// @(#)root/mathcore:$Id: PositionVector3D.h 23735 2008-05-07 21:18:33Z moneta $
// Authors: W. Brown, M. Fischler, L. Moneta    2005  

 /**********************************************************************
  *                                                                    *
  * Copyright (c) 2005 , LCG ROOT MathLib Team                         *
  *                                                                    *
  *                                                                    *
  **********************************************************************/

// Header file for class PositionVector3D
//
// Created by: Lorenzo Moneta  at Mon May 30 15:25:04 2005
//
// Last update: $Id: PositionVector3D.h 23735 2008-05-07 21:18:33Z moneta $
//
#ifndef ROOT_Math_GenVector_PositionVector3D 
#define ROOT_Math_GenVector_PositionVector3D  1

#ifndef ROOT_Math_GenVector_DisplacementVector3Dfwd 
#include "Math/GenVector/DisplacementVector3Dfwd.h"
#endif

#ifndef ROOT_Math_GenVector_Cartesian3D 
#include "Math/GenVector/Cartesian3D.h"
#endif

#ifndef ROOT_Math_GenVector_GenVectorIO
#include "Math/GenVector/GenVectorIO.h"
#endif

#ifndef ROOT_Math_GenVector_BitReproducible 
#include "Math/GenVector/BitReproducible.h"
#endif

#ifndef ROOT_Math_GenVector_CoordinateSystemTags 
#include "Math/GenVector/CoordinateSystemTags.h"
#endif


#include <cassert>

namespace ROOT {

  namespace Math {


//__________________________________________________________________________________________
    /**
              Class describing a generic position vector (point) in 3 dimensions.
              This class is templated on the type of Coordinate system.
              One example is the XYZPoint which is a vector based on
              double precision x,y,z data members by using the
              ROOT::Math::Cartesian3D<double> Coordinate system.
	      The class is having also an extra template parameter, the coordinate system tag, 
	      to be able to identify (tag) vector described in different reference coordinate system, 
	      like global or local coordinate systems.   

	      @ingroup GenVector
    */

    template <class CoordSystem, class Tag = DefaultCoordinateSystemTag >
    class PositionVector3D {

    public:

      typedef typename CoordSystem::Scalar Scalar;
      typedef CoordSystem CoordinateType;
      typedef Tag  CoordinateSystemTag;

      // ------ ctors ------

      /**
         Default constructor. Construct an empty object with zero values
      */

      PositionVector3D() : fCoordinates() { }

      /**
         Construct from three values of type <em>Scalar</em>.
         In the case of a XYZPoint the values are x,y,z
         In the case of  a polar vector they are r,theta,phi
      */
      PositionVector3D(const Scalar & a, const Scalar & b, const Scalar & c) :
        fCoordinates ( a , b,  c)  { }

     /**
          Construct from a position vector expressed in different
          coordinates, or using a different Scalar type
      */
      template <class T>
      explicit PositionVector3D( const PositionVector3D<T,Tag> & v) :
        fCoordinates ( v.Coordinates() ) { }

     /**
          Construct from an arbitrary displacement vector
      */
      template <class T>
      explicit PositionVector3D( const DisplacementVector3D<T,Tag> & p) :
        fCoordinates ( p.Coordinates() ) { }

      /**
          Construct from a foreign 3D vector type, for example, Hep3Vector
          Precondition: v must implement methods x(), y() and z()
      */
      template <class ForeignVector>
      explicit PositionVector3D( const ForeignVector & v) :
        fCoordinates ( Cartesian3D<Scalar>( v.x(), v.y(), v.z() ) ) { }

#ifdef LATER
      /**
         construct from a generic linear algebra  vector of at least size 3
         implementing operator []. This could be also a C array
         \par v  LAVector
         \par index0   index where coordinates starts (typically zero)
         It works for all Coordinates types,
         ( x= v[index0] for Cartesian and r=v[index0] for Polar )
      */
      template <class LAVector>
      PositionVector3D(const LAVector & v, size_t index0 ) {
        fCoordinates = CoordSystem  ( v[index0], v[index0+1], v[index0+2] );
      }
#endif

      // compiler-generated copy ctor and dtor are fine.

