#ifndef __JAANET__JEVTWEIGHTFACTORGSEAGEN__
#define __JAANET__JEVTWEIGHTFACTORGSEAGEN__

#include "km3net-dataformat/definitions/w2list_gseagen.hh"

#include "km3net-dataformat/offline/Evt.hh"
#include "km3net-dataformat/offline/Trk.hh"

#include "JLang/JClonable.hh"
#include "JLang/JException.hh"

#include "JAAnet/JEvtWeightFactorTFormula.hh"


/**
 * \author bjung
 */

namespace JAANET {}
namespace JPP { using namespace JAANET; }

namespace JAANET {

  using JLANG::JClonable;
  

  /**
   * Implementation of reweighting factor for simulated neutrino interactions according to a specifiable ROOT TFormula.
   *
   * Note: The ROOT TFormula may assume any number of parameters, but should be restricted to\n
   *       the physical variables listed among `JEvtWeightFactorGSeaGen::variables`.\n
   *       These variables may be specified within the ROOT TFormula as 'x[\<index\>]',\n
   *       where \<index\> corresponds to the index of the desired physical variable within `JEvtWeightFactorGSeaGen::variables`.
   */
  class JEvtWeightFactorGSeaGen final :
    public JClonable<JEvtWeightFactorTFormula, JEvtWeightFactorGSeaGen>
  {
  public:
    
    /**
     * Indices of reweighting variables for GSeaGen.
     */
    enum variables {
      COSTH,                 //!< Cosine zenith angle
      INITIAL_STATE_ENERGY,  //!< Initial state energy
      NEUTRINO_ENERGY,       //!< Initial state neutrino energy
      FINAL_STATE_ENERGY,    //!< Final state energy
      LEADING_LEPTON_ENERGY, //!< Final state leading lepton energy
      BJORKEN_X,             //!< Björken-x (= fractional momentum carried by the struck nucleon)
      INELASTICITY,          //!< Inelasticity (= Björken-y)
      INTERACTION_TYPE,      //!< Interaction channel type
      CURRENT_TYPE,          //!< Weak current type (CC or NC)
      XSEC,                  //!< Exclusive total cross-section of the interaction
      XSEC_MEAN,             //!< Average interaction cross-section per nucleon along neutrino path [m2]
      XSEC_DIFFERENTIAL,     //!< Differential cross-section of the interaction
      XSEC_WATER,            //!< Inclusive cross-section in water
      INT_LENGTH_WATER,      //!< Interaction length in pure water
      COLUMN_DEPTH,          //!< Column density [m.w.e]
      P_EARTH,               //!< Earth transmission probability
      P_SCALE,               //!< GENIE ineraction probability scale
      TARGET_A,              //!< Number of nucleons in the target
      TARGET_Z,              //!< Number of protons  in the target
      
      NUMBER_OF_VARIABLES    //!< Number of reweighting variables; \n
                             //!< N.B.\ This enum value needs to be specified last!
    }; 

    
    /**
     * Default constructor.
     */
    JEvtWeightFactorGSeaGen()
    {}


    /**
     * Check whether this formula is valid.
     *
     * \return                 true if valid; else false
     */
    bool is_valid() const override final
    {
      const int N = getFormula().GetNpar();

      return N >= 0 && N <= (int) NUMBER_OF_VARIABLES;
    }

    
    /**
     * Get weighting factor for given event.
     *
     * \param  evt             event
     * \return                 weighting factor
     */
    double getFactor(const Evt& evt) const override final
    {
      using namespace std;
      using namespace JPP;

      Double_t vars[NUMBER_OF_VARIABLES] = { 0.0 };
	
      const Trk& neutrino       = get_neutrino      (evt);
      const Trk& leading_lepton = get_leading_lepton(evt);
      
      vars[COSTH]                 = neutrino.dir.z;
      vars[INITIAL_STATE_ENERGY]  = getE0(evt);
      vars[NEUTRINO_ENERGY]       = neutrino.E;
      vars[FINAL_STATE_ENERGY]    = getE1(evt);
      vars[LEADING_LEPTON_ENERGY] = leading_lepton.E;
      vars[BJORKEN_X]             = evt.w2list[W2LIST_GSEAGEN_BX];
      vars[INELASTICITY]          = evt.w2list[W2LIST_GSEAGEN_BY];
      vars[INTERACTION_TYPE]      = evt.w2list[W2LIST_GSEAGEN_ICHAN];
      vars[CURRENT_TYPE]          = evt.w2list[W2LIST_GSEAGEN_CC];
      vars[XSEC]                  = evt.w2list[W2LIST_GSEAGEN_XSEC];
      vars[XSEC_MEAN]             = evt.w2list[W2LIST_GSEAGEN_XSEC_MEAN];
      vars[XSEC_DIFFERENTIAL]     = evt.w2list[W2LIST_GSEAGEN_DXSEC];
      vars[XSEC_WATER]            = evt.w2list[W2LIST_GSEAGEN_WATERXSEC];
      vars[INT_LENGTH_WATER]      = evt.w2list[W2LIST_GSEAGEN_WATER_INT_LEN];
      vars[COLUMN_DEPTH]          = evt.w2list[W2LIST_GSEAGEN_COLUMN_DEPTH];
      vars[P_EARTH]               = evt.w2list[W2LIST_GSEAGEN_P_EARTH];
      vars[P_SCALE]               = evt.w2list[W2LIST_GSEAGEN_P_SCALE];
      vars[TARGET_A]              = evt.w2list[W2LIST_GSEAGEN_TARGETA];
      vars[TARGET_Z]              = evt.w2list[W2LIST_GSEAGEN_TARGETZ];

      return getFormula().EvalPar(&vars[0]);
    }
  };
}

#endif