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/** \author Jia Pan */


#ifndef FCL_BROAD_PHASE_SSAP_H
#define FCL_BROAD_PHASE_SSAP_H

#include "fcl/broadphase/broadphase.h"

namespace fcl
{

/// @brief Simple SAP collision manager 
class SSaPCollisionManager : public BroadPhaseCollisionManager
{
public:
  SSaPCollisionManager() : setup_(false)
  {}

  /// @brief remove one object from the manager
  void registerObject(CollisionObject* obj);

  /// @brief add one object to the manager
  void unregisterObject(CollisionObject* obj);

  /// @brief initialize the manager, related with the specific type of manager
  void setup();

  /// @brief update the condition of manager
  void update();

  /// @brief clear the manager
  void clear();

  /// @brief return the objects managed by the manager
  void getObjects(std::vector<CollisionObject*>& objs) const;

  /// @brief perform collision test between one object and all the objects belonging to the manager
  void collide(CollisionObject* obj, void* cdata, CollisionCallBack callback) const;

  /// @brief perform distance computation between one object and all the objects belonging to the manager
  void distance(CollisionObject* obj, void* cdata, DistanceCallBack callback) const;

  /// @brief perform collision test for the objects belonging to the manager (i.e., N^2 self collision)
  void collide(void* cdata, CollisionCallBack callback) const;

  /// @brief perform distance test for the objects belonging to the manager (i.e., N^2 self distance)
  void distance(void* cdata, DistanceCallBack callback) const;

  /// @brief perform collision test with objects belonging to another manager
  void collide(BroadPhaseCollisionManager* other_manager, void* cdata, CollisionCallBack callback) const;

  /// @brief perform distance test with objects belonging to another manager
  void distance(BroadPhaseCollisionManager* other_manager, void* cdata, DistanceCallBack callback) const;

  /// @brief whether the manager is empty
  bool empty() const;
  
  /// @brief the number of objects managed by the manager
  inline size_t size() const { return objs_x.size(); }

protected:
  /// @brief check collision between one object and a list of objects, return value is whether stop is possible
  bool checkColl(std::vector<CollisionObject*>::const_iterator pos_start, std::vector<CollisionObject*>::const_iterator pos_end,
                 CollisionObject* obj, void* cdata, CollisionCallBack callback) const;
  
  /// @brief check distance between one object and a list of objects, return value is whether stop is possible
  bool checkDis(std::vector<CollisionObject*>::const_iterator pos_start, std::vector<CollisionObject*>::const_iterator pos_end,
                CollisionObject* obj, void* cdata, DistanceCallBack callback, FCL_REAL& min_dist) const;

  bool collide_(CollisionObject* obj, void* cdata, CollisionCallBack callback) const;
  
  bool distance_(CollisionObject* obj, void* cdata, DistanceCallBack callback, FCL_REAL& min_dist) const;

  static inline size_t selectOptimalAxis(const std::vector<CollisionObject*>& objs_x, const std::vector<CollisionObject*>& objs_y, const std::vector<CollisionObject*>& objs_z, std::vector<CollisionObject*>::const_iterator& it_beg, std::vector<CollisionObject*>::const_iterator& it_end)
  {
    /// simple sweep and prune method
    double delta_x = (objs_x[objs_x.size() - 1])->getAABB().min_[0] - (objs_x[0])->getAABB().min_[0];
    double delta_y = (objs_x[objs_y.size() - 1])->getAABB().min_[1] - (objs_y[0])->getAABB().min_[1];
    double delta_z = (objs_z[objs_z.size() - 1])->getAABB().min_[2] - (objs_z[0])->getAABB().min_[2];

    int axis = 0;
    if(delta_y > delta_x && delta_y > delta_z)
      axis = 1;
    else if(delta_z > delta_y && delta_z > delta_x)
      axis = 2;

    switch(axis)
    {
    case 0:
      it_beg = objs_x.begin();
      it_end = objs_x.end();
      break;
    case 1:
      it_beg = objs_y.begin();
      it_end = objs_y.end();
      break;
    case 2:
      it_beg = objs_z.begin();
      it_end = objs_z.end();
      break;
    }

    return axis;
  }


  /// @brief Objects sorted according to lower x value
  std::vector<CollisionObject*> objs_x;

  /// @brief Objects sorted according to lower y value
  std::vector<CollisionObject*> objs_y;

  /// @brief Objects sorted according to lower z value
  std::vector<CollisionObject*> objs_z;

  /// @brief tag about whether the environment is maintained suitably (i.e., the objs_x, objs_y, objs_z are sorted correctly
  bool setup_;
};


}

#endif
