#include <iostream></iostream>

#include <utility></utility>

#include <gdkmm pixbuf.h=""></gdkmm>

#include <gtkmm hvbox.h=""></gtkmm>

#include <gtkmm image.h=""></gtkmm>

#include "mainwindow.h"

// it's not a math cross product

// just speculative name for function: dot(a, Vector2(-y, x))

static Real

cross_product2(const Vector2 &a, const Vector2 &b)

	{ return a*b.perp(); }

static bool

line_cross(const Pair2 &line_a, const Pair2 &line_b, Vector2 &out) {

	Vector2 da = line_a.distance();

	Vector2 db = line_b.distance();

	Real denominator = cross_product2(da, db);

	if (real_equal(denominator, 0.0))

		return false;

	Real numerator = cross_product2(da, line_a.p0 - line_b.p0);

	out = line_a.p0 + db*(numerator/denominator);

	return true;

}

static Vector4

make_matrix_row(const Vector2 &p0, const Vector2 &p1)

	{ return Vector4(p1.x - p0.x, p1.y - p0.y, 0.0, 0.0); }

static Vector4

make_matrix_row(const Vector2 &p0, const Vector2 &p1, const Vector2 &p2) {

	Real l2 = (p2 - p1).length();

	if (real_less_or_equal(l2, 0.0))

		return Vector4();

	Real l1 = (p1 - p0).length();

	Real w = l1/l2;

	return Vector4(p2.x*w, p2.y*w, 0.0, w);

}

static Matrix4

make_perspective_matrix(const Vector2 &p0, const Vector2 &px, const Vector2 &py, const Vector2 &p1) {

	Vector2 focus;

	Matrix4 m;

	m[0] = line_cross(Pair2(p0, px), Pair2(py, p1), focus)

		 ? make_matrix_row(p0, px, focus)

		 : make_matrix_row(p0, px);

	m[1] = line_cross(Pair2(p0, py), Pair2(px, p1), focus)

		 ? make_matrix_row(p0, py, focus)

		 : make_matrix_row(p0, py);

	m[2] = Vector4(0.0, 0.0, 1.0, 0.0);

	m[3] = Vector4(p0.x, p0.y, 0.0, 1.0);

	return m;

}

static Matrix4

make_plain_matrix(const Pair2 &bounds) {

	const Vector2 &p = bounds.p0;

	const Vector2 d = bounds.distance();

	return Matrix4(

		Vector4(d.x, 0.0, 0.0, 0.0),

		Vector4(0.0, d.y, 0.0, 0.0),

		Vector4(0.0, 0.0, 1.0, 0.0),

		Vector4(p.x, p.y, 0.0, 1.0) );

}

static void

make_layers(const Pair2 &bounds, const Matrix4 &matrix, MainWindow::LayerList &out_layers) {

	const Real min_distance_to_horizon = 1.0; // one pixel

	if (bounds.empty() || real_equal(matrix.row_w().w, 0.0))

		return;

	// get focuses

	Vector2 focus_x, focus_y;

	bool focus_x_exists = real_not_equal(matrix.row_x().w, 0.0);

	bool focus_y_exists = real_not_equal(matrix.row_y().w, 0.0);

	if (focus_x_exists)

		focus_x = matrix.row_x().vec2() / matrix.row_x().w;

	if (focus_y_exists)

		focus_y = matrix.row_y().vec2() / matrix.row_y().w;

	// get horizon

	Vector2 h, dh;

	if (focus_x_exists && focus_x_exists) {

		h = focus_x;

		dh = (focus_y - focus_x).normalized();

	} else

	if (focus_x_exists) {

		h = focus_x;

		dh = matrix.row_y().vec2().normalized();

	} else

	if (focus_y_exists) {

		h = focus_y;

		dh = matrix.row_x().vec2().normalized();

	} else {

		// TODO

		return;

