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//
// Class Description:
//
// A utility static class, responsable for keeping common parameters
// for all transportation processes.  These parameters can be relevant only
// to some types of particles, e.g. only stable charged particles.
//
// Constraints (creation/update):
// - It must initialized only by the master thread.
// - It should be updated before the transportation processes have been instantiated.
// Note: It can be updated only if the state of the simulation is PreInit, Init or Idle.
//
//  Only those instances of G4Transportation (and derived classes) that are created
//    *after* G4TransportationParameters will be aware of it and will copy
//    the values of its parameters.
//  (So in a multithreaded application, runs that start after this is created will obtain them.)
//
// Use: Parameters may be used in run time or at initialisation
//
// Meaning of parameters:
// - Warning   energy: below this, looping tracks can be killed without any message  
// - Important energy: between warning E and this, looping tracks will complain and die
// - Number of Trials: above 'important energy' looping tracks get this number of chances.

// Author:  J. Apostolakis Nov 2022
//          Inspired by G4EmParameters by V. Ivanchenko
// -------------------------------------------------------------------
//

#ifndef G4TransportationParameters_hh
#define G4TransportationParameters_hh

#include "globals.hh"

class G4TransportationParameters
{
public:
  static   G4TransportationParameters* Instance();

  ~G4TransportationParameters() = default;

  G4bool   SetNumberOfTrials(  G4int val );

   // All three methods below enforce the relation WarningE <= ImportantE   
  G4bool   SetWarningEnergy(   G4double val );
  G4bool   SetImportantEnergy( G4double val );
   //  If the relation fails, the methods above warn and use the new value for both.
  G4bool   SetWarningAndImportantEnergies( G4double warnE, G4double imprtE );
   //  If the relation does *not* hold, it warns and
   //     uses the smaller as the 'warning Energy'
   //     and  the larger  as the 'important energy'

  G4int    GetNumberOfTrials() const { return fNumberOfTrials; }
  G4double GetWarningEnergy() const { return fWarningEnergy; }
  G4double GetImportantEnergy() const { return fImportantEnergy; }
  G4bool   IsMagneticMomentEnabled() const { return fUseMagneticMoment; }

  G4bool   EnableUseOfMagneticMoment(G4bool useMoment=true);
   // Whether to deflect particles with force due to magnetic moment

  G4bool   SetHighLooperThresholds(); // Shortcut method - old values (meant for HEP)
  G4bool   SetIntermediateLooperThresholds();  // Intermediate values - also used as default
  G4bool   SetLowLooperThresholds();  // Set low thresholds - for low-E applications
  G4bool   SetSilenceAllLooperWarnings(G4bool val=true);
  // return value = success or failure of setting the parameter
  
  G4bool   GetSilenceAllLooperWarnings(){ return fSilenceLooperWarnings; }

  void     ReportLockError(G4String methodName, G4bool verbose= false) const;
   // Report error - in case the state of G4 is incorrect, and update methods fail
   
  // Probe whether the 'default' instance exists, without creating it
  static G4bool  Exists() { return theInstance != nullptr; } 

   // printing
  void StreamInfo(std::ostream& os) const;
  void Dump() const;
  friend std::ostream& operator<< (std::ostream& os, const G4TransportationParameters&);
   
private:
  G4TransportationParameters();
  //  Currently private - but potentially will open it up, to allow per-particle specialisation

  // void   Initialise();

  G4bool IsLocked() const;

  void   PrintWarning(G4ExceptionDescription& ed) const; 

private:
  static   G4TransportationParameters* theInstance;

  // STATE
  // Values for initialising 'loopers' parameters of Transport process
  G4double fWarningEnergy   =  -1.0;  //  Warn above this energy
  G4double fImportantEnergy =  -1.0;  //  Give a few trials above this E
  G4int    fNumberOfTrials  =    10;  //  Number of trials an important looper survives

  // Flags for use of gravity field(s) or fields which interact with the magnetic moment
  G4bool   fUseMagneticMoment = false;
  G4bool   fUseGravity        = false;

  // Flag to *Supress* all 'looper' warnings   
  G4bool   fSilenceLooperWarnings= false;  
};

#endif