/**********************************************************************

  Audacity: A Digital Audio Editor

  Export.cpp

  Dominic Mazzoni

*******************************************************************//**

\class Export
\brief Main class to control the export function.

*//****************************************************************//**

\class ExportType
\brief Container for information about supported export types.

*//****************************************************************//**

\class ExportMixerDialog
\brief Dialog for advanced mixing.

*//****************************************************************//**

\class ExportMixerPanel
\brief Panel that displays mixing for advanced mixing option.

*//********************************************************************/

#include "../Audacity.h" // for USE_* macros
#include "Export.h"

#include <wx/dcclient.h>
#include <wx/file.h>
#include <wx/filectrl.h>
#include <wx/filename.h>
#include <wx/progdlg.h>
#include <wx/simplebook.h>
#include <wx/sizer.h>
#include <wx/slider.h>
#include <wx/statbox.h>
#include <wx/stattext.h>
#include <wx/string.h>
#include <wx/textctrl.h>
#include <wx/timer.h>
#include <wx/dcmemory.h>
#include <wx/window.h>

#include "sndfile.h"

#include "FileDialog.h"

#include "../DirManager.h"
#include "../FileFormats.h"
#include "../Mix.h"
#include "../Prefs.h"
#include "../prefs/ImportExportPrefs.h"
#include "../Project.h"
#include "../ProjectHistory.h"
#include "../ProjectSettings.h"
#include "../ProjectWindow.h"
#include "../ShuttleGui.h"
#include "../Tags.h"
#include "../TimeTrack.h"
#include "../WaveTrack.h"
#include "../widgets/AudacityMessageBox.h"
#include "../widgets/Warning.h"
#include "../widgets/HelpSystem.h"
#include "../AColor.h"
#include "../Dependencies.h"
#include "../FileNames.h"
#include "../widgets/HelpSystem.h"
#include "../widgets/ProgressDialog.h"

//----------------------------------------------------------------------------
// ExportPlugin
//----------------------------------------------------------------------------

ExportPlugin::ExportPlugin()
{
}

ExportPlugin::~ExportPlugin()
{
}

bool ExportPlugin::CheckFileName(wxFileName & WXUNUSED(filename), int WXUNUSED(format))
{
  return true;
}

/** \brief Add a NEW entry to the list of formats this plug-in can export
 *
 * To configure the format use SetFormat, SetCanMetaData etc with the index of
 * the format.
 * @return The number of formats currently set up. This is one more than the
 * index of the newly added format.
 */
int ExportPlugin::AddFormat()
{
   FormatInfo nf;
   mFormatInfos.push_back(nf);
   return mFormatInfos.size();
}

int ExportPlugin::GetFormatCount()
{
   return mFormatInfos.size();
}

/**
 * @param index The plugin to set the format for (range 0 to one less than the
 * count of formats)
 */
void ExportPlugin::SetFormat(const wxString & format, int index)
{
   mFormatInfos[index].mFormat = format;
}

void ExportPlugin::SetDescription(const TranslatableString & description, int index)
{
   mFormatInfos[index].mDescription = description;
}

void ExportPlugin::AddExtension(const FileExtension &extension, int index)
{
   mFormatInfos[index].mExtensions.push_back(extension);
}

void ExportPlugin::SetExtensions(FileExtensions extensions, int index)
{
   mFormatInfos[index].mExtensions = std::move(extensions);
}

void ExportPlugin::SetMask(FileNames::FileTypes mask, int index)
{
   mFormatInfos[index].mMask = std::move( mask );
}

void ExportPlugin::SetMaxChannels(unsigned maxchannels, unsigned index)
{
   mFormatInfos[index].mMaxChannels = maxchannels;
}

void ExportPlugin::SetCanMetaData(bool canmetadata, int index)
{
   mFormatInfos[index].mCanMetaData = canmetadata;
}

wxString ExportPlugin::GetFormat(int index)
{
   return mFormatInfos[index].mFormat;
}

TranslatableString ExportPlugin::GetDescription(int index)
{
   return mFormatInfos[index].mDescription;
}

FileExtension ExportPlugin::GetExtension(int index)
{
   return mFormatInfos[index].mExtensions[0];
}

FileExtensions ExportPlugin::GetExtensions(int index)
{
   return mFormatInfos[index].mExtensions;
}

FileNames::FileTypes ExportPlugin::GetMask(int index)
{
   if (!mFormatInfos[index].mMask.empty())
      return mFormatInfos[index].mMask;

   return { { GetDescription(index), GetExtensions(index) } };
}

unsigned ExportPlugin::GetMaxChannels(int index)
{
   return mFormatInfos[index].mMaxChannels;
}

bool ExportPlugin::GetCanMetaData(int index)
{
   return mFormatInfos[index].mCanMetaData;
}

bool ExportPlugin::IsExtension(const FileExtension & ext, int index)
{
   bool isext = false;
   for (int i = index; i < GetFormatCount(); i = GetFormatCount())
   {
      const auto &defext = GetExtension(i);
      const auto &defexts = GetExtensions(i);
      int indofext = defexts.Index(ext, false);
      if (defext.empty() || (indofext != wxNOT_FOUND))
         isext = true;
   }
   return isext;
}

bool ExportPlugin::DisplayOptions(wxWindow * WXUNUSED(parent), int WXUNUSED(format))
{
   return false;
}

void ExportPlugin::OptionsCreate(ShuttleGui &S, int WXUNUSED(format))
{
   S.StartHorizontalLay(wxCENTER);
   {
      S.StartHorizontalLay(wxCENTER, 0);
      {
         S.Prop(1).AddTitle(XO("No format specific options"));
      }
      S.EndHorizontalLay();
   }
   S.EndHorizontalLay();
}

