/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2019 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * In addition, as a special exception, the copyright holders of this
 * program give permission to link the code of its release with the
 * OpenSSL project's "OpenSSL" library (or with modified versions of it
 * that use the same license as the "OpenSSL" library), and distribute
 * the linked executables. You must obey the GNU General Public License
 * in all respects for all of the code used other than "OpenSSL". If you
 * modify file(s) with this exception, you may extend this exception to
 * your version of the file(s), but you are not obligated to do so. If
 * you do not wish to do so, delete this exception statement from your
 * version. If you delete this exception statement from all source files
 * in the program, then also delete it here.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "../PrecompiledHeadersServer.h"
#include "ArchiveJob.h"

#include "../../Core/Compression/HierarchicalZipWriter.h"
#include "../../Core/DicomParsing/DicomDirWriter.h"
#include "../../Core/Logging.h"
#include "../../Core/OrthancException.h"

#include <stdio.h>

#if defined(_MSC_VER)
#define snprintf _snprintf
#endif

static const uint64_t MEGA_BYTES = 1024 * 1024;
static const uint64_t GIGA_BYTES = 1024 * 1024 * 1024;

static const char* const MEDIA_IMAGES_FOLDER = "IMAGES"; 
static const char* const KEY_DESCRIPTION = "Description";
static const char* const KEY_INSTANCES_COUNT = "InstancesCount";
static const char* const KEY_UNCOMPRESSED_SIZE_MB = "UncompressedSizeMB";


namespace Orthanc
{
  static bool IsZip64Required(uint64_t uncompressedSize,
                              unsigned int countInstances)
  {
    static const uint64_t      SAFETY_MARGIN = 64 * MEGA_BYTES;  // Should be large enough to hold DICOMDIR
    static const unsigned int  FILES_MARGIN = 10;

    /**
     * Determine whether ZIP64 is required. Original ZIP format can
     * store up to 2GB of data (some implementation supporting up to
     * 4GB of data), and up to 65535 files.
     * https://en.wikipedia.org/wiki/Zip_(file_format)#ZIP64
     **/

    const bool isZip64 = (uncompressedSize >= 2 * GIGA_BYTES - SAFETY_MARGIN ||
                          countInstances >= 65535 - FILES_MARGIN);

    LOG(INFO) << "Creating a ZIP file with " << countInstances << " files of size "
              << (uncompressedSize / MEGA_BYTES) << "MB using the "
              << (isZip64 ? "ZIP64" : "ZIP32") << " file format";

    return isZip64;
  }


  class ArchiveJob::ResourceIdentifiers : public boost::noncopyable
  {
  private:
    ResourceType   level_;
    std::string    patient_;
    std::string    study_;
    std::string    series_;
    std::string    instance_;

    static void GoToParent(ServerIndex& index,
                           std::string& current)
    {
      std::string tmp;

      if (index.LookupParent(tmp, current))
      {
        current = tmp;
      }
      else
      {
        throw OrthancException(ErrorCode_UnknownResource);
      }
    }


  public:
    ResourceIdentifiers(ServerIndex& index,
                        const std::string& publicId)
    {
      if (!index.LookupResourceType(level_, publicId))
      {
        throw OrthancException(ErrorCode_UnknownResource);
      }

      std::string current = publicId;;
      switch (level_)  // Do not add "break" below!
      {
        case ResourceType_Instance:
          instance_ = current;
          GoToParent(index, current);
            
        case ResourceType_Series:
          series_ = current;
          GoToParent(index, current);

        case ResourceType_Study:
          study_ = current;
          GoToParent(index, current);

        case ResourceType_Patient:
          patient_ = current;
          break;

        default:
          throw OrthancException(ErrorCode_InternalError);
      }
    }

