// PropDispatch.h

#ifndef PropDispatch_H
#define PropDispatch_H

// This is propagator dispatcher.  Propagators are registered for each
// pair of intial and final surface types.  The appropriate propagator
// is then invoked when any of the usual propagator methods are called.
//
// Objstream example:
//
// [ propd PropDispatch
//   begin_surfs = string( "SurfCyl" "SurfCyl" "SurfDCA" )
//     end_surfs = string( "SurfCyl" "SurfDCA" "SurfCyl" )
//        propagators = @(    propc    propcd    propdc  )
// ]

#include "Propagator.h"
#include <map>
#include "ptr/Ptr.h"
#include "ptr/NullPolicy.h"
#include "PropagatorPtr.h"

namespace trf {

class PropDispatch : public Propagator {

private:  // typedefs

  // A pair of surface types.
  typedef std::pair<Type,Type> TypePair;

  // Comparator for surface type pairs.
  typedef std::less<TypePair> Cmp;

  // Map of propagators indexed by surface type pairs.
  typedef std::map<TypePair,PropagatorPtr,Cmp> PropMap;

public:  // static methods

  // Return the type name.
  static TypeName get_type_name() { return "PropDispatch"; }

  // Return the creator.
  static ObjCreator get_creator();

  // Return the type.
  static Type get_static_type() { return get_creator(); }

private:  // attributes

  // map of propagators
  PropMap _props;

private:  // methods

  // output stream
  void ostr(std::ostream& stream) const;

public:  // methods

  // constructor
  PropDispatch();

  // destructor
  ~PropDispatch();

  // Return the type.
  Type get_type() const { return get_static_type(); }

  // Write object data.
  ObjData write_data() const;

  // register a propagator
  // return nonzero for error (e.g. surface pair already used)
  int add_propagator(Type stype1, Type stype2, const PropagatorPtr& pprop);

  // Return the number of registrations.
  int get_propagator_count() const;

  // Return the propagator for a specified pair of surfaces.
  const PropagatorPtr& get_propagator(Type stype1, Type stype2) const;

  // Clone, i.e. create a copy on the free store.
  Propagator* new_propagator() const;

  // propagate a track without error
  PropStat vec_prop(VTrack& trv, const Surface& srf,
                    TrackDerivative* pder =0) const;

  // propagate a track without error in the specified direction
  PropStat vec_dir_prop( VTrack& trv, const Surface& srf,
                         PropDir dir, TrackDerivative* pder =0 ) const;

  // propagate a track with error
  PropStat err_prop(ETrack& trv, const Surface& srf,
                    TrackDerivative* pder =0) const;

  // propagate a track with error in the specified direction
  PropStat err_dir_prop(ETrack& trv, const Surface& srf, PropDir dir,
                        TrackDerivative* pder =0) const;

};

}  // end namespace trf

#endif