#ifndef FitBase_H
#define FitBase_H

  /// Common functions which is used to implement FitFunctional in every KF-approach.


#include <math.h>
#include "FitFunctional.h"

#include "tsc.h"



class FitBase: public virtual FitFunctional{ // base class for all approaches
 public:

    /// Fit tracks
  void Fit( TrackV &t, Station vStations[], int NStations ) const;
};

inline void FitBase::Fit( TrackV &t, Station vStations[], int nStations ) const
{
  // upstream 

  GuessVec( t, vStations, nStations );
  
  // downstream

  FieldRegion f;
  Fvec_t z0,z1,z2, dz;
  FieldVector H0, H1, H2;

  Fvec_t qp0 = t.T[4];
  Int_t i = nStations-1;
  HitV *h = &t.vHits[i];

  FilterFirst( t, *h, vStations[i] );
  AddMaterial( t, vStations[ i ], qp0 );

  z1 = vStations[ i ].z;
  vStations[i].Map.GetField(t.T[0],t.T[1], H1);
  H1.Combine( h->H, h->w );

  z2 = vStations[ i-2 ].z;
  dz = z2-z1;
  vStations[ i-2 ].Map.GetField(t.T[0]+t.T[2]*dz,t.T[1]+t.T[3]*dz,H2);
  h = &t.vHits[i-2];
  H2.Combine( h->H, h->w );

  const int iFirstStation = 0;
  for( --i; i>=iFirstStation; i-- ){
    h = &t.vHits[i];
    Station &st = vStations[i];
    z0 = st.z;    
    dz = (z1-z0);
    st.Map.GetField(t.T[0]-t.T[2]*dz,t.T[1]-t.T[3]*dz,H0);
    H0.Combine( h->H, h->w );
    f.Set( H0, z0, H1, z1, H2, z2);
    if ( i == iFirstStation ) 
      t.f = f;
    
    // ExtrapolateALight( t.T, t.C, st.zhit, qp0, f );
    // AddMaterial( t, st, qp0 );
    if ( i == 1 ) { // 2nd MVD
      ExtrapolateWithMaterial( t, st.zhit, qp0, f, st, true ); // add pipe
    }
    else
      ExtrapolateWithMaterial( t, st.zhit, qp0, f, st );

    Fvec_t u = h->x*st.UInfo.cos_phi + h->y*st.UInfo.sin_phi;
    Fvec_t v = h->x*st.VInfo.cos_phi + h->y*st.VInfo.sin_phi;
    Filter( t, st.UInfo, u, h->w );
    Filter( t, st.VInfo, v, h->w );
    H2 = H1; 
    z2 = z1;
    H1 = H0; 
    z1 = z0;
  }
}

#endif