    ResourceType GetLevel() const
    {
      return level_;
    }

    const std::string& GetIdentifier(ResourceType level) const
    {
      // Some sanity check to ensure enumerations are not altered
      assert(ResourceType_Patient < ResourceType_Study);
      assert(ResourceType_Study < ResourceType_Series);
      assert(ResourceType_Series < ResourceType_Instance);

      if (level > level_)
      {
        throw OrthancException(ErrorCode_InternalError);
      }

      switch (level)
      {
        case ResourceType_Patient:
          return patient_;

        case ResourceType_Study:
          return study_;

        case ResourceType_Series:
          return series_;

        case ResourceType_Instance:
          return instance_;

        default:
          throw OrthancException(ErrorCode_InternalError);
      }
    }
  };


  class ArchiveJob::IArchiveVisitor : public boost::noncopyable
  {
  public:
    virtual ~IArchiveVisitor()
    {
    }

    virtual void Open(ResourceType level,
                      const std::string& publicId) = 0;

    virtual void Close() = 0;

    virtual void AddInstance(const std::string& instanceId,
                             const FileInfo& dicom) = 0;
  };


  class ArchiveJob::ArchiveIndex : public boost::noncopyable
  {
  private:
    struct Instance
    {
      std::string  id_;
      FileInfo     dicom_;

      Instance(const std::string& id,
               const FileInfo& dicom) : 
        id_(id), dicom_(dicom)
      {
      }
    };

    // A "NULL" value for ArchiveIndex indicates a non-expanded node
    typedef std::map<std::string, ArchiveIndex*>   Resources;

    ResourceType         level_;
    Resources            resources_;   // Only at patient/study/series level
    std::list<Instance>  instances_;   // Only at instance level


    void AddResourceToExpand(ServerIndex& index,
                             const std::string& id)
    {
      if (level_ == ResourceType_Instance)
      {
        FileInfo tmp;
        if (index.LookupAttachment(tmp, id, FileContentType_Dicom))
        {
          instances_.push_back(Instance(id, tmp));
        }
      }
      else
      {
        resources_[id] = NULL;
      }
    }


  public:
    ArchiveIndex(ResourceType level) :
      level_(level)
    {
    }

    ~ArchiveIndex()
    {
      for (Resources::iterator it = resources_.begin();
           it != resources_.end(); ++it)
      {
        delete it->second;
      }
    }


    void Add(ServerIndex& index,
             const ResourceIdentifiers& resource)
    {
      const std::string& id = resource.GetIdentifier(level_);
      Resources::iterator previous = resources_.find(id);

      if (level_ == ResourceType_Instance)
      {
        AddResourceToExpand(index, id);
      }
      else if (resource.GetLevel() == level_)
      {
        // Mark this resource for further expansion
        if (previous != resources_.end())
        {
          delete previous->second;
        }

        resources_[id] = NULL;
      }
      else if (previous == resources_.end())
      {
        // This is the first time we meet this resource
        std::auto_ptr<ArchiveIndex> child(new ArchiveIndex(GetChildResourceType(level_)));
        child->Add(index, resource);
        resources_[id] = child.release();
      }
      else if (previous->second != NULL)
      {
        previous->second->Add(index, resource);
      }
      else
      {
        // Nothing to do: This item is marked for further expansion
      }
    }


    void Expand(ServerIndex& index)
    {
      if (level_ == ResourceType_Instance)
      {
        // Expanding an instance node makes no sense
        return;
      }

      for (Resources::iterator it = resources_.begin();
           it != resources_.end(); ++it)
      {
        if (it->second == NULL)
        {
          // This is resource is marked for expansion
          std::list<std::string> children;
          index.GetChildren(children, it->first);

          std::auto_ptr<ArchiveIndex> child(new ArchiveIndex(GetChildResourceType(level_)));

          for (std::list<std::string>::const_iterator 
                 it2 = children.begin(); it2 != children.end(); ++it2)
          {
            child->AddResourceToExpand(index, *it2);
          }

          it->second = child.release();
        }

        assert(it->second != NULL);
        it->second->Expand(index);
      }        
    }


    void Apply(IArchiveVisitor& visitor) const
    {
      if (level_ == ResourceType_Instance)
      {
        for (std::list<Instance>::const_iterator 
               it = instances_.begin(); it != instances_.end(); ++it)
        {
          visitor.AddInstance(it->id_, it->dicom_);
        }          
      }
      else
      {
        for (Resources::const_iterator it = resources_.begin();
             it != resources_.end(); ++it)
        {
          assert(it->second != NULL);  // There must have been a call to "Expand()"
          visitor.Open(level_, it->first);
          it->second->Apply(visitor);
          visitor.Close();
        }
      }
    }
  };



  class ArchiveJob::ZipCommands : public boost::noncopyable
  {
  private:
    enum Type
    {
      Type_OpenDirectory,
      Type_CloseDirectory,
      Type_WriteInstance
    };

    class Command : public boost::noncopyable
    {
    private:
      Type          type_;
      std::string   filename_;
      std::string   instanceId_;
      FileInfo      info_;

    public:
      explicit Command(Type type) :
        type_(type)
      {
        assert(type_ == Type_CloseDirectory);
      }
        
