#pragma once
#include "basedata.h"
#include "comdefs.h"

using michlib::real;

template<class D> class LinearInterpolator: public D
{
 public:
 LinearInterpolator(D&& d): D(std::move(d)) {}

 real operator()(const struct Point2D& in) const
 {
  const auto gp = D::GridPos(in.x, in.y);
  if(!gp.Valid()) return NAN;

  if(gp.x == 0.0 && gp.y == 0.0) return D::V(gp.ix, gp.iy);

  real   v00;
  real   v10;
  real   v01;
  real   v11;
  bool   isfill = false;
  size_t fx, fy;

  // Count fills
  for(size_t ix = 0; ix <= 1; ix++)
   for(size_t iy = 0; iy <= 1; iy++)
   {
    if(isfill && D::IsFill(gp.ix + ix, gp.iy + iy)) return NAN;
    if(D::IsFill(gp.ix + ix, gp.iy + iy))
    {
     fx     = ix;
     fy     = iy;
     isfill = true;
    }
   }

  v00 = D::V(gp.ix, gp.iy);
  v10 = D::V(gp.ix + 1, gp.iy);
  v01 = D::V(gp.ix, gp.iy + 1);
  v11 = D::V(gp.ix + 1, gp.iy + 1);

  if(isfill && fx == 0 && fy == 0) v00 = (v10 + v01 + v11) / 3.0;
  if(isfill && fx == 1 && fy == 0) v10 = (v00 + v01 + v11) / 3.0;
  if(isfill && fx == 0 && fy == 1) v01 = (v10 + v00 + v11) / 3.0;
  if(isfill && fx == 1 && fy == 1) v11 = (v10 + v01 + v00) / 3.0;

  return v00 + gp.y * (v01 - v00) + gp.x * ((v10 - v00) + gp.y * (v00 - v01 + v11 - v10));
 };
};