//Create a mixer by computing the time warp factor
std::unique_ptr<Mixer> ExportPlugin::CreateMixer(const TrackList &tracks,
         bool selectionOnly,
         double startTime, double stopTime,
         unsigned numOutChannels, size_t outBufferSize, bool outInterleaved,
         double outRate, sampleFormat outFormat,
         bool highQuality, MixerSpec *mixerSpec)
{
   WaveTrackConstArray inputTracks;

   bool anySolo = !(( tracks.Any<const WaveTrack>() + &WaveTrack::GetSolo ).empty());

   auto range = tracks.Any< const WaveTrack >()
      + (selectionOnly ? &Track::IsSelected : &Track::Any )
      - ( anySolo ? &WaveTrack::GetNotSolo : &WaveTrack::GetMute);
   for (auto pTrack: range)
      inputTracks.push_back(
         pTrack->SharedPointer< const WaveTrack >() );
   const auto timeTrack = *tracks.Any<const TimeTrack>().begin();
   auto envelope = timeTrack ? timeTrack->GetEnvelope() : nullptr;
   // MB: the stop time should not be warped, this was a bug.
   return std::make_unique<Mixer>(inputTracks,
                  // Throw, to stop exporting, if read fails:
                  true,
                  Mixer::WarpOptions(envelope),
                  startTime, stopTime,
                  numOutChannels, outBufferSize, outInterleaved,
                  outRate, outFormat,
                  highQuality, mixerSpec);
}

void ExportPlugin::InitProgress(std::unique_ptr<ProgressDialog> &pDialog,
   const TranslatableString &title, const TranslatableString &message)
{
   if (!pDialog)
      pDialog = std::make_unique<ProgressDialog>( title, message );
   else {
      pDialog->SetTitle( title );
      pDialog->SetMessage( message );
      pDialog->Reinit();
   }
}

void ExportPlugin::InitProgress(std::unique_ptr<ProgressDialog> &pDialog,
   const wxFileNameWrapper &title, const TranslatableString &message)
{
   return InitProgress(
      pDialog, Verbatim( title.GetName() ), message );
}

//----------------------------------------------------------------------------
// Export
//----------------------------------------------------------------------------


wxDEFINE_EVENT(AUDACITY_FILE_SUFFIX_EVENT, wxCommandEvent);

BEGIN_EVENT_TABLE(Exporter, wxEvtHandler)
   EVT_FILECTRL_FILTERCHANGED(wxID_ANY, Exporter::OnFilterChanged)
   EVT_BUTTON(wxID_HELP, Exporter::OnHelp)
   EVT_COMMAND( wxID_ANY, AUDACITY_FILE_SUFFIX_EVENT, Exporter::OnExtensionChanged)
END_EVENT_TABLE()

namespace {
const auto PathStart = wxT("Exporters");

static Registry::GroupItem &sRegistry()
{
   static Registry::TransparentGroupItem<> registry{ PathStart };
   return registry;
}

struct ExporterItem final : Registry::SingleItem {
   ExporterItem(
      const Identifier &id, const Exporter::ExportPluginFactory &factory )
      : SingleItem{ id }
      , mFactory{ factory }
   {}

   Exporter::ExportPluginFactory mFactory;
};

   using ExportPluginFactories = std::vector< Exporter::ExportPluginFactory >;
   ExportPluginFactories &sFactories()
   {
      static ExportPluginFactories theList;
      return theList;
   }
}

Exporter::RegisteredExportPlugin::RegisteredExportPlugin(
   const Identifier &id,
   const ExportPluginFactory &factory,
   const Registry::Placement &placement )
{
   if ( factory )
      Registry::RegisterItem( sRegistry(), placement,
         std::make_unique< ExporterItem >( id, factory ) );
}

Exporter::Exporter( AudacityProject &project )
: mProject{ &project }
{
   using namespace Registry;
   static OrderingPreferenceInitializer init{
      PathStart,
      { {wxT(""), wxT("PCM,MP3,OGG,FLAC,MP2,CommandLine,FFmpeg") } },
   };

   mMixerSpec = NULL;
   mBook = NULL;

   // build the list of export plugins.
   for ( const auto &factory : sFactories() )
      mPlugins.emplace_back( factory() );

   struct MyVisitor final : Visitor {
      MyVisitor()
      {
         // visit the registry to collect the plug-ins properly
         // sorted
         TransparentGroupItem<> top{ PathStart };
         Registry::Visit( *this, &top, &sRegistry() );
      }

      void Visit( SingleItem &item, const Path &path ) override
      {
         mPlugins.emplace_back(
            static_cast<ExporterItem&>( item ).mFactory() );
      }

      ExportPluginArray mPlugins;
   } visitor;

   mPlugins.swap( visitor.mPlugins );

   SetFileDialogTitle( XO("Export Audio") );
}

Exporter::~Exporter()
{
}

// Beginnings of a fix for bug 1355.
// 'Other Uncompressed Files' Header option updates do not update
// the extension shown in the file dialog.
// Unfortunately, although we get the new extension here, we
// can't do anything with it as the FileDialog does not provide
// methods for setting its standard controls.
// We would need OS specific code that 'knows' about the system 
// dialogs.
void Exporter::OnExtensionChanged(wxCommandEvent &evt) {
   wxString ext = evt.GetString();
   ext = ext.BeforeFirst(' ').Lower();
   wxLogDebug("Extension changed to '.%s'", ext);
//   wxString Name = mDialog->GetFilename();
//   Name = Name.BeforeLast('.')+ext;
//   mDialog->SetFilename(Name);
}

void Exporter::OnHelp(wxCommandEvent& WXUNUSED(evt))
{
   wxWindow * pWin = FindProjectFrame( mProject );
   HelpSystem::ShowHelp(pWin, wxT("File_Export_Dialog"), true);
}

void Exporter::SetFileDialogTitle( const TranslatableString & DialogTitle )
{
   // The default title is "Export File"
   mFileDialogTitle = DialogTitle;
}

int Exporter::FindFormatIndex(int exportindex)
{
   int c = 0;
   for (const auto &pPlugin : mPlugins)
   {
      for (int j = 0; j < pPlugin->GetFormatCount(); j++)
      {
         if (exportindex == c) return j;
         c++;
      }
   }
   return 0;
}

const ExportPluginArray &Exporter::GetPlugins()
{
   return mPlugins;
}

bool Exporter::DoEditMetadata(AudacityProject &project,
   const TranslatableString &title,
   const TranslatableString &shortUndoDescription, bool force)
{
   auto &settings = ProjectSettings::Get( project );
   auto &tags = Tags::Get( project );