      Command(Type type,
              const std::string& filename) :
        type_(type),
        filename_(filename)
      {
        assert(type_ == Type_OpenDirectory);
      }
        
      Command(Type type,
              const std::string& filename,
              const std::string& instanceId,
              const FileInfo& info) :
        type_(type),
        filename_(filename),
        instanceId_(instanceId),
        info_(info)
      {
        assert(type_ == Type_WriteInstance);
      }
        
      void Apply(HierarchicalZipWriter& writer,
                 ServerContext& context,
                 DicomDirWriter* dicomDir,
                 const std::string& dicomDirFolder) const
      {
        switch (type_)
        {
          case Type_OpenDirectory:
            writer.OpenDirectory(filename_.c_str());
            break;

          case Type_CloseDirectory:
            writer.CloseDirectory();
            break;

          case Type_WriteInstance:
          {
            std::string content;

            try
            {
              context.ReadAttachment(content, info_);
            }
            catch (OrthancException& e)
            {
              LOG(WARNING) << "An instance was removed after the job was issued: " << instanceId_;
              return;
            }

            //boost::this_thread::sleep(boost::posix_time::milliseconds(300));
            
            writer.OpenFile(filename_.c_str());
            writer.Write(content);

            if (dicomDir != NULL)
            {
              ParsedDicomFile parsed(content);
              dicomDir->Add(dicomDirFolder, filename_, parsed);
            }
              
            break;
          }

          default:
            throw OrthancException(ErrorCode_InternalError);
        }
      }
    };
      
    std::deque<Command*>  commands_;
    uint64_t              uncompressedSize_;
    unsigned int          instancesCount_;

      
    void ApplyInternal(HierarchicalZipWriter& writer,
                       ServerContext& context,
                       size_t index,
                       DicomDirWriter* dicomDir,
                       const std::string& dicomDirFolder) const
    {
      if (index >= commands_.size())
      {
        throw OrthancException(ErrorCode_ParameterOutOfRange);
      }

      commands_[index]->Apply(writer, context, dicomDir, dicomDirFolder);
    }
      
  public:
    ZipCommands() :
      uncompressedSize_(0),
      instancesCount_(0)
    {
    }
      
    ~ZipCommands()
    {
      for (std::deque<Command*>::iterator it = commands_.begin();
           it != commands_.end(); ++it)
      {
        assert(*it != NULL);
        delete *it;
      }
    }

    size_t GetSize() const
    {
      return commands_.size();
    }

    unsigned int GetInstancesCount() const
    {
      return instancesCount_;
    }

    uint64_t GetUncompressedSize() const
    {
      return uncompressedSize_;
    }

    void Apply(HierarchicalZipWriter& writer,
               ServerContext& context,
               size_t index,
               DicomDirWriter& dicomDir,
               const std::string& dicomDirFolder) const
    {
      ApplyInternal(writer, context, index, &dicomDir, dicomDirFolder);
    }

    void Apply(HierarchicalZipWriter& writer,
               ServerContext& context,
               size_t index) const
    {
      ApplyInternal(writer, context, index, NULL, "");
    }
      
    void AddOpenDirectory(const std::string& filename)
    {
      commands_.push_back(new Command(Type_OpenDirectory, filename));
    }

    void AddCloseDirectory()
    {
      commands_.push_back(new Command(Type_CloseDirectory));
    }

    void AddWriteInstance(const std::string& filename,
                          const std::string& instanceId,
                          const FileInfo& info)
    {
      commands_.push_back(new Command(Type_WriteInstance, filename, instanceId, info));
      instancesCount_ ++;
      uncompressedSize_ += info.GetUncompressedSize();
    }

    bool IsZip64() const
    {
      return IsZip64Required(GetUncompressedSize(), GetInstancesCount());
    }
  };
    
