#include <iostream></iostream>

#include "perspective.h"

#include "perspectivesandboxview.h"

PerspectiveSandBoxView::PerspectiveSandBoxView():

	persp_p0  (new View::Point( Vector2(-1, -1) )),

	persp_px  (new View::Point( Vector2( 1, -1) )),

	persp_py  (new View::Point( Vector2(-1,  1) )),

	persp_p1  (new View::Point( Vector2( 1,  1) )),

	bounds_p0 (new View::Point( Vector2(-2, -2) )),

	bounds_p1 (new View::Point( Vector2( 2,  2) ))

{

	transform.scale(50, 50);

	points.push_back(persp_p0);

	points.push_back(persp_px);

	points.push_back(persp_py);

	points.push_back(persp_p1);

	points.push_back(bounds_p0);

	points.push_back(bounds_p1);

}

static Vector2 calc_optimal_resolution(

	const Vector2 &ox,

	const Vector2 &oy )

{

	const Real a = ox.x * ox.x;

	const Real b = ox.y * ox.y;

	const Real c = oy.x * oy.x;

	const Real d = oy.y * oy.y;

	Real e = fabs(ox.x*oy.y - ox.y*oy.x);

	if (e < real_precision_sqr)

		return Vector2(); // paranoid check, e must be non-zero when matrix is invertible

	e = 1.0/e;

	const Real sum = a*d + b*c;

	Vector2 scale;

	if (2*a*b + real_precision_sqr >= sum) {

		scale.x = sqrt(2*b)*e;

		scale.y = sqrt(2*a)*e;

	} else

	if (2*c*d + real_precision_sqr >= sum) {

		scale.x = sqrt(2*d)*e;

		scale.y = sqrt(2*c)*e;

	} else {

		const Real dif = a*d - b*c;

		scale.x = sqrt(dif/(a - c))*e;

		scale.y = sqrt(dif/(d - b))*e;

	}

	return scale;

}

void PerspectiveSandBoxView::update_background(

	const Matrix3 &matrix,

	int width,

	int height )

{

	DataSurface surface(width, height);

	for(int r = 0; r < height; ++r) {

		for(int c = 0; c < width; ++c) {

			Vector3 v = matrix*Vector3(c, r, 1);

			if (v.z <= real_precision)

				continue;

			const Real k = 1/(v.z*v.z);

			const Vector2 ox = Vector2( v.z*matrix.m00 - matrix.m02*v.x,

										v.z*matrix.m10 - matrix.m12*v.x )*k;

			const Vector2 oy = Vector2( v.z*matrix.m01 - matrix.m02*v.y,

										v.z*matrix.m11 - matrix.m12*v.y )*k;

			const Vector2 resolution = calc_optimal_resolution(ox, oy)*100;

			if (resolution.x <= real_precision || resolution.y <= real_precision)

				continue;

			const int lx = (int)round(log2(resolution.x));

			const int ly = (int)round(log2(resolution.y));

			Color color;

			color.r = lx < 0 ? lx%2 + 1 : lx%2;

			color.g = 0;

			color.b = ly < 0 ? ly%2 + 1 : ly%2;

			color.a = 1;

			surface[r][c] = color;

		}

	}

	background = surface.to_cairo_surface();

}

void

PerspectiveSandBoxView::draw_grid(

	const Cairo::RefPtr<cairo::context> &context,</cairo::context>

	const Matrix &matrix,

	const Color &color )

{

	const int count = 100;

	const int subcount = 10;

	const Real ps = get_pixel_size();

	for(int i = -count; i < count; ++i) {

		for(int j = -count; j < count; ++j) {

			Vector4 src(i/(Real)subcount, j/(Real)subcount, 0, 1);

			Vector4 dst = matrix*src;

			Real w = dst.w;

			if (w > real_precision) {

				Vector2 pos(dst.x/w, dst.y/w);

				Real ka = clamp(1/w, 0, 1);

				Real a = color.a*ka;

				Real r = 4*ps;

				if (i) r *= 0.5;

				if (j) r *= 0.5;

				if (i % 10) r *= 0.75;

				if (j % 10) r *= 0.75;

				context->set_source_rgba(color.r, color.g, color.b, a);

				context->arc(pos.x, pos.y, r, 0, 2.0*M_PI);

				context->fill();

			}

		}

	}

}

void

PerspectiveSandBoxView::draw_line(

	const Cairo::RefPtr<cairo::context> &context,</cairo::context>

	const Pair2 &bounds,

	Real a,

	Real b,

	Real c,

	const Color &color )

{

	// equatation of line is a*x + b*y = c

	int count = 0;

	Vector2 points[4];

	if (fabs(a) > real_precision) {

		Real x0 = (c - bounds.p0.y*b)/a;

		if ( x0 + real_precision >= bounds.p0.x

		  && x0 - real_precision <= bounds.p1.x )

			points[count++] = Vector2(x0, bounds.p0.y);

		Real x1 = (c - bounds.p1.y*b)/a;

		if ( x1 + real_precision >= bounds.p0.x

		  && x1 - real_precision <= bounds.p1.x )

			points[count++] = Vector2(x1, bounds.p1.y);

	}

	if (fabs(b) > real_precision) {

		Real y0 = (c - bounds.p0.x*a)/b;

		if ( y0 + real_precision >= bounds.p0.y

		  && y0 - real_precision <= bounds.p1.y )

			points[count++] = Vector2(bounds.p0.x, y0);

		Real y1 = (c - bounds.p1.x*a)/b;

		if ( y1 + real_precision >= bounds.p0.y

		  && y1 - real_precision <= bounds.p1.y )

			points[count++] = Vector2(bounds.p1.x, y1);