      // ------ assignment ------

      /**
          Assignment operator from a position vector of arbitrary type
      */
      template <class OtherCoords>
      PositionVector3D & operator=
                        ( const PositionVector3D<OtherCoords,Tag> & v) {
        fCoordinates = v.Coordinates();
        return *this;
      }

      /**
          Assignment operator from a displacement vector of arbitrary type
      */
      template <class OtherCoords>
      PositionVector3D & operator=
                        ( const DisplacementVector3D<OtherCoords,Tag> & v) {
        fCoordinates = v.Coordinates();
        return *this;
      }

      /**
          Assignment from a foreign 3D vector type, for example, Hep3Vector
          Precondition: v must implement methods x(), y() and z()
      */
      template <class ForeignVector>
      PositionVector3D & operator= ( const ForeignVector & v) {
        SetXYZ( v.x(),  v.y(), v.z() );
        return *this;
      }

#ifdef LATER
      /**
         assign from a generic linear algebra  vector of at least size 3
         implementing operator [].
         \par v  LAVector
         \par index0   index where coordinates starts (typically zero)
         It works for all Coordinates types,
         ( x= v[index0] for Cartesian and r=v[index0] for Polar )
      */
      template <class LAVector>
      PositionVector3D & assignFrom(const LAVector & v, size_t index0 = 0) {
        fCoordinates = CoordSystem  ( v[index0], v[index0+1], v[index0+2] );
        return *this;
      }
#endif

      /**
          Retrieve a copy of the coordinates object
      */
      const CoordSystem & Coordinates() const {
        return fCoordinates;
      }

      /**
         Set internal data based on a C-style array of 3 Scalar numbers
       */
      PositionVector3D<CoordSystem, Tag>& SetCoordinates( const Scalar src[] )
       { fCoordinates.SetCoordinates(src); return *this;  }

      /**
         Set internal data based on 3 Scalar numbers
       */
      PositionVector3D<CoordSystem, Tag>& SetCoordinates( Scalar a, Scalar b, Scalar c )
       { fCoordinates.SetCoordinates(a, b, c); return *this; }

      /**
         Set internal data based on 3 Scalars at *begin to *end
       */
      template <class IT>
      PositionVector3D<CoordSystem, Tag>& SetCoordinates( IT begin, IT end ) 
      { IT a = begin; IT b = ++begin; IT c = ++begin;
        assert (++begin==end);
        SetCoordinates (*a,*b,*c);
        return *this;
      }

      /**
        get internal data into 3 Scalar numbers
       */
      void GetCoordinates( Scalar& a, Scalar& b, Scalar& c ) const
                            { fCoordinates.GetCoordinates(a, b, c);  }

      /**
         get internal data into a C-style array of 3 Scalar numbers
       */
      void GetCoordinates( Scalar dest[] ) const
                            { fCoordinates.GetCoordinates(dest);  }

      /**
         get internal data into 3 Scalars at *begin to *end (3 past begin)
       */
      template <class IT>
      void GetCoordinates( IT begin, IT end ) const
      { IT a = begin; IT b = ++begin; IT c = ++begin;
        assert (++begin==end);
        GetCoordinates (*a,*b,*c);
      }

      /**
         get internal data into 3 Scalars at *begin
       */
      template <class IT>
      void GetCoordinates( IT begin ) const {
         Scalar a,b,c = 0; 
         GetCoordinates (a,b,c);
         *begin++ = a; 
         *begin++ = b; 
         *begin   = c; 
      }

      /**
         set the values of the vector from the cartesian components (x,y,z)
         (if the vector is held in polar or cylindrical eta coordinates,
         then (x, y, z) are converted to that form)
       */
      PositionVector3D<CoordSystem, Tag>& SetXYZ (Scalar a, Scalar b, Scalar c) {
            fCoordinates.SetXYZ(a,b,c);
            return *this;
      }

      // ------------------- Equality -----------------

      /**
        Exact equality
       */
      bool operator==(const PositionVector3D & rhs) const {
        return fCoordinates==rhs.fCoordinates;
      }
      bool operator!= (const PositionVector3D & rhs) const {
        return !(operator==(rhs));
      }