   // Back up my tags
   // Tags (artist name, song properties, MP3 ID3 info, etc.)
   // The structure may be shared with undo history entries
   // To keep undo working correctly, always replace this with a NEW duplicate
   // BEFORE doing any editing of it!
   auto newTags = tags.Duplicate();

   if (newTags->ShowEditDialog(&GetProjectFrame( project ), title, force)) {
      if (tags != *newTags) {
         // Commit the change to project state only now.
         Tags::Set( project, newTags );
         ProjectHistory::Get( project ).PushState( title, shortUndoDescription);
      }
      bool bShowInFuture;
      gPrefs->Read(wxT("/AudioFiles/ShowId3Dialog"), &bShowInFuture, true);
      settings.SetShowId3Dialog( bShowInFuture );
      return true;
   }

   return false;
}

bool Exporter::Process(bool selectedOnly, double t0, double t1)
{
   // Save parms
   mSelectedOnly = selectedOnly;
   mT0 = t0;
   mT1 = t1;

   // Gather track information
   if (!ExamineTracks()) {
      return false;
   }

   // Ask user for file name
   if (!GetFilename()) {
      return false;
   }

   // Check for down mixing
   if (!CheckMix()) {
      return false;
   }

   // Let user edit MetaData
   if (mPlugins[mFormat]->GetCanMetaData(mSubFormat)) {
      if (!DoEditMetadata( *mProject,
         XO("Edit Metadata Tags"), XO("Exported Tags"),
         ProjectSettings::Get( *mProject ).GetShowId3Dialog())) {
         return false;
      }
   }

   // Ensure filename doesn't interfere with project files.
   if (!CheckFilename()) {
      return false;
   }

   // Export the tracks
   bool success = ExportTracks();

   // Get rid of mixerspec
   mMixerSpec.reset();

   return success;
}

bool Exporter::Process(unsigned numChannels,
                       const FileExtension &type, const wxString & filename,
                       bool selectedOnly, double t0, double t1)
{
   // Save parms
   mChannels = numChannels;
   mFilename = filename;
   mSelectedOnly = selectedOnly;
   mT0 = t0;
   mT1 = t1;
   mActualName = mFilename;

   int i = -1;
   for (const auto &pPlugin : mPlugins) {
      ++i;
      for (int j = 0; j < pPlugin->GetFormatCount(); j++)
      {
         if (pPlugin->GetFormat(j).IsSameAs(type, false))
         {
            mFormat = i;
            mSubFormat = j;
            return CheckFilename() && ExportTracks();
         }
      }
   }

   return false;
}

bool Exporter::ExamineTracks()
{
   // Init
   mNumSelected = 0;
   mNumLeft = 0;
   mNumRight = 0;
   mNumMono = 0;

   // First analyze the selected audio, perform sanity checks, and provide
   // information as appropriate.

   // Tally how many are right, left, mono, and make sure at
   // least one track is selected (if selectedOnly==true)

   double earliestBegin = mT1;
   double latestEnd = mT0;

   auto &tracks = TrackList::Get( *mProject );

   bool anySolo = !(( tracks.Any<const WaveTrack>() + &WaveTrack::GetSolo ).empty());

   for (auto tr :
         tracks.Any< const WaveTrack >()
            + ( mSelectedOnly ? &Track::IsSelected : &Track::Any )
            - ( anySolo ? &WaveTrack::GetNotSolo : &WaveTrack::GetMute)
   ) {
      mNumSelected++;

      if (tr->GetChannel() == Track::LeftChannel) {
         mNumLeft++;
      }
      else if (tr->GetChannel() == Track::RightChannel) {
         mNumRight++;
      }
      else if (tr->GetChannel() == Track::MonoChannel) {
         // It's a mono channel, but it may be panned
         float pan = tr->GetPan();

         if (pan == -1.0)
            mNumLeft++;
         else if (pan == 1.0)
            mNumRight++;
         else if (pan == 0)
            mNumMono++;
         else {
            // Panned partially off-center. Mix as stereo.
            mNumLeft++;
            mNumRight++;
         }
      }

      if (tr->GetOffset() < earliestBegin) {
         earliestBegin = tr->GetOffset();
      }

      if (tr->GetEndTime() > latestEnd) {
         latestEnd = tr->GetEndTime();
      }
   }

   if (mNumSelected == 0) {
      TranslatableString message;
      if(mSelectedOnly)
         message = XO("All selected audio is muted.");
      else
         message = XO("All audio is muted.");
      AudacityMessageBox(
         message,
         XO("Unable to export"),
         wxOK | wxICON_INFORMATION);
      return false;
   }

   // The skipping of silent space could be cleverer and take 
   // into account clips.
   // As implemented now, it can only skip initial silent space that 
   // has no clip before it, and terminal silent space that has no clip 
   // after it.
   if (mT0 < earliestBegin){
      // Bug 1904 
      // Previously we always skipped initial silent space.
      // Now skipping it is an opt-in option.
      bool skipSilenceAtBeginning;
      gPrefs->Read(wxT("/AudioFiles/SkipSilenceAtBeginning"),
                                      &skipSilenceAtBeginning, false);
      if (skipSilenceAtBeginning)
         mT0 = earliestBegin;
   }

   // We still skip silent space at the end
   if (mT1 > latestEnd)
      mT1 = latestEnd;

   return true;
}

bool Exporter::GetFilename()
{
   mFormat = -1;

   FileNames::FileTypes fileTypes;
   auto defaultFormat = mFormatName;
   if( defaultFormat.empty() )
      defaultFormat = gPrefs->Read(wxT("/Export/Format"),
                                         wxT("WAV"));

   mFilterIndex = 0;

