////////////////////////////////////////////////////////////////////////
/// \class RAT::Noise
///
/// \brief   Generates noise
///
/// \author P G Jones <p.g.jones@qmul.ac.uk>
/// \author Josh Klein <jrk@hep.upenn.edu> -- contact person
/// \author Gabriel Orebi Gann <gorebigann@lbl.gov> -- contact person
///
/// REVISION HISTORY:\n
///     21/03/2012 : P G Jones - New file. Code from Gsim, GOG & JK.
///     13/05/2015 : W Heintzelman - make ENoiseModel public
///     09/07/2015 : GDOG - Update noise DB tables, and correct noise to be
///                  generated for online, normal+OWL channels only (OWL optional)
///
/// \details Generates noise hits. Noise can either be generated given a
///         detector wide rate or a per channel rate.
///
////////////////////////////////////////////////////////////////////////

#ifndef __RAT_Noise_hh__
#define __RAT_Noise_hh__

#include <vector>

namespace RAT
{

namespace DS
{
  class MCPMT;
  class MCPE;
}

class Noise
{
public:
  Noise();
  ~Noise();

  /// This method initializes the settings from the ratdb
  void BeginOfRun();
  /// Generate noise hits for the MC event
  void GenerateNoise();
  /// Noise generation models, no-noise, use detector average or per channel rates
  enum ENoiseModel { eNoNoise = 0, eAverageNoise = 1, ePerChannelNoise = 2 };
  /// Noise table to use for average/individual noise rate
  enum ENoiseTable { eRunLevelTable = 0, eIntegratedTable = 1 };

protected:
  /// Generate noise based on the available PMT hits.
  void GenerateNoiseFromPMTHits(const std::vector<DS::MCPMT*>& pmtHits);

  /// Generate noise hits in a certain time window
  void GenerateNoiseInWindow( double windowStart, ///< Start MC time in ns
                              double windowEnd ); ///< End MC time in ns

  /// Generate noise using the detector average rate model
  void GenerateAverageNoise( const double windowStart,
                             const double windowEnd );

  /// Generate noise using the per channel rate model
  void GeneratePerChannelNoise( const double windowStart,
                                const double windowEnd );

  /// Generate a noise hit on a channel
  void GenerateNoiseHit( const int lcn,
                         const double windowStart,
                         const double windowEnd );

  /// Detect photoelectron at a given PMT and modify hits.
  virtual void DetectPhotoelectron( const unsigned int pmtID,
                                    DS::MCPE& photoelectron );

  std::vector<double> fChannelRate; ///< Noise rates per channel (lcn)
  double fTriggerWindow; ///< Length of the trigger window in ns
  double fNoiseRate; ///< Average noise rate in hits per ns
  bool fNoiseGroupFlag; ///< True if noise should be generated around groups of hits only
  double fNoiseTEarly; ///< Times before  a hit group where noise will be added.
  double fNoiseTLate; ///< Times after a hit group where noise will be added.
  ENoiseModel fNoiseFlag; ///< Noise generation model to use
  ENoiseTable fTableFlag; ///< Noise table to use
  int fNumChannels; ///< Number of daq channels
  double fDefaultWindowStart; ///< Default window start time in ns
  double fDefaultWindowEnd; ///< Default window end time in ns
  double fAveChanEff; ///< Average channel efficiency
  int fOWLnoise; ///< Flag for whether to generate noise on OWLs
};

}// ::RAT

#endif