#include "Polygon3.h"
#include "Mesh.h"
#include "AxisAlignedBox3.h"
#include "Ray.h"
#include "Triangle3.h"

Polygon3::Polygon3(): 
mMaterial(NULL), mParent(NULL), mPiercingRays(0)
{}

Polygon3::Polygon3(const VertexContainer &vertices): 
mVertices(vertices), mMaterial(NULL), mParent(NULL), mPiercingRays(0)
{}

Polygon3::Polygon3(MeshInstance *parent): 
mMaterial(NULL), mParent(parent), mPiercingRays(0)
{}

Polygon3::Polygon3(Face *face, Mesh *parentMesh):
mMaterial(NULL), mParent(NULL), mPiercingRays(0)
{	
	VertexIndexContainer::iterator it = face->mVertexIndices.begin();
	for (; it != face->mVertexIndices.end();  ++it)
	{
		mVertices.push_back(parentMesh->mVertices[*it]);
		mMaterial = parentMesh->mMaterial;
	}
}

Plane3 Polygon3::GetSupportingPlane() const
{
	return Plane3(mVertices[0], mVertices[1], mVertices[2]);
}

Vector3 Polygon3::GetNormal() const 
{
    return Normalize(CrossProd(mVertices[2] - mVertices[1],
							   mVertices[0] - mVertices[1]));
}

void Polygon3::Split(const Plane3 &partition, 
					 Polygon3 &front, 
					 Polygon3 &back,
					 const float epsilon)
{
	Vector3 ptA = mVertices.back();
	
	int sideA = partition.Side(ptA, epsilon);
	
	VertexContainer::const_iterator it;
	
	Vector3 lastSplit;

	bool foundSplit = false;

	//-- find line - plane intersections
	for (it = mVertices.begin(); it != mVertices.end(); ++ it)
	{
		Vector3 ptB = *it;
		int sideB = partition.Side(ptB, epsilon);
	
		// vertices on different sides => split
	    if (sideB > 0)
		{
			if (sideA < 0)
			{
				//-- plane - line intersection
				Vector3 splitPt = partition.FindIntersection(ptA, ptB);
			
				// test if split point not too close to previous split point
				if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
				{
					// add vertex to both polygons
					front.mVertices.push_back(splitPt);
					back.mVertices.push_back(splitPt);
					
					lastSplit = splitPt;
					foundSplit = true;
				}
			}
			front.mVertices.push_back(ptB);
		}
		else if (sideB < 0)
		{
			if (sideA > 0)
			{
				//-- plane - line intersection
				Vector3 splitPt = partition.FindIntersection(ptA, ptB);
				// test if split point not too close to other split point
					// test if split point not too close to previous split point
				if (!foundSplit || (!EpsilonEqualV3(splitPt, lastSplit, epsilon)))
				{
					// add vertex to both polygons
					front.mVertices.push_back(splitPt);
					back.mVertices.push_back(splitPt);

					lastSplit = splitPt;
					foundSplit = true;
				}	
			}
			back.mVertices.push_back(ptB);
		}
		else
		{
			// vertex on plane => add vertex to both polygons
			front.mVertices.push_back(ptB);
			back.mVertices.push_back(ptB); 
		}
	
		ptA = ptB;
		sideA = sideB;
	}
}

float Polygon3::GetArea() const
{
	Vector3 v = CrossProd(mVertices.back(), mVertices.front());
    
    for (int i=0; i < mVertices.size() - 1; ++i)
		v += CrossProd(mVertices[i], mVertices[i+1]);
    
    return 0.5f * fabs(DotProd(GetNormal(), v));
}

int Polygon3::Side(const Plane3 &plane, 
				   const float epsilon) const
{
	int classification = ClassifyPlane(plane, epsilon);
	
	if (classification == BACK_SIDE)
		return -1;
	else if (classification == FRONT_SIDE)
		return 1;
	// plane splits polygon
	return 0;
}

int Polygon3::ClassifyPlane(const Plane3 &plane, 
							const float epsilon) const
{
	VertexContainer::const_iterator it;

	bool onFrontSide = false;
	bool onBackSide = false;
	
	int count = 0;
	// find possible line-plane intersections
	for (it = mVertices.begin(); it != mVertices.end(); ++ it)
	{
		const int side = plane.Side(*it, epsilon);
		
		if (side > 0)
			onFrontSide = true;
		else if (side < 0)
			onBackSide = true;
		
		//TODO: check if split goes through vertex
		if (onFrontSide && onBackSide) // split 
		{
			return SPLIT;
		}
		// 3 vertices enough to decide coincident
		else if (((++ count) >= 3) && !onFrontSide && !onBackSide)
		{   
			return COINCIDENT; 
		}
	}

	if (onBackSide)
	{
		return BACK_SIDE;
	}
	else if (onFrontSide)
	{
		return FRONT_SIDE;
	}
	
	return COINCIDENT; // plane and polygon are coincident
}

/*int Polygon3::ClassifyPlane(const Plane3 &plane) const
{
	return ClassifyPlane(plane, Limits::Small);
}*/