   {
      int i = -1;
      for (const auto &pPlugin : mPlugins) {
         ++i;
         for (int j = 0; j < pPlugin->GetFormatCount(); j++)
         {
            auto mask = pPlugin->GetMask(j);
            fileTypes.insert( fileTypes.end(), mask.begin(), mask.end() );
            if (mPlugins[i]->GetFormat(j) == defaultFormat) {
               mFormat = i;
               mSubFormat = j;
            }
            if (mFormat == -1) mFilterIndex++;
         }
      }
   }
   if (mFormat == -1)
   {
      mFormat = 0;
      mFilterIndex = 0;
      mSubFormat = 0;
   }
   wxString defext = mPlugins[mFormat]->GetExtension(mSubFormat).Lower();

//Bug 1304: Set a default path if none was given.  For Export.
   mFilename = FileNames::DefaultToDocumentsFolder(wxT("/Export/Path"));
   mFilename.SetName(mProject->GetProjectName());
   if (mFilename.GetName().empty())
      mFilename.SetName(_("untitled"));
   while (true) {
      // Must reset each iteration
      mBook = NULL;

      {
         auto useFileName = mFilename;
         if (!useFileName.HasExt())
            useFileName.SetExt(defext);
         FileDialogWrapper fd( ProjectWindow::Find( mProject ),
                       mFileDialogTitle,
                       mFilename.GetPath(),
                       useFileName.GetFullName(),
                       fileTypes,
                       wxFD_SAVE | wxRESIZE_BORDER);
         mDialog = &fd;
         mDialog->PushEventHandler(this);

         fd.SetUserPaneCreator(CreateUserPaneCallback, (wxUIntPtr) this);
         fd.SetFilterIndex(mFilterIndex);

         int result = fd.ShowModal();

         mDialog->PopEventHandler();

         if (result == wxID_CANCEL) {
            return false;
         }

         mFilename = fd.GetPath();
         if (mFilename == wxT("")) {
            return false;
         }

         mFormat = fd.GetFilterIndex();
         mFilterIndex = fd.GetFilterIndex();
      }

      {
         int c = 0;
         int i = -1;
         for (const auto &pPlugin : mPlugins)
         {
            ++i;
            for (int j = 0; j < pPlugin->GetFormatCount(); j++)
            {
               if (mFilterIndex == c)
               {
                  mFormat = i;
                  mSubFormat = j;
               }
               c++;
            }
         }
      }

      const auto ext = mFilename.GetExt();
      defext = mPlugins[mFormat]->GetExtension(mSubFormat).Lower();

      //
      // Check the extension - add the default if it's not there,
      // and warn user if it's abnormal.
      //
      if (ext.empty()) {
         //
         // Make sure the user doesn't accidentally save the file
         // as an extension with no name, like just plain ".wav".
         //
         if (mFilename.GetName().Left(1) == wxT(".")) {
            auto prompt =
               XO("Are you sure you want to export the file as \"%s\"?\n")
                  .Format( mFilename.GetFullName() );

            int action = AudacityMessageBox(
               prompt,
               XO("Warning"),
               wxYES_NO | wxICON_EXCLAMATION);
            if (action != wxYES) {
               continue;
            }
         }

         mFilename.SetExt(defext);
      }
      else if (!mPlugins[mFormat]->CheckFileName(mFilename, mSubFormat))
      {
         continue;
      }
      else if (!ext.empty() && !mPlugins[mFormat]->IsExtension(ext,mSubFormat) && ext.CmpNoCase(defext)) {
         auto prompt = XO("You are about to export a %s file with the name \"%s\".\n\nNormally these files end in \".%s\", and some programs will not open files with nonstandard extensions.\n\nAre you sure you want to export the file under this name?")
               .Format(mPlugins[mFormat]->GetFormat(mSubFormat),
                       mFilename.GetFullName(),
                       defext);

         int action = AudacityMessageBox(
            prompt,
            XO("Warning"),
            wxYES_NO | wxICON_EXCLAMATION);
         if (action != wxYES) {
            continue;
         }
      }

      if (mFilename.GetFullPath().length() >= 256) {
         AudacityMessageBox(
            XO( "Sorry, pathnames longer than 256 characters not supported.") );
         continue;
      }

      // Check to see if we are writing to a path that a missing aliased file existed at.
      // This causes problems for the exporter, so we don't allow it.
      // Overwritting non-missing aliased files is okay.
      // Also, this can only happen for uncompressed audio.
      bool overwritingMissingAliasFiles;
      overwritingMissingAliasFiles = false;
      for (auto pProject : AllProjects{}) {
         AliasedFileArray aliasedFiles;
         FindDependencies(pProject.get(), aliasedFiles);
         for (const auto &aliasedFile : aliasedFiles) {
            if (mFilename.GetFullPath() == aliasedFile.mFileName.GetFullPath() &&
                !mFilename.FileExists()) {
               // Warn and return to the dialog
               AudacityMessageBox(XO(
"You are attempting to overwrite an aliased file that is missing.\n\
The file cannot be written because the path is needed to restore the original audio to the project.\n\
Choose Help > Diagnostics > Check Dependencies to view the locations of all missing files.\n\
If you still wish to export, please choose a different filename or folder."));
               overwritingMissingAliasFiles = true;
            }
         }
      }
      if (overwritingMissingAliasFiles)
         continue;

      if (mFilename.FileExists()) {
         auto prompt = XO("A file named \"%s\" already exists. Replace?")
            .Format( mFilename.GetFullPath() );

         int action = AudacityMessageBox(
            prompt,
            XO("Warning"),
            wxYES_NO | wxICON_EXCLAMATION);
         if (action != wxYES) {
            continue;
         }
      }

      break;
   }

   return true;
}

//
// For safety, if the file already exists it stores the filename
// the user wants in actualName, and returns a temporary file name.
// The calling function should rename the file when it's successfully
// exported.
//
bool Exporter::CheckFilename()
{
   //
   // Ensure that exporting a file by this name doesn't overwrite
   // one of the existing files in the project.  (If it would
   // overwrite an existing file, DirManager tries to rename the
   // existing file.)
   //

   if (!DirManager::Get( *mProject ).EnsureSafeFilename(mFilename))
      return false;

   if( mFormatName.empty() )
      gPrefs->Write(wxT("/Export/Format"), mPlugins[mFormat]->GetFormat(mSubFormat));
   gPrefs->Write(wxT("/Export/Path"), mFilename.GetPath());
   gPrefs->Flush();

