage);
            }
        }
    }
}

void FContentDirectoryMonitor::ExtractAssetsToDelete(TArray<FAssetData>& OutAssetsToDelete)
{
    for (auto& Deletion: DeletedFiles)
    {
        for (const auto& AssetData: Utils::FindAssetsPertainingToFile(*Registry, Cache.GetDirectory() + Deletion.Filename.Get()))
        {
            OutAssetsToDelete.Add(AssetData);
        }

        // Let the cache know that we've dealt with this change (it will be imported in due course)
        Cache.CompleteTransaction(MoveTemp(Deletion));
    }

    DeletedFiles.Empty();
}

void FContentDirectoryMonitor::Abort()
{
    for (auto& Add: AddedFiles)
    {
        Cache.CompleteTransaction(MoveTemp(Add));
    }
    AddedFiles.Empty();

    for (auto& Mod: ModifiedFiles)
    {
        Cache.CompleteTransaction(MoveTemp(Mod));
    }
    ModifiedFiles.Empty();

    for (auto& Del: DeletedFiles)
    {
        Cache.CompleteTransaction(MoveTemp(Del));
    }
    DeletedFiles.Empty();

    for (auto& Change: Cache.GetOutstandingChanges())
    {
        Cache.CompleteTransaction(MoveTemp(Change));
    }
}

#undef LOCTEXT_NAMESPACE