#ifndef __FPA__BASE__DIJKSTRA__H__
#define __FPA__BASE__DIJKSTRA__H__

#include <vector>
#include <fpa/Base/Algorithm.h>

namespace fpa
{
  namespace Base
  {
    /**
     * Dijkstra is a front propagation algorithm that minimizes costs
     *
     * @param V  Vertex type.
     * @param C  Vertex value type.
     * @param R  Result value type.
     * @param VC Vertex lexicographical compare.
     * @param B  Base class for this algorithm. It should be any itk-based
     *           filter (itk::ProcessObject).
     *
     */
    template< class V, class C, class R, class VC, class B >
    class Dijkstra
      : public Algorithm< V, C, R, VC, B >
    {
    public:
      typedef Dijkstra                         Self;
      typedef Algorithm< V, C, R, VC, B >      Superclass;
      typedef itk::SmartPointer< Self >        Pointer;
      typedef itk::SmartPointer< const Self >  ConstPointer;

      typedef typename Superclass::TVertex        TVertex;
      typedef typename Superclass::TValue         TValue;
      typedef typename Superclass::TResult        TResult;
      typedef typename Superclass::TVertexCompare TVertexCompare;

      typedef typename Superclass::TStartEvent     TStartEvent;
      typedef typename Superclass::TStartLoopEvent TStartLoopEvent;
      typedef typename Superclass::TEndEvent       TEndEvent;
      typedef typename Superclass::TEndLoopEvent   TEndLoopEvent;
      typedef typename Superclass::TAliveEvent     TAliveEvent;
      typedef typename Superclass::TFrontEvent     TFrontEvent;
      typedef typename Superclass::TFreezeEvent    TFreezeEvent;

      typedef typename Superclass::TStartBacktrackingEvent TStartBacktrackingEvent;
      typedef typename Superclass::TEndBacktrackingEvent TEndBacktrackingEvent;
      typedef typename Superclass::TBacktrackingEvent TBacktrackingEvent;

    protected:
      typedef typename Superclass::_TVertices      _TVertices;
      typedef typename Superclass::_TCollision     _TCollision;
      typedef typename Superclass::_TCollisionsRow _TCollisionsRow;
      typedef typename Superclass::_TCollisions    _TCollisions;
      typedef typename Superclass::_TNode          _TNode;
      typedef typename Superclass::_TNodes         _TNodes;

      struct _TQueueNode
      {
        TVertex Vertex;
        _TNode  Node;

        // Make the min-heap behave as a max-heap
        bool operator<( const _TQueueNode& other ) const
          { return( other.Node.Result < this->Node.Result ); }
      };
      typedef std::vector< _TQueueNode > _TQueue;

    public:
      itkTypeMacro( Dijkstra, Algorithm );

    protected:
      Dijkstra( );
      virtual ~Dijkstra( );

      virtual TResult _Cost( const TVertex& v, const TVertex& p ) const = 0;

      // Results-related abstract methods
      virtual bool _ComputeNeighborResult(
        TResult& result, const TVertex& neighbor, const TVertex& parent
        ) const;

      // Queue-related abstract methods
      virtual bool _IsQueueEmpty( ) const;
      virtual void _QueuePush( const TVertex& v, const _TNode& n );
      virtual void _QueuePop( TVertex& v, _TNode& n );
      virtual void _QueueClear( );

    private:
      // Purposely not implemented
      Dijkstra( const Self& other );
      Self& operator=( const Self& other );

    protected:
      _TQueue m_Queue;
    };

  } // ecapseman

} // ecapseman

#include <fpa/Base/Dijkstra.hxx>

#endif // __FPA__BASE__DIJKSTRA__H__

// eof - $RCSfile$