// Copyright (C) 2007-2015  CEA/DEN, EDF R&D, OPEN CASCADE
//
// Copyright (C) 2003-2007  OPEN CASCADE, EADS/CCR, LIP6, CEA/DEN,
// CEDRAT, EDF R&D, LEG, PRINCIPIA R&D, BUREAU VERITAS
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
//
// See http://www.salome-platform.org/ or email : webmaster.salome@opencascade.com
//

// File      : StdMeshers_FaceSide.hxx
// Created   : Wed Jan 31 18:41:25 2007
// Author    : Edward AGAPOV (eap)
// Module    : SMESH
//
#include "StdMeshers_FaceSide.hxx"

#include "SMDS_EdgePosition.hxx"
#include "SMDS_MeshNode.hxx"
#include "SMESHDS_Mesh.hxx"
#include "SMESHDS_SubMesh.hxx"
#include "SMESH_Algo.hxx"
#include "SMESH_Mesh.hxx"
#include "SMESH_MesherHelper.hxx"
#include "SMESH_ComputeError.hxx"
#include "SMESH_Block.hxx"

#include <Adaptor2d_Curve2d.hxx>
#include <BRepAdaptor_CompCurve.hxx>
#include <BRep_Builder.hxx>
#include <BRep_Tool.hxx>
#include <GCPnts_AbscissaPoint.hxx>
#include <Geom2dAdaptor_Curve.hxx>
#include <Geom_Line.hxx>
#include <TopExp.hxx>
#include <TopExp_Explorer.hxx>
#include <TopoDS.hxx>
#include <TopoDS_Face.hxx>
#include <TopoDS_Vertex.hxx>
#include <TopoDS_Wire.hxx>

#include <map>
#include <limits>

#include "utilities.h"

//================================================================================
/*!
 * \brief Constructor of a side of one edge
  * \param theFace - the face
  * \param theEdge - the edge
 */
//================================================================================

StdMeshers_FaceSide::StdMeshers_FaceSide(const TopoDS_Face&   theFace,
                                         const TopoDS_Edge&   theEdge,
                                         SMESH_Mesh*          theMesh,
                                         const bool           theIsForward,
                                         const bool           theIgnoreMediumNodes,
                                         SMESH_ProxyMesh::Ptr theProxyMesh)
{
  list<TopoDS_Edge> edges(1,theEdge);
  *this = StdMeshers_FaceSide( theFace, edges, theMesh, theIsForward,
                               theIgnoreMediumNodes, theProxyMesh );
}

//================================================================================
/*!
 * \brief Constructor of a side of several edges
 */
//================================================================================

StdMeshers_FaceSide::StdMeshers_FaceSide(const TopoDS_Face&   theFace,
                                         list<TopoDS_Edge>&   theEdges,
                                         SMESH_Mesh*          theMesh,
                                         const bool           theIsForward,
                                         const bool           theIgnoreMediumNodes,
                                         SMESH_ProxyMesh::Ptr theProxyMesh)
{
  int nbEdges = theEdges.size();
  myEdge.resize      ( nbEdges );
  myEdgeID.resize    ( nbEdges );
  myC2d.resize       ( nbEdges );
  myC3dAdaptor.resize( nbEdges );
  myFirst.resize     ( nbEdges );
  myLast.resize      ( nbEdges );
  myNormPar.resize   ( nbEdges );
  myEdgeLength.resize( nbEdges );
  myIsUniform.resize ( nbEdges, true );
  myFace               = theFace;
  myLength             = 0;
  myNbPonits           = myNbSegments = 0;
  myProxyMesh          = theProxyMesh;
  myMissingVertexNodes = false;
  myIgnoreMediumNodes  = theIgnoreMediumNodes;
  myDefaultPnt2d       = gp_Pnt2d( 1e+100, 1e+100 );
  if ( !myProxyMesh ) myProxyMesh.reset( new SMESH_ProxyMesh( *theMesh ));
  if ( nbEdges == 0 ) return;

  SMESHDS_Mesh* meshDS = myProxyMesh->GetMeshDS();

  int nbDegen = 0;
  list<TopoDS_Edge>::iterator edge = theEdges.begin();
  for ( int index = 0; edge != theEdges.end(); ++index, ++edge )
  {
    int i = theIsForward ? index : nbEdges-index-1;
    myEdgeLength[i] = SMESH_Algo::EdgeLength( *edge );
    if ( myEdgeLength[i] < DBL_MIN ) nbDegen++;
    myLength += myEdgeLength[i];
    myEdge  [i] = *edge;
    myEdgeID[i] = meshDS->ShapeToIndex( *edge );
    if ( !theIsForward ) myEdge[i].Reverse();

    if ( theFace.IsNull() )
      BRep_Tool::Range( *edge, myFirst[i], myLast[i] );
    else
      myC2d[i] = BRep_Tool::CurveOnSurface( *edge, theFace, myFirst[i], myLast[i] );
    if ( myEdge[i].Orientation() == TopAbs_REVERSED )
      std::swap( myFirst[i], myLast[i] );

    // check if the edge has a non-uniform parametrization (issue 0020705)
    if ( !myC2d[i].IsNull() )
    {
      if ( myEdgeLength[i] > DBL_MIN )
      {
        Geom2dAdaptor_Curve A2dC( myC2d[i],
                                  std::min( myFirst[i], myLast[i] ),
                                  std::max( myFirst[i], myLast[i] ));
        double p2 = myFirst[i]+(myLast[i]-myFirst[i])/2.;
        double p4 = myFirst[i]+(myLast[i]-myFirst[i])/4.;
        double d2 = GCPnts_AbscissaPoint::Length( A2dC, myFirst[i], p2 );
        double d4 = GCPnts_AbscissaPoint::Length( A2dC, myFirst[i], p4 );
        //cout<<"len = "<<len<<"  d2 = "<<d2<<"  fabs(2*d2/len-1.0) = "<<fabs(2*d2/len-1.0)<<endl;
        myIsUniform[i] = !( fabs(2*d2/myEdgeLength[i]-1.0) > 0.01 || fabs(2*d4/d2-1.0) > 0.01 );
        Handle(Geom_Curve) C3d = BRep_Tool::Curve(myEdge[i],d2,d4);
        myC3dAdaptor[i].Load( C3d, d2,d4 );
      }
      else
      {
        const TopoDS_Vertex& V = SMESH_MesherHelper::IthVertex( 0, *edge );
        Handle(Geom_Curve) C3d = new Geom_Line( BRep_Tool::Pnt( V ), gp::DX() );
        myC3dAdaptor[i].Load( C3d, 0, 0.5 * BRep_Tool::Tolerance( V ));
      }
    }
    // reverse a proxy sub-mesh
    if ( !theIsForward )
      reverseProxySubmesh( myEdge[i] );

