#include <psemek/geom/camera.hpp>
#include <psemek/geom/gauss.hpp>
#include <psemek/geom/perspective.hpp>
#include <psemek/geom/translation.hpp>
#include <psemek/geom/rotation.hpp>
#include <psemek/geom/homogeneous.hpp>

#include <cmath>

namespace psemek::geom
{

	matrix<float, 4, 4> camera::transform() const
	{
		return projection() * view();
	}

	point<float, 3> camera::position() const
	{
		vector<float, 4> b{ 0.f, 0.f, 0.f, 1.f };
		gauss(view(), b);
		return { b[0], b[1], b[2] };
	}

	vector<float, 3> camera::axis_x() const
	{
		vector<float, 4> b{ 1.f, 0.f, 0.f, 0.f };
		gauss(view(), b);
		return { b[0], b[1], b[2] };
	}

	vector<float, 3> camera::axis_y() const
	{
		vector<float, 4> b{ 0.f, 1.f, 0.f, 0.f };
		gauss(view(), b);
		return { b[0], b[1], b[2] };
	}

	vector<float, 3> camera::axis_z() const
	{
		vector<float, 4> b{ 0.f, 0.f, 1.f, 0.f };
		gauss(view(), b);
		return { b[0], b[1], b[2] };
	}

	vector<float, 3> camera::direction(float x, float y) const
	{
		vector<float, 4> b{ x, y, -1.f, 1.f};
		gauss(transform(), b);

		point<float, 3> p{ b[0] / b[3], b[1] / b[3], b[2] / b[3] };
		return p - position();
	}

	std::array<vector<float, 4>, 6> camera::clip_planes() const
	{
		auto const m = transpose(transform());

		std::array<vector<float, 4>, 6> p;

		p[0] = m * vector{1.f, 0.f, 0.f, 1.f};
		p[1] = m * vector{-1.f, 0.f, 0.f, 1.f};
		p[2] = m * vector{0.f, 1.f, 0.f, 1.f};
		p[3] = m * vector{0.f, -1.f, 0.f, 1.f};
		p[4] = m * vector{0.f, 0.f, 1.f, 1.f};
		p[5] = m * vector{0.f, 0.f, -1.f, 1.f};

		return p;
	}

	matrix<float, 4, 4> perspective_camera::projection() const
	{
		return perspective<float, 3>(fov_x, fov_y, near_clip, far_clip).homogeneous_matrix();
	}

	matrix<float, 4, 4> spherical_camera::view() const
	{
		return
			  translation<float, 3>({0.f, 0.f, -distance}).homogeneous_matrix()
			* homogeneous(plane_rotation<float, 3>(1, 2, elevation_angle).matrix())
			* homogeneous(plane_rotation<float, 3>(2, 0, azimuthal_angle).matrix())
			* translation<float, 3>({ -target[0], -target[1], -target[2] }).homogeneous_matrix()
			;
	}

}