#ifndef __JVERSOR3Z__
#define __JVERSOR3Z__

#include <istream>
#include <ostream>
#include <limits>
#include <cmath>

#include "JIO/JSerialisable.hh"
#include "JLang/JManip.hh"
#include "JMath/JMath.hh"
#include "JGeometry2D/JVersor2D.hh"
#include "JGeometry3D/JAngle3D.hh"
#include "JGeometry3D/JVector3D.hh"
#include "JGeometry3D/JVersor3D.hh"


/**
 * \author mdejong
 */

namespace JGEOMETRY3D {}
namespace JPP { using namespace JGEOMETRY3D; }

namespace JGEOMETRY3D {

  using JMATH::JMath;
  using JIO::JReader;
  using JIO::JWriter;
  using JGEOMETRY2D::JVersor2D;
  

  /**
   * Data structure for normalised vector in positive z-direction.
   * The member methods getDX() and getDY() refer to the corresponding direction cosines.
   * Note that the direction cosines may have any value.
   * The method getDZ() will simply return 0 if the sum of the squares of the direction cosines is larger than 1.
   */
  class JVersor3Z :
    public JMath<JVersor3Z>
  {
  public:
    /**
     * Default constructor.
     */
    JVersor3Z() :
      __dx(0.0),
      __dy(0.0)
    {}


    /**
     * Constructor.
     *
     * \param  dir              direction cosines
     */
    JVersor3Z(const JVersor2D& dir) :
      __dx(dir.getDX()),
      __dy(dir.getDY())
    {}


    /**
     * Constructor.
     *
     * \param  dx               direction cosine dx/dz
     * \param  dy               direction cosine dy/dz
     */
    JVersor3Z(const double dx,
	      const double dy) :
      __dx(dx),
      __dy(dy)
    {}


    /**
     * Get direction.
     *
     * \return                  direction
     */
    const JVersor3Z& getDirection() const 
    { 
      return static_cast<const JVersor3Z&>(*this);
    }


    /**
     * Get direction.
     *
     * \return                  direction
     */
    JVersor3Z& getDirection() 
    { 
      return static_cast<JVersor3Z&>(*this);
    }


    /**
     * Set direction.
     *
     * \param  direction        direction
     */
    void setDirection(const JVersor3Z& direction)
    { 
      static_cast<JVersor3Z&>(*this) = direction;
    }


    /**
     * Get angle.
     *
     * \return                  angle
     */
    operator JAngle3D() const 
    { 
      return JAngle3D(getDX(), getDY(), getDZ());
    }


    /**
     * Type conversion operator.
     *
     * \return                  position
     */
    operator JVector3D() const
    {
      return JVector3D(getDX(), getDY(), getDZ());
    }


    /**
     * Type conversion operator.
     *
     * \return                  direction
     */
    operator JVersor3D() const
    {
      return JVersor3D(getDX(), getDY(), getDZ());
    }


    /**
     * Get x direction.
     *
     * \return                  x direction
     */
    double getDX() const
    {
      return __dx;
    }


    /**
     * Get y direction.
     *
     * \return                  y direction
     */
    double getDY() const
    {
      return __dy;
    }


    /**
     * Get z direction.
     *
     * \return                  z direction
     */
    double getDZ() const
    {
      const double v = getDX()*getDX() + getDY()*getDY();

      if (v <= 1.0) 
	return sqrt(1.0 - v);
      else
	return 0.0;
    }

    
    /**
     * Prefix unary minus.
     *
     * \return                  this versor
     */
    JVersor3Z& negate()
    {
      __dx = -__dx;
      __dy = -__dy;

      return *this;
    }


    /**
     * Addition operator.
     *
     * \param  value            versor
     * \return                  this versor
     */
    JVersor3Z& add(const JVersor3Z& value)
    {
      __dx += value.getDX();
      __dy += value.getDY();

      return *this;
    }


    /**
     * Subtraction operator.
     *
     * \param  value            versor
     * \return                  this versor
     */
    JVersor3Z& sub(const JVersor3Z& value)
    {
      __dx -= value.getDX();
      __dy -= value.getDY();

      return *this;
    }


    /**
     * Multiplication operator.
     *
     * \param  value            multiplication factor
     * \return                  this versor
     */
    JVersor3Z& mul(const double value)
    {
      __dx *= value;
      __dy *= value;

      return *this;
    }


    /**
     * Division operator.
     *
     * \param  value            multiplication factor
     * \return                  this versor
     */
    JVersor3Z& div(const double value)
    {
      __dx /= value;
      __dy /= value;

      return *this;
    }


    /**
     * Check equality.
     *
     * \param  versor        versor
     * \param  precision     precision
     * \return               true if versors are equal; else false
     */
    bool equals(const JVersor3D& versor,
                const double     precision = std::numeric_limits<double>::min()) const
    {
      return (fabs(getDX() - versor.getDX()) <= precision &&
              fabs(getDY() - versor.getDY()) <= precision);
    }


    /**
     * Get dot product.
     *
     * \param  dir              direction
     * \return                  dot product
     */
    double getDot(const JVersor3Z& dir) const
    {
      return
	getDX() * dir.getDX() + 
	getDY() * dir.getDY() +
	getDZ() * dir.getDZ();
    }

    
    /**
     * Get dot product.
     *
     * \param  angle            angle
     * \return                  dot product
     */
    double getDot(const JAngle3D& angle) const
    {
      return
	getDX() * angle.getDX() + 
	getDY() * angle.getDY() +
	getDZ() * angle.getDZ();
    }

    
    /**
     * Get dot product.
     *
     * \param  pos              position
     * \return                  dot product
     */
    double getDot(const JVector3D& pos) const
    {
      return
	getDX() * pos.getX() + 
	getDY() * pos.getY() +
	getDZ() * pos.getZ();
    }

    
    /**
     * Get dot product.
     *
     * \param  dir              direction
     * \return                  dot product
     */
    double getDot(const JVersor3D& dir) const
    {
      return
	getDX() * dir.getDX() + 
	getDY() * dir.getDY() +
	getDZ() * dir.getDZ();
    }


    /**
     * Read versor from input.
     *
     * \param  in               input stream
     * \param  versor           versor
     * \return                  input stream
     */
    friend inline std::istream& operator>>(std::istream& in, JVersor3Z& versor)
    {
      return in >> versor.__dx >> versor.__dy;
    }


    /**
     * Write versor to output.
     *
     * \param  out              output stream
     * \param  versor           versor
     * \return                  output stream
     */
    friend inline std::ostream& operator<<(std::ostream& out, const JVersor3Z& versor)
    {
      const JFormat format(out, getFormat<JVersor3Z>(JFormat_t(9, 6, std::ios::fixed | std::ios::showpos)));

      return out << format << versor.getDX() << ' ' << format << versor.getDY();
    }
    

    /**
     * Read versor from input.
     *
     * \param  in               reader
     * \param  versor           versor
     * \return                  reader
     */
    friend inline JReader& operator>>(JReader& in, JVersor3Z& versor)
    {
      return in >> versor.__dx >> versor.__dy;
    }


    /**
     * Write versor to output.
     *
     * \param  out              writer
     * \param  versor           versor
     * \return                  writer
     */
    friend inline JWriter& operator<<(JWriter& out, const JVersor3Z& versor)
    {
      return out << versor.__dx << versor.__dy;
    }

  protected:
    double __dx;
    double __dy;
  };
}

#endif