/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkHigherOrderTriangle.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
/**
 * @class   vtkHigherOrderTriangle
 * @brief   A 2D cell that represents an arbitrary order HigherOrder triangle
 *
 * vtkHigherOrderTriangle is a concrete implementation of vtkCell to represent a
 * 2D triangle using HigherOrder shape functions of user specified order.
 *
 * The number of points in a HigherOrder cell determines the order over which they
 * are iterated relative to the parametric coordinate system of the cell. The
 * first points that are reported are vertices. They appear in the same order in
 * which they would appear in linear cells. Mid-edge points are reported next.
 * They are reported in sequence. For two- and three-dimensional (3D) cells, the
 * following set of points to be reported are face points. Finally, 3D cells
 * report points interior to their volume.
 */

#ifndef vtkHigherOrderTriangle_h
#define vtkHigherOrderTriangle_h

#include <functional> //For std::function

#include "vtkCommonDataModelModule.h" // For export macro
#include "vtkNew.h"                   // For member variable.
#include "vtkNonLinearCell.h"
#include "vtkSmartPointer.h" // For member variable.

#include <vector> // For caching

class vtkDoubleArray;
class vtkHigherOrderCurve;
class vtkTriangle;

class VTKCOMMONDATAMODEL_EXPORT vtkHigherOrderTriangle : public vtkNonLinearCell
{
public:
  vtkTypeMacro(vtkHigherOrderTriangle, vtkNonLinearCell);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  int GetCellType() override = 0;
  int GetCellDimension() override { return 2; }
  int RequiresInitialization() override { return 1; }
  int GetNumberOfEdges() override { return 3; }
  int GetNumberOfFaces() override { return 0; }
  vtkCell* GetEdge(int edgeId) override = 0;
  void SetEdgeIdsAndPoints(int edgeId,
    const std::function<void(const vtkIdType&)>& set_number_of_ids_and_points,
    const std::function<void(const vtkIdType&, const vtkIdType&)>& set_ids_and_points);
  vtkCell* GetFace(int) override { return nullptr; }

  void Initialize() override;

  int CellBoundary(int subId, const double pcoords[3], vtkIdList* pts) override;
  int EvaluatePosition(const double x[3], double closestPoint[3], int& subId, double pcoords[3],
    double& dist2, double weights[]) override;
  void EvaluateLocation(int& subId, const double pcoords[3], double x[3], double* weights) override;
  void Contour(double value, vtkDataArray* cellScalars, vtkIncrementalPointLocator* locator,
    vtkCellArray* verts, vtkCellArray* lines, vtkCellArray* polys, vtkPointData* inPd,
    vtkPointData* outPd, vtkCellData* inCd, vtkIdType cellId, vtkCellData* outCd) override;
  void Clip(double value, vtkDataArray* cellScalars, vtkIncrementalPointLocator* locator,
    vtkCellArray* polys, vtkPointData* inPd, vtkPointData* outPd, vtkCellData* inCd,
    vtkIdType cellId, vtkCellData* outCd, int insideOut) override;
  int IntersectWithLine(const double p1[3], const double p2[3], double tol, double& t, double x[3],
    double pcoords[3], int& subId) override;
  int Triangulate(int index, vtkIdList* ptIds, vtkPoints* pts) override;
  void JacobianInverse(const double pcoords[3], double** inverse, double* derivs);
  void Derivatives(
    int subId, const double pcoords[3], const double* values, int dim, double* derivs) override;
  void SetParametricCoords();
  double* GetParametricCoords() override;

  int GetParametricCenter(double pcoords[3]) override;
  double GetParametricDistance(const double pcoords[3]) override;

  void InterpolateFunctions(const double pcoords[3], double* weights) override = 0;
  void InterpolateDerivs(const double pcoords[3], double* derivs) override = 0;

  vtkIdType GetOrder() const { return this->Order; }
  vtkIdType ComputeOrder();

  void ToBarycentricIndex(vtkIdType index, vtkIdType* bindex);
  vtkIdType ToIndex(const vtkIdType* bindex);

  static void BarycentricIndex(vtkIdType index, vtkIdType* bindex, vtkIdType order);
  static vtkIdType Index(const vtkIdType* bindex, vtkIdType order);

  static double eta(vtkIdType n, vtkIdType chi, double sigma);
  static double d_eta(vtkIdType n, vtkIdType chi, double sigma);
  virtual vtkHigherOrderCurve* getEdgeCell() = 0;

protected:
  vtkHigherOrderTriangle();
  ~vtkHigherOrderTriangle() override;

  vtkIdType GetNumberOfSubtriangles() const { return this->NumberOfSubtriangles; }
  vtkIdType ComputeNumberOfSubtriangles();

  // Description:
  // Given the index of the subtriangle, compute the barycentric indices of
  // the subtriangle's vertices.
  void SubtriangleBarycentricPointIndices(vtkIdType cellIndex, vtkIdType (&pointBIndices)[3][3]);

  vtkTriangle* Face;
  vtkDoubleArray* Scalars; // used to avoid New/Delete in contouring/clipping
  vtkIdType Order;
  vtkIdType NumberOfSubtriangles;
  vtkSmartPointer<vtkPoints> PointParametricCoordinates;

  std::vector<vtkIdType> BarycentricIndexMap;
  std::vector<vtkIdType> IndexMap;
  std::vector<vtkIdType> SubtriangleIndexMap;

private:
  vtkHigherOrderTriangle(const vtkHigherOrderTriangle&) = delete;
  void operator=(const vtkHigherOrderTriangle&) = delete;
};

#endif