/*
 * Copyright (C) 2005-2020 Centre National d'Etudes Spatiales (CNES)
 *
 * This file is part of Orfeo Toolbox
 *
 *     https://www.orfeo-toolbox.org/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef otbLabelObjectToPolygonFunctor_h
#define otbLabelObjectToPolygonFunctor_h

#include <vector>

// TODO change this include  have to define from what inherate this class
#include "otbPolyLineParametricPathWithValue.h" //for std::abs

#include "itkPoint.h"
#include "itkIndex.h"

namespace otb
{

namespace Functor
{

/** \class LabelObjectToPolygonFunctor
 *  \brief This class vectorizes a LabelObject to a Polygon.
 *
 * The algorithm follows a finite states machine described in the
 * following paper:
 *
 * "An algorithm for the rapid computation of boundaries of run-length
 * encoded regions", Francis K. H. Queck, in Pattern Recognition 33
 * (2000), p 1637-1649.
 *
 * Lines in the RLE are first sorted in lexicographical order (to
 * ensure ordered RLE), and the finite states machine tracks the edge
 * following 8 canonical states given by the configuration of two
 * consecutive raws of lines.
 *
 * Iterations are done until convergence which is guaranteed to
 * happen.
 *
 * Please be aware that this functor is not thread-safe.
 *
 *
 * \ingroup OTBLabelMap
 */
template <class TLabelObject, class TPolygon>
class LabelObjectToPolygonFunctor
{
public:
  /** Template parameters typedefs */
  typedef TLabelObject LabelObjectType;
  /** Const iterator over LabelObject lines */
  typedef typename LabelObjectType::ConstLineIterator ConstLineIteratorType;

  typedef typename LabelObjectType::LineType LineType;
  typedef typename LineType::IndexType       IndexType;
  typedef TPolygon                           PolygonType;
  typedef typename PolygonType::Pointer      PolygonPointerType;
  typedef typename PolygonType::VertexType   VertexType;
  typedef itk::Point<double, 2>  PointType;
  typedef itk::Vector<double, 2> SpacingType;
  typedef itk::Index<2> RegionIndexType;

  /**
   * \param labelObject the label object to vectorize
   * \return The vectorized label object as a polygon.
   */
  inline PolygonType* operator()(LabelObjectType* labelObject);

  /** Get  name of class. */
  const char* GetNameOfClass()
  {
    return "LabelObjectToPolygonFunctor";
  }

  /** Set the start index of the underlying image */
  void SetStartIndex(const RegionIndexType& index)
  {
    m_StartIndex = index;
  }
  /** Get the start index */
  const RegionIndexType& GetStartIndex() const
  {
    return m_StartIndex;
  }
  /** Set the origin of the underlying image */
  void SetOrigin(const PointType& origin)
  {
    m_Origin = origin;
  }
  /** Get the origin */
  const PointType& GetOrigin() const
  {
    return m_Origin;
  }
  /** Set the spacing of the underlying image */
  void SetSpacing(const SpacingType& spacing)
  {
    m_Spacing = spacing;
  }
  /** Get the spacing */
  const SpacingType& GetSpacing() const
  {
    return m_Spacing;
  }

  /** Constructor */
  LabelObjectToPolygonFunctor()
    : m_Polygon(nullptr),
      m_CurrentState(UP_LEFT),
      m_PositionFlag(LEFT_END),
      m_StartingPoint(),
      m_CurrentPoint(),
      m_CurrentRun(),
      m_CurrentLine(0),
      m_Solution(),
      m_LineOffset(0),
      m_StartIndex(),
      m_Origin(),
      m_Spacing(1.)
  {
    m_StartingPoint.Fill(0);
    m_CurrentPoint.Fill(0);
    m_CurrentRun.Fill(0);
    m_StartIndex.Fill(0);
    m_Origin.Fill(0);
  }

  /** Destructor */
  virtual ~LabelObjectToPolygonFunctor()
  {
  }

private:
  /// Internal structures
  typedef std::vector<LineType>        RunsPerLineType;
  typedef std::vector<RunsPerLineType> RunsPerLineVectorType;
  typedef std::vector<IndexType>       IndexVectorType;

  /// Internal enums
  enum StateType
  {
    UP_LEFT,
    UP_RIGHT,
    DOWN_LEFT,
    DOWN_RIGHT
  };
  enum PositionFlagType
  {
    LEFT_END,
    RIGHT_END
  };

  /// Compare two line in the lexicographical order
  static bool LexicographicalLineCompare(const LineType& l1, const LineType& l2);

  /// Check if the given run index (index in line, line) is valid
  inline bool IsRunIndexValid(const IndexType& index) const;

  /// Check if the point lies within the range of the line
  inline IndexType Within(const IndexType& point, unsigned int line) const;

  /// Return the left-end of the run
  inline IndexType LeftEnd(const IndexType& runIndex) const;

  /// Return the right-end of the run
  inline IndexType RightEnd(const IndexType& runIndex) const;

  /** Return the right-most run whose left end lies within the range of
   * the given run.
   */
  inline IndexType RightMostLeftEndInside(unsigned int line, const IndexType& point, const IndexType& run) const;

  /** Return the left-most run whose right end lies within the range of
   * the given run.
   */
  inline IndexType LeftMostRightEndInside(unsigned int line, const IndexType& point, const IndexType& run) const;

  /// Walk left to update the finite states machine.
  inline void WalkLeft(unsigned int line, const IndexType& startPoint, const IndexType& endPoint, PolygonType* polygon, const StateType state);

  /// Walk right to update the finite states machine.
  inline void WalkRight(unsigned int line, const IndexType& startPoint, const IndexType& endPoint, PolygonType* polygon, const StateType state);

  // Apply origin and spacing
  VertexType IndexToPoint(const VertexType& index) const;

  PolygonPointerType m_Polygon;

  // Internal structure to store runs
  RunsPerLineVectorType m_InternalDataSet;

  /// The current state
  StateType m_CurrentState;
  /// The position flag
  PositionFlagType m_PositionFlag;

  // The starting point for vectorization
  IndexType m_StartingPoint;

  /// The current point for vectorization
  IndexType m_CurrentPoint;

  /// The current run for vectorization
  IndexType m_CurrentRun;

  /// The current line for vectorization
  int m_CurrentLine;

  /// The vector of vectorized boundaries
  IndexVectorType m_Solution;

  /// The line offset from start of the region
  unsigned int m_LineOffset;

  // The following will be used for coordinate transform
  RegionIndexType m_StartIndex;
  PointType       m_Origin;
  SpacingType     m_Spacing;

}; // end class LabelObjectToPolygonFunctor

} // end namespace Functor

} // end namespace otb

#ifndef OTB_MANUAL_INSTANTIATION
#include "otbLabelObjectToPolygonFunctor.hxx"
#endif

#endif
