#include "RayCaster.h"
#include "VssRay.h"
#include "Ray.h"
#include "Preprocessor.h"
#include "ViewCellsManager.h"


namespace GtpVisibilityPreprocessor {


#define DEBUG_RAYCAST 0

#define EXACT_BOX_CLIPPING 0

RayCaster::RayCaster(const Preprocessor &preprocessor):
mPreprocessor(preprocessor)
{
}


RayCaster::~RayCaster()
{
}


VssRay *RayCaster::CastRay(const SimpleRay &simpleRay,
						   const AxisAlignedBox3 &box,
						   const bool castDoubleRay) 
{
	VssRayContainer rays;
	CastRay(simpleRay, rays, box, castDoubleRay, true);
    
	if (!rays.empty())
		return rays.back();
	else
		return NULL;
}


bool
RayCaster::ClipToViewSpaceBox(const Vector3 &origin,
							  const Vector3 &termination,
							  Vector3 &clippedOrigin,
							  Vector3 &clippedTermination)
{
  
  Ray ray(origin, termination - origin, Ray::LINE_SEGMENT);	
  ray.Precompute();
  
  float tmin, tmax;
  if ((!mPreprocessor.mViewCellsManager->
	   GetViewSpaceBox().ComputeMinMaxT(ray, &tmin, &tmax)) ||
	  tmin>=tmax
	  )
	return false;

  if (tmin >= 1.0f || tmax <=0.0f)
	return false;
  
  if (tmin > 0.0f)
	clippedOrigin = ray.Extrap(tmin);
  else
	clippedOrigin = origin;
  
  if (tmax < 1.0f)
	clippedTermination = ray.Extrap(tmax);
  else
	clippedTermination = termination;
  
  return true;
}

/** Checks if ray is valid, (e.g., not in empty view space or outside the view space)
*/
bool
RayCaster::ValidateRay(const Vector3 &origin,
					   const Vector3 &direction,
					   const AxisAlignedBox3 &box,
					   Intersection &hit)
{
	if (!hit.mObject)  
	{
		// compute intersection with the scene bounding box
#if EXACT_BOX_CLIPPING
		static Ray ray;
		mPreprocessor.SetupRay(ray, origin, direction);

		float tmin, tmax;
		if (box.ComputeMinMaxT(ray, &tmin, &tmax) && (tmin < tmax)) 
		{
			hit.mPoint = ray.Extrap(tmax);
		}
		else 
		{
			// cout<<" invalid hp "<<tmin<<" "<<tmax<<endl;
			// cout<<" box "<<box<<endl;
			// cout<<" origin "<<origin<<endl;
			// cout<<" direction "<<direction<<endl;
			// cout<< "inv dir"<<ray.GetInvDir()<<endl;
			return false;
		}
#else
		hit.mPoint = origin + direction * Magnitude(box.Diagonal());
#endif
	}
	else
	{
		if (mPreprocessor.mDetectEmptyViewSpace) 
		{
			if (DotProd(hit.mNormal, direction) >= -Limits::Small) 
			{	
				hit.mObject = NULL;
				return false;
			}
		}
	}

	return true;
}

void
RayCaster::SortRays(SimpleRayContainer &rays)
{
  AxisAlignedBox3 box =
	mPreprocessor.mViewCellsManager->GetViewSpaceBox();
	
  float b[12]={
	box.Min().x,
	box.Min().y,
	box.Min().z,
	-1,
	-1,
	-1,
	box.Max().x,
	box.Max().y,
	box.Max().z,
	1,
	1,
	1
  };

  _SortRays(rays,
			0,
			(int)rays.size()-1,
			0,
			b
			);
}
					
void
RayCaster::_SortRays(SimpleRayContainer &rays,
					 const int l,
					 const int r,
					 const int depth,
					 float box[12])
{
  // pick-up a pivot
  int axis;
  
  float maxDiff = -1.0f;
  // get the largest axis
  int offset = 0;
  int i;

  const int batchsize = 8192;

  //  if (r - l < 32*batchsize)
  //  	offset = 3;
	
  //  if (depth%5==0)
  //	offset = 3;
  
  for (i=offset; i < offset + 3; i++) {
	float diff = box[i + 6] - box[i];
	if (diff > maxDiff) {
	  maxDiff = diff;
	  axis = i;
	}
  }

