// Copyright (c) 2012 INRIA Sophia-Antipolis (France).
// Copyright (c) 2017 GeometryFactory Sarl (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/Classification/include/CGAL/Classification/Feature/Vertical_range.h $
// $Id: include/CGAL/Classification/Feature/Vertical_range.h b26b07a1242 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s)     : Florent Lafarge, Simon Giraudot

#ifndef CGAL_CLASSIFICATION_FEATURE_VERTICAL_RANGE_H
#define CGAL_CLASSIFICATION_FEATURE_VERTICAL_RANGE_H

#include <CGAL/license/Classification.h>

#include <vector>

#include <CGAL/Classification/Feature_base.h>
#include <CGAL/Classification/compressed_float.h>
#include <CGAL/Classification/Image.h>
#include <CGAL/Classification/Planimetric_grid.h>

namespace CGAL {

namespace Classification {

namespace Feature {

  /*!
    \ingroup PkgClassificationFeatures

    %Feature based on local height distribution. This feature computes
    the distance between the maximum and the minimum height on the
    local cell of the planimetric grid.

    Its default name is "vertical_range".

    \tparam GeomTraits model of \cgal Kernel.
    \tparam PointRange model of `ConstRange`. Its iterator type
    is `RandomAccessIterator` and its value type is the key type of
    `PointMap`.
    \tparam PointMap model of `ReadablePropertyMap` whose key
    type is the value type of the iterator of `PointRange` and value type
    is `GeomTraits::Point_3`.

  */
template <typename GeomTraits, typename PointRange, typename PointMap>
class Vertical_range : public Feature_base
{
  using Image_float = Image<float>;
  using Grid = Planimetric_grid<GeomTraits, PointRange, PointMap>;

  const PointRange& input;
  PointMap point_map;
  const Grid& grid;
  Image_float dtm;
  std::vector<float> values;

public:
  /*!
    \brief constructs the feature.

    \param input point range.
    \param point_map property map to access the input points.
    \param grid precomputed `Planimetric_grid`.
  */
  Vertical_range (const PointRange& input,
                  PointMap point_map,
                  const Grid& grid)
    : input(input), point_map(point_map), grid(grid)
  {
    this->set_name ("vertical_range");

    dtm = Image_float(grid.width(),grid.height());

    for (std::size_t j = 0; j < grid.height(); ++ j)
      for (std::size_t i = 0; i < grid.width(); ++ i)
        if (grid.has_points(i,j))
        {
          float z_max = -(std::numeric_limits<float>::max)();
          float z_min = (std::numeric_limits<float>::max)();

          typename Grid::iterator end = grid.indices_end(i,j);
          for (typename Grid::iterator it = grid.indices_begin(i,j); it != end; ++ it)
          {
            float z = float(get(point_map, *(input.begin()+(*it))).z());
            z_max = ((std::max)(z_max, z));
            z_min = ((std::min)(z_min, z));
          }

          dtm(i,j) = z_max - z_min;
        }

    if (grid.width() * grid.height() > input.size())
    {
      values.resize (input.size(), 0.f);
      for (std::size_t i = 0; i < input.size(); ++ i)
      {
        std::size_t I = grid.x(i);
        std::size_t J = grid.y(i);
        values[i] = dtm(I,J);
      }
      (dtm.free)();
    }

  }

  /// \cond SKIP_IN_MANUAL
  virtual float value (std::size_t pt_index)
  {
    if (values.empty())
    {
      std::size_t I = grid.x(pt_index);
      std::size_t J = grid.y(pt_index);
      return dtm(I,J);
    }

    return values[pt_index];
  }

  /// \endcond
};

} // namespace Feature

} // namespace Classification


} // namespace CGAL

#endif // CGAL_CLASSIFICATION_FEATURE_VERTICAL_RANGE_H