  } // loop on edges

  // count nodes and segments
  NbPoints( /*update=*/true );

  if ( nbEdges > 1 && myLength > DBL_MIN ) {
    const double degenNormLen = 1.e-5;
    double totLength = myLength;
    if ( nbDegen )
      totLength += myLength * degenNormLen * nbDegen;
    double prevNormPar = 0;
    for ( int i = 0; i < nbEdges; ++i ) {
      if ( myEdgeLength[ i ] < DBL_MIN )
        myEdgeLength[ i ] = myLength * degenNormLen;
      myNormPar[ i ] = prevNormPar + myEdgeLength[i]/totLength;
      prevNormPar = myNormPar[ i ];
    }
  }
  myNormPar[nbEdges-1] = 1.;
  //dump();
}

//================================================================================
/*!
 * \brief Constructor of a side for vertex using data from other FaceSide
 */
//================================================================================

StdMeshers_FaceSide::StdMeshers_FaceSide(const StdMeshers_FaceSide*  theSide,
                                         const SMDS_MeshNode*        theNode,
                                         const gp_Pnt2d*             thePnt2d1,
                                         const gp_Pnt2d*             thePnt2d2,
                                         const Handle(Geom2d_Curve)& theC2d,
                                         const double                theUFirst,
                                         const double                theULast)
{
  myC2d.push_back      ( theC2d );
  myFirst.push_back    ( theUFirst );
  myLast.push_back     ( theULast );
  myNormPar.push_back  ( 1. );
  myIsUniform.push_back( true );
  myEdgeID.push_back   ( 0 );
  myLength       = 0;
  myProxyMesh    = theSide->myProxyMesh;
  myDefaultPnt2d = *thePnt2d1;
  myPoints       = theSide->GetUVPtStruct();
  myNbPonits     = myPoints.size();
  myNbSegments   = theSide->myNbSegments;
  if ( thePnt2d2 )
    for ( size_t i = 0; i < myPoints.size(); ++i )
    {
      double r = i / ( myPoints.size() - 1. );
      myPoints[i].u = (1-r) * thePnt2d1->X() + r * thePnt2d2->X();
      myPoints[i].v = (1-r) * thePnt2d1->Y() + r * thePnt2d2->Y();
      myPoints[i].node = theNode;
    }
  else
    for ( size_t i = 0; i < myPoints.size(); ++i )
    {
      myPoints[i].u = thePnt2d1->X();
      myPoints[i].v = thePnt2d1->Y();
      myPoints[i].node = theNode;
    }
}

//================================================================================
/*
 * Create a side from an UVPtStructVec
 */
//================================================================================

StdMeshers_FaceSide::StdMeshers_FaceSide(UVPtStructVec&     theSideNodes,
                                         const TopoDS_Face& theFace)
{
  myEdge.resize( 1 );
  myEdgeID.resize( 1, -1 );
  myC2d.resize( 1 );
  myC3dAdaptor.resize( 1 );
  myFirst.resize( 1, 0. );
  myLast.resize( 1, 1. );
  myNormPar.resize( 1, 1. );
  myIsUniform.resize( 1, 1 );
  myMissingVertexNodes = myIgnoreMediumNodes = false;
  myDefaultPnt2d.SetCoord( 1e100, 1e100 );

  myFace       = theFace;
  myPoints     = theSideNodes;
  myNbPonits   = myPoints.size();
  myNbSegments = myNbPonits + 1;

  myLength = 0;
  if ( !myPoints.empty() )
  {
    myPoints[0].normParam = 0;
    if ( myPoints[0].node &&
         myPoints.back().node &&
         myPoints[ myNbPonits/2 ].node )
    {
      gp_Pnt pPrev = SMESH_TNodeXYZ( myPoints[0].node );
      for ( size_t i = 1; i < myPoints.size(); ++i )
      {
        gp_Pnt p = SMESH_TNodeXYZ( myPoints[i].node );
        myLength += p.Distance( pPrev );
        myPoints[i].normParam = myLength;
        pPrev = p;
      }
    }
    else if ( !theFace.IsNull() )
    {
      TopLoc_Location loc;
      Handle(Geom_Surface) surf = BRep_Tool::Surface( theFace, loc );
      gp_Pnt pPrev = surf->Value( myPoints[0].u, myPoints[0].v );
      for ( size_t i = 1; i < myPoints.size(); ++i )
      {
        gp_Pnt p = surf->Value( myPoints[i].u, myPoints[i].v );
        myLength += p.Distance( pPrev );
        myPoints[i].normParam = myLength;
        pPrev = p;
      }
    }
    else
    {
      gp_Pnt2d pPrev = myPoints[0].UV();
      for ( size_t i = 1; i < myPoints.size(); ++i )
      {
        gp_Pnt2d p = myPoints[i].UV();
        myLength += p.Distance( pPrev );
        myPoints[i].normParam = myLength;
        pPrev = p;
      }
    }
    if ( myLength > std::numeric_limits<double>::min() )
      for ( size_t i = 1; i < myPoints.size(); ++i )
        myPoints[i].normParam /= myLength;
  }
  myEdgeLength.resize( 1, myLength );
}

//================================================================================
/*
 * Return info on nodes on the side
 */
//================================================================================

const vector<UVPtStruct>& StdMeshers_FaceSide::GetUVPtStruct(bool   isXConst,
                                                             double constValue) const
{
  if ( myPoints.empty() )
  {
    if ( NbEdges() == 0 ) return myPoints;

    StdMeshers_FaceSide* me = const_cast< StdMeshers_FaceSide* >( this );
    SMESHDS_Mesh*    meshDS = myProxyMesh->GetMeshDS();
    SMESH_MesherHelper eHelper( *myProxyMesh->GetMesh() );
    SMESH_MesherHelper fHelper( *myProxyMesh->GetMesh() );
    fHelper.SetSubShape( myFace );
    bool paramOK;
    double eps = 1e-100;

