// Gmsh - Copyright (C) 1997-2011 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file for license information. Please report all
// bugs and problems to <gmsh@geuz.org>.

#include <math.h>
#include "GmshMessage.h"
#include "GmshDefines.h"
#include "GModel.h"
#include "MLine.h"
#include "MTriangle.h"
#include "MQuadrangle.h"
#include "MTetrahedron.h"
#include "MHexahedron.h"
#include "MPrism.h"
#include "MPyramid.h"
#include "MElementCut.h"
#include "Context.h"
#include "VertexArray.h"
#include "SmoothData.h"

unsigned int getColorByEntity(GEntity *e)
{
  if(e->getSelection()){ // selection
    return CTX::instance()->color.geom.selection;
  }
  else if(e->useColor()){ // forced from a script
    return e->getColor();
  }
  else if(CTX::instance()->mesh.colorCarousel == 1){ // by elementary entity
    return CTX::instance()->color.mesh.carousel[abs(e->tag() % 20)];
  }
  else if(CTX::instance()->mesh.colorCarousel == 2){ // by physical entity
    int np = e->physicals.size();
    int p = np ? e->physicals[np - 1] : 0;
    return CTX::instance()->color.mesh.carousel[abs(p % 20)];
  }
  else{
    return CTX::instance()->color.fg;
  }
}

static unsigned int getColorByElement(MElement *ele)
{
  if(ele->getVisibility() > 1){ // selection
    return CTX::instance()->color.geom.selection;
  }
  else if(CTX::instance()->mesh.colorCarousel == 0){ // by element type
    switch(ele->getType()){
    case TYPE_LIN: return CTX::instance()->color.mesh.line;
    case TYPE_TRI: return CTX::instance()->color.mesh.triangle;
    case TYPE_QUA: return CTX::instance()->color.mesh.quadrangle;
    case TYPE_TET: return CTX::instance()->color.mesh.tetrahedron;
    case TYPE_HEX: return CTX::instance()->color.mesh.hexahedron;
    case TYPE_PRI: return CTX::instance()->color.mesh.prism;
    case TYPE_PYR: return CTX::instance()->color.mesh.pyramid;
    default: return CTX::instance()->color.mesh.vertex;
    }
  }
  else if(CTX::instance()->mesh.colorCarousel == 3){ // by partition
    return CTX::instance()->color.mesh.carousel[abs(ele->getPartition() % 20)];
  }
  else{ 
    // by elementary or physical entity (this is not perfect (since
    // e.g. a triangle can have no vertices categorized on a surface),
    // but it's the best we can do "fast" since we don't store the
    // associated entity in the element
    for(int i = 0; i < ele->getNumVertices(); i++){
      GEntity *e = ele->getVertex(i)->onWhat();
      if(e && (e->dim() == ele->getDim()))
        return getColorByEntity(e);
    }
  }
  return CTX::instance()->color.fg;
}

static double evalClipPlane(int clip, double x, double y, double z)
{
  return CTX::instance()->clipPlane[clip][0] * x + 
    CTX::instance()->clipPlane[clip][1] * y + 
    CTX::instance()->clipPlane[clip][2] * z + 
    CTX::instance()->clipPlane[clip][3];
}

static double intersectClipPlane(int clip, MElement *ele)
{
  MVertex *v = ele->getVertex(0);
  double val = evalClipPlane(clip, v->x(), v->y(), v->z());
  for(int i = 1; i < ele->getNumVertices(); i++){
    v = ele->getVertex(i);
    if(val * evalClipPlane(clip, v->x(), v->y(), v->z()) <= 0)
      return 0.; // the element intersects the cut plane
  }
  return val;
}

