//
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//
//
// Author: Mathieu Karamitros

// The code is developed in the framework of the ESA AO7146
//
// We would be very happy hearing from you, send us your feedback! :)
//
// In order for Geant4-DNA to be maintained and still open-source,
// article citations are crucial. 
// If you use Geant4-DNA chemistry and you publish papers about your software, 
// in addition to the general paper on Geant4-DNA:
//
// Int. J. Model. Simul. Sci. Comput. 1 (2010) 157–178
//
// we would be very happy if you could please also cite the following
// reference papers on chemistry:
//
// J. Comput. Phys. 274 (2014) 841-882
// Prog. Nucl. Sci. Tec. 2 (2011) 503-508 

#pragma once

#include "G4VITTimeStepComputer.hh"
#include "G4KDTreeResult.hh"
#include "G4ITTrackHolder.hh"
#include "G4ITReaction.hh"

class G4VDNAReactionModel;
class G4DNAMolecularReactionTable;
class G4MolecularConfiguration;

class G4Molecule;

/**
 * Given a molecule G4DNAMoleculeEncounterStepper will calculate for its possible reactants
 * what will be the minimum encounter time and the associated molecules.*
 *
 * This model includes dynamical time steps as explained in
 * "Computer-Aided Stochastic Modeling of the Radiolysis of Liquid Water",
 * V. Michalik, M. Begusová, E. A. Bigildeev,
 * Radiation Research, Vol. 149, No. 3 (Mar., 1998), pp. 224-236
 *
 */

class G4DNAMoleculeEncounterStepper : public G4VITTimeStepComputer
{
public:
    G4DNAMoleculeEncounterStepper();
    ~G4DNAMoleculeEncounterStepper() override;
    G4DNAMoleculeEncounterStepper(const G4DNAMoleculeEncounterStepper&) = delete;
    G4DNAMoleculeEncounterStepper& operator=(const G4DNAMoleculeEncounterStepper&) = delete;

    void Prepare() override;
    G4double CalculateStep(const G4Track&, const G4double&) override;
    G4double CalculateMinTimeStep(G4double, G4double) override;

    void SetReactionModel(G4VDNAReactionModel*);
    G4VDNAReactionModel* GetReactionModel();

    void SetVerbose(int);
    // Final time returned when reaction is available in the reaction table = 1
    // All details = 2

private:
    void InitializeForNewTrack();

    class Utils;
    void CheckAndRecordResults(const Utils&,
#ifdef G4VERBOSE
                               const G4double reactionRange,
#endif
                               G4KDTreeResultHandle&);

    G4bool fHasAlreadyReachedNullTime{false};
    const G4DNAMolecularReactionTable*& fMolecularReactionTable;
    G4VDNAReactionModel* fReactionModel{nullptr};
    G4ITTrackHolder* fpTrackContainer;
    G4ITReactionSet* fReactionSet;
    G4int fVerbose{0};

    class Utils
    {
    public:
        Utils(const G4Track& tA, const G4MolecularConfiguration* mB);
        ~Utils() = default;

        G4double GetConstant() const
        {
            return fConstant;
        }

        const G4Track& fpTrackA;
        const G4MolecularConfiguration* fpMoleculeB;
        const G4Molecule* fpMoleculeA;
        G4double fDA;
        G4double fDB;
        G4double fConstant;
    };
};