#ifndef IRESAMPLER_HXX
#define IRESAMPLER_HXX
/// G4
#include "G4String.hh"
/// ICEDUST
#include "ICOMETEvent.hxx"
#include "IRooTrackerFile.hxx"

/// IResampler: backward sampling functionalities using the GOUPIL/PUMAS backend
/// 
/// This class uses Geant4 to calculate step sizes in the geometry and EM field and
/// passes the information down to GOUPIL to compute the rate of each input event.

class G4RunManager;
class PrimaryGenerator;
class StackingAction;

class IResampler {
public:
    /// Constructor arguments:
    /// geometryMacro: name of the master geometry macro, e.g. Phase-I-CyDet.macro, 
    ///         Phase-II.macro
    /// fieldmapDirectory: directory of the fieldmap. If empty, the directory pointed
    ///         to by the ICEDUST_FIELDMAPS environment variable will be used
    /// nResamplings: number of backward MC propagations to perform to estimate the
    ///         flux of each primary particle.
    /// outputDebugData: whether to output backward stepping information to a csv
    ///         file as we perform the backward propagation.
    IResampler(const std::string& geometryMacro, const std::string& fieldmapDirectory,
            int nResamplings, bool detailedTransport, bool outputDebugData);
    ~IResampler();

    /// Computes the flux of a primary event by backward Monte Carlo
    /// propagation to an atmospheric flux distribution.
    void ComputeFlux(COMET::ICOMETEvent& event, 
            COMET::IHandle<COMET::IRooTrackerFile> output);

private:
    G4RunManager* fRunManager;
    PrimaryGenerator* fPrimaryGenerator;
    StackingAction* fStackingAction;
    /// Number of backward samplings to perform per primary event to evaluate the
    /// average flux.
    int fNResamplings;
    /// Vector of flux values stored over resamplings for each primary event.
    std::vector<double> fFluxVector;
};

#endif