    // sort nodes of all edges putting them into a map

    map< double, const SMDS_MeshNode*>            u2node;
    vector< pair< double, const SMDS_MeshNode*> > u2nodeVec;
    vector<const SMDS_MeshNode*>                  nodes;
    set<const SMDS_MeshNode*>                     vertexNodes;
    vector< const SMESH_ProxyMesh::SubMesh* >     proxySubMesh( myEdge.size() );
    int nbProxyNodes = 0;
    size_t iE;

    for ( iE = 0; iE < myEdge.size(); ++iE )
    {
      proxySubMesh[iE] = myProxyMesh->GetProxySubMesh( myEdge[iE] );
      if ( proxySubMesh[iE] )
      {
        if ( proxySubMesh[iE]->GetUVPtStructVec().empty() ) {
          proxySubMesh[iE] = 0;
        }
        else {
          nbProxyNodes += proxySubMesh[iE]->GetUVPtStructVec().size() - 1;
          if ( iE+1 == myEdge.size() )
            ++nbProxyNodes;
          continue;
        }
      }

      // Add 1st vertex node of a current edge
      const SMDS_MeshNode* node = VertexNode( iE );
      const double  prevNormPar = ( iE == 0 ? 0 : myNormPar[ iE-1 ]); // normalized param
      if ( node ) // nodes on internal vertices may be missing
      {
        if ( vertexNodes.insert( node ).second ||
             fHelper.IsRealSeam  ( node->getshapeId() ) ||
             fHelper.IsDegenShape( node->getshapeId() ))
          u2node.insert( u2node.end(), make_pair( prevNormPar, node ));
      }
      else if ( iE == 0 )
      {
        for ( ++iE; iE < myEdge.size(); ++iE )
          if (( node = VertexNode( iE ))) {
            u2node.insert( make_pair( prevNormPar, node ));
            break;
          }
        --iE;

        if ( !node )
          return myPoints;
        vertexNodes.insert( node );
      }

      // Add internal nodes
      nodes.clear();
      if ( !GetEdgeNodes( iE, nodes, /*v0=*/false, /*v1=*/false ))
        return myPoints;
      if ( !nodes.empty() )
      {
        u2nodeVec.clear();
        double paramSize = myLast[iE] - myFirst[iE];
        double r         = myNormPar[iE] - prevNormPar;
        eHelper.SetSubShape( myEdge[iE] );
        eHelper.ToFixNodeParameters( true );
        if ( !myIsUniform[iE] )
          for ( size_t i = 0; i < nodes.size(); ++i )
          {
            double     u = eHelper.GetNodeU( myEdge[iE], nodes[i], 0, &paramOK );
            double aLenU = GCPnts_AbscissaPoint::Length( me->myC3dAdaptor[iE], myFirst[iE], u );
            if ( myEdgeLength[iE] < aLenU ) // nonregression test "3D_mesh_NETGEN/G6"
            {
              u2nodeVec.clear();
              break;
            }
            double normPar = prevNormPar + r * aLenU / myEdgeLength[iE];
            u2nodeVec.push_back( make_pair( normPar, nodes[i] ));
          }
        if ( u2nodeVec.empty() )
          for ( size_t i = 0; i < nodes.size(); ++i )
          {
            double u = eHelper.GetNodeU( myEdge[iE], nodes[i], 0, &paramOK );
            // paramSize is signed so orientation is taken into account
            double normPar = prevNormPar + r * ( u - myFirst[iE] ) / paramSize;
            u2nodeVec.push_back( make_pair( normPar, nodes[i] ));
          }
        for ( size_t j = 0; j < u2nodeVec.size(); ++j )
          u2node.insert( u2node.end(), u2nodeVec[j] );
      }
    } // loop on myEdge's

    // Add 2nd VERTEX node for a last EDGE
    if ( !proxySubMesh.back() )
    {
      if ( u2node.empty() ) return myPoints;

      const SMDS_MeshNode* node;
      if ( IsClosed() )
        node = u2node.begin()->second;
      else
      {
        node = VertexNode( iE );
        while ( !node && iE > 0 )
          node = VertexNode( --iE );
        if ( !node )
          return myPoints;
      }
      if ( u2node.rbegin()->second == node &&
           !fHelper.IsRealSeam  ( node->getshapeId() ) &&
           !fHelper.IsDegenShape( node->getshapeId() ))
        u2node.erase( --u2node.end() );

      u2node.insert( u2node.end(), make_pair( 1., node ));
    }

    if ( u2node.size() + nbProxyNodes != myNbPonits &&
         u2node.size() + nbProxyNodes != NbPoints( /*update=*/true ))
    {
      MESSAGE("Wrong node parameters on edges, u2node.size():"
              <<u2node.size()<<" !=  myNbPonits:"<<myNbPonits);
      return myPoints;
    }

    // fill array of UVPtStruct

    UVPtStructVec& points = me->myPoints;
    points.resize( myNbPonits );

    int iPt = 0;
    double prevNormPar = 0, paramSize = myNormPar[ 0 ];
    map< double, const SMDS_MeshNode*>::iterator u_node = u2node.begin();
    for ( size_t iE = 0; iE < myEdge.size(); ++iE )
    {
      if ( proxySubMesh[ iE ] ) // copy data from a proxy sub-mesh
      {
        const UVPtStructVec& edgeUVPtStruct = proxySubMesh[iE]->GetUVPtStructVec();
        std::copy( edgeUVPtStruct.begin(), edgeUVPtStruct.end(), & points[iPt] );
        // check orientation
        double du1 = edgeUVPtStruct.back().param - edgeUVPtStruct[0].param;
        double du2 = myLast[iE] - myFirst[iE];
        if ( du1 * du2 < 0 )
        {
          std::reverse( & points[iPt], & points[iPt + edgeUVPtStruct.size()]);
          for ( size_t i = 0; i < edgeUVPtStruct.size(); ++i )
            points[iPt+i].normParam = 1. - points[iPt+i].normParam;
        }
        // update normalized params
        if ( myEdge.size() > 1 ) {
          for ( size_t i = 0; i < edgeUVPtStruct.size(); ++i, ++iPt )
          {
            UVPtStruct & uvPt = points[iPt];
            uvPt.normParam    = prevNormPar + uvPt.normParam * paramSize;
            uvPt.x = uvPt.y   = uvPt.normParam;
          }
          --iPt; // to point to the 1st VERTEX of the next EDGE
        }
      }
      else
      {
        for ( ; u_node != u2node.end(); ++u_node, ++iPt )
        {
          if ( myNormPar[ iE ]-eps < u_node->first )
            break; // u_node is at VERTEX of the next EDGE 

