#include <stack>
using namespace std;
#include "KdTree.h"
#include "AxisAlignedBox3.h"
#include "Ray.h"
#include "MutualVisibility.h"


void
TriangleSample::Init(
		     const Triangle3 &source,
		     const Triangle3 &target)
{
  mDepth = 0;
  mSource = source;
  mTarget = target;
}


Vector3
TriangleSample::GetIntersectionPoint(const int rayIndex,
				     const int depth) const
{
  Vector3 origin, direction;
  GetRay(rayIndex, origin, direction);
  return origin + direction*mIntersections[rayIndex][depth].mT;
}

void
TriangleSample::GetRay(const int rayIndex,
		       Vector3 &origin,
		       Vector3 &direction) const
{
  const int indices[][2] = {
    {0,0}, {0,1}, {0,2},
    {1,0}, {1,1}, {1,2},
    {2,0}, {2,1}, {2,2}
  };
  
  origin = mSource.mVertices[indices[rayIndex][0]];
  direction = mTarget.mVertices[indices[rayIndex][1]] - origin;
}

void
MutualVisibilitySampler::PerformSplit(
				      const TriangleSample &sample,
				      const bool splitSource,
				      const int edge,
				      const Vector3 &splitPoint,
				      const Ray &ray,
				      TriangleSample &sample1,
				      TriangleSample &sample2
				      )
{


  const Triangle3 *triangle;
  Triangle3 *triangle1, *triangle2;
  // split the triangles
  if (splitSource) {
    sample1.mTarget = sample.mTarget;
    sample2.mTarget = sample.mTarget;
    triangle1 = &sample1.mSource;
    triangle2 = &sample2.mSource;
    triangle = &sample.mSource;
  } else {
    sample1.mSource = sample.mSource;
    sample2.mSource = sample.mSource;
    triangle1 = &sample1.mTarget;
    triangle2 = &sample2.mTarget;
    triangle = &sample.mTarget;
  }
  
  // split the intersections
  switch (edge) {
  case 0:
    sample1.mIntersections[0] = sample.mIntersections[0];
    sample1.mIntersections[1] = sample.mIntersections[1];
    triangle1->mVertices[0] = triangle->mVertices[0];
    triangle1->mVertices[1] = triangle->mVertices[1];
    
    sample2.mIntersections[0] = sample.mIntersections[2];
    sample2.mIntersections[1] = sample.mIntersections[0];
    triangle2->mVertices[0] = triangle->mVertices[2];
    triangle2->mVertices[1] = triangle->mVertices[0];
    break;

  case 1:
    sample1.mIntersections[0] = sample.mIntersections[0];
    sample1.mIntersections[1] = sample.mIntersections[1];
    triangle1->mVertices[0] = triangle->mVertices[0];
    triangle1->mVertices[1] = triangle->mVertices[1];

    sample2.mIntersections[0] = sample.mIntersections[1];
    sample2.mIntersections[1] = sample.mIntersections[2];
    triangle2->mVertices[0] = triangle->mVertices[1];
    triangle2->mVertices[1] = triangle->mVertices[2];
    break;
    
  case 2:
    sample1.mIntersections[0] = sample.mIntersections[2];
    sample1.mIntersections[1] = sample.mIntersections[0];
    triangle1->mVertices[0] = triangle->mVertices[2];
    triangle1->mVertices[1] = triangle->mVertices[0];

    sample2.mIntersections[0] = sample.mIntersections[1];
    sample2.mIntersections[1] = sample.mIntersections[2];
    triangle2->mVertices[0] = triangle->mVertices[1];
    triangle2->mVertices[1] = triangle->mVertices[2];
    break;
  }
  
  // the new sample
  sample1.mIntersections[2] = ray.intersections;
  sample2.mIntersections[2] = ray.intersections;
  triangle1->mVertices[2] = splitPoint;
  triangle2->mVertices[2] = splitPoint;
  