	}

	// get horison perpendicular

	Vector2 hp = dh.perp().normalized();

	// get perspective bounds

	Vector2 corners[] = {

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

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

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

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

		Vector2(bounds.p0.x, bounds.p0.y) }; // close the ring

	Real lmin = 1.0/real_precision;

	Real lmax = 0.0;

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

		Real p = hp*(corners[i] - h);

		if (p < lmin) lmin = p;

		if (p > lmax) lmax = p;

	}

	lmin = std::max(min_distance_to_horizon, lmin);

	lmax = std::max(min_distance_to_horizon, lmax);

	if (real_less_or_equal(lmax, min_distance_to_horizon))

		return;

	// layers

	Real scale_step = 4.0;

	Real l = lmin;

	Matrix4 back_matrix = matrix.inverted();

	while(real_less(l, lmax)) {

		Vector2 p0 = h + hp*l;

		l *= scale_step;

		Vector2 p1 = h + hp*l;

		Vector4 points[8];

		int points_count = 0;

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

			const Vector2 &cp0 = corners[i];

			const Vector2 &cp1 = corners[i+1];

			Vector2 dc = cp1 - cp0;

			Real kk = hp*dc;

			if (real_not_equal(kk, 0.0)) {

				kk = 1.0/kk;

				Real cl0 = clamp( hp*(p0 - cp0)*kk, 0.0, 1.0 );

				Real cl1 = clamp( hp*(p1 - cp0)*kk, 0.0, 1.0 );

				if (real_not_equal(cl1 - cl0, 0.0)) {

					points[points_count++] = Vector4(cp0 + dc*cl0, 0.0, 1.0);

					points[points_count++] = Vector4(cp0 + dc*cl1, 0.0, 1.0);

				}

			}

		}

		Vector2 src_res;

		{

			Vector2 c = (p0 + p1)*0.5;

			Vector2 px = c*0.75 + p1*0.25;

			Vector2 dx = px - c;

			Vector2 dy = dx.perp();

			Vector2 py = c + dy;

			Real len = dx.length();

			Vector2 cc  = (back_matrix*Vector4(c , 0, 1)).persp_divide().vec2();

			Vector2 cpx = (back_matrix*Vector4(px, 0, 1)).persp_divide().vec2();

			Vector2 cpy = (back_matrix*Vector4(py, 0, 1)).persp_divide().vec2();

			Vector2 ddx = cpx - cc;

			Vector2 ddy = cpy - cc;

			src_res = Vector2(

				len/std::max(fabs(ddx.x), fabs(ddy.x)),

				len/std::max(fabs(ddx.y), fabs(ddy.y)) );

		}

		Pair2 src_rect;

		Pair2 dst_rect;

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

			const Vector4 &p = points[i];

			Vector4 pp = back_matrix*p;

			assert(real_not_equal(pp.w, 0.0));

			pp /= pp.w;

			if (i) {

				if (src_rect.p0.x > pp.x) src_rect.p0.x = pp.x;

				if (src_rect.p0.y > pp.y) src_rect.p0.y = pp.y;

				if (src_rect.p1.x < pp.x) src_rect.p1.x = pp.x;

				if (src_rect.p1.y < pp.y) src_rect.p1.y = pp.y;

				if (dst_rect.p0.x > p.x) dst_rect.p0.x = p.x;

				if (dst_rect.p0.y > p.y) dst_rect.p0.y = p.y;

				if (dst_rect.p1.x < p.x) dst_rect.p1.x = p.x;

				if (dst_rect.p1.y < p.y) dst_rect.p1.y = p.y;

			} else {

				src_rect.p0 = src_rect.p1 = pp.vec2();

				dst_rect.p0 = dst_rect.p1 = points[i].vec2();

			}

		}

		if (!src_rect.empty() && !dst_rect.empty())

		{

			Vector2 src_size_r = src_rect.size();

