/*]  Copyright (c) 2009-2010, Charles McGarvey  [**************************
**]  All rights reserved.
*
* vi:ts=4 sw=4 tw=75
*
* Distributable under the terms and conditions of the 2-clause BSD license;
* see the file COPYING for a complete text of the license.
*
**************************************************************************/

#ifndef _MOOF_LINE_HH_
#define _MOOF_LINE_HH_

#include <Moof/Contact.hh>
#include <Moof/Drawable.hh>
#include <Moof/Log.hh>
#include <Moof/Math.hh>
#include <Moof/OpenGL.hh>
#include <Moof/Ray.hh>
#include <Moof/Shape.hh>
#include <Moof/Sphere.hh>
#include <Moof/Texture.hh>


namespace Mf {


template <int D>
struct Line : public Drawable, public Shape<D>
{
	typedef cml::vector< Scalar, cml::fixed<D> > Vector;

	Vector	a;
	Vector	b;


	Line() {}

	Line(const Vector& point1, const Vector& point2) :
		a(point1),
		b(point2) {}


	Vector getDirection() const
	{
		return b - a;
	}

	Scalar getLength() const
	{
		return getDirection().length();
	}


	bool intersect(const Line& other, Contact<D>& hit) const
	{
		Scalar d = (other.b[1] - other.a[1]) * (b[0] - a[0]) -
				   (other.b[0] - other.a[0]) * (b[1] - a[1]);

		if (d == SCALAR(0.0)) return false;			// lines are parallel
		// ignoring the (somewhat remote) possibility of coincidence

		Scalar m = ((other.b[0] - other.a[0]) * (a[1] - other.a[1]) -
					(other.b[1] - other.a[1]) * (a[0] - other.a[0])) / d;

		Scalar n = ((b[0] - a[0]) * (b[1] - other.a[1]) -
					(b[1] - a[1]) * (b[0] - other.a[0])) / d;

		if (m < SCALAR(0.0) || m > SCALAR(1.0) ||	// not intersecting
			n < SCALAR(0.0) || n > SCALAR(1.0)) return false;

		Vector2 tangent = b - a;
		Vector2 normal = cml::perp(tangent).normalize();

		if (cml::dot(normal, other.a - other.b) < SCALAR(0.0))
		{
			normal = -normal;
		}

		hit.point = a + m * tangent;
		hit.normal = normal;
		hit.distance = (other.b - hit.point).length();

		return true;
	}

	bool intersect(const Sphere<D>& other, Contact<D>& hit) const
	{
		Vector surface = b - a;
		Vector toPoint = other.point - a;

		Scalar surfaceLength = surface.length();
		surface.normalize();

		Scalar projection = cml::dot(surface, toPoint);

		if (projection < SCALAR(0.0) || projection > surfaceLength)
		{
			// try endpoints
			
			if (other.intersect(a, hit))
			{
				hit.normal = -hit.normal;
				hit.point = a;
				return true;
			}
			else if (other.intersect(b, hit))
			{
				hit.normal = -hit.normal;
				hit.point = b;
				return true;
			}
			
			return false;
		}

		Vector point = a + surface * projection;
		Vector normal = other.point - point;

		Scalar distance = normal.length();

		if (distance > other.radius) false;		// not intersecting

		normal.normalize();

		hit.distance = other.radius - distance;
		hit.point = point;
		hit.normal = normal;

		return true;
	}


	bool intersectRay(const Ray<2>& ray, Ray<2>::Contact& hit) const
	{
		Vector2	v1 = a - ray.point;
		Scalar	a1 = cml::signed_angle_2D(v1, b - ray.point);

		//logWarning << "angle:::::::::: " << a1 << std::endl;

		if (a1 == Constants::pi())
		{
			hit.distance = 5.4321;
			return true;
		}
		else if (a1 == SCALAR(0.0))
		{
			hit.distance = 99999.0;
			return true;
		}

		Scalar	a2 = cml::signed_angle_2D(v1, ray.direction);

		if (a2 < SCALAR(0.0) || a2 > a1) return false;

		//hit.distance = 1.23456;
		//hit.normal = Vector2(0.0, 0.0);

		Vector2	n = (b - a).normalize();
		Scalar	z = cml::dot(ray.point - a, n);
		Vector2	p = a + n * z;
		hit.distance = (ray.point - p).length();
		hit.normal = cml::perp(a - b);
		return true;


		/*
		// solve: Cx + r*Dx = Ax + s(Bx - Ax)
		//        Cy + r*Dy = Ay + s(By - Ay)
		// where: 0 <= s <= 1 if intersection
		// given: A = a
		//        B = b
		//        C = ray.point
		//        D = ray.direction

		Scalar denom = ray.direction[0] * (b[1] - a[1]) +
					   ray.direction[1] * (a[0] - b[0]);

		// check if the ray and line are parallel
		//if (isEqual(denom, SCALAR(0.0)))
		if (denom == SCALAR(0.0))
		{
			Scalar numer = a[0] * (ray.point[1] - b[1]) +
						   b[0] * (a[1] - ray.point[1]) +
						   ray.point[0] * (b[1] - a[1]);

			// check if they are collinear
			if (isEqual(numer, SCALAR(0.0)))
			{
				hit.distance = SCALAR(0.0);
				hit.normal.set(0.0, 0.0);
				return true;
			}

			return false;
		}

		Scalar s = (ray.direction[0] * (ray.point[1] - a[1]) +
					ray.direction[1] * (a[0] - ray.point[0])) / denom;

		// check if the ray hits the segment
		if (s < SCALAR(0.0) || s > SCALAR(1.0)) return false;

		hit.distance = -(a[0] * (ray.point[1] - b[1]) +
						 b[0] * (a[1] - ray.point[1]) +
						 ray.point[0] * (b[1] - a[1])) / denom;

		// check if the intersection is behind the ray
		if (hit.distance < SCALAR(0.0)) return false;

		Vector normal = cml::perp(a - b);
		if (cml::dot(a - ray.point, normal) < 0) hit.normal = normal;
		else                                     hit.normal = -normal;
		return true;
		*/
	}


	void draw(Scalar alpha = 0.0) const
	{
		Mf::Texture::resetBind();
		glBegin(GL_LINES);
			glVertex(a);
			glVertex(b);
		glEnd();
	}
};


typedef Line<2>		Line2;
typedef Line<3>		Line3;


template <int D, int N>
struct Polygon : public Drawable, public Shape<D>
{
	typedef cml::vector< Scalar, cml::fixed<D> > Vector;

	Vector	points[N];

	Polygon() {}

	bool intersectRay(const Ray<D>& ray, typename Ray<D>::Contact& hit)
	{
		return false;
	}

	void draw(Scalar alpha = 0.0) const
	{
		Mf::Texture::resetBind();
		glBegin(GL_POLYGON);
		for (int i = 0; i < D; ++i)
		{
			glVertex(points[0]);
		}
		glEnd();
	}
};


typedef Polygon<2,3>	Triangle2;
typedef Polygon<3,3>	Triangle3;


template <int D>
bool intersect(const Line<D>& line, const Sphere<D>& sphere,
			   Contact<D>& hit)
{
	return false;
}


} // namespace Mf

#endif // _MOOF_LINE_HH_