    

  class ArchiveJob::ArchiveIndexVisitor : public IArchiveVisitor
  {
  private:
    ZipCommands&    commands_;
    ServerContext&  context_;
    char            instanceFormat_[24];
    unsigned int    counter_;

    static std::string GetTag(const DicomMap& tags,
                              const DicomTag& tag)
    {
      const DicomValue* v = tags.TestAndGetValue(tag);
      if (v != NULL &&
          !v->IsBinary() &&
          !v->IsNull())
      {
        return v->GetContent();
      }
      else
      {
        return "";
      }
    }

  public:
    ArchiveIndexVisitor(ZipCommands& commands,
                        ServerContext& context) :
      commands_(commands),
      context_(context),
      counter_(0)
    {
      if (commands.GetSize() != 0)
      {
        throw OrthancException(ErrorCode_BadSequenceOfCalls);
      }
        
      snprintf(instanceFormat_, sizeof(instanceFormat_) - 1, "%%08d.dcm");
    }

    virtual void Open(ResourceType level,
                      const std::string& publicId)
    {
      std::string path;

      DicomMap tags;
      if (context_.GetIndex().GetMainDicomTags(tags, publicId, level, level))
      {
        switch (level)
        {
          case ResourceType_Patient:
            path = GetTag(tags, DICOM_TAG_PATIENT_ID) + " " + GetTag(tags, DICOM_TAG_PATIENT_NAME);
            break;

          case ResourceType_Study:
            path = GetTag(tags, DICOM_TAG_ACCESSION_NUMBER) + " " + GetTag(tags, DICOM_TAG_STUDY_DESCRIPTION);
            break;

          case ResourceType_Series:
          {
            std::string modality = GetTag(tags, DICOM_TAG_MODALITY);
            path = modality + " " + GetTag(tags, DICOM_TAG_SERIES_DESCRIPTION);

            if (modality.size() == 0)
            {
              snprintf(instanceFormat_, sizeof(instanceFormat_) - 1, "%%08d.dcm");
            }
            else if (modality.size() == 1)
            {
              snprintf(instanceFormat_, sizeof(instanceFormat_) - 1, "%c%%07d.dcm", 
                       toupper(modality[0]));
            }
            else if (modality.size() >= 2)
            {
              snprintf(instanceFormat_, sizeof(instanceFormat_) - 1, "%c%c%%06d.dcm", 
                       toupper(modality[0]), toupper(modality[1]));
            }

            counter_ = 0;

            break;
          }

          default:
            throw OrthancException(ErrorCode_InternalError);
        }
      }

      path = Toolbox::StripSpaces(Toolbox::ConvertToAscii(path));

      if (path.empty())
      {
        path = std::string("Unknown ") + EnumerationToString(level);
      }

      commands_.AddOpenDirectory(path.c_str());
    }

    virtual void Close()
    {
      commands_.AddCloseDirectory();
    }

    virtual void AddInstance(const std::string& instanceId,
                             const FileInfo& dicom)
    {
      char filename[24];
      snprintf(filename, sizeof(filename) - 1, instanceFormat_, counter_);
      counter_ ++;

      commands_.AddWriteInstance(filename, instanceId, dicom);
    }
  };

    
  class ArchiveJob::MediaIndexVisitor : public IArchiveVisitor
  {
  private:
    ZipCommands&    commands_;
    ServerContext&  context_;
    unsigned int    counter_;

  public:
    MediaIndexVisitor(ZipCommands& commands,
                      ServerContext& context) :
      commands_(commands),
      context_(context),
      counter_(0)
    {
    }

    virtual void Open(ResourceType level,
                      const std::string& publicId)
    {
    }

    virtual void Close()
    {
    }

    virtual void AddInstance(const std::string& instanceId,
                             const FileInfo& dicom)
    {
      // "DICOM restricts the filenames on DICOM media to 8
      // characters (some systems wrongly use 8.3, but this does not
      // conform to the standard)."
      std::string filename = "IM" + boost::lexical_cast<std::string>(counter_);
      commands_.AddWriteInstance(filename, instanceId, dicom);