          UVPtStruct & uvPt = points[iPt];
          uvPt.node       = u_node->second;
          // -- normParam, x, y --------------------------------
          uvPt.normParam  = u_node->first;
          uvPt.x = uvPt.y = uvPt.normParam;
          // -- U ----------------------------------------------
          const SMDS_EdgePosition* epos =
            dynamic_cast<const SMDS_EdgePosition*>(uvPt.node->GetPosition());
          if ( epos && uvPt.node->getshapeId() == myEdgeID[iE] ) {
            uvPt.param = epos->GetUParameter();
          }
          else {
            double r = ( uvPt.normParam - prevNormPar )/ paramSize;
            uvPt.param = ( r > 0.5 ? myLast[iE] : myFirst[iE] );
          }
          // -- UV ---------------------------------------------
          if ( !myC2d[ iE ].IsNull() ) {
            gp_Pnt2d p = myC2d[ iE ]->Value( uvPt.param );
            uvPt.u = p.X();
            uvPt.v = p.Y();
          }
          else {
            uvPt.u = uvPt.v = 1e+100;
          }
        }
      }
      // prepare for the next EDGE
      if ( iE+1 < myEdge.size() )
      {
        prevNormPar = myNormPar[ iE ];
        paramSize   = myNormPar[ iE+1 ] - prevNormPar;
      }
    } // loop on myEdge's

    // set <constValue>
    if ( isXConst )
      for ( iPt = 0; iPt < points.size(); ++iPt ) points[ iPt ].x = constValue;
    else
      for ( iPt = 0; iPt < points.size(); ++iPt ) points[ iPt ].y = constValue;

  } // if ( myPoints.empty())

  return myPoints;
}

//================================================================================
/*!
 * \brief Falsificate info on nodes
 * \param nbSeg - nb of segments on the side
 * \retval UVPtStruct* - array of data structures
 */
//================================================================================

const vector<UVPtStruct>& StdMeshers_FaceSide::SimulateUVPtStruct(int    nbSeg,
                                                                  bool   isXConst,
                                                                  double constValue) const
{
  if ( myFalsePoints.empty() ) {

    if ( NbEdges() == 0 ) return myFalsePoints;

    vector<uvPtStruct>* points = const_cast<vector<uvPtStruct>*>( &myFalsePoints );
    points->resize( nbSeg+1 );

    int EdgeIndex = 0;
    double prevNormPar = 0, paramSize = myNormPar[ EdgeIndex ];
    for (int i = 0 ; i < myFalsePoints.size(); ++i ) {
      double normPar = double(i) / double(nbSeg);
      UVPtStruct & uvPt = (*points)[i];
      uvPt.node = 0;
      uvPt.x = uvPt.y = uvPt.param = uvPt.normParam = normPar;
      if ( isXConst ) uvPt.x = constValue;
      else            uvPt.y = constValue;
      if ( myNormPar[ EdgeIndex ] < normPar ) {
        prevNormPar = myNormPar[ EdgeIndex ];
        ++EdgeIndex;
        paramSize = myNormPar[ EdgeIndex ] - prevNormPar;
      }
      double r = ( normPar - prevNormPar )/ paramSize;
      uvPt.param = myFirst[EdgeIndex] * ( 1 - r ) + myLast[EdgeIndex] * r;
      if ( !myC2d[ EdgeIndex ].IsNull() ) {
        gp_Pnt2d p = myC2d[ EdgeIndex ]->Value( uvPt.param );
        uvPt.u = p.X();
        uvPt.v = p.Y();
      }
      else {
        uvPt.u = uvPt.v = 1e+100;
      }
    }
  }
  return myFalsePoints;
}

//=======================================================================
//function : GetOrderedNodes
//purpose  : Return nodes in the order they encounter while walking along the side
//=======================================================================

std::vector<const SMDS_MeshNode*> StdMeshers_FaceSide::GetOrderedNodes(int theEdgeInd) const
{
  vector<const SMDS_MeshNode*> resultNodes;
  if ( myPoints.empty() || ( theEdgeInd >= 0 && NbEdges() > 0 ))
  {
    if ( NbEdges() == 0 ) return resultNodes;

    SMESHDS_Mesh* meshDS = myProxyMesh->GetMeshDS();
    SMESH_MesherHelper eHelper( *myProxyMesh->GetMesh() );
    SMESH_MesherHelper fHelper( *myProxyMesh->GetMesh() );
    fHelper.SetSubShape( myFace );
    bool paramOK = true;

    // Sort nodes of all edges putting them into a map

    map< double, const SMDS_MeshNode*> u2node;
    vector<const SMDS_MeshNode*>       nodes;
    set<const SMDS_MeshNode*>          vertexNodes;
    int iE = 0, iEnd = myEdge.size();
    if ( theEdgeInd >= 0 )
    {
      iE   = theEdgeInd % NbEdges();
      iEnd = iE + 1;
    }
    for ( iE = 0; iE < iEnd; ++iE )
    {
      double prevNormPar = ( iE == 0 ? 0 : myNormPar[ iE-1 ]); // normalized param

      const SMESH_ProxyMesh::SubMesh* proxySM = myProxyMesh->GetProxySubMesh( myEdge[iE] );
      if ( proxySM )
      {
        const UVPtStructVec& points = proxySM->GetUVPtStructVec();
        for ( size_t i = 0; i < points.size(); ++i )
          u2node.insert( make_pair( prevNormPar + points[i].normParam, points[i].node ));
        continue;
      }

