#ifndef __JANGLE2D__
#define __JANGLE2D__

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

#include "JIO/JSerialisable.hh"
#include "JLang/JManip.hh"
#include "JMath/JMath.hh"
#include "JMath/JConstants.hh"


/**
 * \author mdejong
 */

namespace JGEOMETRY2D {}
namespace JPP { using namespace JGEOMETRY2D; }

namespace JGEOMETRY2D {

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


  /**
   * Data structure for angle in two dimensions.
   * This class serves as input to the rotation matrix JRotation2D.
   */
  class JAngle2D :
    public JMath<JAngle2D>
  {
  public:
    /**
     * Default constructor.
     */
    JAngle2D() :
      __phi(0.0)
    {}


    /**
     * Constructor.
     *
     * \param  phi           phi angle [rad]
     */
    JAngle2D(const double phi) :
      __phi(phi)
    {}


    /**
     * Constructor.
     *
     * \param  x             x value
     * \param  y             y value
     */
    JAngle2D(const double x,
	     const double y) :
      __phi(atan2(y,x))
    {}


    /**
     * Get phi angle.
     *
     * \return               phi angle
     */
    double getPhi() const 
    { 
      return __phi;
    }


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


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


    /**
     * Negate angle.
     *
     * \return               this angle
     */
    JAngle2D& negate()
    {
      __phi = -__phi;

      return *this;
    }


    /**
     * Add angle.
     *
     * \param  angle         angle
     * \return               this angle
     */
    JAngle2D& add(const JAngle2D& angle)
    {
      __phi += angle.getPhi();

      return *this;
    }


    /**
     * Subtract angle.
     *
     * \param  angle         angle
     * \return               this angle
     */
    JAngle2D& sub(const JAngle2D& angle)
    {
      __phi -= angle.getPhi();

      return *this;
    }


    /**
     * Scale angle.
     *
     * \param  factor        multiplication factor
     * \return               this angle
     */
    JAngle2D& mul(const double factor)
    {
      __phi *= factor;

      return *this;
    }


    /**
     * Scale angle.
     *
     * \param  factor        division factor
     * \return               this angle
     */
    JAngle2D& div(const double factor)
    {
      __phi /= factor;

      return *this;
    }


    /**
     * Check equality.
     *
     * \param  angle         angle
     * \param  precision     precision
     * \return               true if angles are equal; else false
     */
    bool equals(const JAngle2D& angle,
                const double    precision = std::numeric_limits<double>::min()) const
    {
      return fabs(getPhi()   - angle.getPhi())   <= precision;
    }


    /**
     * Get dot product.
     *
     * \param  angle         angle
     * \return               dot product
     */
    double getDot(const JAngle2D& angle) const
    {
      return cos(getPhi() - angle.getPhi());
    }


    /**
     * Normalise angle.
    
     * - phi angle will be between 0 and 2&pi;
     *
     * \return               this angle
     */
    JAngle2D& normalise()
    {
      using JMATH::PI;

      if (__phi > 2*PI) { do { __phi -= 2*PI; } while (__phi > 2*PI); }
      if (__phi < 0.0)  { do { __phi += 2*PI; } while (__phi < 0.0); }

      return *this;
    }

    
    /**
     * Read angle from input.
     *
     * \param  in            input stream
     * \param  angle         angle
     * \return               input stream
     */
    friend inline std::istream& operator>>(std::istream& in, JAngle2D& angle)
    {
      return in >> angle.__phi;
    }


    /**
     * Write angle to output.
     *
     * \param  out           output stream
     * \param  angle         angle
     * \return               output stream
     */
    friend inline std::ostream& operator<<(std::ostream& out, const JAngle2D& angle)
    {
      const JFormat format(out, getFormat<JAngle2D>(JFormat_t(9, 5, std::ios::fixed | std::ios::showpos)));

      return out << format << angle.getPhi();
    }


    /**
     * Read angle from input.
     *
     * \param  in            reader
     * \param  angle         angle
     * \return               reader
     */
    friend inline JReader& operator>>(JReader& in, JAngle2D& angle)
    {
      return in >> angle.__phi;
    }


    /**
     * Write angle to output.
     *
     * \param  out           writer
     * \param  angle         angle
     * \return               writer
     */
    friend inline JWriter& operator<<(JWriter& out, const JAngle2D& angle)
    {
      return out << angle.__phi;
    }

  protected:
    double __phi;
  };
}

#endif