// This file is part of libigl, a simple c++ geometry processing library.
// 
// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
// 
// This Source Code Form is subject to the terms of the Mozilla Public License 
// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
// obtain one at http://mozilla.org/MPL/2.0/.
#include "is_edge_manifold.h"

#include <algorithm>

template <typename DerivedV, typename DerivedF>
IGL_INLINE bool igl::is_edge_manifold(const Eigen::PlainObjectBase<DerivedV>& /*V*/,
                                 const Eigen::PlainObjectBase<DerivedF>& F)
{
  // List of edges (i,j,f,c) where edge i<j is associated with corner i of face
  // f
  std::vector<std::vector<int> > TTT;
  for(int f=0;f<F.rows();++f)
    for (int i=0;i<3;++i)
    {
      // v1 v2 f ei 
      int v1 = F(f,i);
      int v2 = F(f,(i+1)%3);
      if (v1 > v2) std::swap(v1,v2);
      std::vector<int> r(4);
      r[0] = v1; r[1] = v2;
      r[2] = f;  r[3] = i;
      TTT.push_back(r);
    }
  // Sort lexicographically
  std::sort(TTT.begin(),TTT.end());
  
  for(int i=2;i<(int)TTT.size();++i)
  {
    // Check any edges occur 3 times
    std::vector<int>& r1 = TTT[i-2];
    std::vector<int>& r2 = TTT[i-1];
    std::vector<int>& r3 = TTT[i];
    if ( (r1[0] == r2[0] && r2[0] == r3[0]) 
        && 
        (r1[1] == r2[1] && r2[1] == r3[1]) )
    {
      return false;
    }
  }
  return true;
}

#ifdef IGL_STATIC_LIBRARY
// Explicit template specialization
// generated by autoexplicit.sh
template bool igl::is_edge_manifold<Eigen::Matrix<float, -1, 3, 1, -1, 3>, Eigen::Matrix<unsigned int, -1, -1, 1, -1, -1> >(Eigen::PlainObjectBase<Eigen::Matrix<float, -1, 3, 1, -1, 3> > const&, Eigen::PlainObjectBase<Eigen::Matrix<unsigned int, -1, -1, 1, -1, -1> > const&);
// generated by autoexplicit.sh
//template bool igl::is_edge_manifold<double>(Eigen::Matrix<double, -1, -1, 0, -1, -1> const&, Eigen::Matrix<int, -1, -1, 0, -1, -1> const&);
template bool igl::is_edge_manifold<Eigen::Matrix<double, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1> >(Eigen::PlainObjectBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&);
#endif