   //
   // To be even safer, return a temporary file name based
   // on this one...
   //

   mActualName = mFilename;

   int suffix = 0;
   while (mFilename.FileExists()) {
      mFilename.SetName(mActualName.GetName() +
                        wxString::Format(wxT("%d"), suffix));
      suffix++;
   }

   return true;
}

void Exporter::DisplayOptions(int index)
{
   int c = 0;
   int mf = -1, msf = -1;
   int i = -1;
   for (const auto &pPlugin : mPlugins)
   {
      ++i;
      for (int j = 0; j < pPlugin->GetFormatCount(); j++)
      {
         if (index == c)
         {
            mf = i;
            msf = j;
         }
         c++;
      }
   }
   // This shouldn't happen...
   if (index >= c) {
      return;
   }

#if defined(__WXMSW__)
   mPlugins[mf]->DisplayOptions( FindProjectFrame( mProject ), msf);
#else
   mPlugins[mf]->DisplayOptions(mDialog, msf);
#endif
}

bool Exporter::CheckMix()
{
   // Clean up ... should never happen
   mMixerSpec.reset();

   // Detemine if exported file will be stereo or mono or multichannel,
   // and if mixing will occur.

   auto downMix = ImportExportPrefs::ExportDownMixSetting.ReadEnum();
   int exportedChannels = mPlugins[mFormat]->SetNumExportChannels();

   if (downMix) {
      if (mNumRight > 0 || mNumLeft > 0) {
         mChannels = 2;
      }
      else {
         mChannels = 1;
      }
      mChannels = std::min(mChannels,
                           mPlugins[mFormat]->GetMaxChannels(mSubFormat));

      auto numLeft =  mNumLeft + mNumMono;
      auto numRight = mNumRight + mNumMono;

      if (numLeft > 1 || numRight > 1 || mNumLeft + mNumRight + mNumMono > mChannels) {
         wxString exportFormat = mPlugins[mFormat]->GetFormat(mSubFormat);
         if (exportFormat != wxT("CL") && exportFormat != wxT("FFMPEG") && exportedChannels == -1)
            exportedChannels = mChannels;

         auto pWindow = ProjectWindow::Find( mProject );
         if (exportedChannels == 1) {
            if (ShowWarningDialog(pWindow,
                                  wxT("MixMono"),
                                  XO("Your tracks will be mixed down and exported as one mono file."),
                                  true) == wxID_CANCEL)
               return false;
         }
         else if (exportedChannels == 2) {
            if (ShowWarningDialog(pWindow,
                                  wxT("MixStereo"),
                                  XO("Your tracks will be mixed down and exported as one stereo file."),
                                  true) == wxID_CANCEL)
               return false;
         }
         else {
            if (ShowWarningDialog(pWindow,
                                  wxT("MixUnknownChannels"),
                                  XO("Your tracks will be mixed down to one exported file according to the encoder settings."),
                                  true) == wxID_CANCEL)
               return false;
         }
      }
   }
   else
   {
      if (exportedChannels < 0)
         exportedChannels = mPlugins[mFormat]->GetMaxChannels(mSubFormat);

      ExportMixerDialog md(&TrackList::Get( *mProject ),
                           mSelectedOnly,
                           exportedChannels,
                           NULL,
                           1,
                           XO("Advanced Mixing Options"));

      if (md.ShowModal() != wxID_OK) {
         return false;
      }

      mMixerSpec = std::make_unique<MixerSpec>(*(md.GetMixerSpec()));
      mChannels = mMixerSpec->GetNumChannels();
   }

   return true;
}

bool Exporter::ExportTracks()
{
   // Keep original in case of failure
   if (mActualName != mFilename) {
      ::wxRenameFile(mActualName.GetFullPath(), mFilename.GetFullPath());
   }

   bool success = false;

   auto cleanup = finally( [&] {
      if (mActualName != mFilename) {
         // Remove backup
         if ( success )
            ::wxRemoveFile(mFilename.GetFullPath());
         else {
            // Restore original, if needed
            ::wxRemoveFile(mActualName.GetFullPath());
            ::wxRenameFile(mFilename.GetFullPath(), mActualName.GetFullPath());
         }
      }
      else {
         if ( ! success )
            // Remove any new, and only partially written, file.
            ::wxRemoveFile(mFilename.GetFullPath());
      }
   } );

   std::unique_ptr<ProgressDialog> pDialog;
   auto result = mPlugins[mFormat]->Export(mProject,
                                       pDialog,
                                       mChannels,
                                       mActualName.GetFullPath(),
                                       mSelectedOnly,
                                       mT0,
                                       mT1,
                                       mMixerSpec.get(),
                                       NULL,
                                       mSubFormat);

   success =
      result == ProgressResult::Success || result == ProgressResult::Stopped;

   return success;
}

void Exporter::CreateUserPaneCallback(wxWindow *parent, wxUIntPtr userdata)
{
   Exporter *self = (Exporter *) userdata;
   if (self)
   {
      self->CreateUserPane(parent);
   }
}

void Exporter::CreateUserPane(wxWindow *parent)
{
   ShuttleGui S(parent, eIsCreating);

   S.StartVerticalLay();
   {
      S.StartHorizontalLay(wxEXPAND);
      {
         S.StartStatic(XO("Format Options"), 1);
         {
            mBook = S.Position(wxEXPAND)
               .StartSimplebook();

            for (const auto &pPlugin : mPlugins)
            {
               for (int j = 0; j < pPlugin->GetFormatCount(); j++)
               {
                  // Name of simple book page is not displayed
                  S.StartNotebookPage( {} );
                  pPlugin->OptionsCreate(S, j);
                  S.EndNotebookPage();
               }
            }