bool isElementVisible(MElement *ele)
{
  if(!ele->getVisibility()) return false;
  if(CTX::instance()->mesh.qualitySup) {
    double q;
    if(CTX::instance()->mesh.qualityType == 3)
      q = ele->distoShapeMeasure();
    else if(CTX::instance()->mesh.qualityType == 2)
      q = ele->rhoShapeMeasure();
    else if(CTX::instance()->mesh.qualityType == 1)
      q = ele->etaShapeMeasure();
    else
      q = ele->gammaShapeMeasure();
    if(q < CTX::instance()->mesh.qualityInf || 
       q > CTX::instance()->mesh.qualitySup) return false;
  }
  if(CTX::instance()->mesh.radiusSup) {
    double r = ele->maxEdge();
    if(r < CTX::instance()->mesh.radiusInf || 
       r > CTX::instance()->mesh.radiusSup) return false;
  }
  if(CTX::instance()->clipWholeElements){
    bool hidden = false;
    for(int clip = 0; clip < 6; clip++){
      if(CTX::instance()->mesh.clip & (1 << clip)){
        if(ele->getDim() < 3 && CTX::instance()->clipOnlyVolume){
        }
        else{
          double d = intersectClipPlane(clip, ele);
          if(ele->getDim() == 3 && 
             CTX::instance()->clipOnlyDrawIntersectingVolume && d){
            hidden = true;
            break;
          }
          else if(d < 0){
            hidden = true;
            break;
          }
        }
      }
    }
    if(hidden) return false;
  }
  return true;
}

template<class T>
static bool areAllElementsVisible(std::vector<T*> &elements)
{
  for(unsigned int i = 0; i < elements.size(); i++)
    if(!isElementVisible(elements[i])) return false;
  return true;
}

template<class T>
static bool areSomeElementsCurved(std::vector<T*> &elements)
{
  for(unsigned int i = 0; i < elements.size(); i++)
    if(elements[i]->getPolynomialOrder() > 1) return true;
  return false;
}

template<class T>
static void addSmoothNormals(GEntity *e, std::vector<T*> &elements)
{
  for(unsigned int i = 0; i < elements.size(); i++){
    MElement *ele = elements[i];
    SPoint3 pc(0., 0., 0.);
    if(CTX::instance()->mesh.explode != 1.) pc = ele->barycenter();
    for(int j = 0; j < ele->getNumFacesRep(); j++){
      double x[3], y[3], z[3];
      SVector3 n[3];
      ele->getFaceRep(j, x, y, z, n);
      for(int k = 0; k < 3; k++){
        if(CTX::instance()->mesh.explode != 1.){
          x[k] = pc[0] + CTX::instance()->mesh.explode * (x[k] - pc[0]);
          y[k] = pc[1] + CTX::instance()->mesh.explode * (y[k] - pc[1]);
          z[k] = pc[2] + CTX::instance()->mesh.explode * (z[k] - pc[2]);
        }
        e->model()->normals->add(x[k], y[k], z[k], n[k][0], n[k][1], n[k][2]);
      }
    }
  }
}

template<class T>
static void addElementsInArrays(GEntity *e, std::vector<T*> &elements,
                                bool edges, bool faces)
{
  for(unsigned int i = 0; i < elements.size(); i++){
    MElement *ele = elements[i];

    if(!isElementVisible(ele) || ele->getDim() < 1) continue;
    
    unsigned int c = getColorByElement(ele);
    unsigned int col[4] = {c, c, c, c};

    SPoint3 pc(0., 0., 0.);
    if(CTX::instance()->mesh.explode != 1.) pc = ele->barycenter();

    if(edges){
      bool unique = e->dim() > 1 && !CTX::instance()->pickElements;
      for(int j = 0; j < ele->getNumEdgesRep(); j++){
        double x[2], y[2], z[2];
        SVector3 n[2];
        ele->getEdgeRep(j, x, y, z, n);
        if(CTX::instance()->mesh.explode != 1.){
          for(int k = 0; k < 2; k++){
            x[k] = pc[0] + CTX::instance()->mesh.explode * (x[k] - pc[0]);
            y[k] = pc[1] + CTX::instance()->mesh.explode * (y[k] - pc[1]);
            z[k] = pc[2] + CTX::instance()->mesh.explode * (z[k] - pc[2]);
          }
        }
        if(e->dim() == 2 && CTX::instance()->mesh.smoothNormals)
          for(int k = 0; k < 2; k++)
            e->model()->normals->get(x[k], y[k], z[k], n[k][0], n[k][1], n[k][2]);
        e->va_lines->add(x, y, z, n, col, ele, unique);
      }
    }

