// -------------------------------------------------------------------------
// -----                  CbmSttGeomHelix header file                  -----
// -----                  Created 30/03/06  by R. Castelijns           -----
// -------------------------------------------------------------------------


#ifndef CBMSTTGEOMHELIX_H
#define CBMSTTGEOMHELIX_H 1

#include "TObject.h"
#include "TVector3.h"

#include "CbmSttTrack.h"
#include "CbmMCTrack.h"

#include "CbmSttGeomCircle.h"
#include "CbmSttGeomLine.h"
#include "CbmSttGeomPoint.h"


#ifndef __CINT__
#include "CLHEP/Matrix/Vector.h"
using CLHEP::HepVector;
#endif
#ifdef __CINT__
class HepVector;
#endif

class CbmSttGeomHelix : public TObject
{
 public:
    /** Default constructor **/
    CbmSttGeomHelix();
    
    /** Standard constructor **/
    CbmSttGeomHelix(Double_t distance, Double_t phi, Double_t radius, Double_t zdistance, Double_t alpha, Double_t charge);
    CbmSttGeomHelix(CbmSttTrack *track);
    CbmSttGeomHelix(CbmMCTrack *track);
    CbmSttGeomHelix(Double_t px, Double_t py, Double_t pz, Double_t vx, Double_t vy, Double_t vz, Double_t charge);
    CbmSttGeomHelix(CbmSttGeomHelix const &other);
    CbmSttGeomHelix(HepVector const babarVector);

    /** Destructor **/
    ~CbmSttGeomHelix();

    /** Operators */
    void operator=(CbmSttGeomHelix const &other);
    
    /** Geometry functions */
    Double_t DistanceTo(CbmSttGeomPoint myPoint);
    Double_t DistanceTo(CbmSttGeomLine myLine);
    Double_t DistanceTo(CbmSttGeomHelix myHelix);

    CbmSttGeomPoint ClosestPointTo(CbmSttGeomPoint myPoint);
    CbmSttGeomPoint ClosestPointTo(CbmSttGeomLine myLine);

    /** Getters */
    Double_t GetAxisX() const;
    Double_t GetAxisY() const;
    Double_t GetRadius() const {return fRadius;}
    Double_t GetAlpha() const {return fAlpha;}
    Double_t GetDistance() const {return fDistance;}
    Double_t GetDistanceZ() const {return fDistanceZ;}
    Double_t GetPhi() const {return fPhi;}
    Double_t GetPt() const;
    Double_t GetP() const;
    Double_t GetTheta() const;
    Double_t GetPhiAt(CbmSttGeomPoint myPoint);
    TVector3 GetMomentumAt(CbmSttGeomPoint thePoint);
    Double_t GetTolerance() const {return fTolerance;}
    Int_t GetMaxIterations() const {return fMaxIterations;}
    Double_t GetChargeSign() const;
    CbmSttGeomPoint At(Double_t phi) const;

    /** Setters */
    void SetTolerance(Double_t newTolerance) {fTolerance = newTolerance;}
    void SetMaxIterations(Int_t newMaxIterations) {fMaxIterations = newMaxIterations;}
    void Transform(Double_t shiftX, Double_t shiftY, Double_t shiftZ);

    /** Graphics functions */
    void Draw(Double_t size = 0.5, Int_t color = 1) const;
    void DrawFromVertex(CbmSttGeomPoint vertex, Double_t size, Int_t color) const;

 private:
    void Copy(CbmSttGeomHelix const &other);
    void Destroy();

    void ConstructHelixFromMomenta(Double_t px, Double_t py, Double_t pz, Double_t vx, Double_t vy, Double_t vz);
    void ConstructHelixFromBabarVector(HepVector const babarVector);
    
    Double_t GetPhiEstimate(CbmSttGeomLine myLine);
    Double_t GetPhiEstimate(CbmSttGeomPoint myPoint);
    Double_t GetPhiEstimate(CbmSttGeomHelix myHelix);

    void SetupMinimization(CbmSttGeomLine myLine);
    void SetupMinimization(CbmSttGeomPoint myPoint);
   
    Bool_t Minimize(Double_t &phi);

    // function and derivative for minimization
    Double_t f(Double_t phi);
    Double_t fder(Double_t phi);

    // temporary variables for minimization
    Double_t m_a0;
    Double_t m_a1;
    Double_t m_a2;
    Double_t m_a3;
    Double_t m_a4;
    Double_t m_a5;
    Double_t m_a6;
    Double_t m_a7;
    
    // helix representation
    Double_t fAlpha;
    Double_t fRadius;
    Double_t fDistanceZ;
    Double_t fDistance;
    Double_t fPhi;
    
    Double_t fCharge;

    // accuracy
    Double_t fTolerance;
    Int_t fMaxIterations;

    ClassDef(CbmSttGeomHelix,1);
};


#endif