            S.EndSimplebook();
         }
         S.EndStatic();
      }
      S.EndHorizontalLay();
   }
   S.StartHorizontalLay(wxALIGN_RIGHT, 0);
   {
      S.AddStandardButtons(eHelpButton);
   }
   S.EndHorizontalLay();
   S.EndVerticalLay();

   return;
}

void Exporter::OnFilterChanged(wxFileCtrlEvent & evt)
{
   int index = evt.GetFilterIndex();

   // On GTK, this event can fire before the userpane is created
   if (mBook == NULL || index < 0 || index >= (int) mBook->GetPageCount())
   {
      return;
   }

   mBook->ChangeSelection(index);
}

bool Exporter::ProcessFromTimerRecording(bool selectedOnly,
                                         double t0,
                                         double t1,
                                         wxFileName fnFile,
                                         int iFormat,
                                         int iSubFormat,
                                         int iFilterIndex)
{
   // Save parms
   mSelectedOnly = selectedOnly;
   mT0 = t0;
   mT1 = t1;

   // Auto Export Parameters
   mFilename = fnFile;
   mFormat = iFormat;
   mSubFormat = iSubFormat;
   mFilterIndex = iFilterIndex;

   // Gather track information
   if (!ExamineTracks()) {
      return false;
   }

   // Check for down mixing
   if (!CheckMix()) {
      return false;
   }

   // Ensure filename doesn't interfere with project files.
   if (!CheckFilename()) {
      return false;
   }

   // Export the tracks
   bool success = ExportTracks();

   // Get rid of mixerspec
   mMixerSpec.reset();

   return success;
}

int Exporter::GetAutoExportFormat() {
   return mFormat;
}

int Exporter::GetAutoExportSubFormat() {
   return mSubFormat;
}

int Exporter::GetAutoExportFilterIndex() {
   return mFormat;
}

wxFileName Exporter::GetAutoExportFileName() {
   return mFilename;
}

bool Exporter::SetAutoExportOptions() {
   mFormat = -1;

   if( GetFilename()==false )
        return false;

   // Let user edit MetaData
   if (mPlugins[mFormat]->GetCanMetaData(mSubFormat)) {
      if (!DoEditMetadata( *mProject,
         XO("Edit Metadata Tags"),
         XO("Exported Tags"),
         ProjectSettings::Get(*mProject).GetShowId3Dialog())) {
         return false;
      }
   }

   return true;
}

//----------------------------------------------------------------------------
// ExportMixerPanel
//----------------------------------------------------------------------------

BEGIN_EVENT_TABLE(ExportMixerPanel, wxPanelWrapper)
    EVT_PAINT(ExportMixerPanel::OnPaint)
    EVT_MOUSE_EVENTS(ExportMixerPanel::OnMouseEvent)
END_EVENT_TABLE()

ExportMixerPanel::ExportMixerPanel( wxWindow *parent, wxWindowID id,
      MixerSpec *mixerSpec,
      wxArrayString trackNames,
      const wxPoint& pos, const wxSize& size):
   wxPanelWrapper(parent, id, pos, size)
   , mMixerSpec{mixerSpec}
   , mChannelRects{ mMixerSpec->GetMaxNumChannels() }
   , mTrackRects{ mMixerSpec->GetNumTracks() }
{
   mBitmap = NULL;
   mWidth = 0;
   mHeight = 0;
   mSelectedTrack = mSelectedChannel = -1;

   mTrackNames = trackNames;
}

ExportMixerPanel::~ExportMixerPanel()
{
}

//set the font on memDC such that text can fit in specified width and height
void ExportMixerPanel::SetFont(wxMemoryDC &memDC, const wxString &text, int width,
      int height )
{
   int l = 0, u = 13, m, w, h;
   wxFont font = memDC.GetFont();
   while( l < u - 1 )
   {
      m = ( l + u ) / 2;
      font.SetPointSize( m );
      memDC.SetFont( font );
      memDC.GetTextExtent( text, &w, &h );

      if( w < width && h < height )
         l = m;
      else
         u = m;
   }
   font.SetPointSize( l );
   memDC.SetFont( font );
}

void ExportMixerPanel::OnPaint(wxPaintEvent & WXUNUSED(event))
{
   wxPaintDC dc( this );

   int width, height;
   GetSize( &width, &height );

   if( !mBitmap || mWidth != width || mHeight != height )
   {
      mWidth = width;
      mHeight = height;
      mBitmap = std::make_unique<wxBitmap>( mWidth, mHeight,24 );
   }

   wxColour bkgnd = GetBackgroundColour();
   wxBrush bkgndBrush( bkgnd, wxBRUSHSTYLE_SOLID );

   wxMemoryDC memDC;
   memDC.SelectObject( *mBitmap );

   //draw background
   wxRect bkgndRect;
   bkgndRect.x = 0;
   bkgndRect.y = 0;
   bkgndRect.width = mWidth;
   bkgndRect.height = mHeight;

   memDC.SetBrush( *wxWHITE_BRUSH );
   memDC.SetPen( *wxBLACK_PEN );
   memDC.DrawRectangle( bkgndRect );

   //box dimensions
   mBoxWidth = mWidth / 6;

   mTrackHeight = ( mHeight * 3 ) / ( mMixerSpec->GetNumTracks() * 4 );
   if( mTrackHeight > 30 )
      mTrackHeight = 30;

   mChannelHeight = ( mHeight * 3 ) / ( mMixerSpec->GetNumChannels() * 4 );
   if( mChannelHeight > 30 )
      mChannelHeight = 30;

   static double PI = 2 * acos( 0.0 );
   double angle = atan( ( 3.0 * mHeight ) / mWidth );
   double radius = mHeight / ( 2.0 * sin( PI - 2.0 * angle ) );
   double totAngle = ( asin( mHeight / ( 2.0 * radius ) ) * 2.0 );