    if(faces){
      bool unique = e->dim() > 2 && !CTX::instance()->pickElements;
      bool skin = e->dim() > 2 && CTX::instance()->mesh.drawSkinOnly;
      for(int j = 0; j < ele->getNumFacesRep(); j++){
        double x[3], y[3], z[3];
        SVector3 n[3];
        ele->getFaceRep(j, x, y, z, n);
        if(CTX::instance()->mesh.explode != 1.){
          for(int k = 0; k < 3; k++){
            x[k] = pc[0] + CTX::instance()->mesh.explode * (x[k] - pc[0]);
            y[k] = pc[1] + CTX::instance()->mesh.explode * (y[k] - pc[1]);
            z[k] = pc[2] + CTX::instance()->mesh.explode * (z[k] - pc[2]);
          }
        }
        if(e->dim() == 2 && CTX::instance()->mesh.smoothNormals)
          for(int k = 0; k < 3; k++)
            e->model()->normals->get(x[k], y[k], z[k], n[k][0], n[k][1], n[k][2]);
        e->va_triangles->add(x, y, z, n, col, ele, unique, skin);
      }
    }
  }
}

class initMeshGEdge {
 private:
  int _estimateNumLines(GEdge *e)
  {
    int num = 0;
    if(CTX::instance()->mesh.lines){
      num += e->lines.size();
      if(areSomeElementsCurved(e->lines)) num *= 2;
    }
    return num + 100;
  }
 public:
  void operator () (GEdge *e)
  {
    if(!e->getVisibility()) return;

    e->deleteVertexArrays();
    e->setAllElementsVisible(CTX::instance()->mesh.lines &&
                             areAllElementsVisible(e->lines));

    if(CTX::instance()->mesh.lines){
      e->va_lines = new VertexArray(2, _estimateNumLines(e));
      addElementsInArrays(e, e->lines, CTX::instance()->mesh.lines, false);
      e->va_lines->finalize();
    }
  }
};

class initSmoothNormalsGFace {
 public:
  void operator () (GFace *f)
  {
    addSmoothNormals(f, f->triangles);
    addSmoothNormals(f, f->quadrangles);
    addSmoothNormals(f, f->polygons);
  }
};

class initMeshGFace {
 private:
  bool _curved;
  int _estimateNumLines(GFace *f)
  {
    int num = 0;
    if(CTX::instance()->mesh.surfacesEdges){
      num += (3 * f->triangles.size() + 4 * f->quadrangles.size() + 
              4 * f->polygons.size()) / 2;
      if(CTX::instance()->mesh.explode != 1.) num *= 2;
      if(_curved) num *= 2;
    }
    return num + 100;
  }
  int _estimateNumTriangles(GFace *f)
  {
    int num = 0;
    if(CTX::instance()->mesh.surfacesFaces){
      num += (f->triangles.size() + 2 * f->quadrangles.size() +
              2 * f->polygons.size());
      if(_curved) num *= 4;
    }
    return num + 100;
  }
 public:
  void operator () (GFace *f)
  {
    if(!f->getVisibility()) return;

    f->deleteVertexArrays();
    f->setAllElementsVisible
      (CTX::instance()->mesh.triangles && areAllElementsVisible(f->triangles) && 
       CTX::instance()->mesh.quadrangles && areAllElementsVisible(f->quadrangles));

    bool edg = CTX::instance()->mesh.surfacesEdges;
    bool fac = CTX::instance()->mesh.surfacesFaces;
    if(edg || fac){
      _curved = (areSomeElementsCurved(f->triangles) ||
                 areSomeElementsCurved(f->quadrangles));
      f->va_lines = new VertexArray(2, _estimateNumLines(f));
      f->va_triangles = new VertexArray(3, _estimateNumTriangles(f));
      if(CTX::instance()->mesh.triangles) addElementsInArrays(f, f->triangles, edg, fac);
      if(CTX::instance()->mesh.quadrangles) addElementsInArrays(f, f->quadrangles, edg, fac);
      addElementsInArrays(f, f->polygons, edg, fac);
      f->va_lines->finalize();
      f->va_triangles->finalize();
    }
  }
};

