// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2015 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 "unproject_in_mesh.h"
#include "unproject_ray.h"

template < typename Derivedobj>
  IGL_INLINE int igl::unproject_in_mesh(
      const Eigen::Vector2f& pos,
      const Eigen::Matrix4f& model,
      const Eigen::Matrix4f& proj,
      const Eigen::Vector4f& viewport,
      const std::function<
        void(
          const Eigen::Vector3f&,
          const Eigen::Vector3f&,
          std::vector<igl::Hit> &)
          > & shoot_ray,
      Eigen::PlainObjectBase<Derivedobj> & obj,
      std::vector<igl::Hit > & hits)
{
  using namespace igl;
  using namespace std;
  using namespace Eigen;
  Vector3f s,dir;
  unproject_ray(pos,model,proj,viewport,s,dir);
  shoot_ray(s,dir,hits);
  switch(hits.size())
  {
    case 0:
      break;
    case 1:
    {
      obj = (s + dir*hits[0].t).cast<typename Derivedobj::Scalar>();
      break;
    }
    case 2:
    default:
    {
      obj = 0.5*((s + dir*hits[0].t) + (s + dir*hits[1].t)).cast<typename Derivedobj::Scalar>();
      break;
    }
  }
  return hits.size();
}

extern "C"
{
#include "raytri.c"
}

template < typename DerivedV, typename DerivedF, typename Derivedobj>
  IGL_INLINE int igl::unproject_in_mesh(
      const Eigen::Vector2f& pos,
      const Eigen::Matrix4f& model,
      const Eigen::Matrix4f& proj,
      const Eigen::Vector4f& viewport,
      const Eigen::PlainObjectBase<DerivedV> & V,
      const Eigen::PlainObjectBase<DerivedF> & F,
      Eigen::PlainObjectBase<Derivedobj> & obj,
      std::vector<igl::Hit > & hits)
{
  using namespace igl;
  using namespace std;
  using namespace Eigen;
  const auto & shoot_ray = [&V,&F](
    const Eigen::Vector3f& s,
    const Eigen::Vector3f& dir,
    std::vector<igl::Hit> & hits)
  {
    // Should be but can't be const 
    Vector3d s_d = s.template cast<double>();
    Vector3d dir_d = dir.template cast<double>();
    hits.clear();
    // loop over all triangles
    for(int f = 0;f<F.rows();f++)
    {
      // Should be but can't be const 
      RowVector3d v0 = V.row(F(f,0)).template cast<double>();
      RowVector3d v1 = V.row(F(f,1)).template cast<double>();
      RowVector3d v2 = V.row(F(f,2)).template cast<double>();
      // shoot ray, record hit
      double t,u,v;
      if(intersect_triangle1(
        s_d.data(), dir_d.data(), v0.data(), v1.data(), v2.data(), &t, &u, &v))
      {
        hits.push_back({(int)f,(int)-1,(float)u,(float)v,(float)t});
      }
    }
    // Sort hits based on distance
    std::sort(
      hits.begin(),
      hits.end(),
      [](const Hit & a, const Hit & b)->bool{ return a.t < b.t;});
  };
  return unproject_in_mesh(pos,model,proj,viewport,shoot_ray,obj,hits);
}

template < typename DerivedV, typename DerivedF, typename Derivedobj>
  IGL_INLINE int igl::unproject_in_mesh(
      const Eigen::Vector2f& pos,
      const Eigen::Matrix4f& model,
      const Eigen::Matrix4f& proj,
      const Eigen::Vector4f& viewport,
      const Eigen::PlainObjectBase<DerivedV> & V,
      const Eigen::PlainObjectBase<DerivedF> & F,
      Eigen::PlainObjectBase<Derivedobj> & obj)
{
  std::vector<igl::Hit> hits;
  return unproject_in_mesh(pos,model,proj,viewport,V,F,obj,hits);
}
#ifdef IGL_STATIC_LIBRARY
#endif