/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004-2016                                           \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
*                                                                    \      *
* All rights reserved.                                                      *
*                                                                           *
* This program is free software; you can redistribute it and/or modify      *
* it under the terms of the GNU General Public License as published by      *
* the Free Software Foundation; either version 2 of the License, or         *
* (at your option) any later version.                                       *
*                                                                           *
* This program 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 General Public License (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
*                                                                           *
****************************************************************************/
#ifndef __VCG_MESH_RESAMPLER
#define __VCG_MESH_RESAMPLER

#include <vcg/complex/algorithms/update/normal.h>
#include <vcg/complex/algorithms/update/flag.h>
#include <vcg/complex/algorithms/update/bounding.h>
#include <vcg/complex/algorithms/update/component_ep.h>
#include <vcg/complex/algorithms/create/marching_cubes.h>
#include <vcg/space/index/grid_static_ptr.h>
#include <vcg/complex/algorithms/closest.h>
#include <vcg/space/box3.h>

namespace vcg {
namespace tri {


/** \addtogroup trimesh */
/*@{*/
/*@{*/
/** Class Resampler.
    This is class resampling a mesh using marching cubes methods
        @param OldMeshType (Template Parameter) Specifies the type of mesh to be resampled
        @param NewMeshType (Template Parameter) Specifies the type of output mesh.
    All the computations are done in the output mesh scalar type. (e.g. if you have a double mesh and you want to resample int to a float mesh the volume is kept in float)
 */

template <class OldMeshType,
          class NewMeshType,
          class DISTFUNCTOR = vcg::face::PointDistanceBaseFunctor<typename OldMeshType::ScalarType > >
class Resampler : public BasicGrid<typename NewMeshType::ScalarType>
{
  typedef typename NewMeshType::ScalarType NewScalarType;
  typedef typename NewMeshType::BoxType NewBoxType;
  typedef typename NewMeshType::CoordType NewCoordType;
  typedef typename NewMeshType::VertexType* NewVertexPointer;
  typedef typename NewMeshType::VertexIterator NewVertexIterator;
  typedef typename OldMeshType::CoordType OldCoordType;
  typedef typename OldMeshType::FaceContainer OldFaceCont;
  typedef typename OldMeshType::FaceType OldFaceType;
  typedef typename OldMeshType::ScalarType OldScalarType;

  class Walker : BasicGrid<typename NewMeshType::ScalarType>
  {
  private:
    typedef int VertexIndex;
    typedef typename vcg::GridStaticPtr<OldFaceType, OldScalarType> GridType;

  protected:

    int SliceSize;
    int	CurrentSlice;
    typedef tri::FaceTmark<OldMeshType> MarkerFace;
    MarkerFace markerFunctor;

    VertexIndex *_x_cs; // indici dell'intersezioni della superficie lungo gli Xedge della fetta corrente
    VertexIndex	*_y_cs; // indici dell'intersezioni della superficie lungo gli Yedge della fetta corrente
    VertexIndex *_z_cs; // indici dell'intersezioni della superficie lungo gli Zedge della fetta corrente
    VertexIndex *_x_ns; // indici dell'intersezioni della superficie lungo gli Xedge della prossima fetta
    VertexIndex *_z_ns; // indici dell'intersezioni della superficie lungo gli Zedge della prossima fetta

    //float *_v_cs;///values of distance fields for each direction in current slice
    //float *_v_ns;///values of distance fields for each direction in next slice

    typedef typename  std::pair<bool,float> field_value;
    field_value* _v_cs;
    field_value* _v_ns;

    NewMeshType	*_newM;
    OldMeshType	*_oldM;
    GridType _g;

  public:
    NewScalarType max_dim; // the limit value of the search (that takes into account of the offset)
    NewScalarType offset;    // an offset value that is always added to the returned value. Useful for extrarting isosurface  at a different threshold
    bool DiscretizeFlag; // if the extracted surface should be discretized or not.
    bool MultiSampleFlag;
    bool AbsDistFlag; // if true the Distance Field computed is no more a signed one.
    Walker(const Box3<NewScalarType> &_bbox, Point3i _siz )
    {
      this->bbox= _bbox;
      this->siz=_siz;
      this->ComputeDimAndVoxel();