class initMeshGRegion {
 private:
  bool _curved;
  int _estimateIfClipped(int num)
  {
    if(CTX::instance()->clipWholeElements && 
       CTX::instance()->clipOnlyDrawIntersectingVolume){
      for(int clip = 0; clip < 6; clip++){
        if(CTX::instance()->mesh.clip & (1 << clip))
          return (int)sqrt((double)num);
      }
    }
    return num;
  }
  int _estimateNumLines(GRegion *r)
  {
    int num = 0;
    if(CTX::instance()->mesh.volumesEdges){
      // suppose edge shared by 4 elements on averge (pessmistic)
      int numLP = 0;
      for(unsigned int i = 0; i < r->polyhedra.size(); i++)
        numLP += 2 * r->polyhedra[i]->getNumEdges();
      num += (12 * r->tetrahedra.size() + 24 * r->hexahedra.size() +
              18 * r->prisms.size() + 16 * r->pyramids.size() + numLP) / 4;
      num = _estimateIfClipped(num);
      if(CTX::instance()->mesh.explode != 1.) num *= 4;
      if(_curved) num *= 2;
    }
    return num + 100;
  }
  int _estimateNumTriangles(GRegion *r)
  {
    int num = 0;
    if(CTX::instance()->mesh.volumesFaces){
      int numFP = 0;
      for(unsigned int i = 0; i < r->polyhedra.size(); i++)
        numFP += r->polyhedra[i]->getNumFaces();
      num += (4 * r->tetrahedra.size() + 12 * r->hexahedra.size() +
              8 * r->prisms.size() + 6 * r->pyramids.size() + numFP) / 2;
      num = _estimateIfClipped(num);
      if(CTX::instance()->mesh.explode != 1.) num *= 2;
      if(_curved) num *= 4;
    }
    return num + 100;
  }
 public:
  void operator () (GRegion *r)
  {  
    if(!r->getVisibility()) return;

    r->deleteVertexArrays();
    r->setAllElementsVisible
      (CTX::instance()->mesh.tetrahedra && areAllElementsVisible(r->tetrahedra) &&
       CTX::instance()->mesh.hexahedra && areAllElementsVisible(r->hexahedra) &&
       CTX::instance()->mesh.prisms && areAllElementsVisible(r->prisms) &&
       CTX::instance()->mesh.pyramids && areAllElementsVisible(r->pyramids));

    bool edg = CTX::instance()->mesh.volumesEdges;
    bool fac = CTX::instance()->mesh.volumesFaces;
    if(edg || fac){
      _curved = (areSomeElementsCurved(r->tetrahedra) || 
                 areSomeElementsCurved(r->hexahedra) ||
                 areSomeElementsCurved(r->prisms) ||
                 areSomeElementsCurved(r->pyramids));
      r->va_lines = new VertexArray(2, _estimateNumLines(r));
      r->va_triangles = new VertexArray(3, _estimateNumTriangles(r));
      if(CTX::instance()->mesh.tetrahedra) addElementsInArrays(r, r->tetrahedra, edg, fac);
      if(CTX::instance()->mesh.hexahedra) addElementsInArrays(r, r->hexahedra, edg, fac);
      if(CTX::instance()->mesh.prisms) addElementsInArrays(r, r->prisms, edg, fac);
      if(CTX::instance()->mesh.pyramids) addElementsInArrays(r, r->pyramids, edg, fac);
      addElementsInArrays(r, r->polyhedra, edg, fac);
      r->va_lines->finalize();
      r->va_triangles->finalize();
    }
  }
};

void GModel::fillVertexArrays()
{
  if(!getVisibility() || !CTX::instance()->mesh.changed) return;

  Msg::Debug("Mesh has changed: reinitializing vertex arrays");

  int status = getMeshStatus();

  if(status >= 1 && CTX::instance()->mesh.changed & ENT_LINE)
    std::for_each(firstEdge(), lastEdge(), initMeshGEdge());
  
  if(status >= 2 && CTX::instance()->mesh.changed & ENT_SURFACE){
    if(normals) delete normals;
    normals = new smooth_normals(CTX::instance()->mesh.angleSmoothNormals);
    if(CTX::instance()->mesh.smoothNormals)
      std::for_each(firstFace(), lastFace(), initSmoothNormalsGFace());
    std::for_each(firstFace(), lastFace(), initMeshGFace());
  }
  
  if(status >= 3 && CTX::instance()->mesh.changed & ENT_VOLUME)
    std::for_each(firstRegion(), lastRegion(), initMeshGRegion());
}