   //draw tracks
   memDC.SetBrush( AColor::envelopeBrush );
   angle = totAngle / ( mMixerSpec->GetNumTracks() + 1 );

   int max = 0, w, h;
   for( unsigned int i = 1; i < mMixerSpec->GetNumTracks(); i++ )
      if( mTrackNames[ i ].length() > mTrackNames[ max ].length() )
         max = i;

   SetFont( memDC, mTrackNames[ max ], mBoxWidth, mTrackHeight );

   for( unsigned int i = 0; i < mMixerSpec->GetNumTracks(); i++ )
   {
      mTrackRects[ i ].x = (int)( mBoxWidth * 2 + radius - radius *
         cos( totAngle / 2.0 - angle * ( i + 1 ) ) - mBoxWidth + 0.5 );
      mTrackRects[ i ].y = (int)( mHeight * 0.5 - radius *
            sin( totAngle * 0.5 - angle * ( i + 1.0 ) ) -
            0.5 * mTrackHeight + 0.5 );

      mTrackRects[ i ].width = mBoxWidth;
      mTrackRects[ i ].height = mTrackHeight;

      memDC.SetPen( mSelectedTrack == (int)i ? *wxRED_PEN : *wxBLACK_PEN );
      memDC.DrawRectangle( mTrackRects[ i ] );

      memDC.GetTextExtent( mTrackNames[ i ], &w, &h );
      memDC.DrawText( mTrackNames[ i ],
            mTrackRects[ i ].x + ( mBoxWidth - w ) / 2,
            mTrackRects[ i ].y + ( mTrackHeight - h ) / 2 );
   }

   //draw channels
   memDC.SetBrush( AColor::playRegionBrush[ 0 ] );
   angle = ( asin( mHeight / ( 2.0 * radius ) ) * 2.0 ) /
      ( mMixerSpec->GetNumChannels() + 1 );

   SetFont( memDC, wxT( "Channel: XX" ), mBoxWidth, mChannelHeight );
   memDC.GetTextExtent( wxT( "Channel: XX" ), &w, &h );

   for( unsigned int i = 0; i < mMixerSpec->GetNumChannels(); i++ )
   {
      mChannelRects[ i ].x = (int)( mBoxWidth * 4 - radius  + radius *
         cos( totAngle * 0.5 - angle * ( i + 1 ) ) + 0.5 );
      mChannelRects[ i ].y = (int)( mHeight * 0.5 - radius *
            sin( totAngle * 0.5 - angle * ( i + 1 ) ) -
            0.5 * mChannelHeight + 0.5 );

      mChannelRects[ i ].width = mBoxWidth;
      mChannelRects[ i ].height = mChannelHeight;

      memDC.SetPen( mSelectedChannel == (int)i ? *wxRED_PEN : *wxBLACK_PEN );
      memDC.DrawRectangle( mChannelRects[ i ] );

      memDC.DrawText( wxString::Format( _( "Channel: %2d" ), i + 1 ),
            mChannelRects[ i ].x + ( mBoxWidth - w ) / 2,
            mChannelRects[ i ].y + ( mChannelHeight - h ) / 2 );
   }

   //draw links
   memDC.SetPen( wxPen( *wxBLACK, mHeight / 200 ) );
   for( unsigned int i = 0; i < mMixerSpec->GetNumTracks(); i++ )
      for( unsigned int j = 0; j < mMixerSpec->GetNumChannels(); j++ )
         if( mMixerSpec->mMap[ i ][ j ] )
            AColor::Line(memDC, mTrackRects[ i ].x + mBoxWidth,
                  mTrackRects[ i ].y + mTrackHeight / 2, mChannelRects[ j ].x,
                  mChannelRects[ j ].y + mChannelHeight / 2 );

   dc.Blit( 0, 0, mWidth, mHeight, &memDC, 0, 0, wxCOPY, FALSE );
}

double ExportMixerPanel::Distance( wxPoint &a, wxPoint &b )
{
   return sqrt( pow( a.x - b.x, 2.0 ) + pow( a.y - b.y, 2.0 ) );
}

//checks if p is on the line connecting la, lb with tolerence
bool ExportMixerPanel::IsOnLine( wxPoint p, wxPoint la, wxPoint lb )
{
   return Distance( p, la ) + Distance( p, lb ) - Distance( la, lb ) < 0.1;
}

void ExportMixerPanel::OnMouseEvent(wxMouseEvent & event)
{
   if( event.ButtonDown() )
   {
      bool reset = true;
      //check tracks
      for( unsigned int i = 0; i < mMixerSpec->GetNumTracks(); i++ )
         if( mTrackRects[ i ].Contains( event.m_x, event.m_y ) )
         {
            reset = false;
            if( mSelectedTrack == (int)i )
               mSelectedTrack = -1;
            else
            {
               mSelectedTrack = i;
               if( mSelectedChannel != -1 )
                  mMixerSpec->mMap[ mSelectedTrack ][ mSelectedChannel ] =
                     !mMixerSpec->mMap[ mSelectedTrack ][ mSelectedChannel ];
            }
            goto found;
         }

      //check channels
      for( unsigned int i = 0; i < mMixerSpec->GetNumChannels(); i++ )
         if( mChannelRects[ i ].Contains( event.m_x, event.m_y ) )
         {
            reset = false;
            if( mSelectedChannel == (int)i )
               mSelectedChannel = -1;
            else
            {
               mSelectedChannel = i;
               if( mSelectedTrack != -1 )
                  mMixerSpec->mMap[ mSelectedTrack ][ mSelectedChannel ] =
                     !mMixerSpec->mMap[ mSelectedTrack ][ mSelectedChannel ];
            }
            goto found;
         }

      //check links
      for( unsigned int i = 0; i < mMixerSpec->GetNumTracks(); i++ )
         for( unsigned int j = 0; j < mMixerSpec->GetNumChannels(); j++ )
            if( mMixerSpec->mMap[ i ][ j ]  && IsOnLine( wxPoint( event.m_x,
                        event.m_y ), wxPoint( mTrackRects[ i ].x + mBoxWidth,
                           mTrackRects[ i ].y + mTrackHeight / 2 ),
                     wxPoint( mChannelRects[ j ].x, mChannelRects[ j ].y +
                     mChannelHeight / 2 ) ) )
               mMixerSpec->mMap[ i ][ j ] = false;

found:
      if( reset )
         mSelectedTrack = mSelectedChannel = -1;
      Refresh( false );
   }
}

