#ifndef __RAY_H__
#define __RAY_H__

#include <vector>
#include "Matrix4x4.h"
#include "Vector3.h"


namespace GtpVisibilityPreprocessor {

// forward declarations
class Plane3;
class Intersectable;
class KdLeaf;
class MeshInstance;
class ViewCell;
class BspLeaf;
class VssRay;


// -------------------------------------------------------------------
// CRay class.  A ray is defined by a location and a direction.
// The direction is always normalized (length == 1).
// -------------------------------------------------------------------

class Ray
{
public:
  enum RayType { LOCAL_RAY, GLOBAL_RAY, LINE_SEGMENT };
	
  enum { NO_INTERSECTION=0, INTERSECTION_OUT_OF_LIMITS, INTERSECTION };

  /// if ray is on back (front) side of plane, or goes from the 
  /// front (back) to the back (front)
  enum {FRONT, BACK, BACK_FRONT, FRONT_BACK, COINCIDENT};
	
  struct Intersection 
  {
	  /// the point of intersection
	  float mT;

	  /// the normal of the intersection
	  Vector3 mNormal;

	  /// can be either mesh or a viewcell
	  Intersectable *mObject;

	  /// the face of the intersectable
	  int mFace;

	  Intersection(const float t,
		 		   const Vector3 &normal,
				   Intersectable *object,
				   const int face): 
	  mT(t), mNormal(normal), mObject(object), mFace(face) 
	  {}

	  Intersection(): mT(0), mNormal(0,0,0), mObject(NULL), mFace(0) 
	  {}

	  bool operator<(const Intersection &b) const 
	  {
		  return mT < b.mT;
	  }
  };


  // I should have some abstract cell data type !!! here
  // corresponds to the spatial elementary cell
  /** intersection with the source object if any */
  Intersection sourceObject;
  
  vector<Intersection> intersections;
 // vector<BspIntersection> bspIntersections;
  vector<KdLeaf *> kdLeaves;
  vector<Intersectable *> testedObjects;

  // various flags
  enum {STORE_KDLEAVES=1, STORE_BSP_INTERSECTIONS=2, STORE_TESTED_OBJECTS=4, CULL_BACKFACES=8};
  int mFlags;

	
  // constructors
  Ray(const Vector3 &wherefrom,
      const Vector3 &whichdir,
      const int _type):mFlags(CULL_BACKFACES) {
    loc = wherefrom;
    if (_type == LINE_SEGMENT)
      dir = whichdir;
    else
      dir = Normalize(whichdir);
    mType = _type;
    depth = 0;
		Init();
  }
  // dummy constructor
  Ray() {}

  /** Construct ray from a vss ray.
  */
  Ray(const VssRay &vssRay) {
	Init(vssRay);
	mFlags |= CULL_BACKFACES;
  }

  void Clear() {
	intersections.clear();
	kdLeaves.clear();
	testedObjects.clear();
	//	bspIntersections.clear();
  }

  void Init(const VssRay &vssRay);

  Intersectable *GetIntersectionObject(const int i) const {
    return intersections[i].mObject;
  }
  
  Vector3 GetIntersectionPoint(const int i) const {
    return Extrap(intersections[i].mT);
  }
  
  // Inititalize the ray again when already constructed
  void Init(const Vector3 &wherefrom,
			const Vector3 &whichdir,
			const int _type, 
			bool dirNormalized = false) {
    loc = wherefrom;
    dir = (dirNormalized || _type == LINE_SEGMENT) ? whichdir: Normalize(whichdir) ;
    mType = _type;
    depth = 0;
    Init();
  }

  // --------------------------------------------------------
  // Extrapolate ray given a signed distance, returns a point
  // --------------------------------------------------------
  Vector3 Extrap(float t) const {
    return loc + dir * t;
  }

  // -----------------------------------
  // Return parameter given point on ray
  // -----------------------------------
  float Interp(Vector3 &x) const {
    for (int i = 0; i < 3; i++)
      if (Abs(dir[i]) > Limits::Small)
	return (x[i] - loc[i]) / dir[i];
    return 0;
  }

  // -----------------------------------
  // Reflects direction of reflection for the ray, 
  // given the normal to the surface.
  // -----------------------------------
  Vector3 ReflectRay(const Vector3 &N) const {
    return N * 2.0 * DotProd(N, -dir) + dir;
  }
  void ReflectRay(Vector3 &result, const Vector3 &N) const {
    result =  N * 2.0 * DotProd(N, -dir) + dir;
  }

  // Computes the inverted direction of the ray, used optionally by
  // a ray traversal algorithm.
  void ComputeInvertedDir() const;

  // Given the matrix 4x4, transforms the ray to another space
  void ApplyTransform(const Matrix4x4 &tform) {
    loc = tform * loc;
    dir = RotateOnly(tform, dir);
    // note that normalization to the unit size of the direction
    // is NOT computed -- this is what we want.
    Precompute();
  }

