////////////////////////////////////////////////////////////////////////
/// \class RAT::PMTTransitTime
///
/// \brief   Calculates front end time for a given hit (photoelectron) time
///
/// \author P G Jones <p.g.jones@qmul.ac.uk>
/// \author Gabriel Orebi Gann <gorebigann@lbl.gov> -- contact person
///
/// REVISION HISTORY:\n
///     2013-10-29 : P G Jones - Refactor, code from G O Gann.\n
///     2016-04-11 : W Heintzelman, add GetTimeLimits and GetIntervalProbability
///                  functions, revise comments
///     2017-10-30 : W Heintzelman -  provide for inputs either with or without
///                  cable delay to function GetIntervalProbability.
///
/// \details Adds cable delays etc.. to the hit time to give the front
/// end time.
////////////////////////////////////////////////////////////////////////
#ifndef __RAT_PMTTransitTime__
#define __RAT_PMTTransitTime__

#include <RAT/DU/PMTInfo.hh>
#include <RAT/DU/Utility.hh>

#include <vector>

namespace RAT
{

class PMTTransitTime
{
public:
  /// Singleton class instance
  inline static PMTTransitTime* Get();

  /// This method initializes the settings from the ratdb
  void BeginOfRun();

  // Calculate the front end time given the time of photoelectron creation
  double CalculateFrontEndTime( const double PETime, const unsigned int pmtID );

  // Use a different transit time distribution if we have an HQE PMT
  void isHQE( const unsigned int pmtID );

  // Return the smallest and largest possible time values, given the input
  // probability distribution from the database and the cable delay.  (The
  // smallest value can be negative.)
  void GetTimeLimits(double& smallest, double& largest);

  // Return the probability that the time returned by CalculateFrontEndTime
  // will be within the interval bounded by ta and tb (i.e., the pdf).
  // cableDelay=true to indicate that the input times ta and tb include cable
  // delay
  double GetIntervalProbability ( double ta, double tb, bool cableDelay=true);

private:
  std::vector<double> fX; ///< Sampled delay time distribution, ordinate
  std::vector<double> fY; ///< Sampled delay time distribution, abssica
  double fCableDelay; ///< The average cable delay

  std::vector<double> fX_hqe; ///< Sampled delay time distribution, ordinate
  std::vector<double> fY_hqe; ///< Sampled delay time distribution, abssica

  std::vector<double> time;
  std::vector<double> cdf;

  /// Prevent usage of methods below
  PMTTransitTime() { };
  PMTTransitTime( PMTTransitTime& );
  void operator=( PMTTransitTime& );
};

inline PMTTransitTime*
PMTTransitTime::Get()
{
  static PMTTransitTime instance;
  return &instance;
}


} // namespace RAT

#endif