      // Add 1st vertex node of a current EDGE
      const SMDS_MeshNode* node = VertexNode( iE );
      if ( node ) { // nodes on internal vertices may be missing
        if ( vertexNodes.insert( node ).second ||
             fHelper.IsRealSeam  ( node->getshapeId() ) ||
             fHelper.IsDegenShape( node->getshapeId() ))
          u2node.insert( make_pair( prevNormPar, node ));
      }
      else if ( iE == 0 )
      {
        if ( nodes.empty() ) {
          for ( ++iE; iE < iEnd; ++iE )
            if (( node = VertexNode( iE ))) {
              u2node.insert( make_pair( prevNormPar, node ));
              break;
            }
          --iE;
        }
        if ( !node )
          return resultNodes;
        vertexNodes.insert( node );
      }

      // Add internal nodes
      nodes.clear();
      if ( !GetEdgeNodes( iE, nodes, /*v0=*/false, /*v1=*/false ))
        return resultNodes;
      if ( !nodes.empty() )
      {
        double paramSize = myLast[iE] - myFirst[iE];
        double r         = myNormPar[iE] - prevNormPar;
        eHelper.SetSubShape( myEdge[iE] );
        eHelper.ToFixNodeParameters( true );
        for ( size_t i = 0; i < nodes.size(); ++i )
        {
          double u = eHelper.GetNodeU( myEdge[iE], nodes[i], 0, &paramOK );
          // paramSize is signed so orientation is taken into account
          double normPar = prevNormPar + r * ( u - myFirst[iE] ) / paramSize;
          u2node.insert( u2node.end(), make_pair( normPar, nodes[i] ));
        }
      }

    } // loop on myEdges

    if ( u2node.empty() ) return resultNodes;

    // Add 2nd vertex node for a last EDGE
    {
      const SMDS_MeshNode* node;
      if ( IsClosed() && theEdgeInd < 0 )
        node = u2node.begin()->second;
      else
      {
        node = VertexNode( iE );
        while ( !node && iE > 0 )
          node = VertexNode( --iE );
        if ( !node )
          return resultNodes;
      }
      if ( u2node.rbegin()->second == node &&
           !fHelper.IsRealSeam  ( node->getshapeId() ) &&
           !fHelper.IsDegenShape( node->getshapeId() ))
        u2node.erase( --u2node.end() );

      u2node.insert( u2node.end(), make_pair( 1., node ));
    }

    // Fill the result vector

    if ( theEdgeInd < 0 &&
         u2node.size() != myNbPonits &&
         u2node.size() != NbPoints( /*update=*/true ))
    {
      u2node.clear();
    }
    resultNodes.reserve( u2node.size() );
    map< double, const SMDS_MeshNode*>::iterator u2n = u2node.begin();
    for ( ; u2n != u2node.end(); ++u2n )
      resultNodes.push_back( u2n->second );
  }
  else
  {
    resultNodes.resize( myPoints.size() );
    for ( size_t i = 0; i < myPoints.size(); ++i )
      resultNodes[i] = myPoints[i].node;
  }

  return resultNodes;
}

//================================================================================
/*!
 * \brief Return (unsorted) nodes of the i-th EDGE.
 *        Nodes moved to other geometry by MergeNodes() are also returned.
 *  \retval bool - is OK
 */
//================================================================================

bool StdMeshers_FaceSide::GetEdgeNodes(size_t                        i,
                                       vector<const SMDS_MeshNode*>& nodes,
                                       bool                          inlude1stVertex,
                                       bool                          inludeLastVertex) const
{
  if ( i >= myEdge.size() )
    return false;

  SMESH_Mesh*     mesh = myProxyMesh->GetMesh();
  SMESHDS_Mesh* meshDS = mesh->GetMeshDS();
  SMESHDS_SubMesh*  sm = meshDS->MeshElements( myEdge[i] );

  if ( inlude1stVertex )
  {
    if ( const SMDS_MeshNode* n0 = VertexNode( i ))
      nodes.push_back( n0 );
  }

  if ( sm && ( sm->NbElements() > 0 || sm->NbNodes() > 0 ))
  {
    if ( mesh->HasModificationsToDiscard() ) // check nb of nodes on the EDGE sub-mesh
    {
      int iQuad    = sm->NbElements() ? sm->GetElements()->next()->IsQuadratic() : 0;
      int nbExpect = sm->NbElements() - 1 + iQuad * sm->NbElements();
      if ( nbExpect != sm->NbNodes() ) // some nodes are moved from the EDGE by MergeNodes()
      {
        // add nodes of all segments
        typedef set< const SMDS_MeshNode* > TNodeSet;
        TNodeSet sharedNodes;
        SMDS_ElemIteratorPtr segIt = sm->GetElements();
        while ( segIt->more() )
        {
          const SMDS_MeshElement* seg = segIt->next();
          if ( seg->GetType() != SMDSAbs_Edge )
            continue;
          for ( int i = 0; i < 3-myIgnoreMediumNodes; ++i )
          {
            const SMDS_MeshNode* n = seg->GetNode( i );
            if ( i == 2 ) // medium node
            {
              nodes.push_back( n );
            }
            else
            {
              pair<TNodeSet::iterator, bool> it2new = sharedNodes.insert( n );
              if ( !it2new.second ) // n encounters twice == it's on EDGE, not on VERTEX
              {
                nodes.push_back( n );
                sharedNodes.erase( it2new.first );
              }
            }
          }
        }
      }
    }
    if ( nodes.size() < 2 ) // add nodes assigned to the EDGE
    {
      SMDS_NodeIteratorPtr nItr = sm->GetNodes();
      while ( nItr->more() )
      {
        const SMDS_MeshNode* n = nItr->next();
        if ( myIgnoreMediumNodes && SMESH_MeshEditor::IsMedium( n, SMDSAbs_Edge ))
          continue;
        nodes.push_back( n );
      }
    }
  } // if ( sm && sm->NbElements() > 0 )

  if ( inludeLastVertex )
  {
    if ( const SMDS_MeshNode* n1 = VertexNode( i+1 ))
      nodes.push_back( n1 );
  }
  return true;
}

