// =========================================================================
// @author Leonardo Florez Valencia
// @email florez-l@javeriana.edu.co
// =========================================================================

#ifndef __fpa__Image__RandomWalker__hxx__
#define __fpa__Image__RandomWalker__hxx__

#include <sstream>

#include <itkImageRegionConstIteratorWithIndex.h>
#include <itkExceptionObject.h>

#include <fpa/Image/Functors/Dijkstra/Gaussian.h>

// -------------------------------------------------------------------------
template< class _TInputImage, class _TLabelImage, class _TScalar >
itk::ModifiedTimeType
fpa::Image::RandomWalker< _TInputImage, _TLabelImage, _TScalar >::
GetMTime( ) const
{
  const TLabelImage* labels = this->GetLabels( );
  itk::ModifiedTimeType t = this->Superclass::GetMTime( );
  if( labels != NULL )
  {
    itk::ModifiedTimeType q = labels->GetMTime( );
    t = ( q < t )? q: t;

  } // fi
  return( t );
}

// -------------------------------------------------------------------------
template< class _TInputImage, class _TLabelImage, class _TScalar >
fpa::Image::RandomWalker< _TInputImage, _TLabelImage, _TScalar >::
RandomWalker( )
  : Superclass( )
{
  typedef fpa::Image::Functors::Dijkstra::Gaussian< TInputImage, TScalar > _TDefaultFunction;
  this->SetWeightFunction( _TDefaultFunction::New( ) );
}

// -------------------------------------------------------------------------
template< class _TInputImage, class _TLabelImage, class _TScalar >
fpa::Image::RandomWalker< _TInputImage, _TLabelImage, _TScalar >::
~RandomWalker( )
{
}

// -------------------------------------------------------------------------
template< class _TInputImage, class _TLabelImage, class _TScalar >
void fpa::Image::RandomWalker< _TInputImage, _TLabelImage, _TScalar >::
_BeforeGenerateData( )
{
  this->Superclass::_BeforeGenerateData( );
  TWeightFunction* wf =
    dynamic_cast< TWeightFunction* >( this->GetWeightFunction( ) );
  if( wf != NULL )
    wf->SetImage( this->GetInput( ) );
}

// -------------------------------------------------------------------------
template< class _TInputImage, class _TLabelImage, class _TScalar >
void fpa::Image::RandomWalker< _TInputImage, _TLabelImage, _TScalar >::
_QueueInit( )
{
  this->m_Seeds.clear( );
  const TLabelImage* lbl = this->GetLabels( );
  if( lbl == NULL )
  {
    std::ostringstream msg;
    msg << "itk::ERROR: fpa::Image::RandomWalker (" << this
        << "): Labelled image not defined.";
    ::itk::ExceptionObject e(
      __FILE__, __LINE__, msg.str( ).c_str( ), ITK_LOCATION
      );
    throw e;

  } // fi

  // Iterate over labels
  typename TLabelImage::RegionType reg = lbl->GetRequestedRegion( );
  itk::ImageRegionConstIteratorWithIndex< TLabelImage > lIt( lbl, reg );
  for( lIt.GoToBegin( ); !lIt.IsAtEnd( ); ++lIt )
  {
    if( lIt.Get( ) > 0 )
    {
      bool is_seed = false;
      for( unsigned int d = 0; d < TLabelImage::ImageDimension; ++d )
      {
        for( int s = -1; s <= 1; s += 2 )
        {
          TVertex neigh = lIt.GetIndex( );
          neigh[ d ] += s;
          is_seed |= ( lbl->GetPixel( neigh ) == 0 );

        } // rof

      } // rof

      typename TSeedsInterface::TNode node;
      node.Vertex = lIt.GetIndex( );
      node.Parent = lIt.GetIndex( );
      node.FrontId = lIt.Get( );
      node.Value = TScalar( 0 );
      if( !is_seed )
      {
        this->_Mark( lIt.GetIndex( ), lIt.Get( ) );
        this->_UpdateOutputValue( node );
      }
      else
        this->m_Seeds.insert( node );

    } // fi

  } // rof

  // Ok, finish initialization
  this->Superclass::_QueueInit( );
}

#endif // __fpa__Image__RandomWalker__hxx__

// eof - $RCSfile$