#ifndef ALIHBTPARTICLE
#define ALIHBTPARTICLE

//Ali HBT Particle: simplified class TParticle
//Simplified in order to minimize the size of object
//  - we want to keep a lot of such a objects in memory

#include <TObject.h>
#include <TLorentzVector.h>
#include <TMath.h>
#include <TDatabasePDG.h>

class TParticle;

class AliHBTParticle : public TObject
{

public:
                                // ****** constructors and destructor
  AliHBTParticle();

  AliHBTParticle(Int_t pdg, Double_t px, Double_t py, Double_t pz, Double_t etot,
                 Double_t vx, Double_t vy, Double_t vz, Double_t time);

  AliHBTParticle(const TParticle& p);

  virtual ~AliHBTParticle(){};


  Int_t          GetPdgCode      () const { return fPdgCode; }
  Double_t       GetCalcMass     () const { return fCalcMass; }
  Double_t       GetMass         ()       { return GetPDG()->Mass();}

  TParticlePDG*  GetPDG          (){return TDatabasePDG::Instance()->GetParticle(fPdgCode);}

  Int_t          Beauty          ()  { return GetPDG()->Beauty(); }
  Int_t          Charm           ()  { return GetPDG()->Charm(); }
  Int_t          Strangeness     ()  { return GetPDG()->Strangeness();}
  void ProductionVertex(TLorentzVector &v) { v.SetXYZT(fVx,fVy,fVz,fVt);}


  Double_t         Vx    () const { return fVx;}
  Double_t         Vy    () const { return fVy;}
  Double_t         Vz    () const { return fVz;}
  Double_t         T     () const { return fVt;}

  Double_t         Px    () const { return fPx; } //X coordinate of the momentum
  Double_t         Py    () const { return fPy; } //Y coordinate of the momentum
  Double_t         Pz    () const { return fPz; } //Z coordinate of the momentum
  Double_t         P     () const                 //momentum
    { return TMath::Sqrt(fPx*fPx+fPy*fPy+fPz*fPz); }
  
  void Momentum(TLorentzVector &v) { v.SetPxPyPzE(fPx,fPy,fPz,fE);}
    
  Double_t         Pt    () const  //transverse momentum
    { return TMath::Sqrt(fPx*fPx+fPy*fPy); }
  Double_t         Energy() const { return fE; }
  
                                   //Pseudo Rapidity
  Double_t         Eta   () const { if (P() != fPz) return 0.5*TMath::Log((P()+fPz)/(P()-fPz)); 
                                    else return 1.e30;}

                                   //Rapidity
  Double_t         Y     () const { if (fE  != fPz) return 0.5*TMath::Log((fE+fPz)/(fE-fPz));
                                    else return 1.e30;}

  Double_t         Phi   () const { return kPI+TMath::ATan2(-fPy,-fPx); }

  Double_t         Theta () const { return (fPz==0)?kPI/2:TMath::ACos(fPz/P()); }

                                // setters


  void           SetMomentum(Double_t px, Double_t py, Double_t pz, Double_t e)
                             {fPx=px; fPy=py; fPz=pz; fE=e;}
  void           SetMomentum(const TLorentzVector& p)
                             {SetMomentum(p.Px(),p.Py(),p.Pz(),p.Energy());}

  void           SetProductionVertex(Double_t vx, Double_t vy, Double_t vz, Double_t t)
                             {fVx=vx; fVy=vy; fVz=vz; fVt=t;}
  void           SetProductionVertex(const TLorentzVector& v)
                             {SetProductionVertex(v.X(),v.Y(),v.Z(),v.T());}
  const Char_t*  GetName() const;
  
protected:

  Int_t          fPdgCode;              // PDG code of the particle
  Double_t       fCalcMass;             // Calculated mass

  Double_t       fPx;                   // x component of momentum
  Double_t       fPy;                   // y component of momentum
  Double_t       fPz;                   // z component of momentum
  Double_t       fE;                    // Energy

  Double_t       fVx;                   // x of production vertex
  Double_t       fVy;                   // y of production vertex
  Double_t       fVz;                   // z of production vertex
  Double_t       fVt;                   // t of production vertex

public:
  ClassDef(AliHBTParticle,1)  // TParticle vertex particle information
};

#endif