			IntVector2 src_size(

				(int)ceil(src_size_r.x * src_res.x),

				(int)ceil(src_size_r.y * src_res.y) );

			if (src_size.x > 0 && src_size.y > 0 && src_size.x*src_size.x < 100000000) {

				out_layers.push_back(MainWindow::Layer());

				MainWindow::Layer &layer = out_layers.back();

				layer.src_bounds = src_rect;

				layer.src_size = src_size;

				layer.dst_bounds.p0.x = (int)floor(dst_rect.p0.x) - 2;

				layer.dst_bounds.p0.y = (int)floor(dst_rect.p0.y) - 2;

				layer.dst_bounds.p1.x = (int)ceil(dst_rect.p1.x) + 2;

				layer.dst_bounds.p1.y = (int)ceil(dst_rect.p1.y) + 2;

				layer.back_transform = back_matrix;

			}

		}

	}

}

static void

make_surface(const Generator &generator, MainWindow::Layer &layer) {

	if (!layer.src_surface) {

		layer.dst_surface.reset();

		layer.cairo_surface.clear();

		if (layer.src_size.x > 0 && layer.src_size.y > 0) {

			Surface *surface = new DataSurface(layer.src_size.x, layer.src_size.y);

			generator.generate(*surface, layer.src_bounds);

			layer.src_surface = RefPtr<surface>(surface);</surface>

		}

	}

	if (layer.src_surface && !layer.dst_surface) {

		layer.cairo_surface.clear();

		if ( layer.dst_bounds.p0.x < layer.dst_bounds.p1.x

		  && layer.dst_bounds.p0.y < layer.dst_bounds.p1.y )

		{

			int w = layer.dst_bounds.p1.x - layer.dst_bounds.p0.x;

			int h = layer.dst_bounds.p1.y - layer.dst_bounds.p0.y;

			Surface *surface = new DataSurface(w, h);

			for(int y = 0; y < h; ++y) {

				for(int x = 0; x < w; ++x) {

					Vector4 pos = layer.back_transform * Vector4(x + layer.dst_bounds.p0.x, y + layer.dst_bounds.p0.y, 0, 1);

					if (fabs(pos.w) > real_precision)

						pos /= pos.w;

					surface->row(y)[x] = layer.src_surface->get_pixel(pos.x, pos.y);

				}

			}

			layer.dst_surface = RefPtr<surface>(surface);</surface>

		}

	}

	if (layer.dst_surface && !layer.cairo_surface) {

		layer.cairo_surface = layer.dst_surface->to_cairo_surface();

	}

}

MainWindow::MainWindow():

	src_rect_p0   (new View::Point( Vector2(-1, -1) )),

	src_rect_p1   (new View::Point( Vector2( 1,  1) )),

	dst_rect_p0   (new View::Point( Vector2(-1, -1) )),

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

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

	dst_rect_p1   (new View::Point( Vector2( 1,  1) )),

	dst_bounds_p0 (new View::Point( Vector2(-2, -2) )),

	dst_bounds_p1 (new View::Point( Vector2( 2,  2) ))

{

	std::cout << "generator seed: " << generator.seed() << std::endl;

	set_default_size(750, 500);

	Gtk::HBox *hbox = manage(new Gtk::HBox());

	hbox->set_homogeneous(true);

	src_view.transform.scale(50, 50);

	src_view.points.push_back(src_rect_p0);

	src_view.points.push_back(src_rect_p1);

	src_view.signal_point_motion.connect(

		sigc::mem_fun(*this, &MainWindow::on_point_motion) );

	src_view.signal_point_changed.connect(

		sigc::mem_fun(*this, &MainWindow::on_point_changed) );

	src_view.signal_transform_changed.connect(

		sigc::bind(

			sigc::mem_fun(*this, &MainWindow::on_view_transform_changed),

			&src_view ));

	src_view.signal_draw_view.connect(

		sigc::mem_fun(*this, &MainWindow::on_draw_src_view) );