      SliceSize = (this->siz.X()+1)*(this->siz.Z()+1);
      CurrentSlice = 0;
      offset=0;
      DiscretizeFlag=false;
      MultiSampleFlag=false;
      AbsDistFlag=false;

      _x_cs = new VertexIndex[ SliceSize ];
      _y_cs = new VertexIndex[ SliceSize ];
      _z_cs = new VertexIndex[ SliceSize ];
      _x_ns = new VertexIndex[ SliceSize ];
      _z_ns = new VertexIndex[ SliceSize ];

      _v_cs= new field_value[(this->siz.X()+1)*(this->siz.Z()+1)];
      _v_ns= new field_value[(this->siz.X()+1)*(this->siz.Z()+1)];

    };

    ~Walker()
    {}


    NewScalarType V(const Point3i &p)
    {
      return V(p.V(0),p.V(1),p.V(2));
    }


    std::pair<bool,NewScalarType> VV(int x,int y,int z)
    {
      assert ((y==CurrentSlice)||(y==(CurrentSlice+1)));

      //test if it is outside the bb of the mesh
      //vcg::Point3f test=vcg::Point3f((float)x,(float)y,(float)z);
      /*if (!_oldM->bbox.IsIn(test))
                return (1.f);*/
      int index=GetSliceIndex(x,z);

      if (y==CurrentSlice) return _v_cs[index];
      else return _v_ns[index];
    }

    NewScalarType V(int x,int y,int z)
    {
      if(DiscretizeFlag) return VV(x,y,z).second+offset<0?-1:1;
      return VV(x,y,z).second+offset;
    }
    ///return true if the distance form the mesh is less than maxdim and return distance
    field_value DistanceFromMesh(OldCoordType &pp)
    {
      OldScalarType dist;
      const NewScalarType max_dist = max_dim;
      OldCoordType testPt;
      this->IPfToPf(pp,testPt);

      OldCoordType closestPt;
      DISTFUNCTOR PDistFunct;
      OldFaceType *f = _g.GetClosest(PDistFunct,markerFunctor,testPt,max_dist,dist,closestPt);
      if (f==NULL) return field_value(false,0);
      if(AbsDistFlag) return field_value(true,dist);
      assert(!f->IsD());
      bool retIP;

      // To compute the interpolated normal we use the more robust function that require to know what is the most orhogonal direction of the face.
      OldCoordType pip(-1,-1,-1);
      retIP=InterpolationParameters(*f,(*f).cN(),closestPt, pip);
      assert(retIP); // this should happen only if the starting mesh has degenerate faces.

      const NewScalarType InterpolationEpsilon = 0.00001f;
      int zeroCnt=0;
      if(pip[0]<InterpolationEpsilon) ++zeroCnt;
      if(pip[1]<InterpolationEpsilon) ++zeroCnt;
      if(pip[2]<InterpolationEpsilon) ++zeroCnt;
      assert(zeroCnt<3);

      OldCoordType dir=(testPt-closestPt).Normalize();

      // Note that the two signs could be discordant.
      // Always choose the best one according to where the nearest point falls.
      NewScalarType signBest;