      counter_ ++;
    }
  };


  class ArchiveJob::ZipWriterIterator : public boost::noncopyable
  {
  private:
    TemporaryFile&                        target_;
    ServerContext&                        context_;
    ZipCommands                           commands_;
    std::auto_ptr<HierarchicalZipWriter>  zip_;
    std::auto_ptr<DicomDirWriter>         dicomDir_;
    bool                                  isMedia_;

  public:
    ZipWriterIterator(TemporaryFile& target,
                      ServerContext& context,
                      ArchiveIndex& archive,
                      bool isMedia,
                      bool enableExtendedSopClass) :
      target_(target),
      context_(context),
      isMedia_(isMedia)
    {
      if (isMedia)
      {
        MediaIndexVisitor visitor(commands_, context);
        archive.Expand(context.GetIndex());

        commands_.AddOpenDirectory(MEDIA_IMAGES_FOLDER);        
        archive.Apply(visitor);
        commands_.AddCloseDirectory();

        dicomDir_.reset(new DicomDirWriter);
        dicomDir_->EnableExtendedSopClass(enableExtendedSopClass);
      }
      else
      {
        ArchiveIndexVisitor visitor(commands_, context);
        archive.Expand(context.GetIndex());
        archive.Apply(visitor);
      }

      zip_.reset(new HierarchicalZipWriter(target.GetPath().c_str()));
      zip_->SetZip64(commands_.IsZip64());
    }
      
    size_t GetStepsCount() const
    {
      return commands_.GetSize() + 1;
    }

    void RunStep(size_t index)
    {
      if (index > commands_.GetSize())
      {
        throw OrthancException(ErrorCode_ParameterOutOfRange);
      }
      else if (index == commands_.GetSize())
      {
        // Last step: Add the DICOMDIR
        if (isMedia_)
        {
          assert(dicomDir_.get() != NULL);
          std::string s;
          dicomDir_->Encode(s);

          zip_->OpenFile("DICOMDIR");
          zip_->Write(s);
        }
      }
      else
      {
        if (isMedia_)
        {
          assert(dicomDir_.get() != NULL);
          commands_.Apply(*zip_, context_, index, *dicomDir_, MEDIA_IMAGES_FOLDER);
        }
        else
        {
          assert(dicomDir_.get() == NULL);
          commands_.Apply(*zip_, context_, index);
        }
      }
    }

    unsigned int GetInstancesCount() const
    {
      return commands_.GetInstancesCount();
    }

    uint64_t GetUncompressedSize() const
    {
      return commands_.GetUncompressedSize();
    }
  };


  ArchiveJob::ArchiveJob(ServerContext& context,
                         bool isMedia,
                         bool enableExtendedSopClass) :
    context_(context),
    archive_(new ArchiveIndex(ResourceType_Patient)),  // root
    isMedia_(isMedia),
    enableExtendedSopClass_(enableExtendedSopClass),
    currentStep_(0),
    instancesCount_(0),
    uncompressedSize_(0)
  {
  }

  
  ArchiveJob::~ArchiveJob()
  {
    if (!mediaArchiveId_.empty())
    {
      context_.GetMediaArchive().Remove(mediaArchiveId_);
    }
  }


  void ArchiveJob::SetSynchronousTarget(boost::shared_ptr<TemporaryFile>& target)
  {
    if (target.get() == NULL)
    {
      throw OrthancException(ErrorCode_NullPointer);
    }
    else if (writer_.get() != NULL ||  // Already started
             synchronousTarget_.get() != NULL ||
             asynchronousTarget_.get() != NULL)
    {
      throw OrthancException(ErrorCode_BadSequenceOfCalls);
    }
    else
    {
      synchronousTarget_ = target;
    }
  }


  void ArchiveJob::SetDescription(const std::string& description)
  {
    if (writer_.get() != NULL)   // Already started
    {
      throw OrthancException(ErrorCode_BadSequenceOfCalls);
    }
    else
    {
      description_ = description;
    }
  }

  
  void ArchiveJob::AddResource(const std::string& publicId)
  {
    if (writer_.get() != NULL)   // Already started
    {
      throw OrthancException(ErrorCode_BadSequenceOfCalls);
    }
    else
    {
      ResourceIdentifiers resource(context_.GetIndex(), publicId);
      archive_->Add(context_.GetIndex(), resource);
    }
  }

