#ifndef _BFIELD_PROP_H_
#define _BFIELD_PROP_H_

/*
 *   ---- Delphes ----
 *     A Fast Simulator for general purpose LHC detector
 *       S. Ovyn ~~~~ severine.ovyn@uclouvain.be
 *
 *         Center for Particle Physics and Phenomenology (CP3)
 *           Universite Catholique de Louvain (UCL)
 *             Louvain-la-Neuve, Belgium
 *             */

#include "TLorentzVector.h"
#include "SmearUtil.h"
#include "BlockClasses.h"
#include "TSimpleArray.h"

using namespace std;

class TrackPropagation {

 public:
  // Constructor
    TrackPropagation();
    TrackPropagation(const string& DetDatacard);
    TrackPropagation(const RESOLution * DetDatacard);
    TrackPropagation(const TrackPropagation & tp);
    TrackPropagation& operator=(const TrackPropagation & tp);
    ~TrackPropagation() {delete DET;};
    void init(); // for constructors

    // Propagation and bfield are very similar. At the end, after code cleaning,
    // onle bfield will remain in this class 
    void Propagation(const TRootGenParticle *Part,TLorentzVector &genMomentum);
    void bfield(const TRootGenParticle *Part, float& etacalo, float& phicalo);


 private:
   unsigned int MAXITERATION;
   RESOLution *DET;


   /// radial/longitudinal extensions of magnetic field volume
   double R_max, z_max;
   /// magnetic field components
   double B_x, B_y, B_z;
   /// particle charge
   double q;
   /// initial coordinate
   double phi_0;
   /// relativistic gamma \times m
   double gammam;
   /// giration frequency and radius
   double omega, r;
   /// center of the helix in the transverse plane
   double x_c, y_c, R_c, Phi_c;
   // variable for an intermediate computing
   double rr;
   /// times for exiting the magnetic field volume
   double t, t_z, t_T;
   /// coordinates of the exit point
   double x_t, y_t, z_t, R_t, Phi_t, Theta_t, Eta_t;
   /// energy-momentum of the exit point [Gev] et c=1
   double Px_t, Py_t, Pz_t, PT_t, p_t, E_t;

   unsigned int loop_overflow_counter;
};
  
#endif