/**
 * \file CbmLitTrackParam.h
 * \author Andrey Lebedev <andrey.lebedev@gsi.de>
 * \date 2008
 * \brief Data class for track parameters.
 **/

#ifndef CBMTOFTRACKLETPARAM_H_
#define CBMTOFTRACKLETPARAM_H_

#include "TVector3.h"
#include <sstream>
#include <vector>
#include <string>

/**
 * built by on 
 * \class CbmLitTrackletParam
 * \author Andrey Lebedev <andrey.lebedev@gsi.de>
 * \date 2008
 * \brief Data class for track parameters.
 **/
class CbmTofTrackletParam : public TObject
{
public:
   /**
    * \brief Constructor.
    */
   CbmTofTrackletParam():
      fX(0.),
      fY(0.),
      fZ(0.),
      fTx(0.),
      fTy(0.),
      fQp(0.),
      fLz(0.),
      fCovMatrix(15, 0.) { }

   /**
    * \brief Destructor.
    */
   virtual ~CbmTofTrackletParam() { }

   /* Getters */
   Double_t GetX() const { return fX; }
   Double_t GetY() const { return fY; }
   Double_t GetZ() const { return fZ; }
   Double_t GetLz() const { return fLz; }
   Double_t GetTx() const { return fTx; }
   Double_t GetTy() const { return fTy; }
   Double_t GetQp() const { return fQp; }
   Double_t GetCovariance(int index) const { return fCovMatrix[index]; }
   const std::vector<Double_t>& GetCovMatrix() const { return fCovMatrix; }

   /* Setters */
   void SetX(Double_t x) { fX  = x; }
   void SetY(Double_t y) { fY  = y; }
   void SetZ(Double_t z) { fZ  = z; }
   void SetLz(Double_t lz) { fLz = lz; }
   void SetTx(Double_t tx) { fTx = tx; }
   void SetTy(Double_t ty) { fTy = ty; }
   void SetQp(Double_t qp) { fQp = qp; }
   void SetCovMatrix(const std::vector<Double_t>& C) { fCovMatrix.assign(C.begin(), C.end()); }
   void SetCovariance(int index, Double_t cov) { fCovMatrix[index] = cov; }

   /**
    * \brief Return direction cosines.
    * \param[out] nx Output direction cosine for OX axis.
    * \param[out] ny Output direction cosine for OY axis.
    * \param[out] nz Output direction cosine for OZ axis.
    */
   void GetDirCos(Double_t& nx, Double_t& ny, Double_t& nz) const {
      Double_t p  = (std::abs(fQp) != 0.) ? 1. / std::abs(fQp) : 1.e20;
      Double_t pz = std::sqrt(p * p / (fTx * fTx + fTy * fTy + 1));
      Double_t px = fTx * pz;
      Double_t py = fTy * pz;
      TVector3 unit = TVector3(px, py, pz).Unit();
      nx = unit.X();
      ny = unit.Y();
      nz = unit.Z();
   }

   /**
    * \brief Return state vector as vector.
    * \return State vector as vector.
    */
   std::vector<Double_t> GetStateVector() const {
      std::vector<Double_t> state(5, 0.);
      state[0] = GetX();
      state[1] = GetY();
      state[2] = GetTx();
      state[3] = GetTy();
      state[4] = GetQp();
      return state;
   }

   /**
    * \brief Set parameters from vector.
    * \param[in] x State vector.
    */
   void SetStateVector(const std::vector<Double_t>& x) {
      SetX(x[0]);
      SetY(x[1]);
      SetTx(x[2]);
      SetTy(x[3]);
      SetQp(x[4]);
   }

   /**
    * \brief Return string representation of class.
    * \return String representation of class.
    */
   std::string ToString() const {
      std::stringstream ss;
      ss << "TrackletParam: pos=(" << fX << "," << fY << "," << fZ
         << ") tx=" << fTx << " ty=" << fTy << " qp=" << fQp;// << std::endl;
   // ss << "cov: ";
   // for (Int_t i = 0; i < 15; i++) ss << fCovMatrix[i] << " ";
   // ss << endl;
      ss.precision(3);
      ss << " cov: x=" << fCovMatrix[0] <<  " y=" << fCovMatrix[5]
         <<  " tx=" << fCovMatrix[9] <<  " ty=" << fCovMatrix[12]
         <<  " q/p=" << fCovMatrix[14];
      return ss.str();
   }

   Double_t GetZr(Double_t R) const; 

   Double_t GetZy(Double_t Y) const { 
     if ( fTy != 0.) { 
       return (Y-fY)/fTy + fZ;
     }
     return 0.; 
   }


private:
   Double_t fX, fY, fZ; // X, Y, Z coordinates in [cm]
   Double_t fTx, fTy; // Slopes: tx=dx/dz, ty=dy/dz
   Double_t fQp; // Q/p: Q is a charge (+/-1), p is momentum in [GeV/c]
   Double_t fLz;        // tracklength in z - direction 

   /* Covariance matrix.
    * Upper triangle symmetric matrix.
    * a[0,0..4], a[1,1..4], a[2,2..4], a[3,3..4], a[4,4] */
   std::vector<Double_t> fCovMatrix;

   ClassDef(CbmTofTrackletParam, 1);

};

#endif /*CBMTOFTRACKLETPARAM_H_*/