//----------------------------------------------------------------------------
// ExportMixerDialog
//----------------------------------------------------------------------------

enum
{
   ID_MIXERPANEL = 10001,
   ID_SLIDER_CHANNEL
};

BEGIN_EVENT_TABLE( ExportMixerDialog, wxDialogWrapper )
   EVT_BUTTON( wxID_OK, ExportMixerDialog::OnOk )
   EVT_BUTTON( wxID_CANCEL, ExportMixerDialog::OnCancel )
   EVT_BUTTON( wxID_HELP, ExportMixerDialog::OnMixerPanelHelp )
   EVT_SIZE( ExportMixerDialog::OnSize )
   EVT_SLIDER( ID_SLIDER_CHANNEL, ExportMixerDialog::OnSlider )
END_EVENT_TABLE()

ExportMixerDialog::ExportMixerDialog( const TrackList *tracks, bool selectedOnly,
      unsigned maxNumChannels, wxWindow *parent, wxWindowID id, const TranslatableString &title,
      const wxPoint &position, const wxSize& size, long style ) :
   wxDialogWrapper( parent, id, title, position, size, style | wxRESIZE_BORDER )
{
   SetName();

   unsigned numTracks = 0;

   bool anySolo = !(( tracks->Any<const WaveTrack>() + &WaveTrack::GetSolo ).empty());

   for (auto t :
         tracks->Any< const WaveTrack >()
            + ( selectedOnly ? &Track::IsSelected : &Track::Any  )
            - ( anySolo ? &WaveTrack::GetNotSolo :  &WaveTrack::GetMute)
   ) {
      numTracks++;
      const wxString sTrackName = (t->GetName()).Left(20);
      if( t->GetChannel() == Track::LeftChannel )
      /* i18n-hint: track name and L abbreviating Left channel */
         mTrackNames.push_back( wxString::Format( _( "%s - L" ), sTrackName ) );
      else if( t->GetChannel() == Track::RightChannel )
      /* i18n-hint: track name and R abbreviating Right channel */
         mTrackNames.push_back( wxString::Format( _( "%s - R" ), sTrackName ) );
      else
         mTrackNames.push_back(sTrackName);
   }

   // JKC: This is an attempt to fix a 'watching brief' issue, where the slider is
   // sometimes not slidable.  My suspicion is that a mixer may incorrectly
   // state the number of channels - so we assume there are always at least two.
   // The downside is that if someone is exporting to a mono device, the dialog
   // will allow them to output to two channels. Hmm.  We may need to revisit this.

   if (maxNumChannels < 2 )
      // STF (April 2016): AMR (narrowband) and MP3 may export 1 channel.
      // maxNumChannels = 2;
      maxNumChannels = 1;
   if (maxNumChannels > 32)
      maxNumChannels = 32;

   mMixerSpec = std::make_unique<MixerSpec>(numTracks, maxNumChannels);

   auto label = XO("Output Channels: %2d")
      .Format( mMixerSpec->GetNumChannels() );

   ShuttleGui S{ this, eIsCreating };
   {
      S.SetBorder( 5 );

      auto mixerPanel = safenew ExportMixerPanel(
         S.GetParent(), ID_MIXERPANEL, mMixerSpec.get(),
         mTrackNames, wxDefaultPosition, wxSize(400, -1));
      S.Prop(1)
         .Name(XO("Mixer Panel"))
         .Position(wxEXPAND | wxALL)
         .AddWindow(mixerPanel);

      S.StartHorizontalLay(wxALIGN_CENTRE | wxALL, 0);
      {
         mChannelsText = S.AddVariableText(
            label,
            false, wxALIGN_LEFT | wxALL );

         S
            .Id(ID_SLIDER_CHANNEL)
            .Name(label)
            .Size({300, -1})
            .Style(wxSL_HORIZONTAL)
            .Position(wxEXPAND | wxALL)
            .AddSlider( {},
               mMixerSpec->GetNumChannels(),
               mMixerSpec->GetMaxNumChannels(), 1 );
      }
      S.EndHorizontalLay();

      S.AddStandardButtons( eCancelButton | eOkButton | eHelpButton );
   }

   SetAutoLayout(true);
   GetSizer()->Fit( this );
   GetSizer()->SetSizeHints( this );

   SetSizeHints( 640, 480, 20000, 20000 );

   SetSize( 640, 480 );
   Center();
}

ExportMixerDialog::~ExportMixerDialog()
{
}

void ExportMixerDialog::OnSize(wxSizeEvent &event)
{
   ExportMixerPanel *pnl = ( ( ExportMixerPanel* ) FindWindow( ID_MIXERPANEL ) );
   pnl->Refresh( false );
   event.Skip();
}

void ExportMixerDialog::OnSlider( wxCommandEvent & WXUNUSED(event))
{
   wxSlider *channels = ( wxSlider* )FindWindow( ID_SLIDER_CHANNEL );
   ExportMixerPanel *pnl = ( ( ExportMixerPanel* ) FindWindow( ID_MIXERPANEL ) );
   mMixerSpec->SetNumChannels( channels->GetValue() );
   pnl->Refresh( false );
   wxString label;
   label.Printf( _( "Output Channels: %2d" ), mMixerSpec->GetNumChannels() );
   mChannelsText->SetLabel( label );
   channels->SetName( label );
}

void ExportMixerDialog::OnOk(wxCommandEvent & WXUNUSED(event))
{
   EndModal( wxID_OK );
}

void ExportMixerDialog::OnCancel(wxCommandEvent & WXUNUSED(event))
{
   EndModal( wxID_CANCEL );
}

void ExportMixerDialog::OnMixerPanelHelp(wxCommandEvent & WXUNUSED(event))
{
   HelpSystem::ShowHelp(this, wxT("Advanced_Mixing_Options"), true);
}