	hbox->add(src_view);

	dst_view.transform.scale(50, 50);

	dst_view.points.push_back(dst_rect_p0);

	dst_view.points.push_back(dst_rect_px);

	dst_view.points.push_back(dst_rect_py);

	dst_view.points.push_back(dst_rect_p1);

	dst_view.points.push_back(dst_bounds_p0);

	dst_view.points.push_back(dst_bounds_p1);

	dst_view.signal_point_motion.connect(

		sigc::mem_fun(*this, &MainWindow::on_point_motion) );

	dst_view.signal_point_changed.connect(

		sigc::mem_fun(*this, &MainWindow::on_point_changed) );

	src_view.signal_transform_changed.connect(

		sigc::bind(

			sigc::mem_fun(*this, &MainWindow::on_view_transform_changed),

			&dst_view ));

	dst_view.signal_draw_view.connect(

		sigc::mem_fun(*this, &MainWindow::on_draw_dst_view) );

	hbox->add(dst_view);

	//hbox->add(*manage(generator_demo()));

	add(*hbox);

	show_all();

	update_view_surface();

	update_layers();

}

Gtk::Widget*

MainWindow::generator_demo() {

	std::cout << "generator demo: generate" << std::endl;

	DataSurface surface(256, 256);

	generator.generate(surface, Pair2(Vector2(0, 0), Vector2(16, 16)));

	std::cout << "generator demo: convert" << std::endl;

	Glib::RefPtr<gdk::pixbuf> pixbuf = Gdk::Pixbuf::create(</gdk::pixbuf>

		Gdk::COLORSPACE_RGB, true, 8, surface.width(), surface.height() );

	guint8 *pixel = pixbuf->get_pixels();

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

		Color *row = surface[r];

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

			const Color &color = row[c];

			*(pixel++) = (guint8)(color.r*255.9);

			*(pixel++) = (guint8)(color.g*255.9);

			*(pixel++) = (guint8)(color.b*255.9);

			*(pixel++) = (guint8)(color.a*255.9);

		}

	}

	return new Gtk::Image(pixbuf);

}

void

MainWindow::update_view_surface() {

	Matrix4 transform = src_view.transform.inverted();

	int w = src_view.get_width();

	int h = src_view.get_height();

	Pair2 rect(

		(transform * Vector4(0, 0, 0, 1)).vec2(),

		(transform * Vector4(w, h, 0, 1)).vec2() );

	if (w <= 0 || h <= 0) {

		view_surface.clear();

	} else

	if ( !view_surface

	  || view_surface->get_width() != w

	  || view_surface->get_height() != h

	  || view_surface_rect != rect )

	{

		DataSurface surface(w, h);

		generator.generate(surface, rect);

		view_surface = surface.to_cairo_surface();

		view_surface_rect = rect;

	}

}

void

MainWindow::update_layers() {

	Matrix dst_transform = dst_view.transform_to_pixels();

	Vector2 dst_rect_p0_pixels(dst_transform * Vector4(dst_rect_p0->position, 0.0, 1.0));

	Vector2 dst_rect_px_pixels(dst_transform * Vector4(dst_rect_px->position, 0.0, 1.0));

	Vector2 dst_rect_py_pixels(dst_transform * Vector4(dst_rect_py->position, 0.0, 1.0));

	Vector2 dst_rect_p1_pixels(dst_transform * Vector4(dst_rect_p1->position, 0.0, 1.0));

	Vector2 dst_bounds_p0_pixels(dst_transform * Vector4(dst_bounds_p0->position, 0.0, 1.0));

	Vector2 dst_bounds_p1_pixels(dst_transform * Vector4(dst_bounds_p1->position, 0.0, 1.0));

	Matrix in_matrix = make_plain_matrix( Pair2(

		src_rect_p0->position,

		src_rect_p1->position ));

