#ifndef __DRCPHOTON_H__
#define __DRCPHOTON_H__



//! A namespace for encapsulation.
namespace Drc
{
  /*! \enum Drc::PhotonFate
    An enum holding the fate of a photon. */
  enum PhotonFate
    {
      //!                                         Photon is still propagating
      PhotFlying,                        
      //!                                         Photon has hit measuring device.
      PhotMeasured,                      
      //!                                         Photon got lost outside. 
      PhotLost,                           
      //!                                         Photon got lost inside.
      PhotAbsorbed                       
    };
}

class DrcOptDev;


/*! 
  \brief Representation of a photon. 
*/
class DrcPhoton
{
 private:
  //!                                             Wavelength in nm.
  double          m_lambda;             
  //!                                             Actual position of photon.
  XYZPoint        m_position;           
  //!                                             Old position of photon.
  XYZPoint        m_positionOld;        
  //!                                             Normalized direction of photon.
  XYZVector       m_direction;          
  //!                                             The fate of the photon.
  Drc::PhotonFate m_fate;               
  //!                                             Number of suffered reflections.
  int             m_reflections;        
  //!                                             Verbosity level 0-5.
  int             m_verbosity;          
  //!                                             Pointer to device where photon is.
  DrcOptDev*      m_dev;                
  //!                                             Time of flight.
  double          m_time;               

 public:

  //! Empty constructor.
  DrcPhoton();                          

  //! Destructor.
  virtual ~DrcPhoton(){};               


  /*! \brief Verbosity

  Set the verbosity. Range is 0 to 5. 
  \verbatim
  0=quiet, 
  1=constructors,destructors,
  2=member functions, 
  3=functionality
  4=photons
  5=everything
  \endverbatim
  \param level The verbosity level
  */
  void setVerbosity(int level){m_verbosity=level;};

  /*! \brief Verbosity.
    \return Verbosity
    \sa setVerbosity()
  */
  const int verbosity() const {return m_verbosity;};

  /*! \brief Set fate of photon
    \param fate The fate
    \sa Drc::PhotonFate
  */
  void setFate(Drc::PhotonFate fate) {m_fate=fate;};
  /*! \brief Fate of photon
    \return The fate
    \sa Drc::PhotonFate
  */
  const Drc::PhotonFate fate() const {return m_fate;};

  /*! \brief Reflections
    \return Reflections.
  */
  int reflections() const {return m_reflections;};



  /*! \brief Position
    \return Position.
  */
  XYZPoint position() const {return m_position;};
  /*! \brief Set position
    \param pos Position.
  */
  void setPosition(const XYZPoint& pos);

  /*! \brief Direction
    \return Normalized direction.
  */
  XYZVector direction() const {return m_direction;};
  /*! \brief Set normalized direction
    \param dir Direction.
  */
  void setDirection(const XYZVector& dir) {m_direction=dir.Unit();};

  /*! \brief Wavelength
    \return Wavelength in nm.
  */
  double wavelength() const {return m_lambda;};
 /*! \brief Set wavelength
  \param lambda Wavelength in nm.
  */
  void setWavelength(double lambda){m_lambda=lambda;};

  /*! \brief Device where photon is
    \return Device.
  */
  DrcOptDev* device() const {return m_dev;};
 /*! \brief Set device where photon is
  \param dev The device.
  */
  void setDevice(DrcOptDev* dev){m_dev=dev;};


  /*! \brief Time of flight for photon
    \return Time of flight in [ns].
  */
  double time() const {return m_time;};
 /*! \brief Set time of photon
  \param tim The time.
  */
  void setTime(double tim){m_time=tim;};




  /*! \brief Reflect the photon
    \param normal The normal vector of the surface.
  */
  void reflect(const XYZVector& normal);


  /*! \brief Write photon coordinates to stream in root syntax.
    \param stream The stream.
  */
  void print(fstream& stream) const;

  //! Write photon properties to cout.
  void print() const;

  /*! \brief Color number for usage in root
    \param lambda The wavelength in nm.
    \return Color number.
  */
  int colorNumber(double lambda) const;

};
#endif