#pragma once

#include <gazebo/gazebo.hh>

using namespace gazebo;

/**
 * \brief Plugin for reading the angle of a joint.
 *
 * This plugin publishes the angle of a joint to the topic every
 * physics update. Supports reading in either radians or degrees.
 *
 * To add a potentiometer to your robot, add the following XML to your
 * robot model:
 *
 *     <plugin name="my_pot" filename="libgz_potentiometer.so">
 *       <joint>Joint Name</joint>
 *       <topic>~/my/topic</topic>
 *       <units>{degrees, radians}</units>
 *     </plugin>
 *
 * - `joint`: Name of the joint this potentiometer is attached to.
 * - `topic`: Optional. Message will be published as a gazebo.msgs.Float64.
 * - `units`: Optional. Defaults to radians.
 */
class Potentiometer: public ModelPlugin {
public: 
  Potentiometer();
  ~Potentiometer();
  
  /// \brief Load the potentiometer and configures it according to the sdf.
  void Load(physics::ModelPtr model, sdf::ElementPtr sdf);
  
  /// \brief Sends out the potentiometer reading each timestep.
  void Update(const common::UpdateInfo &info);

private:
  /// \brief Publish the angle on this topic.
  std::string topic;

  /// \brief Whether or not this potentiometer measures radians or degrees.
  bool radians;

  /// \brief The joint that this potentiometer measures
  physics::JointPtr joint;


  physics::ModelPtr model;         ///< \brief The model that this is attached to. 
  event::ConnectionPtr updateConn; ///< \brief Pointer to the world update function.
  transport::NodePtr node;         ///< \brief The node we're advertising on.
  transport::PublisherPtr pub;     ///< \brief Publisher handle.
};