Vector3
Polygon3::Center() const
{
	int i;
	Vector3 sum = mVertices[0];
	for (i=1; i < mVertices.size(); i++)
		sum += mVertices[i];
	
	return sum/(float)i;
}


void
Polygon3::Scale(const float scale)
{
	int i;
	Vector3 center = Center();
	for (i=0; i < mVertices.size(); i++) {
		mVertices[i] = center + scale*(mVertices[i] - center);
	}
}

bool Polygon3::Valid(const float epsilon) const
{
	if (mVertices.size() < 3)
		return false;

#if 1
	// check if area exceeds certain size
	if (AREA_LIMIT > GetArea())
	{
		//Debug << "area too small: " << GetArea() << endl;
		return false;
	}
#else
	Vector3 vtx = mVertices.back();
	VertexContainer::const_iterator it, it_end = mVertices.end();

	for (it = mVertices.begin(); it != it_end; ++it)
	{
		if (!(EpsilonEqual(vtx, *it)))
		{
			//Debug << "Malformed vertices:\n" << *this << endl;
			return false;
		}
		vtx = *it;
	}
#endif	
	return true;
}

void Polygon3::IncludeInBox(const PolygonContainer &polys, AxisAlignedBox3 &box)
{
	PolygonContainer::const_iterator it, it_end = polys.end();

	for (it = polys.begin(); it != it_end; ++ it)
		box.Include(*(*it));
}

// int_lineseg returns 1 if the given line segment intersects a 2D
// ray travelling in the positive X direction.	This is used in the
// Jordan curve computation for polygon intersection.
inline int
int_lineseg(float px,
	    float py,
	    float u1,
	    float v1,
	    float u2,
	    float v2)
{
	float t;
	float ydiff;

	u1 -= px; u2 -= px; 	  // translate line
	v1 -= py; v2 -= py;

	if ((v1 > 0 && v2 > 0) ||
		(v1 < 0 && v2 < 0) ||
		(u1 < 0 && u2 < 0))
	return 0;

	if (u1 > 0 && u2 > 0)
	return 1;

	ydiff = v2 - v1;

	if (fabs(ydiff) < Limits::Small) 
	{	  // denominator near 0
		if (((fabs(v1) > Limits::Small) || (u1 > 0) || (u2 > 0)))
			return 0;
		return 1;
	}

	t = -v1 / ydiff;		  // Compute parameter

	return (u1 + t * (u2 - u1)) > 0;
}

int Polygon3::CastRay(const Ray &ray, float &t, const float nearestT)
{
	Plane3 plane = GetSupportingPlane();
	float dot = DotProd(plane.mNormal, ray.GetDir());

	// Watch for near-zero denominator
	// ONLY single sided polygons!!!!!
	if (dot > -Limits::Small)
	//  if (fabs(dot) < Limits::Small)
	return Ray::NO_INTERSECTION;

	t = (-plane.mD - DotProd(plane.mNormal, ray.GetLoc())) / dot;

	if (t <= Limits::Small)
	return Ray::INTERSECTION_OUT_OF_LIMITS;

	if (t >= nearestT) {
	return Ray::INTERSECTION_OUT_OF_LIMITS; // no intersection was found
	}

	int count = 0;
	float u, v, u1, v1, u2, v2;
	int i;

	int paxis = plane.mNormal.DrivingAxis();

	// Project the intersection point onto the coordinate plane
	// specified by which.
	ray.Extrap(t).ExtractVerts(&u, &v, paxis);

	int size = (int)mVertices.size();

	mVertices.back().ExtractVerts(&u1, &v1, paxis );

	if (0 && size <= 4) 
	{
		// assume a convex face
		for (i = 0; i < size; i++) 
		{
      		mVertices[i].ExtractVerts(&u2, &v2, paxis);
	    
			// line u1, v1, u2, v2
	    
			if ((v2 - v1)*(u1 - u) > (u2 - u1)*(v1 - v))
				return Ray::NO_INTERSECTION;

			u1 = u2;
			v1 = v2;
	}

	return Ray::INTERSECTION;
	}

	// We're stuck with the Jordan curve computation.  Count number
	// of intersections between the line segments the polygon comprises
	// with a ray originating at the point of intersection and
	// travelling in the positive X direction.
	for (i = 0; i < size; i++) 
	{
		mVertices[i].ExtractVerts(&u2, &v2, paxis);

		count += (int_lineseg(u, v, u1, v1, u2, v2) != 0);

		u1 = u2;
		v1 = v2;
	}

	// We hit polygon if number of intersections is odd.
	return (count & 1) ? Ray::INTERSECTION : Ray::NO_INTERSECTION;
}

void Polygon3::InheritRays(Polygon3 &front_piece, 
					       Polygon3 &back_piece) const
{
	if (mPiercingRays.empty())
		return;