      // Compute test if the point see the surface normal from inside or outside
      // Surface normal for improved robustness is computed both by face and interpolated from vertices.
      OldCoordType closestNormV, closestNormF;
      if(zeroCnt>0) // we Not are in the middle of the face so the face normal is NOT reliable.
      {
        closestNormV =  (f->V(0)->cN())*pip[0] + (f->V(1)->cN())*pip[1] + (f->V(2)->cN())*pip[2] ;
        signBest =  dir.dot(closestNormV) ;
      }
      else
      {
        closestNormF =  f->cN() ;
        signBest =  dir.dot(closestNormF) ;
      }

      if(signBest<0) dist=-dist;

      return field_value(true,dist);
    }

    field_value MultiDistanceFromMesh(OldCoordType &pp)
    {
      float distSum=0;
      int positiveCnt=0; // positive results counter
      const int MultiSample=7;
      const OldCoordType   delta[7]={OldCoordType(0,0,0),
                                OldCoordType( 0.2,  -0.01, -0.02),
                                OldCoordType(-0.2,   0.01,  0.02),
                                OldCoordType( 0.01,  0.2,   0.01),
                                OldCoordType( 0.03, -0.2,  -0.03),
                                OldCoordType(-0.02, -0.03,  0.2 ),
                                OldCoordType(-0.01,  0.01, -0.2 )};

      for(int qq=0;qq<MultiSample;++qq)
      {
        OldCoordType pp2=pp+delta[qq];
        field_value ff= DistanceFromMesh(pp2);
        if(ff.first==false) return field_value(false,0);
        distSum += fabs(ff.second);
        if(ff.second>0) positiveCnt ++;
      }
      if(positiveCnt<=MultiSample/2) distSum = -distSum;
      return field_value(true, distSum/MultiSample);
    }

    /// compute the values if an entire slice (per y) distances>dig of a cell are signed with double of
    /// the distance of the bb
    void ComputeSliceValues(int slice,field_value *slice_values)
    {
      for (int i=0; i<=this->siz.X(); i++)
      {
        for (int k=0; k<=this->siz.Z(); k++)
        {
          int index=GetSliceIndex(i,k);
          OldCoordType pp(i,slice,k);
          if(this->MultiSampleFlag) slice_values[index] = MultiDistanceFromMesh(pp);
          else	slice_values[index] = DistanceFromMesh(pp);
        }
      }
      //ComputeConsensus(slice,slice_values);
    }

    /*
            For some reasons it can happens that the sign of the computed distance could not correct.
            this function tries to correct these issues by flipping the isolated voxels with discordant sign
        */
    void ComputeConsensus(int /*slice*/, field_value *slice_values)
    {
      float max_dist = min(min(this->voxel[0],this->voxel[1]),this->voxel[2]);
      int flippedCnt=0;
      int flippedTot=0;
      int flippedTimes=0;
      do
      {
        flippedCnt=0;
        for (int i=0; i<=this->siz.X(); i++)
        {
          for (int k=0; k<=this->siz.Z(); k++)
          {
            int goodCnt=0;
            int badCnt=0;
            int index=GetSliceIndex(i,k);
            int index_l,index_r,index_u,index_d;
            if(slice_values[index].first)
            {
              float curVal= slice_values[index].second;
              if(i > 0             ) index_l=GetSliceIndex(i-1,k); else index_l = index;
              if(i < this->siz.X() ) index_r=GetSliceIndex(i+1,k); else index_r = index;
              if(k > 0             ) index_d=GetSliceIndex(i,k-1); else index_d = index;
              if(k < this->siz.Z() ) index_u=GetSliceIndex(i,k+1); else index_u = index;

              if(slice_values[index_l].first) { goodCnt++; if(fabs(slice_values[index_l].second - curVal) > max_dist) badCnt++; }
              if(slice_values[index_r].first) { goodCnt++; if(fabs(slice_values[index_r].second - curVal) > max_dist) badCnt++; }
              if(slice_values[index_u].first) { goodCnt++; if(fabs(slice_values[index_u].second - curVal) > max_dist) badCnt++; }
              if(slice_values[index_d].first) { goodCnt++; if(fabs(slice_values[index_d].second - curVal) > max_dist) badCnt++; }

              if(badCnt >= goodCnt)  {
                slice_values[index].second *=-1.0f;
                //slice_values[index].first = false;
                flippedCnt++;
              }
            }
          }
        }
        flippedTot+=flippedCnt;
        flippedTimes++;
      }	while(flippedCnt>0);


