/*!
 * @file collision_tube.h
 *
 * collision tube collects all collisions from all entities
 *
 *  The collision events are saved in the _collisionList vector in a fixed hirarchy: a collision is defined by the world entities
 *  that collide. For each collision there is an entry in _collisionList. Each collision itself again contains collision events which are
 *  defined as collisions between the boundibg volumes (BV) of the world entities. This could look like this:
 *
 *  - Collision (WorldEntity_i  <=> WorldEntity_j)
 *     +- CollisionEvent( some BV <=> some other BV)
 *     +- CollisionEvent( some BV <=> some other BV)
 *  - Collision (WorldEntity_k <=> WorldEntity_l)
 *     +- CollisionEvent( some BV <=> some other BV)
 *     +- CollisionEvent( some BV <=> some other BV)
 *     +- CollisionEvent( some BV <=> some other BV)
 *     +- CollisionEvent( some BV <=> some other BV)
 *  - ... etc ...
 *
 *
 *  When the collisions are processed by the handleCollision() function each collision pair is checked for their reactions (since each
 *  WorldEntity can define several reactions to a collision). After all the reactions are calculated and applied the collision object is
 *  put back.
 */

#ifndef _COLLISION_TUBE_H
#define _COLLISION_TUBE_H

#include "base_object.h"
#include "cr_engine.h"
#include "world_entity.h"

#include "vector.h"
#include <vector>

class Collision;
class WorldEntity;
class BoundingVolume;

namespace CoRe
{

  class CollisionReaction;

  //! A class containing all CollisionEvents (structured as defined in the file doxygen tags)
  class CollisionTube : public BaseObject
  {
    ObjectListDeclaration(CollisionTube);

    typedef std::vector<Collision*>::iterator     CollisionIterator;
    typedef std::vector<Collision*>               CollisionVector;


    /* Constructor/Deconstructor/Singleton Interface */
  public:
    inline static CollisionTube* getInstance() { if( !singletonRef) singletonRef = new CollisionTube(); return singletonRef; }

    virtual ~CollisionTube();

  private:
    CollisionTube();
    CollisionTube(const CollisionTube& tube) {}

    static CollisionTube*          singletonRef;                         //!< the singleton instance


    /* Collision Handling */
  public:
    void registerCollisionEvent(WorldEntity* entityA, WorldEntity* entityB, BoundingVolume* bvA, BoundingVolume* bvB);
    void registerCollisionEvent(CREngine::CollisionType type, WorldEntity* entity, WorldEntity* groundEntity,
                                const Vector& normal, const Vector& position, bool bInWall = false);
    Collision* registerCollision(WorldEntity* entityA, WorldEntity* entityB);

    void reset();

    /** @returns an iterator pointing to the beginning of the list */
    CollisionIterator begin() { return this->_collisionList.begin(); }
    /** @returns an iterator pointing to the end of the list */
    CollisionIterator end()   { return this->_collisionList.end(); }


  private:
    CollisionVector             _collisionList;                      //!< the list of collisions since the last processing


    /* Misc State Informations */
  public:
    /** @returns true if at least one of both WorldEntities are subscribed for a collision reaction */
    inline bool isReactive(const WorldEntity& entityA, const WorldEntity& entityB) const
      { return (entityA.isReactive(entityB) && entityB.isReactive(entityA)); }

  };

}

#endif /* _COLLISION_TUBE_H */