  // establish the new samples
  sample1.mDepth = sample2.mDepth = sample.mDepth+1;
}

float
MutualVisibilitySampler::GetSpatialAngle(const TriangleSample &sample,
					 const Vector3 &point
					 )
{
  const int sampleIndices[][3]={
    (0,0,0),
    (0,1,0),
    (-1,-1,-1)
  };
  
  float sum = 0.0f;
  int i;
  
  for (i=0; i < 10; i++) {
    Triangle3 triangle(sample.GetIntersectionPoint(sampleIndices[i][0], 0),
			    sample.GetIntersectionPoint(sampleIndices[i][1], 0),
			    sample.GetIntersectionPoint(sampleIndices[i][2], 0));
    
    sum += triangle.GetSpatialAngle(point);
  }
  return sum;
}


void
MutualVisibilitySampler::ComputeError(TriangleSample &sample)
{
  // evaluate minimal error which can be achieved by more precise evaluation
  // if this is above the threshold do not proceed further

  float maxAngle = GetSpatialAngle(sample,
				   sample.mSource.GetCenter());
  
  for (int i=0; i < 3; i++) {
    float angle = GetSpatialAngle(sample,
				  sample.mSource.mVertices[i]);
    if (angle > maxAngle)
      maxAngle = angle;
  }
  
  sample.mError = maxAngle;
}





void
MutualVisibilitySampler::ConstructInitialSamples(
						 const AxisAlignedBox3 &source,
						 const AxisAlignedBox3 &target,
						 vector<TriangleSample *> &samples
						 )
{
  // get all rectangles potentially visible from the source box
  int i;
  int sourceMask = 0;
  for (i=0; i < 8; i++)
    sourceMask |= source.GetFaceVisibilityMask(target.GetVertex(i));

  // now for each visble source face find all visible target faces
  for (i=0; i < 6; i++) {
    Rectangle3 sourceFace = source.GetFace(i);
    if ( sourceMask &(1<<i) ) {
      int mask = target.GetFaceVisibilityMask(sourceFace);
      // construct triangle samples for all visible rectangles
      for (int j=0; j < 6; j++)
	if (mask & (1<<j)) {
	  AddInitialSamples(sourceFace, target.GetFace(j), samples);
	}
    }
  }
}

void
MutualVisibilitySampler::AddInitialSamples(
					   const Rectangle3 &sourceRect,
					   const Rectangle3 &targetRect,
					   vector<TriangleSample *> &samples
					   )
{
  Triangle3 sourceTriangles[2];
  Triangle3 targetTriangles[2];

  sourceTriangles[0].Init(sourceRect.mVertices[0],
			  sourceRect.mVertices[1],
			  sourceRect.mVertices[2]);

  sourceTriangles[1].Init(sourceRect.mVertices[0],
			  sourceRect.mVertices[2],
			  sourceRect.mVertices[3]);

  targetTriangles[0].Init(targetRect.mVertices[0],
			  targetRect.mVertices[1],
			  targetRect.mVertices[2]);

  targetTriangles[1].Init(targetRect.mVertices[0],
			  targetRect.mVertices[2],
			  targetRect.mVertices[3]);
  int i, j;
  for (i=0; i < 2; i++)
    for (j=0; j < 2; j++) {
      TriangleSample *sample = new TriangleSample(sourceTriangles[i], 
						  targetTriangles[j]);
      samples.push_back(sample);
    }
}

int
MutualVisibilitySampler::ComputeVisibility()
{
  stack<TriangleSample *> sampleStack;
  
  Ray ray;
  // now process the samples as long as we have something to do
  while (!sampleStack.empty()) {
    TriangleSample *sample = sampleStack.top();
    sampleStack.pop();
    
//      // cast a new ray
//      int triangleSplitEdge = SetupExtremalRay(sample, source, ray);
    
//      if (!kdTree->CastRay(ray))
//        return VISIBLE;
    
//      // generate 2 new samples
//      TriangleSample newSamples[2];
//      sample.Split(triangleSplitEdge, ray, newSamples[0], newSamples[1]);
//      for (i=0; i < 2; i++) {
//        newSamples[i].ComputeError();
//        if (newSamples[i].mError > solidAngleThreshold) {
//  	sampleStack.push(newSamples[i]);
//        }
//      }
//    }
  }
  return INVISIBLE;
}

MutualVisibilitySampler::MutualVisibilitySampler(KdTree *kdTree,
						 AxisAlignedBox3 &source,
						 AxisAlignedBox3 &target,
						 const float solidAngleThreshold)
{
  mKdTree = kdTree;
  mSource = source;
  mTarget = target;
  mSolidAngleThreshold = solidAngleThreshold;
}
  

int
ComputeBoxVisibility(KdTree *kdTree,
		     AxisAlignedBox3 &source,
		     AxisAlignedBox3 &target,
		     const float solidAngleThreshold)
{
  MutualVisibilitySampler sampler(kdTree, source, target, solidAngleThreshold);

  int visibility = sampler.ComputeVisibility();

  return visibility;
  
}