      // ------ Individual element access, in various coordinate systems ------

      /**
          Cartesian X, converting if necessary from internal coordinate system.
      */
      Scalar X() const { return fCoordinates.X(); }

      /**
          Cartesian Y, converting if necessary from internal coordinate system.
      */
      Scalar Y() const { return fCoordinates.Y(); }

      /**
          Cartesian Z, converting if necessary from internal coordinate system.
      */
      Scalar Z() const { return fCoordinates.Z(); }

      /**
          Polar R, converting if necessary from internal coordinate system.
      */
      Scalar R() const { return fCoordinates.R(); }

      /**
          Polar theta, converting if necessary from internal coordinate system.
      */
      Scalar Theta() const { return fCoordinates.Theta(); }

      /**
          Polar phi, converting if necessary from internal coordinate system.
      */
      Scalar Phi() const { return fCoordinates.Phi(); }

      /**
          Polar eta, converting if necessary from internal coordinate system.
      */
      Scalar Eta() const { return fCoordinates.Eta(); }

      /**
          Cylindrical transverse component rho
      */
      Scalar Rho() const { return fCoordinates.Rho(); }

      // ----- Other fundamental properties -----

      /**
          Magnitute squared ( r^2 in spherical coordinate)
      */
      Scalar Mag2() const { return fCoordinates.Mag2();}

      /**
         Transverse component squared (rho^2 in cylindrical coordinates.
      */
      Scalar Perp2() const { return fCoordinates.Perp2();}

      // It is physically meaningless to speak of the unit vector corresponding
      // to a point.

      // ------ Setting individual elements present in coordinate system ------

      /**
         Change X - Cartesian3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetX (Scalar xx) { fCoordinates.SetX(xx); return *this;}

      /**
         Change Y - Cartesian3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetY (Scalar yy) { fCoordinates.SetY(yy); return *this;}

      /**
         Change Z - Cartesian3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetZ (Scalar zz) { fCoordinates.SetZ(zz); return *this;}

      /**
         Change R - Polar3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetR (Scalar rr) { fCoordinates.SetR(rr); return *this;}

      /**
         Change Theta - Polar3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetTheta (Scalar ang) { fCoordinates.SetTheta(ang); return *this;}

      /**
         Change Phi - Polar3D or CylindricalEta3D coordinates
      */
       PositionVector3D<CoordSystem, Tag>& SetPhi (Scalar ang) { fCoordinates.SetPhi(ang); return *this;}

      /**
         Change Rho - CylindricalEta3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetRho (Scalar rr) { fCoordinates.SetRho(rr); return *this;}

      /**
         Change Eta - CylindricalEta3D coordinates only
      */
       PositionVector3D<CoordSystem, Tag>& SetEta (Scalar etaval) { fCoordinates.SetEta(etaval); return *this;}

      // ------ Operations combining two vectors ------
      // need to specialize to exclude those with a different tags 

     /**
          Return the scalar (Dot) product of this with a displacement vector in 
	  any coordinate system, but with the same tag
      */
      template< class OtherCoords >
      Scalar Dot( const  DisplacementVector3D<OtherCoords,Tag> & v) const {
        return X()*v.x() + Y()*v.y() + Z()*v.z();
      }


      /**
         Return vector (Cross) product of this point with a displacement, as a
         point vector in this coordinate system of the first.
      */
      template< class OtherCoords >
      PositionVector3D Cross( const DisplacementVector3D<OtherCoords,Tag> & v) const  {
        PositionVector3D  result;
        result.SetXYZ (  Y()*v.z() - v.y()*Z(),
                         Z()*v.x() - v.z()*X(),
                         X()*v.y() - v.x()*Y() );
        return result;
      }

      // The Dot and Cross products of a pair of point vectors are physically
      // meaningless concepts and thus are defined as private methods

      // It is physically meaningless to speak of the Unit vector corresponding
      // to a point.


