#ifndef NAVMESHTRIANGLE_H
#define NAVMESHTRIANGLE_H

#include "../geo/Point3.h"
#include "../geo/Point2.h"

class NavMeshTriangle {

public:

	Point3 p1;
	Point3 p2;
	Point3 p3;
	uint8_t type;

private:

	template<typename> friend class NavMesh;

	int _neighbors[3];
	int _numNeighbors;

	/** precalculated stuff */

private:

	Point2 v0;
	Point2 v1;
	float dot00;
	float dot01;
	float dot11;
	float invDenom;
	float area;

	const Point3 center;
	const Point3 v12;
	const Point3 v13;

public:

	/** ctor */
	NavMeshTriangle(const Point3 p1, const Point3 p2, const Point3 p3, const uint8_t type) :
		p1(p1), p2(p2), p3(p3), type(type),
		_neighbors(), _numNeighbors(0),
		center((p1+p2+p3)/3), v12(p2-p1), v13(p3-p1) {
		precompute();
	}

	bool operator == (const NavMeshTriangle& o) const {
		return (p1 == o.p1) && (p2 == o.p2) && (p3 == o.p3);
	}


	Point3 getA() const {
		return p1;
	}

	Point3 getAB() const {
		return v12;
	}

	Point3 getAC() const {
		return v13;
	}

	bool contains(const Point3 p) const {

		const Point2 v2 = p.xy() - p1.xy();

		// Compute dot products
		float dot02 = dot(v0, v2);
		float dot12 = dot(v1, v2);

		// Compute barycentric coordinates
		float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
		float v = (dot00 * dot12 - dot01 * dot02) * invDenom;

		// Check if point is in triangle
		return (u >= 0) && (v >= 0) && (u + v <= 1);

	}

	/** get the triangle's size */
	float getArea() const {
		return area;
	}

	/** get the triangle's center-point */
	Point3 getCenter() const {
		return center;
	}



private:

	/** perform some pre-calculations to speed things up */
	void precompute() {

		// Compute vectors
		v0 = p3.xy() - p1.xy();
		v1 = p2.xy() - p1.xy();

		// Compute dot products
		dot00 = dot(v0, v0);
		dot01 = dot(v0, v1);
		dot11 = dot(v1, v1);

		// Compute barycentric coordinates
		invDenom = 1.0f / (dot00 * dot11 - dot01 * dot01);




		const float a = (p2-p1).length();
		const float b = (p3-p1).length();
		const float c = (p2-p3).length();
		const float s = 0.5f * (a+b+c);
		area = std::sqrt( s * (s-a) * (s-b) * (s-c) );

	}


};

#endif // NAVMESHTRIANGLE_H