	RayContainer::const_iterator it, 
		it_end = mPiercingRays.end();

	for (it = mPiercingRays.begin(); it != it_end; ++ it)
	{
		switch((*it)->GetId())
		{
		case Ray::BACK:
			back_piece.mPiercingRays.push_back(*it);
			break;
		case Ray::FRONT:
			front_piece.mPiercingRays.push_back(*it);
			break;
		case Ray::FRONT_BACK:
			back_piece.mPiercingRays.push_back(*it);
			break;
		case Ray::BACK_FRONT:
			front_piece.mPiercingRays.push_back(*it);
			break;
		default:
			break;
		}
	}
}

int Polygon3::ClassifyPlane(const PolygonContainer &polys, 
							const Plane3 &plane,
							const float epsilon)
{
	PolygonContainer::const_iterator it;

	bool onFrontSide = false;
	bool onBackSide = false;
	
	// find intersections
	for (it = polys.begin(); it != polys.end(); ++ it)
	{
        const int cf = (*it)->ClassifyPlane(plane, epsilon);
		
        if (cf == FRONT_SIDE)
			onFrontSide = true;
		else if (cf == BACK_SIDE)
			onBackSide = true;
		
		if ((cf == SPLIT) || (cf == COINCIDENT) || (onFrontSide && onBackSide))
		{
			return SPLIT;
		}
	}

	if (onBackSide)
	{
		return BACK_SIDE;
	}
	else if (onFrontSide)
	{
		return FRONT_SIDE;
	}
	
	return SPLIT;
}

int Polygon3::ParentObjectsSize(const PolygonContainer &polys)
{
	int count = 0;

	PolygonContainer::const_iterator it, it_end = polys.end();

	MeshInstance::NewMail();

	for (it = polys.begin(); it != it_end; ++ it)
	{
		if ((*it)->mParent && !(*it)->mParent->Mailed())
		{
			++ count;
			(*it)->mParent->Mail();
		}
	}
	return count;
}

float Polygon3::GetArea(const PolygonContainer &cell)
{
	float area = 0;
	PolygonContainer::const_iterator pit;

	for (pit = cell.begin(); pit != cell.end(); ++ pit)
	{
		if ((*pit)->mVertices.size() < 3)
			Debug << "ERROR" << endl;

		area += (*pit)->GetArea();
	}

	return area;
}


Polygon3 *Polygon3::CreateReversePolygon() const
{
	Polygon3 *revPoly = new Polygon3();

	VertexContainer::const_reverse_iterator rit, 
			rit_end = mVertices.rend();

	for(rit = mVertices.rbegin(); rit != rit_end; ++ rit)
		revPoly->mVertices.push_back(*rit);

	return revPoly;
}


void Polygon3::Triangulate(vector<Triangle3> &triangles)
{
	int i = 1;
	int j = 0;
	int k = (int)mVertices.size() - 1;
	int count = 0;

	while (i < k)
	{
		triangles.push_back(Triangle3(mVertices[i], mVertices[j], mVertices[k]));

		if ((count ++) % 2)
			j = i ++;
		else
			j = k --;
	}
}


void Polygon3::Triangulate(VertexIndexContainer &indices)
{
	int i = 1;
	int j = 0;
	int k = (int)mVertices.size() - 1;

	int count = 0;

	while (i < k)
	{
		indices.push_back(k);
		indices.push_back(j);
		indices.push_back(i);

		if ((count ++) % 2)
			j = i ++;
		else
			j = k --;
	}
}


void Polygon3::AddToMesh(Mesh &mesh)
{
	const int n = (int)mesh.mVertices.size();

    //-- add the vertices
    VertexContainer::const_iterator vit, vit_end = mVertices.end();
	for (vit = mVertices.begin(); vit != vit_end; ++ vit)
	{
		mesh.mVertices.push_back(*vit);
	}

	// one quad => no triangulation necessary
	if ((int)mVertices.size() == 4)
	{
		mesh.AddFace(new Face(n, n + 1, n + 2, n + 3));
	}
	else
	{
		VertexIndexContainer indices;
		Triangulate(indices);

		// add indices of triangle strip
		for (int i = 0; i < (int)indices.size(); i += 3)
		{
			Face *face = new Face(n + indices[i], 
								  n + indices[i + 1], 
								  n + indices[i + 2]);
			mesh.AddFace(face);
		}
	}
}