//================================================================================
/*!
 * \brief Return a node from the i-th VERTEX (count starts from zero)
 *        Nodes moved to other geometry by MergeNodes() are also returned.
 *  \param [in] i - the VERTEX index
 *  \param [out] isMoved - returns \c true if the found node is moved by MergeNodes()
 *  \return const SMDS_MeshNode* - the found node
 */
//================================================================================

const SMDS_MeshNode* StdMeshers_FaceSide::VertexNode(std::size_t i, bool* isMoved) const
{
  TopoDS_Vertex V = ( i >= myEdge.size() ) ? LastVertex() : FirstVertex(i);

  const SMDS_MeshNode* n = SMESH_Algo::VertexNode( V, myProxyMesh->GetMeshDS() );

  if ( !n && !myEdge.empty() && myProxyMesh->GetMesh()->HasModificationsToDiscard() )
  {
    size_t iE = ( i < myEdge.size() ) ? i : myEdge.size()-1;
    SMESHDS_SubMesh* sm = myProxyMesh->GetMeshDS()->MeshElements( myEdgeID[ iE ]);

    n = SMESH_Algo::VertexNode( V, sm, myProxyMesh->GetMesh(), /*checkV=*/false );

    if (( !n ) &&
        (( i > 0 && i < NbEdges() ) || IsClosed() ))
    {
      iE = SMESH_MesherHelper::WrapIndex( int(i)-1, NbEdges() );
      sm = myProxyMesh->GetMeshDS()->MeshElements( myEdgeID[ iE ]);
      n  = SMESH_Algo::VertexNode( V, sm, myProxyMesh->GetMesh(), /*checkV=*/false );
    }

    if ( n && n->GetPosition()->GetDim() == 1 ) // check that n does not lie on an EDGE of myFace
    {
      TopoDS_Shape S = SMESH_MesherHelper::GetSubShapeByNode( n, myProxyMesh->GetMeshDS() );
      if ( SMESH_MesherHelper::IsSubShape( S, myFace ))
        n = 0; // VERTEX ignored by e.g. Composite Wire Discretization algo
    }
    if ( isMoved )
      *isMoved = n;
  }
  return n;
}

//================================================================================
/*!
 * \brief reverse order of vector elements
  * \param vec - vector to reverse
 */
//================================================================================

template <typename T > void reverse(vector<T> & vec)
{
  std::reverse( vec.begin(), vec.end() );
}

//================================================================================
/*!
 * \brief Change orientation of side geometry
 */
//================================================================================

void StdMeshers_FaceSide::Reverse()
{
  int nbEdges = myEdge.size();
  for ( int i = nbEdges-1; i >= 0; --i ) {
    std::swap( myFirst[i], myLast[i] );
    if ( !myEdge[i].IsNull() )
      myEdge[i].Reverse();
    if ( i > 0 ) // at the first loop 1. is overwritten
      myNormPar[i] = 1 - myNormPar[i-1];
  }
  if ( nbEdges > 1 ) {
    reverse( myEdge );
    reverse( myEdgeID );
    reverse( myC2d );
    //reverse( myC3dAdaptor );
    reverse( myFirst );
    reverse( myLast );
    reverse( myNormPar );
    reverse( myEdgeLength );
    reverse( myIsUniform );
  }
  if ( nbEdges > 0 )
  {
    myNormPar[nbEdges-1]=1.;
    if ( !myEdge[0].IsNull() )
    {
      for ( size_t i = 0; i < myEdge.size(); ++i )
        reverseProxySubmesh( myEdge[i] );
      myPoints.clear();
      myFalsePoints.clear();
    }
    else
    {
      for ( size_t i = 0; i < myPoints.size(); ++i )
      {
        UVPtStruct & uvPt = myPoints[i];
        uvPt.normParam = 1 - uvPt.normParam;
        uvPt.x         = 1 - uvPt.x;
        uvPt.y         = 1 - uvPt.y;
      }
      reverse( myPoints );

      for ( size_t i = 0; i < myFalsePoints.size(); ++i )
      {
        UVPtStruct & uvPt = myFalsePoints[i];
        uvPt.normParam = 1 - uvPt.normParam;
        uvPt.x         = 1 - uvPt.x;
        uvPt.y         = 1 - uvPt.y;
      }
      reverse( myFalsePoints );
    }
  }
  for ( size_t i = 0; i < myEdge.size(); ++i )
  {
    if ( myEdge[i].IsNull() ) continue; // for a side on points only
    double fp,lp;
    Handle(Geom_Curve) C3d = BRep_Tool::Curve(myEdge[i],fp,lp);
    if ( !C3d.IsNull() )
      myC3dAdaptor[i].Load( C3d, fp,lp );
  }
}

//=======================================================================
//function : SetIgnoreMediumNodes
//purpose  : Make ignore medium nodes
//=======================================================================

void StdMeshers_FaceSide::SetIgnoreMediumNodes(bool toIgnore)
{
  if ( myIgnoreMediumNodes != toIgnore )
  {
    myIgnoreMediumNodes = toIgnore;

    if ( !myPoints.empty() )
    {
      UVPtStructVec newPoints;
      newPoints.reserve( myPoints.size()/2 + 1 );
      for ( size_t i = 0; i < myPoints.size(); i += 2 )
        newPoints.push_back( myPoints[i] );

      myPoints.swap( newPoints );
    }
    else
    {
      NbPoints( /*update=*/true );
    }
  }
}

//=======================================================================
//function : NbPoints
//purpose  : Return nb nodes on edges and vertices (+1 to be == GetUVPtStruct().size() )
//           Call it with update == true if mesh of this side can be recomputed
//           since creation of this side
//=======================================================================

int StdMeshers_FaceSide::NbPoints(const bool update) const
{
  if ( !myPoints.empty() )
    return myPoints.size();

  // if ( !myFalsePoints.empty() )
  //   return myFalsePoints.size();

  if ( update && myEdge.size() > 0 )
  {
    StdMeshers_FaceSide* me = (StdMeshers_FaceSide*) this;
    me->myNbPonits = 0;
    me->myNbSegments = 0;
    me->myMissingVertexNodes = false;

    vector<const SMDS_MeshNode*> nodes;
    for ( int i = 0; i < NbEdges(); ++i )
    {
      if ( const SMESHDS_SubMesh* sm = myProxyMesh->GetSubMesh( Edge(i) ))
      {
        if ( sm->NbNodes() == sm->NbElements()-1 || sm->NbElements() == 0 )
        {
          me->myNbPonits += sm->NbNodes();
          if ( myIgnoreMediumNodes && sm->IsQuadratic() )
            me->myNbPonits -= sm->NbElements();
        }
        else // nodes can be moved to other shapes by MergeNodes()
        {
          nodes.clear();
          GetEdgeNodes( i, nodes, /*v1=*/false, /*v2=*/false );
          me->myNbPonits += nodes.size();
        }
        me->myNbSegments += sm->NbElements();
      }
    }

