/*]  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_

/**
 * \file line.hh
 * Classes related to line segments.
 */

#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 moof {


template <int D>
struct line : public drawable, public shape<D>
{
	typedef moof::vector< scalar, fixed<D> > vector;


	vector	a;
	vector	b;


	line() {}

	line(const vector& point1, const vector& point2) :
		a(point1),
		b(point2) {}


	vector direction() const
	{
		return b - a;
	}

	scalar length() const
	{
		return direction().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 = perp(tangent).normalize();

		if (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 = 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 intersect_ray(const ray<2>& ray, moof::ray<2>::contact& hit) const
	{
		vector2	v1 = a - ray.point;
		scalar	a1 = signed_angle_2D(v1, b - ray.point);

		//log_warning << "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 = 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 = dot(ray.point - a, n);
		vector2	p = a + n * z;
		hit.distance = (ray.point - p).length();
		hit.normal = 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 (is_equal(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 (is_equal(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 = perp(a - b);
		if (dot(a - ray.point, normal) < 0) hit.normal = normal;
		else                                     hit.normal = -normal;
		return true;
		*/
	}


	void draw(scalar alpha = 0.0) const
	{
		texture::reset_binding();
		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 moof::vector< scalar, fixed<D> > vector;

	vector	points[N];

	polygon() {}

	bool intersect_ray(const ray<D>& ray,
					   typename moof::ray<D>::contact& hit)
	{
		return false;
	}

	void draw(scalar alpha = 0.0) const
	{
		texture::reset_binding();
		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 moof

#endif // _MOOF_LINE_HH_