// Gmsh - Copyright (C) 1997-2025 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.

#ifndef MESH_METRIC_H
#define MESH_METRIC_H

#include <map>
#include <algorithm>
#include "STensor3.h"
#include "Field.h"
#include "meshGFaceOptimize.h"

template <class scalar> class simpleFunction;
class MVertex;
class gLevelset;
class MElementOctree;
class STensor3;

/**Anisotropic mesh size field based on a metric */
class meshMetric : public Field {
public:
  typedef enum {
    LEVELSET = 1,
    HESSIAN = 2,
    FREY = 3,
    EIGENDIRECTIONS = 4,
    EIGENDIRECTIONS_LINEARINTERP_H = 5,
    ISOTROPIC_LINEARINTERP_H = 6
  } MetricComputationTechnique;

private:
  // intersect all metrics added in "setOfMetrics", preserve eigendirections of
  // the "most anisotropic" metric
  void updateMetrics();
  int _dim;
  double _epsilon, _e, _e_moins, _np;
  bool needMetricUpdate;
  bool hasAnalyticalMetric;
  meshMetric::MetricComputationTechnique _technique;
  double hmin, hmax;
  simpleFunction<double> *_fct;

  std::vector<MElement *> _elements;
  v2t_cont _adj;
  MElementOctree *_octree;
  std::map<std::size_t, MVertex *> _vertexMap;

  std::map<MVertex *, double> vals;
  std::map<MVertex *, SVector3> grads;
  std::map<MVertex *, SMetric3> hessians;

public:
  typedef std::map<MVertex *, SMetric3> nodalMetricTensor;
  typedef std::map<MVertex *, double> nodalField;

private:
  nodalMetricTensor _nodalMetrics;
  nodalField _nodalSizes, _detMetric;

  std::map<int, nodalMetricTensor> setOfMetrics;
  std::map<int, nodalField> setOfSizes;
  std::map<int, bool> setOfRecomputeBoolean;
  std::map<int, simpleFunction<double> *> setOfFcts;
  std::map<int, std::vector<double> > setOfParameters;
  std::map<int, int> setOfTechniques;
  //  std::map<int,nodalField> setOfDetMetric;

public:
  meshMetric(std::vector<MElement *> elements);
  meshMetric(GModel *gm);

  ~meshMetric();

  // compute a new metric and add it to the set of metrics
  // parameters[1] = lcmin (default : in global gmsh options
  // CTX::instance()->mesh.lcMin) parameters[2] = lcmax (default : in global
  // gmsh options CTX::instance()->mesh.lcMax) Available algorithms
  // ("techniques"): 1: fct is a LS, metric based on Coupez technique
  //    parameters[0] = thickness of the interface (mandatory)
  // 2: metric based on the hessian of fct
  //    parameters[0] = the final number of elements
  // 3: fct is a LS, variant of (1) based on Frey technique (combines Coupez and
  // curvature)
  //    parameters[0] = thickness of the interface (mandatory)
  //    parameters[3] = the required minimum number of elements to represent a
  //    circle - used for curvature-based metric (default: = 15)
  // 4: fct is a LS, variant of (3), metric computed in LS eigendirections
  //    parameters[0] = thickness of the interface in the positive ls direction
  //    (mandatory) parameters[4] = thickness of the interface in the negative
  //    ls direction (default: =parameters[0] if not specified) parameters[3] =
  //    the required minimum number of elements to represent a circle - used for
  //    curvature-based metric (default: = 15)
  // 5: same as 4, except that the transition in band E uses linear
  // interpolation of h, instead of linear interpolation of metric 6: fct is a
  // LS, metric is isotropic with linear interpolation of h in band E 7: metric
  // based on the Hessian of fct, scaled so that the smallest element has size
  // lcmin
  void addMetric(int technique, simpleFunction<double> *fct,
                 const std::vector<double> &parameters);

  inline SMetric3 metricAtVertex(MVertex *v)
  {
    if(needMetricUpdate) updateMetrics();
    return _nodalMetrics[v];
  }
  // this function scales the mesh metric in order
  // to reach a target number of elements
  void scaleMetric(int nbElementsTarget, nodalMetricTensor &nmt);

  void computeMetric(int metricNumber);
  void computeMetricLevelSet(MVertex *ver, SMetric3 &hessian, SMetric3 &metric,
                             double &size, double x = 0.0, double y = 0.0,
                             double z = 0.0);
  void computeMetricHessian(MVertex *ver, SMetric3 &hessian, SMetric3 &metric,
                            double &size, double x = 0.0, double y = 0.0,
                            double z = 0.0);
  void computeMetricFrey(MVertex *ver, SMetric3 &hessian, SMetric3 &metric,
                         double &size, double x = 0.0, double y = 0.0,
                         double z = 0.0);
  void computeMetricEigenDir(MVertex *ver, SMetric3 &hessian, SMetric3 &metric,
                             double &size, double x = 0.0, double y = 0.0,
                             double z = 0.0);
  void computeMetricIsoLinInterp(MVertex *ver, SMetric3 &hessian,
                                 SMetric3 &metric, double &size, double x = 0.0,
                                 double y = 0.0, double z = 0.0);

  void computeValues();
  void computeHessian();

  double getLaplacian(MVertex *v);
  SVector3 getGradient(MVertex *v);
  virtual bool isotropic() const { return false; }
  virtual const char *getName() { return "metricField"; }
  virtual std::string getDescription()
  {
    return "Anisotropic size field based on hessian of a given function";
  }

  // get metric at point(x,y,z)  (previously computes intersection of metrics if
  // not done yet)
  virtual double operator()(double x, double y, double z,
                            GEntity *ge = nullptr);
  virtual void operator()(double x, double y, double z, SMetric3 &metr,
                          GEntity *ge = nullptr);

  // export pos files of fct, fct gradients (fct is the lattest fct passed to
  // meshMetric !!) and resulting metric (intersection of all computed metrics)
  void exportInfo(const char *fileendname);
};

#endif