    SMESH_MesherHelper helper( *myProxyMesh->GetMesh() );
    helper.SetSubShape( myFace );

    std::set< const SMDS_MeshNode* > vNodes;
    const int nbV = NbEdges() + !IsClosed();
    for ( int i = 0; i < nbV; ++i )
      if ( const SMDS_MeshNode* n = VertexNode( i ))
      {
        if ( !vNodes.insert( n ).second &&
             ( helper.IsRealSeam  ( n->getshapeId() ) ||
               helper.IsDegenShape( n->getshapeId() )))
          me->myNbPonits++;
      }
      else
      {
        me->myMissingVertexNodes = true;
      }
    me->myNbPonits += vNodes.size();

    if ( IsClosed() )
      me->myNbPonits++; // closing node is repeated
  }
  return myNbPonits;
}

//=======================================================================
//function : NbSegments
//purpose  : Return nb edges
//           Call it with update == true if mesh of this side can be recomputed
//           since creation of this side
//=======================================================================

int StdMeshers_FaceSide::NbSegments(const bool update) const
{
  return NbPoints( update ), myNbSegments;
}

//================================================================================
/*!
 * \brief Reverse UVPtStructVec if a proxy sub-mesh of E
 */
//================================================================================

void StdMeshers_FaceSide::reverseProxySubmesh( const TopoDS_Edge& E )
{
  if ( !myProxyMesh ) return;
  if ( const SMESH_ProxyMesh::SubMesh* sm = myProxyMesh->GetProxySubMesh( E ))
  {
    UVPtStructVec& edgeUVPtStruct = (UVPtStructVec& ) sm->GetUVPtStructVec();
    for ( size_t i = 0; i < edgeUVPtStruct.size(); ++i )
    {
      UVPtStruct & uvPt = edgeUVPtStruct[i];
      uvPt.normParam = 1 - uvPt.normParam;
      uvPt.x         = 1 - uvPt.x;
      uvPt.y         = 1 - uvPt.y;
    }
    reverse( edgeUVPtStruct );
  }
}

//================================================================================
/*!
 * \brief Show side features
 */
//================================================================================

void StdMeshers_FaceSide::dump(const char* msg) const
{
#ifdef _DEBUG_
  if (msg) MESSAGE ( std::endl << msg );
  MESSAGE_BEGIN ("NB EDGES: "<< myEdge.size() );
  MESSAGE_ADD ( "nbPoints: "<<myNbPonits<<" vecSize: " << myPoints.size()<<" "<<myFalsePoints.size() );
  for ( int i=0; i<myEdge.size(); ++i)
  {
    MESSAGE_ADD ( "\t"<<i+1 );
    MESSAGE_ADD ( "\tEDGE: " );
    if (myEdge[i].IsNull()) {
      MESSAGE_ADD ( "NULL" );
    }
    else {
      TopAbs::Print(myEdge[i].Orientation(),cout)<<" "<<myEdge[i].TShape().operator->()<<endl;
      MESSAGE_ADD ( "\tV1: " << TopExp::FirstVertex( myEdge[i], 1).TShape().operator->()
                 << "  V2: " << TopExp::LastVertex( myEdge[i], 1).TShape().operator->() );
    }
    MESSAGE_ADD ( "\tC2d: ");
    
    if (myC2d[i].IsNull()) {
      MESSAGE_ADD ( "NULL" );
    }
    else {
      MESSAGE_ADD ( myC2d[i].operator->() );
    }
      
    MESSAGE_ADD ( "\tF: "<<myFirst[i]<< " L: "<< myLast[i] );
    MESSAGE_END ( "\tnormPar: "<<myNormPar[i]<<endl );
  }
#endif
}

//================================================================================
/*!
 * \brief Creates a Adaptor2d_Curve2d to be used in SMESH_Block
  * \retval Adaptor2d_Curve2d* - 
 */
//================================================================================

struct Adaptor2dCurve2d : public Adaptor2d_Curve2d
{
  const StdMeshers_FaceSide* mySide;
  Adaptor2dCurve2d(const StdMeshers_FaceSide* faceSide):mySide(faceSide) {}
  gp_Pnt2d Value(const Standard_Real U) const { return mySide->Value2d( U ); }
  Standard_Real FirstParameter() const { return 0; }
  Standard_Real LastParameter() const { return 1; }
};

Adaptor2d_Curve2d* StdMeshers_FaceSide::GetCurve2d() const
{
  return new Adaptor2dCurve2d( this );
}

//================================================================================
/*!
 * \brief Creates a fully functional Adaptor_Curve
 */
//================================================================================

BRepAdaptor_CompCurve* StdMeshers_FaceSide::GetCurve3d() const
{
  if ( myEdge.empty() )
    return 0;

  TopoDS_Wire aWire;
  BRep_Builder aBuilder;
  aBuilder.MakeWire(aWire);
  for ( int i=0; i<myEdge.size(); ++i )
    aBuilder.Add( aWire, myEdge[i] );

  if ( myEdge.size() == 2 && IsClosed() )
    aWire.Closed(true); // issue 0021141

  return new BRepAdaptor_CompCurve( aWire );
}

//================================================================================
/*!
 * \brief Return 2D point by normalized parameter
  * \param U - normalized parameter value
  * \retval gp_Pnt2d - point
 */
//================================================================================

gp_Pnt2d StdMeshers_FaceSide::Value2d(double U) const
{
  if ( !myC2d[0].IsNull() ) {
    int i = EdgeIndex( U );
    double prevU = i ? myNormPar[ i-1 ] : 0;
    double r = ( U - prevU )/ ( myNormPar[ i ] - prevU );

    double par = myFirst[i] * ( 1 - r ) + myLast[i] * r;
    
    // check parametrization of curve
    if( !myIsUniform[i] )
    {
      double aLen3dU = r * myEdgeLength[i] * ( myFirst[i]>myLast[i] ? -1. : 1.);
      GCPnts_AbscissaPoint AbPnt
        ( const_cast<GeomAdaptor_Curve&>( myC3dAdaptor[i]), aLen3dU, myFirst[i] );
      if( AbPnt.IsDone() ) {
        par = AbPnt.Parameter();
      }
    }
    return myC2d[ i ]->Value(par);