#ifdef QT_VERSION
      if(flippedTot>0)
        qDebug("Flipped %i values in %i times",flippedTot,flippedTimes);
#endif
    }
    template<class EXTRACTOR_TYPE>
    void ProcessSlice(EXTRACTOR_TYPE &extractor)
    {
      for (int i=0; i<this->siz.X(); i++)
      {
        for (int k=0; k<this->siz.Z(); k++)
        {
          bool goodCell=true;
          Point3i p1(i,CurrentSlice,k);
          Point3i p2=p1+Point3i(1,1,1);
          for(int ii=0;ii<2;++ii)
            for(int jj=0;jj<2;++jj)
              for(int kk=0;kk<2;++kk)
                goodCell &= VV(p1[0]+ii,p1[1]+jj,p1[2]+kk).first;

          if(goodCell) extractor.ProcessCell(p1, p2);
        }
      }
    }


    template<class EXTRACTOR_TYPE>
    void BuildMesh(OldMeshType &old_mesh,NewMeshType &new_mesh,EXTRACTOR_TYPE &extractor,vcg::CallBackPos *cb)
    {
      _newM=&new_mesh;
      _oldM=&old_mesh;

      // the following two steps are required to be sure that the point-face distance without precomputed data works well.
      tri::UpdateNormal<OldMeshType>::PerFaceNormalized(old_mesh);
      tri::UpdateNormal<OldMeshType>::PerVertexAngleWeighted(old_mesh);
      int _size=(int)old_mesh.fn*100;

      _g.Set(_oldM->face.begin(),_oldM->face.end(),_size);
      markerFunctor.SetMesh(&old_mesh);

      _newM->Clear();

      Begin();
      extractor.Initialize();
      for (int j=0; j<=this->siz.Y(); j++)
      {
        if (cb) cb((100*j)/this->siz.Y(),"Marching ");
        ProcessSlice<EXTRACTOR_TYPE>(extractor);//find cells where there is the isosurface and examine it
        NextSlice();
      }
      extractor.Finalize();
      for(NewVertexIterator vi=new_mesh.vert.begin();vi!=new_mesh.vert.end();++vi)
        if(!(*vi).IsD())
        {
          this->IPfToPf((*vi).cP(),(*vi).P());
        }
    }

    //return the index of a vertex in slide as it was stored
    int GetSliceIndex(int x,int z)
    {
      VertexIndex index = x+z*(this->siz.X()+1);
      return (index);
    }

    //swap slices , the initial value of distance fields ids set as double of bbox of space
    void NextSlice()
    {

      memset(_x_cs, -1, SliceSize*sizeof(VertexIndex));
      memset(_y_cs, -1, SliceSize*sizeof(VertexIndex));
      memset(_z_cs, -1, SliceSize*sizeof(VertexIndex));


      std::swap(_x_cs, _x_ns);
      std::swap(_z_cs, _z_ns);

      std::swap(_v_cs, _v_ns);

      CurrentSlice ++;

      ComputeSliceValues(CurrentSlice + 1,_v_ns);
    }

    //initialize data strucures , the initial value of distance fields ids set as double of bbox of space
    void Begin()
    {

      CurrentSlice = 0;

      memset(_x_cs, -1, SliceSize*sizeof(VertexIndex));
      memset(_y_cs, -1, SliceSize*sizeof(VertexIndex));
      memset(_z_cs, -1, SliceSize*sizeof(VertexIndex));
      memset(_x_ns, -1, SliceSize*sizeof(VertexIndex));
      memset(_z_ns, -1, SliceSize*sizeof(VertexIndex));

