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/*
 * G4DNAIRTMoleculeEncounterStepper.hh
 *
 *  Created on: Jul 23, 2019
 *      Author: W. G. Shin
 *              J. Ramos-Mendez and B. Faddegon
*/

#pragma once

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

class G4VDNAReactionModel;
class G4DNAMolecularReactionTable;
class G4MolecularConfiguration;

class G4Molecule;

/**
 * Given a molecule G4DNAIRTMoleculeEncounterStepper 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 G4DNAIRTMoleculeEncounterStepper : public G4VITTimeStepComputer
{
public:
    G4DNAIRTMoleculeEncounterStepper();
    ~G4DNAIRTMoleculeEncounterStepper() override;
    G4DNAIRTMoleculeEncounterStepper(const G4DNAIRTMoleculeEncounterStepper&) = delete;
    G4DNAIRTMoleculeEncounterStepper& operator=(const G4DNAIRTMoleculeEncounterStepper&) = 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};
    G4ITReactionSet* fReactionSet;
    G4ITTrackHolder* fpTrackContainer;
    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;
    };
};