      /**
          Self Addition with a displacement vector.
      */
      template <class OtherCoords>
      PositionVector3D & operator+= (const  DisplacementVector3D<OtherCoords,Tag> & v)
      {
        SetXYZ( X() + v.X(), Y() + v.Y(), Z() + v.Z() );
        return *this;
      }

      /**
          Self Difference with a displacement vector.
      */
      template <class OtherCoords>
      PositionVector3D & operator-= (const  DisplacementVector3D<OtherCoords,Tag> & v)
      {
        SetXYZ(  X() - v.X(), Y() - v.Y(), Z() - v.Z() );
        return *this;
      }

      /**
         multiply this vector by a scalar quantity
      */
      PositionVector3D & operator *= (Scalar a) {
        fCoordinates.Scale(a);
        return *this;
      }

      /**
         divide this vector by a scalar quantity
      */
      PositionVector3D & operator /= (Scalar a) {
        fCoordinates.Scale(1/a);
        return *this;
      }

      // The following methods (v*a and v/a) could instead be free functions.
      // They were moved into the class to solve a problem on AIX.
      /**
        Multiply a vector by a real number
      */
      PositionVector3D operator * ( Scalar a ) const {
        PositionVector3D tmp(*this);
        tmp *= a;
        return tmp;
      }

      /**
         Division of a vector with a real number
       */
      PositionVector3D operator / (Scalar a) const {
        PositionVector3D tmp(*this);
        tmp /= a;
        return tmp;
      }

      // Limited backward name compatibility with CLHEP

      Scalar x()     const { return fCoordinates.X();     }
      Scalar y()     const { return fCoordinates.Y();     }
      Scalar z()     const { return fCoordinates.Z();     }
      Scalar r()     const { return fCoordinates.R();     }
      Scalar theta() const { return fCoordinates.Theta(); }
      Scalar phi()   const { return fCoordinates.Phi();   }
      Scalar eta()   const { return fCoordinates.Eta();   }
      Scalar rho()   const { return fCoordinates.Rho();   }
      Scalar mag2()  const { return fCoordinates.Mag2();  }
      Scalar perp2() const { return fCoordinates.Perp2(); }

    private:

      CoordSystem fCoordinates;

      // Prohibited methods

      // this should not compile (if from a vector or points with different tag

      template <class OtherCoords, class OtherTag>
      explicit PositionVector3D( const PositionVector3D<OtherCoords, OtherTag> & );

      template <class OtherCoords, class OtherTag>
      explicit PositionVector3D( const DisplacementVector3D<OtherCoords, OtherTag> & );

      template <class OtherCoords, class OtherTag>
      PositionVector3D & operator=( const PositionVector3D<OtherCoords, OtherTag> & );

      template <class OtherCoords, class OtherTag>
      PositionVector3D & operator=( const DisplacementVector3D<OtherCoords, OtherTag> & );
      
      template <class OtherCoords, class OtherTag>
      PositionVector3D & operator+=(const  DisplacementVector3D<OtherCoords, OtherTag> & );

      template <class OtherCoords, class OtherTag>
      PositionVector3D & operator-=(const  DisplacementVector3D<OtherCoords, OtherTag> & );

//       /**
//          Dot product of two position vectors is inappropriate
//       */
//       template <class T2, class U>
//       PositionVector3D Dot( const PositionVector3D<T2,U> & v) const;

//       /**
//          Cross product of two position vectors is inappropriate
//       */
//       template <class T2, class U>
//       PositionVector3D Cross( const PositionVector3D<T2,U> & v) const;



    };

// ---------- PositionVector3D class template ends here ----------------
// ---------------------------------------------------------------------

    /**
       Multiplication of a position vector by real number  a*v
    */
    template <class CoordSystem, class U>
    inline
    PositionVector3D<CoordSystem>
    operator * ( typename PositionVector3D<CoordSystem,U>::Scalar a,
                 PositionVector3D<CoordSystem,U> v) {
      return v *= a;
      // Note - passing v by value and using operator *= may save one
      // copy relative to passing v by const ref and creating a temporary.
    }

