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

#ifndef CBMLITTRACKPARAM_H_
#define CBMLITTRACKPARAM_H_

#include "base/CbmLitFloat.h"
#include "TVector3.h"
#include <sstream>
#include <cmath>
#include <vector>
#include <string>

using std::vector;
using std::string;
using std::stringstream;
using std::endl;

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

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

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

   /* Setters */
   void SetX(litfloat x) { fX  = x; }
   void SetY(litfloat y) { fY  = y; }
   void SetZ(litfloat z) { fZ  = z; }
   void SetTx(litfloat tx) { fTx = tx; }
   void SetTy(litfloat ty) { fTy = ty; }
   void SetQp(litfloat qp) { fQp = qp; }
   void SetCovMatrix(const vector<litfloat>& C) { fCovMatrix.assign(C.begin(), C.end()); }
   void SetCovariance(int index, litfloat 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(litfloat& nx, litfloat& ny, litfloat& nz) const {
      litfloat p  = (std::abs(fQp) != 0.) ? 1. / std::abs(fQp) : 1.e20;
      litfloat pz = std::sqrt(p * p / (fTx * fTx + fTy * fTy + 1));
      litfloat px = fTx * pz;
      litfloat 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.
    */
   vector<litfloat> GetStateVector() const {
      vector<litfloat> 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 vector<litfloat>& 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.
    */
   string ToString() const {
      stringstream ss;
      ss << "TrackParam: 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] << endl;
      return ss.str();
   }

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

   /* 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] */
   vector<litfloat> fCovMatrix;
};

#endif /*CBMLITTRACKPARAM_H_*/