  }
  else if ( !myPoints.empty() )
  {
    int i = U * double( myPoints.size()-1 );
    while ( i > 0 && myPoints[ i ].normParam > U )
      --i;
    while ( i+1 < myPoints.size() && myPoints[ i+1 ].normParam < U )
      ++i;
    double r = (( U - myPoints[ i ].normParam ) /
                ( myPoints[ i+1 ].normParam - myPoints[ i ].normParam ));
    return ( myPoints[ i   ].UV() * ( 1 - r ) +
             myPoints[ i+1 ].UV() * r );
  }
  return myDefaultPnt2d;
}

//================================================================================
/*!
 * \brief Return XYZ by normalized parameter
  * \param U - normalized parameter value
  * \retval gp_Pnt - point
 */
//================================================================================

gp_Pnt StdMeshers_FaceSide::Value3d(double U) const
{
  int        i = EdgeIndex( U );
  double prevU = i ? myNormPar[ i-1 ] : 0;
  double     r = ( U - prevU )/ ( myNormPar[ i ] - prevU );

  double par = myFirst[i] * ( 1 - r ) + myLast[i] * r;

  // check parametrization of curve
  if( !myIsUniform[i] )
  {
    double aLen3dU = r * myEdgeLength[i] * ( myFirst[i]>myLast[i] ? -1. : 1.);
    GCPnts_AbscissaPoint AbPnt
      ( const_cast<GeomAdaptor_Curve&>( myC3dAdaptor[i]), aLen3dU, myFirst[i] );
    if( AbPnt.IsDone() ) {
      par = AbPnt.Parameter();
    }
  }
  return myC3dAdaptor[ i ].Value(par);
}

//================================================================================
/*!
 * \brief Return wires of a face as StdMeshers_FaceSide's
 */
//================================================================================

TSideVector StdMeshers_FaceSide::GetFaceWires(const TopoDS_Face&   theFace,
                                              SMESH_Mesh &         theMesh,
                                              const bool           theIgnoreMediumNodes,
                                              TError &             theError,
                                              SMESH_ProxyMesh::Ptr theProxyMesh,
                                              const bool           theCheckVertexNodes)
{
  list< TopoDS_Edge > edges, internalEdges;
  list< int > nbEdgesInWires;
  int nbWires = SMESH_Block::GetOrderedEdges (theFace, edges, nbEdgesInWires);

  // split list of all edges into separate wires
  TSideVector wires( nbWires );
  list< int >::iterator nbE = nbEdgesInWires.begin();
  list< TopoDS_Edge >::iterator from = edges.begin(), to = from;
  for ( int iW = 0; iW < nbWires; ++iW, ++nbE )
  {
    std::advance( to, *nbE );
    if ( *nbE == 0 ) // Issue 0020676
    {
      --nbWires;
      --iW;
      wires.resize( nbWires );
      continue;
    }
    list< TopoDS_Edge > wireEdges( from, to );
    // assure that there is a node on the first vertex
    // as StdMeshers_FaceSide::GetUVPtStruct() requires
    if ( wireEdges.front().Orientation() != TopAbs_INTERNAL ) // Issue 0020676
    {
      if ( theCheckVertexNodes )
        while ( !SMESH_Algo::VertexNode( TopExp::FirstVertex( wireEdges.front(), true),
                                         theMesh.GetMeshDS()))
        {
          wireEdges.splice(wireEdges.end(), wireEdges,
                           wireEdges.begin(), ++wireEdges.begin());
          if ( from->IsSame( wireEdges.front() )) {
            theError = TError
              ( new SMESH_ComputeError(COMPERR_BAD_INPUT_MESH,"No nodes on vertices"));
            return TSideVector(0);
          }
        }
    }
    else if ( *nbE > 1 ) // Issue 0020676 (Face_pb_netgen.brep) - several internal edges in a wire
    {
      internalEdges.splice( internalEdges.end(), wireEdges, ++wireEdges.begin(), wireEdges.end());
    }

    StdMeshers_FaceSide* wire = new StdMeshers_FaceSide( theFace, wireEdges, &theMesh,
                                                         /*isForward=*/true, theIgnoreMediumNodes,
                                                         theProxyMesh );
    wires[ iW ] = StdMeshers_FaceSidePtr( wire );
    from = to;
  }
  while ( !internalEdges.empty() )
  {
    StdMeshers_FaceSide* wire = new StdMeshers_FaceSide( theFace, internalEdges.back(), &theMesh,
                                                         /*isForward=*/true, theIgnoreMediumNodes,
                                                         theProxyMesh );
    wires.push_back( StdMeshers_FaceSidePtr( wire ));
    internalEdges.pop_back();
  }
  return wires;
}

//================================================================================
/*!
 * \brief Return 1st vertex of the i-the edge
 */
//================================================================================

TopoDS_Vertex StdMeshers_FaceSide::FirstVertex(int i) const
{
  TopoDS_Vertex v;
  if ( i < NbEdges() )
  {
    v = myEdge[i].Orientation() <= TopAbs_REVERSED ? // FORWARD || REVERSED
        TopExp::FirstVertex( myEdge[i], 1 )        :
        TopoDS::Vertex( TopoDS_Iterator( myEdge[i] ).Value() );
  }
  return v;
}

//================================================================================
/*!
 * \brief Return last vertex of the i-the edge
 */
//================================================================================

TopoDS_Vertex StdMeshers_FaceSide::LastVertex(int i) const
{
  TopoDS_Vertex v;
  if ( i < NbEdges() )
  {
    const TopoDS_Edge& edge = i<0 ? myEdge[ NbEdges() + i ] : myEdge[i];
    if ( edge.Orientation() <= TopAbs_REVERSED ) // FORWARD || REVERSED
      v = TopExp::LastVertex( edge, 1 );
    else
      for ( TopoDS_Iterator vIt( edge ); vIt.More(); vIt.Next() )
        v = TopoDS::Vertex( vIt.Value() );
  }
  return v;
}

//================================================================================
/*!
 * \brief Return \c true if the chain of EDGEs is closed
 */
//================================================================================

bool StdMeshers_FaceSide::IsClosed() const
{
  return myEdge.empty() ? false : FirstVertex().IsSame( LastVertex() );
}