	Matrix out_matrix = make_perspective_matrix(

		dst_rect_p0_pixels,

		dst_rect_px_pixels,

		dst_rect_py_pixels,

		dst_rect_p1_pixels );

	Matrix matrix = out_matrix * in_matrix.inverted();

	Pair2 bounds(

		dst_bounds_p0_pixels,

		dst_bounds_p1_pixels );

	bounds.sort();

	LayerList layers;

	make_layers(bounds, matrix, layers);

	for(LayerList::iterator i = layers.begin(); i != layers.end(); ++i)

		make_surface(generator, *i);

	target_surface.clear();

	int w = dst_view.get_width();

	int h = dst_view.get_height();

	if (w > 0 && h > 0) {

		target_surface = Cairo::ImageSurface::create(Cairo::FORMAT_ARGB32, w, h);

		Cairo::RefPtr<cairo::context> context = Cairo::Context::create(target_surface);</cairo::context>

		context->set_operator(Cairo::OPERATOR_ADD);

		for(LayerList::const_iterator i = layers.begin(); i != layers.end(); ++i) {

			if (i->cairo_surface) {

				context->set_source(i->cairo_surface, i->dst_bounds.p0.x, i->dst_bounds.p0.y);

				context->paint();

			}

		}

	}

}

void

MainWindow::on_point_motion(const View::PointPtr &/*point*/) {

	queue_draw();

}

void

MainWindow::on_point_changed(const View::PointPtr &/*point*/) {

	update_layers();

}

void

MainWindow::on_view_transform_changed(View *view) {

	if (view == &src_view) {

		update_view_surface();

		view->queue_draw();

	}

}

void

MainWindow::on_draw_src_view(const Cairo::RefPtr<cairo::context> &context) {</cairo::context>

	const Real ps = src_view.get_pixel_size();

	context->save();

	if ( !view_surface

	  || src_view.get_width() != view_surface->get_width()

	  || src_view.get_height() != view_surface->get_height() )

		update_view_surface();

	if (view_surface) {

		context->save();

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

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

		context->paint();

		context->restore();

	}

	context->move_to(src_rect_p0->position.x, src_rect_p0->position.y);

	context->line_to(src_rect_p0->position.x, src_rect_p1->position.y);

	context->line_to(src_rect_p1->position.x, src_rect_p1->position.y);

	context->line_to(src_rect_p1->position.x, src_rect_p0->position.y);

	context->close_path();

	context->set_line_width(ps);

	context->set_source_rgba(1, 1, 0, 0.5);

	context->stroke();

	context->restore();

}

void

MainWindow::on_draw_dst_view(const Cairo::RefPtr<cairo::context> &context) {</cairo::context>

	const Real ps = src_view.get_pixel_size();

	context->save();

	if (target_surface) {

		context->save();

		context->transform( dst_view.transform.inverted().to_cairo() );

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

		context->paint();

		context->restore();

	}

	context->move_to(dst_rect_p0->position.x, dst_rect_p0->position.y);

	context->line_to(dst_rect_px->position.x, dst_rect_px->position.y);

	context->line_to(dst_rect_p1->position.x, dst_rect_p1->position.y);

	context->line_to(dst_rect_py->position.x, dst_rect_py->position.y);

	context->close_path();

	context->set_line_width(ps);

	context->set_source_rgba(1, 1, 0, 0.5);

	context->stroke();

	context->move_to(dst_bounds_p0->position.x, dst_bounds_p0->position.y);

	context->line_to(dst_bounds_p0->position.x, dst_bounds_p1->position.y);

	context->line_to(dst_bounds_p1->position.x, dst_bounds_p1->position.y);

	context->line_to(dst_bounds_p1->position.x, dst_bounds_p0->position.y);

	context->close_path();

	context->set_line_width(ps);

	context->set_source_rgba(1, 0, 0, 0.5);

	context->stroke();

	context->restore();

}