#ifndef __JVECTOR2D__
#define __JVECTOR2D__

#include <limits>
#include <utility>
#include <cmath>

#include "JMath/JMath.hh"
#include "JGeometry2D/JMatrix2D.hh"


/**
 * \author mdejong
 */

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

namespace JGEOMETRY2D {

  using JMATH::JMath;

  typedef std::pair<double, double>  JRangeX; //!< Type definition of range along x-axis.
  typedef std::pair<double, double>  JRangeY; //!< Type definition of range along y-axis.
  
  
  /**
   * Data structure for vector in two dimensions.
   *
   * This class implements the JMATH::JMath interface.
   */
  class JVector2D :
    public JMath<JVector2D>
  {
  public:
    /**
     * Default constructor.
     */
    JVector2D() :
      __x(0.0),
      __y(0.0)
    {}


    /**
     * Constructor.
     *
     * \param  x             x value
     * \param  y             y value
     */
    JVector2D(const double x,
	      const double y) :
      __x(x),
      __y(y)
    {}


    /**
     * Get x position.
     *
     * \return               x position
     */
    double getX() const
    { 
      return __x;
    }


    /**
     * Get y position.
     *
     * \return               y position
     */
    double getY() const
    { 
      return __y;
    }


    /** 
     * Negate vector.
     *
     * \return               this vector
     */
    JVector2D& negate()
    {
      __x = -__x;
      __y = -__y;

      return *this;
    }


    /** 
     * Add vector.
     *
     * \param  vector        vector
     * \return               this vector
     */
    JVector2D& add(const JVector2D& vector)
    {
      __x += vector.getX();
      __y += vector.getY();

      return *this;
    }


    /** 
     * Subtract vector.
     *
     * \param  vector        vector
     * \return               this vector
     */
    JVector2D& sub(const JVector2D& vector)
    {
      __x -= vector.getX();
      __y -= vector.getY();

      return *this;
    }


    /** 
     * Scale vector.
     *
     * \param  factor        multiplication factor
     * \return               this vector
     */
    JVector2D& mul(const double factor)
    {
      __x *= factor;
      __y *= factor;

      return *this;
    }


    /** 
     * Scale vector.
     *
     * \param  factor        division factor
     * \return               this vector
     */
    JVector2D& div(const double factor)
    {
      __x /= factor;
      __y /= factor;

      return *this;
    }
    

    /**
     * Transform.
     *
     * \param  T             matrix
     * \return               this vector
     */
    JVector2D& transform(const JMatrix2D& T)
    {
      T.transform(__x, __y);

      return *this;
    }


    /**
     * Check equality.
     *
     * \param  vector        vector
     * \param  precision     precision
     * \return               true if vectors are equal; else false
     */
    bool equals(const JVector2D& vector,
                const double     precision = std::numeric_limits<double>::min()) const
    {
      return (fabs(getX() - vector.getX()) <= precision &&
              fabs(getY() - vector.getY()) <= precision);
    }


    /**
     * Get length squared.
     *
     * \return               square of length
     */
    double getLengthSquared() const 
    { 
      return getX()*getX() + getY()*getY();
    }


    /**
     * Get length.
     *
     * \return               length
     */
    double getLength() const 
    { 
      return sqrt(getLengthSquared());
    }


    /**
     * Get squared of distance to point.
     *
     * \param  point         point
     * \return               square of distance
     */
    double getDistanceSquared(const JVector2D& point) const
    {
      return JVector2D(point).sub(*this).getLengthSquared();
    }


    /**
     * Get distance to point.
     *
     * \param  point         point
     * \return               distance
     */
    double getDistance(const JVector2D& point) const
    {
      return sqrt(getDistanceSquared(point));
    }


    /**
     * Get dot product.
     *
     * \param  point         vector
     * \return               dot product
     */
    double getDot(const JVector2D& point) const
    {
      return
	getX() * point.getX() + 
	getY() * point.getY();
    }


    /**
     * Get perpendicular dot product.
     *
     * \param  point         vector
     * \return               perpendicular dot product
     */
    double getPerpDot(const JVector2D& point) const
    {
      return
	getX() * point.getY() - 
	getY() * point.getX();
    }

  protected:
    double __x;
    double __y;
  };


  /**
   * Check sequence of three points.
   *
   * \param  a       1st point
   * \param  b       2nd point
   * \param  c       3rd point
   * \return         true if points a, b, c are counter clockwise; else false
   */
  inline bool getCCW(const JVector2D& a,
		     const JVector2D& b,
		     const JVector2D& c)
  {
    const double A = a.getX() - b.getX();
    const double B = a.getY() - b.getY();
    const double C = c.getX() - b.getX();
    const double D = c.getY() - b.getY();
    
    return (A*D - B*C) <= 0.0;
  }
}

#endif