// 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 DIVIDE_AND_CONQUER_H
#define DIVIDE_AND_CONQUER_H

#include <vector>
#include <algorithm>
#include "SPoint2.h"
#include "simpleFunction.h"
#include "Octree.h"
#include "MElement.h"

template <class scalar> class fullMatrix;
class GFace;

typedef struct CDList DListRecord, *DListPeek;
typedef int PointNumero;

typedef struct {
  double v;
  double h;
} DPoint;

struct PointRecord {
  DPoint where;
  DListPeek adjacent;
  void *data;
  int flag; // 0:to be kept, 1:to be removed
  int identificator;
  std::vector<void *> vicinity;
  PointRecord() : adjacent(nullptr), data(nullptr), flag(0), identificator(0)
  {
    where.v = where.h = 0.;
  }
};

struct CDList {
  PointNumero point_num;
  DListPeek next, prev;
};

typedef struct {
  PointNumero *t;
  int t_length;
} STriangle;

typedef struct {
  PointNumero begin;
  PointNumero end;
} DT;

typedef struct {
  PointNumero from;
  PointNumero to;
} Segment;

typedef struct {
  PointNumero a, b, c;
} Triangle;

class DocRecord {
private:
  int _hullSize;
  PointNumero *_hull;
  PointNumero Predecessor(PointNumero a, PointNumero b);
  PointNumero Successor(PointNumero a, PointNumero b);
  int FixFirst(PointNumero x, PointNumero f);
  PointNumero First(PointNumero x);
  int IsLeftOf(PointNumero x, PointNumero y, PointNumero check);
  int IsRightOf(PointNumero x, PointNumero y, PointNumero check);
  Segment LowerCommonTangent(DT vl, DT vr);
  Segment UpperCommonTangent(DT vl, DT vr);
  int Qtest(PointNumero h, PointNumero i, PointNumero j, PointNumero k);
  int Merge(DT vl, DT vr);
  DT RecurTrig(PointNumero left, PointNumero right);
  int DListInsert(PointNumero centerPoint, PointNumero newPoint);
  int Insert(PointNumero a, PointNumero b);
  int DListDelete(DListPeek *dlist, PointNumero oldPoint);
  int Delete(PointNumero a, PointNumero b);
  void ConvertDListToVoronoiData();
  int ConvertDListToTriangles();
  void RemoveAllDList();
  int BuildDelaunay();
  int CountPointsOnHull();
  void ConvexHull();
  bool AdjacentNullptrExists();

public:
  STriangle *_adjacencies;
  int numPoints; // number of points
  int size_points;
  PointRecord *points; // points to triangulate
  int numTriangles; // number of triangles
  Triangle *triangles; // 2D results
  DocRecord(int n);
  double &x(int i) { return points[i].where.h; }
  double &y(int i) { return points[i].where.v; }
  void *&data(int i) { return points[i].data; }
  void setPoints(fullMatrix<double> *p);
  ~DocRecord();
  void MakeMeshWithPoints();
  void Voronoi();
  int hullSize() { return _hullSize; }
  int onHull(PointNumero i)
  {
    return std::binary_search(_hull, _hull + _hullSize, i);
  }
  void makePosView(const std::string &, GFace *gf = nullptr);
  void printMedialAxis(Octree *_octree, const std::string &,
                       GFace *gf = nullptr, GEdge *ge = nullptr);
  void voronoiCell(PointNumero pt, std::vector<SPoint2> &pts) const;

  std::set<std::pair<void *, void *> > boundaryEdges;

  void addBoundaryEdge(void *p1, void *p2)
  {
    void *a = (p1 < p2) ? p1 : p2;
    void *b = (p1 > p2) ? p1 : p2;
    boundaryEdges.insert(std::make_pair(a, b));
  }
  bool lookForBoundaryEdge(void *p1, void *p2)
  {
    void *a = (p1 < p2) ? p1 : p2;
    void *b = (p1 > p2) ? p1 : p2;
    auto it = boundaryEdges.find(std::make_pair(a, b));
    return it != boundaryEdges.end();
  }

  void recur_tag_triangles(
    int, std::set<int> &,
    std::map<std::pair<void *, void *>, std::pair<int, int> > &);
  std::set<int> tagInterior(double, double);
  void concave(double, double, GFace *);
  bool contain(int, int, int);
  void add(int, int);

  void initialize();
  bool remove_point(int);
  void remove_all();
  void add_point(double, double, GFace *);

  std::set<std::pair<void *, void *> > mesh_edges;

  void add_edge(void *p1, void *p2)
  {
    void *a = (p1 < p2) ? p1 : p2;
    void *b = (p1 > p2) ? p1 : p2;
    mesh_edges.insert(std::make_pair(a, b));
  }
  bool find_edge(void *p1, void *p2)
  {
    void *a = (p1 < p2) ? p1 : p2;
    void *b = (p1 > p2) ? p1 : p2;
    auto it = mesh_edges.find(std::make_pair(a, b));
    return it != mesh_edges.end();
  }

  void build_edges();
  void clear_edges();
  bool delaunay_conformity(GFace *);

  PointNumero *ConvertDlistToArray(DListPeek *dlist, int *n);
};

void centroidOfOrientedBox(std::vector<SPoint2> &pts, const double &angle,
                           double &xc, double &yc, double &inertia,
                           double &area);
void centroidOfPolygon(SPoint2 &pc, std::vector<SPoint2> &pts, double &xc,
                       double &yc, double &inertia, double &areaCell,
                       simpleFunction<double> *bgm = nullptr);

#endif
