/*
 * Copyright (c) 2011-2022, The DART development contributors
 * All rights reserved.
 *
 * The list of contributors can be found at:
 *   https://github.com/dartsim/dart/blob/master/LICENSE
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 *   without modification, are permitted provided that the following
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 *     disclaimer in the documentation and/or other materials provided
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 */

#include "Controller.hpp"

//==============================================================================
Controller::Controller(
    dart::dynamics::SkeletonPtr _robot, dart::dynamics::BodyNode* _endEffector)
  : mRobot(_robot), mEndEffector(_endEffector)
{
  assert(_robot != nullptr);
  assert(_endEffector != nullptr);

  int dof = mRobot->getNumDofs();

  mForces.setZero(dof);

  mKp.setZero();
  mKv.setZero();

  for (int i = 0; i < 3; ++i)
  {
    mKp(i, i) = 750.0;
    mKv(i, i) = 250.0;
  }

  // Remove position limits
  for (int i = 0; i < dof; ++i)
    _robot->getJoint(i)->setLimitEnforcement(false);

  // Set joint damping
  for (int i = 0; i < dof; ++i)
    _robot->getJoint(i)->setDampingCoefficient(0, 0.5);
}

//==============================================================================
Controller::~Controller() {}

//==============================================================================
void Controller::update(const Eigen::Vector3d& _targetPosition)
{
  using namespace dart;

  // Get equation of motions
  Eigen::Vector3d x = mEndEffector->getTransform().translation();
  Eigen::Vector3d dx = mEndEffector->getLinearVelocity();
  Eigen::MatrixXd invM = mRobot->getInvMassMatrix();                 // n x n
  Eigen::VectorXd Cg = mRobot->getCoriolisAndGravityForces();        // n x 1
  math::LinearJacobian Jv = mEndEffector->getLinearJacobian();       // 3 x n
  math::LinearJacobian dJv = mEndEffector->getLinearJacobianDeriv(); // 3 x n
  Eigen::VectorXd dq = mRobot->getVelocities();                      // n x 1

  // Compute operational space values
  Eigen::MatrixXd A = Jv * invM;                   // 3 x n
  Eigen::Vector3d b = /*-(A*Cg) + */ dJv * dq;     // 3 x 1
  Eigen::MatrixXd M2 = Jv * invM * Jv.transpose(); // 3 x 3

  // Compute virtual operational space spring force at the end effector
  Eigen::Vector3d f = -mKp * (x - _targetPosition) - mKv * dx;

  // Compute desired operational space acceleration given f
  Eigen::Vector3d desired_ddx = b + M2 * f;

  // Gravity compensation
  mForces = Cg;

  // Compute joint space forces to acheive the desired acceleration by solving:
  // A tau + b = desired_ddx
  mForces += A.colPivHouseholderQr().solve(desired_ddx - b);

  // Apply the joint space forces to the robot
  mRobot->setForces(mForces);
}

//==============================================================================
dart::dynamics::SkeletonPtr Controller::getRobot() const
{
  return mRobot;
}

//==============================================================================
dart::dynamics::BodyNode* Controller::getEndEffector() const
{
  return mEndEffector;
}

//==============================================================================
void Controller::keyboard(unsigned char /*_key*/, int /*_x*/, int /*_y*/) {}