  // returns ID of this ray (use for mailboxes)
  int GetId() const { return ID; }

  // returns the transfrom ID of the ray (use for ray transformations)
  int GetTransformID() const { return transfID; }

  // copy the transform ID from an input ray
  void CopyTransformID(const Ray &ray) { transfID = ray.transfID; }
  
  // set unique ID for a given ray - always avoid setting to zero
  void SetId() {
    if ((ID = ++genID) == 0)
      ID = ++genID;
    transfID = ID;
  }
  // set ID to explicit value - it can be even 0 for rays transformed
  // to the canonical object space to supress the mailbox failure.
  void SetId(int newID) {
    ID = newID;
    // note that transfID is not changed!
  }


  // the object on which the ray starts at
  const Intersection* GetStartObject() const { return &intersections[0]; }
  const Intersection* GetStopObject() const { return &intersections[intersections.size()-1]; }
  
  
  void SetLoc(const Vector3 &l);
  Vector3& GetLoc() { return loc; }
  Vector3  GetLoc() const { return loc; }

  float  GetLoc(const int axis) const { return loc[axis]; }

  void SetDir(const Vector3 &ndir) { dir = ndir;} 
  Vector3& GetDir() { return dir; }
  Vector3  GetDir() const { return dir; }
  float  GetDir(const int axis) const { return dir[axis]; }

  int GetType() const { return mType; }
  
  // make such operation to slightly change the ray direction
  // in case any component of ray direction is zero.
  void CorrectZeroComponents();

  // the depth of the ray - primary rays are in the depth 0
  int GetDepth() const { return depth;}
  void SetDepth(int newDepth) { depth = newDepth;}
  
  /** Classifies ray with respect to the plane.
  */
  int ClassifyPlane(const Plane3 &plane, 
					const float minT, 
					const float maxT,
					Vector3 &entP,
					Vector3 &extP) const;

private:
  Vector3 loc, dir;		// Describes ray origin and vector
  
  // The inverted direction of the ray components. It is computed optionally
  // by the ray traversal algorithm using function ComputeInvertedDir();
  mutable Vector3 invDir;

  // Type of the ray: primary, shadow, dummy etc., see ERayType above
  int mType;
 
  
  // unique ID of a ray for the use in the mailboxes
  int ID;
  
  // unique ID of a ray for the use with a transformations - this one
  // never can be changed that allows the nesting of transformations
  // and caching the transformed rays correctly
  int transfID;
  
  // the ID generator fo each ray instantiated
  static int genID;  

  // When ray shot from the source(camera/light), this number is equal
  // to the number of bounces of the ray, also called the depth of the
  // ray (primary ray has its depth zero)
  int depth;

	
	
  void Init();

  // precompute some values that are necessary
  void Precompute();

  friend class AxisAlignedBox3;
  friend class Plane3;

  // for CKDR GEMS
  friend float DistanceToXPlane(const Vector3 &vec, const Ray &ray);
  friend float DistanceToYPlane(const Vector3 &vec, const Ray &ray);
  friend float DistanceToZPlane(const Vector3 &vec, const Ray &ray);
  friend int MakeIntersectLine(const Plane3 &p, const Plane3 &q, Ray &ray);

	friend ostream &operator<<(ostream &s, const Ray &r) {
		return s<<"Ray:loc="<<r.loc<<" dir="<<r.dir;
	}
};


class PassingRaySet {
public:
  enum { Resolution = 2 };
  int mDirectionalContributions[3*Resolution*Resolution];
  int mRays;
  int mContributions;

	PassingRaySet() {
    Reset();
  }

	void
  Reset();
  
  void AddRay(const Ray &ray, const int contributions);
	void AddRay2(const Ray &ray,
							 const int objects,
							 const int viewcells);

  int GetEntryIndex(const Vector3 &direction) const;

  friend ostream &operator<<(ostream &s, const PassingRaySet &set);

};

struct SimpleRay
{
  Vector3 mOrigin;
  Vector3 mDirection;
  float mPdf;

  SimpleRay() {}
  SimpleRay(const Vector3 &o, const Vector3 &d, const float p=1.0f):
	mOrigin(o), mDirection(d), mPdf(p) {}

  Vector3 Extrap(const float t) const {
	return mOrigin + mDirection * t;
  }
};

class SimpleRayContainer : public vector<SimpleRay>
{
public:
    
  SimpleRayContainer():vector<SimpleRay>() {}
  
  void NormalizePdf(float scale = 1.0f) {
	iterator it = begin();
	float sumPdf = 0.0f;
	for (; it != end(); it++)
	  sumPdf += (*it).mPdf;

	float c = scale/sumPdf;
	
	for (it = begin(); it != end(); it++) {
	  (*it).mPdf*=c;
	}
  }
  
  void AddRay(const SimpleRay &ray) {
	push_back(ray);
  }
};

}

#endif