/**
 * Stone of Orthanc
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2020 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 **/


#pragma once

#include "../Toolbox/AffineTransform2D.h"
#include "../Toolbox/LinearAlgebra.h"

namespace OrthancStone
{
  class ScenePoint2D
  {
  private:
    double  x_;
    double  y_;

  public:
    ScenePoint2D() :
      x_(0),
      y_(0)
    {
    }

    ScenePoint2D(double x,
      double y) :
      x_(x),
      y_(y)
    {
    }

    double GetX() const
    {
      return x_;
    }

    double GetY() const
    {
      return y_;
    }

    ScenePoint2D Apply(const AffineTransform2D& t) const
    {
      double x = x_;
      double y = y_;
      t.Apply(x, y);
      return ScenePoint2D(x, y);
    }

    const ScenePoint2D operator-(const ScenePoint2D& a) const
    {
      ScenePoint2D v;
      v.x_ = x_ - a.x_;
      v.y_ = y_ - a.y_;

      return v;
    }

    const ScenePoint2D operator+(const ScenePoint2D& a) const
    {
      ScenePoint2D v;
      v.x_ = x_ + a.x_;
      v.y_ = y_ + a.y_;

      return v;
    }

    const ScenePoint2D operator*(double a) const
    {
      ScenePoint2D v;
      v.x_ = x_ * a;
      v.y_ = y_ * a;

      return v;
    }

    const ScenePoint2D operator/(double a) const
    {
      ScenePoint2D v;
      v.x_ = x_ / a;
      v.y_ = y_ / a;

      return v;
    }

    static void MidPoint(ScenePoint2D& result, const ScenePoint2D& a, const ScenePoint2D& b)
    {
      result.x_ = 0.5 * (a.x_ + b.x_);
      result.y_ = 0.5 * (a.y_ + b.y_);
    }

    static double Dot(const ScenePoint2D& a, const ScenePoint2D& b)
    {
      return a.x_ * b.x_ + a.y_ * b.y_;
    }

    static double SquaredMagnitude(const ScenePoint2D& v)
    {
      return v.x_ * v.x_ + v.y_ * v.y_;
    }

    static double Magnitude(const ScenePoint2D& v)
    {
      double squaredMagnitude = SquaredMagnitude(v);
      if (LinearAlgebra::IsCloseToZero(squaredMagnitude))
        return 0.0;
      return sqrt(squaredMagnitude);
    }

    static double SquaredDistancePtPt(const ScenePoint2D& a, const ScenePoint2D& b)
    {
      ScenePoint2D n = b - a;
      return Dot(n, n);
    }

    static double DistancePtPt(const ScenePoint2D& a, const ScenePoint2D& b)
    {
      double squaredDist = SquaredDistancePtPt(a, b);
      return sqrt(squaredDist);
    }

    /**
    Distance from point p to [a,b] segment

    Rewritten from https://www.randygaul.net/2014/07/23/distance-point-to-line-segment/
    */
    static double SquaredDistancePtSegment(const ScenePoint2D& a, const ScenePoint2D& b, const ScenePoint2D& p)
    {
      ScenePoint2D n = b - a;
      ScenePoint2D pa = a - p;

      double c = Dot(n, pa);

      // Closest point is a
      if (c > 0.0)
        return Dot(pa, pa);

      ScenePoint2D bp = p - b;

      // Closest point is b
      if (Dot(n, bp) > 0.0)
        return Dot(bp, bp);

      // if segment length is very short, we approximate distance to the
      // distance with a
      double nq = Dot(n, n);
      if (LinearAlgebra::IsCloseToZero(nq))
      {
        // segment is very small: approximate distance from point to segment
        // with distance from p to a
        return Dot(pa, pa);
      }
      else
      {
        // Closest point is between a and b
        ScenePoint2D e = pa - n * (c / nq);
        return Dot(e, e);
      }
    }
  };
}