/**
   @file
   @author Dane Johnson <dane@danejohnson.org>
 
   @section LICENSE
 
   Couch  Copyright (C) 2021 Dane Johnson

   This program comes with ABSOLUTELY NO WARRANTY; without event the
   implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for details at
   https://www.gnu.org/licenses/gpl-3.0.html
  
   This is free software, and you are welcome to redistribute it
   under the terms of the GNU General Public License as published
   by the Free Software Foundation; either version 3 of the License,
   or (at your option) any later version.
 
   @section DESCRIPTION
 
   The physics world
*/
#ifndef WORLD_H
#define WORLD_H

#include <btBulletDynamicsCommon.h>

#include "Rigidbody.h"

/**
   Holds information about the results of a raycast
*/
struct RaycastResult {
  bool hit;
  Vector3 position;
  Vector3 normal;
  Rigidbody *object;
};

/**
   World is the object that performs the rigidbody physics simulation. Presently there is only one world.
*/
class World {
public:
  /**
     @returns the World singleton
  */
  static World* GetWorld();
  /**
     Add a rigidbody to the physics simulation
     @param rigidbody the rigidbody to add
  */
  void AddRigidbody(Rigidbody *rigidbody);
  /**
     Advance the physics simulation
     @param delta the time that has passed since the last physics update
  */
  void Step(float delta);

  /**
     Performs a raycast
     @param from the start location of the raycast
     @param to the end location of the raycast
     @returns a RaycastResult with data collected by the raycast
  */
  RaycastResult Raycast(const Vector3 &from, const Vector3 &to);
private:
  static World* world;
  // Some hocus pocus
  btDiscreteDynamicsWorld *btWorld;
  btDefaultCollisionConfiguration *collisionConfiguration;
  btCollisionDispatcher *dispatcher;
  btBroadphaseInterface *overlappingPairCache;
  btSequentialImpulseConstraintSolver *solver;
  World();
  ~World();
  
};

#endif /* WORLD_H */