      ComputeSliceValues(CurrentSlice,_v_cs);
      ComputeSliceValues(CurrentSlice+1,_v_ns);
    }




    bool Exist(const vcg::Point3i &p1, const vcg::Point3i &p2, NewVertexPointer &v)
    {
      int i = p1.X();// - _bbox.min.X())/_cell_size.X();
      int z = p1.Z();// - _bbox.min.Z())/_cell_size.Z();
      VertexIndex index = i+z*this->siz.X();

      //VertexIndex index =GetSliceIndex(//
      int v_ind = 0;
      if (p1.X()!=p2.X()) //intersezione della superficie con un Xedge
      {
        if (p1.Y()==CurrentSlice)
        {
          if (_x_cs[index]!=-1)
          {
            v_ind = _x_cs[index];
            v = &_newM->vert[v_ind];
            assert(!v->IsD());
            return true;
          }

        }
        else
        {
          if (_x_ns[index]!=-1)
          {
            v_ind = _x_ns[index];
            v = &_newM->vert[v_ind];
            assert(!v->IsD());
            return true;
          }
        }
        v = NULL;
        return false;
      }
      else if (p1.Y()!=p2.Y()) //intersezione della superficie con un Yedge
      {
        if (_y_cs[index]!=-1)
        {
          v_ind =_y_cs[index];
          v = &_newM->vert[v_ind];
          assert(!v->IsD());
          return true;
        }
        else
        {
          v = NULL;
          return false;
        }

      }
      else if (p1.Z()!=p2.Z())
        //intersezione della superficie con un Zedge
      {
        if (p1.Y()==CurrentSlice)
        {
          if ( _z_cs[index]!=-1)
          {
            v_ind = _z_cs[index];
            v = &_newM->vert[v_ind];
            assert(!v->IsD());
            return true;
          }

        }
        else
        {
          if (_z_ns[index]!=-1)
          {
            v_ind = _z_ns[index];
            v = &_newM->vert[v_ind];
            assert(!v->IsD());
            return true;
          }
        }
        v = NULL;
        return false;
      }
      assert (0);
      return false;
    }

    ///interpolate
    NewCoordType Interpolate(const vcg::Point3i &p1, const vcg::Point3i &p2,int dir)
    {
      NewScalarType f1 = V(p1);
      NewScalarType f2 = V(p2);
      NewScalarType u =  f1/(f1-f2);
      NewCoordType ret(p1.V(0),p1.V(1),p1.V(2));
      ret.V(dir) = p1.V(dir)*(1.f-u) + u*p2.V(dir);
      return (ret);
    }

    ///if there is a vertex in z axis of a cell return the vertex or create it
    void GetXIntercept(const vcg::Point3i &p1, const vcg::Point3i &p2, NewVertexPointer &v)
    {
      assert(p1.X()+1 == p2.X());
      assert(p1.Y()   == p2.Y());
      assert(p1.Z()   == p2.Z());

      int i = p1.X();// (p1.X() - _bbox.min.X())/_cell_size.X();
      int z = p1.Z();//(p1.Z() - _bbox.min.Z())/_cell_size.Z();
      VertexIndex index = i+z*this->siz.X();
      VertexIndex pos=-1;
      if (p1.Y()==CurrentSlice)
      {
        if ((pos=_x_cs[index])==-1)
        {
          _x_cs[index] = (VertexIndex) _newM->vert.size();
          pos = _x_cs[index];
          Allocator<NewMeshType>::AddVertices( *_newM, 1 );
          v = &_newM->vert[pos];
          v->P()=Interpolate(p1,p2,0);
          return;
        }
      }
      if (p1.Y()==CurrentSlice+1)
      {
        if ((pos=_x_ns[index])==-1)
        {
          _x_ns[index] = (VertexIndex) _newM->vert.size();
          pos = _x_ns[index];
          Allocator<NewMeshType>::AddVertices( *_newM, 1 );
          v = &_newM->vert[pos];
          v->P()=Interpolate(p1,p2,0);
          return;
        }
      }
      assert(pos>=0);
      v = &_newM->vert[pos];
    }

