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#include "dart/dynamics/LineSegmentShape.hpp"
#include "dart/common/Console.hpp"
#include "dart/math/Geometry.hpp"

namespace dart {
namespace dynamics {

//==============================================================================
const Eigen::Vector3d LineSegmentShape::mDummyVertex = Eigen::Vector3d::Zero();

//==============================================================================
LineSegmentShape::LineSegmentShape(float _thickness)
  : Shape(LINE_SEGMENT),
    mThickness(_thickness)
{
  if (_thickness <= 0.0f)
  {
    dtwarn << "[LineSegmentShape::LineSegmentShape] Attempting to set "
           << "non-positive thickness. We set the thickness to 1.0f instead."
           << std::endl;
    mThickness = 1.0f;
  }

  mVariance = DYNAMIC_VERTICES;
}

//==============================================================================
LineSegmentShape::LineSegmentShape(const Eigen::Vector3d& _v1,
                                   const Eigen::Vector3d& _v2,
                                   float _thickness)
  : Shape(),
    mThickness(_thickness)
{
  if (_thickness <= 0.0f)
  {
    dtwarn << "[LineSegmentShape::LineSegmentShape] Attempting to set "
           << "non-positive thickness. We set the thickness to 1.0f instead."
           << std::endl;
    mThickness = 1.0f;
  }

  addVertex(_v1);
  addVertex(_v2);
  mVariance = DYNAMIC_VERTICES;
}

//==============================================================================
const std::string& LineSegmentShape::getType() const
{
  return getStaticType();
}

//==============================================================================
const std::string& LineSegmentShape::getStaticType()
{
  static const std::string type("LineSegmentShape");
  return type;
}

//==============================================================================
void LineSegmentShape::setThickness(float _thickness)
{
  if (_thickness <= 0.0f)
  {
    dtwarn << "[LineSegmentShape::setThickness] Attempting to set non-positive "
           << "thickness. We set the thickness to 1.0f instead." << std::endl;
    mThickness = 1.0f;
    return;
  }

  mThickness = _thickness;
}

//==============================================================================
float LineSegmentShape::getThickness() const
{
  return mThickness;
}

//==============================================================================
std::size_t LineSegmentShape::addVertex(const Eigen::Vector3d& _v)
{
  std::size_t parent = mVertices.size();
  if(parent > 0)
    return addVertex(_v, parent-1);

  mVertices.push_back(_v);
  return 0;
}

//==============================================================================
std::size_t LineSegmentShape::addVertex(const Eigen::Vector3d& _v, std::size_t _parent)
{
  std::size_t index = mVertices.size();
  mVertices.push_back(_v);

  if(_parent > mVertices.size())
  {
    if(mVertices.size() == 0)
      dtwarn << "[LineSegmentShape::addVertex(const Eigen::Vector3d&, std::size_t)] "
             << "Attempting to add a vertex to be a child of vertex #"
             << _parent << ", but no vertices exist yet. No connection will be "
             << "created for the new vertex yet.\n";
    else
      dtwarn << "[LineSegmentShape::addVertex(const Eigen::Vector3d&, std::size_t)] "
             << "Attempting to add a vertex to be a child of vertex #"
             << _parent << ", but the vertex indices only go up to "
             << mVertices.size()-1 << ". No connection will be created for the "
             << "new vertex yet.\n";
  }
  else
  {
    mConnections.push_back(Eigen::Vector2i(_parent, index));
  }

  return index;
}

//==============================================================================
void LineSegmentShape::removeVertex(std::size_t _idx)
{
  if(_idx >= mVertices.size())
  {
    if(mVertices.size() == 0)
      dtwarn << "[LineSegmentShape::removeVertex] Attempting to remove vertex #"
             << _idx << ", but "
             << "this LineSegmentShape contains no vertices. "
             << "No vertex will be removed.\n";
    else
      dtwarn << "[LineSegmentShape::removeVertex] Attempting to remove vertex #"
             << _idx << ", but "
             << "vertex indices only go up to #" << mVertices.size()-1 << ". "
             << "No vertex will be removed.\n";

    return;
  }

  mVertices.erase(mVertices.begin()+_idx);
}

//==============================================================================
void LineSegmentShape::setVertex(std::size_t _idx, const Eigen::Vector3d& _v)
{
  if(_idx >= mVertices.size())
  {
    if(mVertices.size() == 0)
      dtwarn << "[LineSegmentShape::setVertex] Attempting to set vertex #" << _idx
             << ", but "
             << "no vertices exist in this LineSegmentShape yet.\n";
    else
      dtwarn << "[LineSegmentShape::setVertex] Attempting to set vertex #" << _idx
             << ", but "
             << "the vertices of this LineSegmentShape only go up to #"
             << mVertices.size()-1 << ".\n";

    return;
  }
  mVertices[_idx] = _v;
}

//==============================================================================
const Eigen::Vector3d& LineSegmentShape::getVertex(std::size_t _idx) const
{
  if(_idx < mVertices.size())
    return mVertices[_idx];

  if(mVertices.empty())
  {
    dtwarn << "[LineSegmentShape::getVertex] Requested vertex #" << _idx
           << ", but no vertices currently exist in this LineSegmentShape\n";
  }
  else
  {
    dtwarn << "[LineSegmentShape::getVertex] Requested vertex #" << _idx
           << ", but vertex indices currently only go up to "
           << mVertices.size()-1 << "\n";
  }

  return mDummyVertex;
}

//==============================================================================
const std::vector<Eigen::Vector3d>& LineSegmentShape::getVertices() const
{
  return mVertices;
}

