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

 Audacity: A Digital Audio Editor

 SelectionState.h

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

#include "Audacity.h"
#include "SelectionState.h"

#include "ViewInfo.h"
#include "Track.h"
#include "Project.h"

static const AudacityProject::AttachedObjects::RegisteredFactory key{
  [](AudacityProject &){ return std::make_shared< SelectionState >(); }
};

SelectionState &SelectionState::Get( AudacityProject &project )
{
   return project.AttachedObjects::Get< SelectionState >( key );
}

const SelectionState &SelectionState::Get( const AudacityProject &project )
{
   return Get( const_cast< AudacityProject & >( project ) );
}

// Set selection length to the length of a track -- but if sync-lock is turned
// on, use the largest possible selection in the sync-lock group.
// If it's a stereo track, do the same for the stereo channels.
void SelectionState::SelectTrackLength
( ViewInfo &viewInfo, Track &track, bool syncLocked )
{
   auto trackRange = syncLocked
   // If we have a sync-lock group and sync-lock linking is on,
   // check the sync-lock group tracks.
   ? TrackList::SyncLockGroup(&track)

   // Otherwise, check for a stereo pair
   : TrackList::Channels(&track);

   auto minOffset = trackRange.min( &Track::GetOffset );
   auto maxEnd = trackRange.max( &Track::GetEndTime );

   // PRL: double click or click on track control.
   // should this select all frequencies too?  I think not.
   viewInfo.selectedRegion.setTimes(minOffset, maxEnd);
}

void SelectionState::SelectTrack(
   Track &track, bool selected, bool updateLastPicked )
{
   //bool wasCorrect = (selected == track.GetSelected());

   for (auto channel : TrackList::Channels(&track))
      channel->SetSelected(selected);

   if (updateLastPicked)
      mLastPickedTrack = track.SharedPointer();

//The older code below avoids an anchor on an unselected track.

   /*
   if (selected) {
      // This handles the case of linked tracks, selecting all channels
      mTracks->Select(pTrack, true);
      if (updateLastPicked)
         mLastPickedTrack = Track::Pointer( pTrack );
   }
   else {
      mTracks->Select(pTrack, false);
      if (updateLastPicked && pTrack == mLastPickedTrack.lock().get())
         mLastPickedTrack.reset();
   }
*/
}

void SelectionState::SelectRangeOfTracks
( TrackList &tracks, Track &rsTrack, Track &reTrack )
{
   Track *sTrack = &rsTrack, *eTrack = &reTrack;
   // Swap the track pointers if needed
   if (eTrack->GetIndex() < sTrack->GetIndex())
      std::swap(sTrack, eTrack);

   for (auto track :
        tracks.Any().StartingWith(sTrack).EndingAfter(eTrack))
      SelectTrack(*track, true, false);
}

void SelectionState::SelectNone( TrackList &tracks )
{
   for (auto t : tracks.Any())
      SelectTrack( *t, false, false );
}

void SelectionState::ChangeSelectionOnShiftClick
( TrackList &tracks, Track &track )
{
   // We will either extend from the first or from the last.
   auto pExtendFrom = tracks.Lock(mLastPickedTrack);

   if( !pExtendFrom ) {
      auto trackRange = tracks.Selected();
      auto pFirst = *trackRange.begin();

      // If our track is at or after the first, extend from the first.
      if( pFirst && track.GetIndex() >= pFirst->GetIndex() )
         pExtendFrom = pFirst->SharedPointer();

      // Our track was earlier than the first.  Extend from the last.
      if( !pExtendFrom )
         pExtendFrom = Track::SharedPointer( *trackRange.rbegin() );
   }

   SelectNone( tracks );
   if( pExtendFrom )
      SelectRangeOfTracks( tracks, track, *pExtendFrom );
   else
      SelectTrack( track, true, true );
   mLastPickedTrack = pExtendFrom;
}

void SelectionState::HandleListSelection
( TrackList &tracks, ViewInfo &viewInfo,
  Track &track, bool shift, bool ctrl, bool syncLocked )
{
   // AS: If the shift button is being held down, invert
   //  the selection on this track.
   if (ctrl)
      SelectTrack( track, !track.GetSelected(), true );
   else {
      if (shift && mLastPickedTrack.lock())
         ChangeSelectionOnShiftClick( tracks, track );
      else {
         SelectNone( tracks );
         SelectTrack( track, true, true );
         SelectTrackLength( viewInfo, track, syncLocked );
      }
   }
}

SelectionStateChanger::SelectionStateChanger
( SelectionState &state, TrackList &tracks )
   : mpState{ &state }
   , mTracks{ tracks }
   , mInitialLastPickedTrack{ state.mLastPickedTrack }
{
   // Save initial state of track selections
   mInitialTrackSelection.clear();
   for (const auto track : tracks.Any()) {
      const bool isSelected = track->GetSelected();
      mInitialTrackSelection.push_back(isSelected);
   }
}

SelectionStateChanger::~SelectionStateChanger()
{
   if ( mpState ) {
      // roll back changes
      mpState->mLastPickedTrack = mInitialLastPickedTrack;
      std::vector<bool>::const_iterator
         it = mInitialTrackSelection.begin(),
         end = mInitialTrackSelection.end();

      for (auto track : mTracks.Any()) {
         if (it == end)
            break;
         track->SetSelected( *it++ );
      }
   }
}

void SelectionStateChanger::Commit()
{
   mpState = nullptr;
}