    ///if there is a vertex in y axis of a cell return the vertex or create it
    void GetYIntercept(const vcg::Point3i &p1, const vcg::Point3i &p2, NewVertexPointer &v)
    {
      assert(p1.X()   == p2.X());
      assert(p1.Y()+1 == p2.Y());
      assert(p1.Z()   == p2.Z());

      int i = p1.X(); // (p1.X() - _bbox.min.X())/_cell_size.X();
      int z = p1.Z(); // (p1.Z() - _bbox.min.Z())/_cell_size.Z();
      VertexIndex index = i+z*this->siz.X();
      VertexIndex pos=-1;
      if ((pos=_y_cs[index])==-1)
      {
        _y_cs[index] = (VertexIndex) _newM->vert.size();
        pos = _y_cs[index];
        Allocator<NewMeshType>::AddVertices( *_newM, 1);
        v = &_newM->vert[ pos ];
        v->P()=Interpolate(p1,p2,1);
      }
      assert(pos>=0);
      v = &_newM->vert[pos];
    }

    ///if there is a vertex in z axis of a cell return the vertex or create it
    void GetZIntercept(const vcg::Point3i &p1, const vcg::Point3i &p2, NewVertexPointer &v)
    {
      assert(p1.X()   == p2.X());
      assert(p1.Y()   == p2.Y());
      assert(p1.Z()+1 == p2.Z());

      int i = p1.X(); //(p1.X() - _bbox.min.X())/_cell_size.X();
      int z = p1.Z(); //(p1.Z() - _bbox.min.Z())/_cell_size.Z();
      VertexIndex index = i+z*this->siz.X();

      VertexIndex pos=-1;
      if (p1.Y()==CurrentSlice)
      {
        if ((pos=_z_cs[index])==-1)
        {
          _z_cs[index] = (VertexIndex) _newM->vert.size();
          pos = _z_cs[index];
          Allocator<NewMeshType>::AddVertices( *_newM, 1 );
          v = &_newM->vert[pos];
          v->P()=Interpolate(p1,p2,2);
          return;
        }
      }
      if (p1.Y()==CurrentSlice+1)
      {
        if ((pos=_z_ns[index])==-1)
        {
          _z_ns[index] = (VertexIndex) _newM->vert.size();
          pos = _z_ns[index];
          Allocator<NewMeshType>::AddVertices( *_newM, 1 );
          v = &_newM->vert[pos];
          v->P()=Interpolate(p1,p2,2);
          return;
        }
      }
      assert(pos>=0);
      v = &_newM->vert[pos];
    }

  };//end class walker

public:

  typedef Walker  /*< Old_Mesh,New_Mesh>*/  MyWalker;

  typedef vcg::tri::MarchingCubes<NewMeshType, MyWalker> MyMarchingCubes;

  ///resample the mesh using marching cube algorithm ,the accuracy is the dimension of one cell the parameter
  static void Resample(OldMeshType &old_mesh, NewMeshType &new_mesh,  NewBoxType volumeBox, vcg::Point3<int> accuracy,float max_dist, float thr=0, bool DiscretizeFlag=false, bool MultiSampleFlag=false, bool AbsDistFlag=false, vcg::CallBackPos *cb=0 )
  {
    ///be sure that the bounding box is updated
    vcg::tri::UpdateBounding<OldMeshType>::Box(old_mesh);

    MyWalker	walker(volumeBox,accuracy);

    walker.max_dim=max_dist+fabs(thr);
    walker.offset = - thr;
    walker.DiscretizeFlag = DiscretizeFlag;
    walker.MultiSampleFlag = MultiSampleFlag;
    walker.AbsDistFlag = AbsDistFlag;
    MyMarchingCubes mc(new_mesh, walker);
    walker.BuildMesh(old_mesh,new_mesh,mc,cb);
  }


};//end class resampler

}//end namespace tri
}//end namespace vcg
#endif
