// McTrack.hpp

#ifndef gtr_McTrack_H
#define gtr_McTrack_H

// This class describes a propagated Monte Carlo track.
// It is made up of a set of McTrackStates along the trajectory
// of the track.
//
// We use a set to guarantee ordering in s.
//
// The first state is the start of the trajectory (production
// or entering detector volume) and the last is the end of the
// trajectory (decay or volume exit).
//
// The VTrack's represent the changing state of the track.
//
// Users may fetch the entire set of states or may request the
// state at a specified surface.
//

#include <set>
#include <iosfwd>
#include "McTrackState.hpp"
#include "McParent.hpp"

class McTrack {

public:  // typedefs

  // Set of track states.
  typedef std::set<McTrackState> StateList;

private:  // attributes

  // Version number
  int _version;

  // List of states.
  StateList _states;

  // MC Particle Id
  // Id of the MC particle which created the states of this track
  int _mctrackid;

  // PDG particle type
  int _pdgid;

  // Particle Parentage
  // Packed word containing information about particles heritage
  int _parentword;

private:  // methods

  // Return the iterator for the first matching state.
  // Return end if there is no match.
  StateList::const_iterator find(const trf::Surface& srf) const;

public:  // methods

  // Default constructor.
  // Leaves object in invalid state.
  McTrack();

  // Constructor from a list of states, the MC Track ID, and a 
  // packed parent word (see gtrbase/McParent).
  // Size must be nonzero and all states must be valid or 
  // assertion is thrown and all states are discarded.
  McTrack(const StateList& states, int mcid, int parentword, int pdgid=13);

  // Destructor
  ~McTrack();

  // Return if object is valid (has one or more states).
  bool is_valid() const { return _states.size(); }

  // Fetch the list of states.
  const StateList& get_states() const { return _states; };

  // Return whether a surface can be matched.
  bool has_surface(const trf::Surface& srf) const;

  // Return the state for a particular surface.
  // The first match is returned.
  // Surface bounds are not required to match.
  // A reference to an invalid state is returned if the surface
  // cannot be matched.
  const McTrackState& get_state(const trf::Surface& srf) const;

  //Return the MC Id for the Track creating this track's states
  int get_mctrackid() const;

  //Return the PDG particle Id for the Track creating this track's states
  int get_pdgid() const;

  //Return the parentage of this particle
  McParent get_parent() const;

};

// Output stream.
std::ostream& operator<<(std::ostream& stream, const McTrack& rhs);

// Equality.
bool operator==(const McTrack& lhs, const McTrack& rhs);

// Inequality.
bool operator!=(const McTrack& lhs, const McTrack& rhs);

#endif