  //  cout<<depth<<" "<<axis<<" "<<l<<" "<<r<<endl;
  
  i=l;
  int j=r;

  float x = (box[axis] + box[axis+6])*0.5f;
  //  float x = rays[(l+r)/2].GetParam(axis);
  do {
	while(i<j && rays[i].GetParam(axis) < x)
	  i++;
	while(i<j && x < rays[j].GetParam(axis))
	  j--;
	
	if (i <= j) {
	  swap(rays[i], rays[j]);
	  i++;
	  j--;
	}
  } while (i<=j);

  
  if (l + batchsize < j ) {
	// set new max
	float save = box[axis+6];
	box[axis+6] = x;
	_SortRays(rays, l, j, depth+1, box);
	box[axis+6] = save;
  } else {
	//	for (int k=0; k < 6; k++)
	//	  cout<<k<<" "<<box[k]<<" - "<<box[k+6]<<endl;
  }
  
  if (i + batchsize < r) {
	// set new min
	box[axis] = x;
    _SortRays(rays, i, r, depth+1, box);
  } else {
	//	for (int k=0; k < 6; k++)
	//	  cout<<k<<" "<<box[k]<<" - "<<box[k+6]<<endl;
  }
	
}
  
					

int
RayCaster::ProcessRay(const SimpleRay &simpleRay,
					  Intersection &hitA,
					  Intersection &hitB,
					  VssRayContainer &vssRays,
					  const AxisAlignedBox3 &box,
					  const bool castDoubleRay,
					  const bool pruneInvalidRays)
{
  int hits = 0;

#if DEBUG_RAYCAST
	static int id=0;
	Debug<<"PRA "<<id++<<endl<<flush;
#endif
	
	if (pruneInvalidRays) 
	{
	  if (!hitA.mObject && !hitB.mObject) {
		return 0;
	  }
	}

	
	// regardless of the pruneInvalidRays setting reject rays whic degenerate to a point
	if (EpsilonEqualV3(hitA.mPoint, hitB.mPoint, Limits::Small)) {
		return 0;
	}
	
	
	const bool validA = ValidateRay(simpleRay.mOrigin, simpleRay.mDirection, box, hitA);
	const bool validB = //castDoubleRay && 
	  ValidateRay(simpleRay.mOrigin, -simpleRay.mDirection, box, hitB);
	
	
#if DEBUG_RAYCAST
	Debug<<"PR1"<<flush;
#endif
	
	// reset both contributions
	if (!validA || !validB) {
	  if (pruneInvalidRays)
		return 0;
	  
	  // reset both contributions of this ray
	  hitA.mObject = NULL;
	  hitB.mObject = NULL;
	}
	
	// 8.11. 2007 JB
	// degenerate rays checked by geometrical constraint...
	//	!pruneInvalidRays || (hitA.mObject != hitB.mObject);

	
#if DEBUG_RAYCAST
	Debug<<"PR2"<<flush;
#endif
	const bool validSample = true;
	if (validSample) {
	  Vector3 clipA, clipB;
	  if (!ClipToViewSpaceBox(hitA.mPoint,
							  hitB.mPoint,
							  clipA,
							  clipB))
		return 0;

	  if (!pruneInvalidRays || hitA.mObject) {
		VssRay *vssRay = mVssRayPool.Alloc();

		*vssRay = VssRay(
						 !castDoubleRay ? simpleRay.mOrigin : clipB,
						 hitA.mPoint,
						 hitB.mObject,
						 hitA.mObject,
						 mPreprocessor.mPass,
						 simpleRay.mPdf
						 );

		if (validA)
			vssRay->mFlags |= VssRay::Valid;

		vssRay->mDistribution = simpleRay.mDistribution;
		vssRay->mGeneratorId = simpleRay.mGeneratorId;

		vssRays.push_back(vssRay);
		++ hits;
		//cout << "vssray 1: " << *vssRay << " " << vssRay->mTermination - vssRay->mOrigin << endl;
	}

#if DEBUG_RAYCAST
	Debug<<"PR3"<<flush;
#endif

	  if (castDoubleRay && (!pruneInvalidRays || hitB.mObject))
		{
		  VssRay *vssRay = mVssRayPool.Alloc();
		  *vssRay = VssRay(
						   clipA,
						   hitB.mPoint,
						   hitA.mObject,
						   hitB.mObject,
						   mPreprocessor.mPass,
						   simpleRay.mPdf
						   );
		  if (validB)
			vssRay->mFlags |= VssRay::Valid;

		vssRay->mDistribution = simpleRay.mDistribution;
		vssRay->mGeneratorId = simpleRay.mGeneratorId;
		vssRays.push_back(vssRay);
		++ hits;
		//cout << "vssray 2: " << *vssRay << endl;
		}
#if DEBUG_RAYCAST
	  Debug<<"PR4"<<flush;
#endif
	}
	
	return hits;
}

}