//==============================================================================
void LineSegmentShape::addConnection(std::size_t _idx1, std::size_t _idx2)
{
  if(_idx1 >= mVertices.size() || _idx2 >= mVertices.size())
  {
    if(mVertices.size() == 0)
      dtwarn << "[LineSegmentShape::createConnection] Attempted to create a "
             << "connection between vertex #" << _idx1 << " and vertex #" << _idx2
             << ", but no vertices exist for this LineSegmentShape yet. "
             << "No connection will be made for these non-existent vertices.\n";
    else
      dtwarn << "[LineSegmentShape::createConnection] Attempted to create a "
             << "connection between vertex #" << _idx1 << " and vertex #" << _idx2
             << ", but the vertices only go up to #" << mVertices.size() << ". "
             << "No connection will be made for these non-existent vertices.\n";

    return;
  }

  mConnections.push_back(Eigen::Vector2i(_idx1, _idx2));
}

//==============================================================================
void LineSegmentShape::removeConnection(std::size_t _vertexIdx1, std::size_t _vertexIdx2)
{
  // Search through all connections to remove any that match the request
  common::aligned_vector<Eigen::Vector2i>::iterator it = mConnections.begin();
  while(it != mConnections.end())
  {
    const Eigen::Vector2i c = (*it);
    if(    (c[0] == (int)_vertexIdx1 && c[1] == (int)_vertexIdx2)
        || (c[0] == (int)_vertexIdx2 && c[1] == (int)_vertexIdx1) )
    {
      // Erase this iterator, but not before stepping it forward to the next
      // iterator in the sequence.
      mConnections.erase(it++);
    }
    else
      ++it;
  }
}

//==============================================================================
void LineSegmentShape::removeConnection(std::size_t _connectionIdx)
{
  if(_connectionIdx >= mConnections.size())
  {
    if(mConnections.size() == 0)
      dtwarn << "[LineSegmentShape::removeConnection(std::size_t)] Attempting to "
             << "remove connection #" << _connectionIdx << ", but "
             << "no connections exist yet. "
             << "No connection will be removed.\n";
    else
      dtwarn << "[LineSegmentShape::removeConnection(std::size_t)] Attempting to "
             << "remove connection #" << _connectionIdx << ", but "
             << "connection indices only go up to #" << mConnections.size()-1
             << ". " << "No connection will be removed.\n";

    return;
  }

  mConnections.erase(mConnections.begin()+_connectionIdx);
}

//==============================================================================
const common::aligned_vector<Eigen::Vector2i>&
LineSegmentShape::getConnections() const
{
  return mConnections;
}

//==============================================================================
Eigen::Matrix3d LineSegmentShape::computeInertia(double _mass) const
{
  Eigen::Matrix3d inertia = Eigen::Matrix3d::Zero();

  double totalLength = 0;
  for(const Eigen::Vector2i& c : mConnections)
  {
    const Eigen::Vector3d& v0 = mVertices[c[0]];
    const Eigen::Vector3d& v1 = mVertices[c[1]];

    totalLength += (v1-v0).norm();
  }

  for(const Eigen::Vector2i& c : mConnections)
  {
    const Eigen::Vector3d& v0 = mVertices[c[0]];
    const Eigen::Vector3d& v1 = mVertices[c[1]];

    double radius = 1e-6;
    double height = (v1-v0).norm();

    double partialMass = _mass * height/totalLength;

    Eigen::Matrix3d partialInertia = Eigen::Matrix3d::Zero();
    partialInertia(0, 0) = partialMass * (3.0 * radius*radius + height*height) / 12.0;
    partialInertia(1, 1) = partialInertia(0, 0);
    partialInertia(2, 2) = 0.5 * _mass * radius * radius;

    Eigen::Vector3d v = v1-v0;
    Eigen::Vector3d axis;
    double angle;
    if(v.norm() == 0)
    {
      angle = 0;
      axis = Eigen::Vector3d::UnitX();
    }
    else
    {
      v.normalize();
      Eigen::Vector3d axis = Eigen::Vector3d::UnitZ().cross(v);
      if(axis.norm() == 0)
      {
        angle = 0;
        axis = Eigen::Vector3d::UnitX();
      }
      else
      {
        axis.normalize();
        angle = acos(Eigen::Vector3d::UnitZ().dot(v));
      }
    }

    Eigen::AngleAxisd R(angle, axis);
    Eigen::Vector3d center = (v1+v0)/2.0;
    inertia += R.matrix()
        * math::parallelAxisTheorem(partialInertia, center, partialMass)
        * R.matrix().transpose();
  }

  return inertia;
}

//==============================================================================
void LineSegmentShape::updateBoundingBox() const
{
  if (mVertices.empty())
  {
    mBoundingBox.setMin(Eigen::Vector3d::Zero());
    mBoundingBox.setMax(Eigen::Vector3d::Zero());
    mIsBoundingBoxDirty = false;
    return;
  }

  Eigen::Vector3d min
      = Eigen::Vector3d::Constant(std::numeric_limits<double>::infinity());
  Eigen::Vector3d max
      = Eigen::Vector3d::Constant(-std::numeric_limits<double>::infinity());

  for (const auto& vertex : mVertices)
  {
    min = min.cwiseMin(vertex);
    max = max.cwiseMax(vertex);
  }

  mBoundingBox.setMin(min);
  mBoundingBox.setMax(max);

  mIsBoundingBoxDirty = false;
}

//==============================================================================
void LineSegmentShape::updateVolume() const
{
  mVolume = 0.0;
  mIsVolumeDirty = false;
}

} // namespace dynamics
} // namespace dart