    /**
        Difference between two PositionVector3D vectors.
        The result is a DisplacementVector3D.
        The (coordinate system) type of the returned vector is defined to
        be identical to that of the first position vector.
    */

    template <class CoordSystem1, class CoordSystem2, class U>
    inline
    DisplacementVector3D<CoordSystem1,U>
    operator-( const PositionVector3D<CoordSystem1,U> & v1,
               const PositionVector3D<CoordSystem2,U> & v2) {
      return DisplacementVector3D<CoordSystem1,U>( Cartesian3D<typename CoordSystem1::Scalar>(
                                                                               v1.X()-v2.X(), v1.Y()-v2.Y(),v1.Z()-v2.Z() )
                                             );
    }

    /**
        Addition of a PositionVector3D and a DisplacementVector3D.
        The return type is a PositionVector3D,
        of the same (coordinate system) type as the input PositionVector3D.
    */
    template <class CoordSystem1, class CoordSystem2, class U>
    inline
    PositionVector3D<CoordSystem2,U>
    operator+( PositionVector3D<CoordSystem2,U> p1,
               const DisplacementVector3D<CoordSystem1,U>  & v2)        {
      return p1 += v2;
    }

    /**
        Addition of a DisplacementVector3D and a PositionVector3D.
        The return type is a PositionVector3D,
        of the same (coordinate system) type as the input PositionVector3D.
    */
    template <class CoordSystem1, class CoordSystem2, class U>
    inline
    PositionVector3D<CoordSystem2,U>
    operator+( DisplacementVector3D<CoordSystem1,U> const & v1,
               PositionVector3D<CoordSystem2,U> p2)        {
      return p2 += v1;
    }

    /**
        Subtraction of a DisplacementVector3D from a PositionVector3D.
        The return type is a PositionVector3D,
        of the same (coordinate system) type as the input PositionVector3D.
    */
    template <class CoordSystem1, class CoordSystem2, class U>
    inline
    PositionVector3D<CoordSystem2,U>
    operator-( PositionVector3D<CoordSystem2,U> p1,
               DisplacementVector3D<CoordSystem1,U> const & v2)        {
      return p1 -= v2;
    }

    // Scaling of a position vector with a real number is not physically meaningful

    // ------------- I/O to/from streams -------------

    template< class char_t, class traits_t, class T, class U >
      inline
      std::basic_ostream<char_t,traits_t> &
      operator << ( std::basic_ostream<char_t,traits_t> & os
                  , PositionVector3D<T,U> const & v
                  )
    {
      if( !os )  return os;

      typename T::Scalar a, b, c;
      v.GetCoordinates(a, b, c);

      if( detail::get_manip( os, detail::bitforbit ) )  {
        detail::set_manip( os, detail::bitforbit, '\00' );
        typedef GenVector_detail::BitReproducible BR;
        BR::Output(os, a);
        BR::Output(os, b);
        BR::Output(os, c);
      }
      else  {
        os << detail::get_manip( os, detail::open  ) << a
           << detail::get_manip( os, detail::sep   ) << b
           << detail::get_manip( os, detail::sep   ) << c
           << detail::get_manip( os, detail::close );
      }

      return os;

    }  // op<< <>()


    template< class char_t, class traits_t, class T, class U >
      inline
      std::basic_istream<char_t,traits_t> &
      operator >> ( std::basic_istream<char_t,traits_t> & is
                  , PositionVector3D<T,U> & v
                  )
    {
      if( !is )  return is;

      typename T::Scalar a, b, c;

      if( detail::get_manip( is, detail::bitforbit ) )  {
        detail::set_manip( is, detail::bitforbit, '\00' );
        typedef GenVector_detail::BitReproducible BR;
        BR::Input(is, a);
        BR::Input(is, b);
        BR::Input(is, c);
      }
      else  {
        detail::require_delim( is, detail::open  );  is >> a;
        detail::require_delim( is, detail::sep   );  is >> b;
        detail::require_delim( is, detail::sep   );  is >> c;
        detail::require_delim( is, detail::close );
      }

      if( is )
        v.SetCoordinates(a, b, c);
      return is;

    }  // op>> <>()




  } // namespace Math

} // namespace ROOT


#endif /* ROOT_Math_GenVector_PositionVector3D  */