	}

	if (count >= 2) {

		context->set_source_rgba(color.r, color.g, color.b, color.a);

		context->move_to(points[0].x, points[0].y);

		context->line_to(points[1].x, points[1].y);

		context->stroke();

	}

}

void

PerspectiveSandBoxView::draw_subdivisions(

	const Cairo::RefPtr<cairo::context> &context,</cairo::context>

	const Matrix &matrix,

	const Pair2 &bounds,

	const Color &color )

{

	const Real ps = get_pixel_size();

	Vector4 a = matrix.row_x();

	Vector4 b = matrix.row_y();

	Vector4 c = matrix.row_w();

	// calc coefficient for equatation of "horizontal" line: A*x + B*y = C + D/w

	//                     equatation of line of horizon is: A*x + B*y = C

	Real A = a.y*b.w - a.w*b.y;

	Real B = a.w*b.x - a.x*b.w;

	Real C = a.y*b.x - a.x*b.y;

	Real D = a.w*(b.x*c.y - b.y*c.x) + b.w*(a.y*c.x - a.x*c.y) - C*c.w;

	if (D < 0) {

		A = -A;

		B = -B;

		C = -C;

		D = -D;

	}

	Real hd = ps*sqrt(A*A + B*B);

	if (hd <= real_precision)

		return; // orthogonal projection - no prespective - no subdiviosions

	hd = D/hd;

	Real horizonw  = hd;

	Real horizonw2 = hd/4;

	Real maxw = -INFINITY, minw = INFINITY;

	Vector2 corners[] = {

		Vector2(bounds.p0.x, bounds.p0.y),

		Vector2(bounds.p1.x, bounds.p0.y),

		Vector2(bounds.p1.x, bounds.p1.y),

		Vector2(bounds.p0.x, bounds.p1.y) };

	for(int i = 0; i < 4; ++i) {

		Real w = A*corners[i].x + B*corners[i].y - C;

		if (fabs(w) > real_precision) {

			w = D/w;

			if (w < 0 || w > horizonw) w = horizonw;

			if (minw > w) minw = w;

			if (maxw < w) maxw = w;

		}

	}

	if (minw >= maxw - real_precision)

		return; // all bounds too thin

	Real maxw2 = maxw < horizonw2 ? maxw : horizonw2;

	// draw limits

	Color limits_color = color;

	limits_color.a *= 0.5;

	draw_line(context, get_bounds(), A, B, C + D/minw, limits_color);

	draw_line(context, get_bounds(), A, B, C + D/maxw, limits_color);

	// split

	int minlog = (int)ceil (log2(minw ) + real_precision);

	int maxlog = (int)floor(log2(maxw2) - real_precision);

	for(int i = minlog; i <= maxlog; ++i)

		draw_line(context, bounds, A, B, C + D/exp2(i), color);

}

void

PerspectiveSandBoxView::on_draw_view(const Cairo::RefPtr<cairo::context> &context) {</cairo::context>

	context->save();

	const Real ps = get_pixel_size();

	context->set_line_width(ps);

	Vector2 p0 = persp_p0->position;

	Vector2 px = persp_px->position;

	Vector2 py = persp_py->position;

	Vector2 p1 = persp_p1->position;

	Pair2 bounds(bounds_p0->position, bounds_p1->position);

	// perspective matrix

	Matrix matrix;

	{

		Vector2 A = px - p1;

		Vector2 B = py - p1;

		Vector2 C = p0 + p1 - px - py;

		Real cw = A.y*B.x - A.x*B.y;

		Real aw = B.x*C.y - B.y*C.x;

		Real bw = A.y*C.x - A.x*C.y;

		if (cw < 0) {

			aw = -aw;

			bw = -bw;

			cw = -cw;

		}

		Vector2 c = p0*cw;

		Vector2 a = px*(cw + aw) - c;

		Vector2 b = py*(cw + bw) - c;

		matrix.row_x() = Vector4(a, 0, aw);

		matrix.row_y() = Vector4(b, 0, bw);

		matrix.row_w() = Vector4(c, 0, cw);

	}

	{ // update background

		Matrix4 m4 = transform_to_pixels()*matrix;

		Matrix3 m3(

			Vector3( m4.m00, m4.m01, m4.m03 ),

			Vector3( m4.m10, m4.m11, m4.m13 ),

			Vector3( m4.m30, m4.m31, m4.m33 ) );

		Matrix3 back_matrix = Perspective::normalize_matrix( m3.inverted() );

		update_background(back_matrix, get_width(), get_height());

	}

	if (background) {

		context->save();

		context->transform(transform_from_pixels().to_cairo());

		context->set_source(background, 0, 0);

		context->paint();

		context->restore();

	}

	draw_grid(context, matrix, Color(0, 1, 0, 1));

	draw_subdivisions(context, matrix, bounds, Color(0, 0, 1, 1));

	// draw frames

	context->set_source_rgba(0, 0, 1, 0.75);

	context->move_to(p0.x, p0.y);

	context->line_to(px.x, px.y);

	context->line_to(p1.x, p1.y);

	context->line_to(py.x, py.y);

	context->close_path();

	context->stroke();

	context->move_to(bounds.p0.x, bounds.p0.y);

	context->line_to(bounds.p1.x, bounds.p0.y);

	context->line_to(bounds.p1.x, bounds.p1.y);

	context->line_to(bounds.p0.x, bounds.p1.y);

	context->close_path();

	context->stroke();

	context->restore();

}