  
  void ArchiveJob::Reset()
  {
    throw OrthancException(ErrorCode_BadSequenceOfCalls,
                           "Cannot resubmit the creation of an archive");
  }

  
  void ArchiveJob::Start()
  {
    TemporaryFile* target = NULL;
    
    if (synchronousTarget_.get() == NULL)
    {
      asynchronousTarget_.reset(new TemporaryFile);
      target = asynchronousTarget_.get();
    }
    else
    {
      target = synchronousTarget_.get();
    }
    
    if (writer_.get() != NULL)
    {
      throw OrthancException(ErrorCode_BadSequenceOfCalls);
    }

    writer_.reset(new ZipWriterIterator(*target, context_, *archive_,
                                        isMedia_, enableExtendedSopClass_));

    instancesCount_ = writer_->GetInstancesCount();
    uncompressedSize_ = writer_->GetUncompressedSize();
  }



  namespace
  {
    class DynamicTemporaryFile : public IDynamicObject
    {
    private:
      std::auto_ptr<TemporaryFile>   file_;

    public:
      DynamicTemporaryFile(TemporaryFile* f) : file_(f)
      {
        if (f == NULL)
        {
          throw OrthancException(ErrorCode_NullPointer);
        }
      }

      const TemporaryFile& GetFile() const
      {
        assert(file_.get() != NULL);
        return *file_;
      }
    };
  }
  

  void ArchiveJob::FinalizeTarget()
  {
    writer_.reset();  // Flush all the results

    if (asynchronousTarget_.get() != NULL)
    {
      // Asynchronous behavior: Move the resulting file into the media archive
      mediaArchiveId_ = context_.GetMediaArchive().Add(
        new DynamicTemporaryFile(asynchronousTarget_.release()));
    }
  }
    

  JobStepResult ArchiveJob::Step()
  {
    assert(writer_.get() != NULL);

    if (synchronousTarget_.get() != NULL &&
        synchronousTarget_.unique())
    {
      LOG(WARNING) << "A client has disconnected while creating an archive";
      return JobStepResult::Failure(ErrorCode_NetworkProtocol);          
    }
        
    if (writer_->GetStepsCount() == 0)
    {
      FinalizeTarget();
      return JobStepResult::Success();
    }
    else
    {
      writer_->RunStep(currentStep_);

      currentStep_ ++;

      if (currentStep_ == writer_->GetStepsCount())
      {
        FinalizeTarget();
        return JobStepResult::Success();
      }
      else
      {
        return JobStepResult::Continue();
      }
    }
  }


  float ArchiveJob::GetProgress()
  {
    if (writer_.get() == NULL ||
        writer_->GetStepsCount() == 0)
    {
      return 1;
    }
    else
    {
      return (static_cast<float>(currentStep_) /
              static_cast<float>(writer_->GetStepsCount() - 1));
    }
  }

    
  void ArchiveJob::GetJobType(std::string& target)
  {
    if (isMedia_)
    {
      target = "Media";
    }
    else
    {
      target = "Archive";
    }
  }


  void ArchiveJob::GetPublicContent(Json::Value& value)
  {
    value = Json::objectValue;
    value[KEY_DESCRIPTION] = description_;
    value[KEY_INSTANCES_COUNT] = instancesCount_;
    value[KEY_UNCOMPRESSED_SIZE_MB] =
      static_cast<unsigned int>(uncompressedSize_ / MEGA_BYTES);
  }


  bool ArchiveJob::GetOutput(std::string& output,
                             MimeType& mime,
                             const std::string& key)
  {   
    if (key == "archive" &&
        !mediaArchiveId_.empty())
    {
      SharedArchive::Accessor accessor(context_.GetMediaArchive(), mediaArchiveId_);

      if (accessor.IsValid())
      {
        const DynamicTemporaryFile& f = dynamic_cast<DynamicTemporaryFile&>(accessor.GetItem());
        f.GetFile().Read(output);
        mime = MimeType_Zip;
        return true;
      }
      else
      {
        return false;
      }
    }    
    else
    {
      return false;
    }
  }
}