#include <psemek/ui/controller.hpp>

#include <psemek/ui/painter_impl.hpp>
#include <psemek/ui/box_shape.hpp>
#include <psemek/gfx/gl.hpp>
#include <psemek/util/recursive.hpp>
#include <psemek/geom/camera.hpp>

namespace psemek::ui
{

	namespace
	{

		struct root_proxy
			: element
		{
			children_range children() const override
			{
				return children_range{&root_raw, &root_raw + 1};
			}

			struct shape const & shape() const override
			{
				return shape_;
			}

			using element::reshape;

			void reshape(geom::box<float, 2> const & bbox) override
			{
				shape_.box = bbox;
				if (root)
					root->reshape(bbox);
				if (on_reshape)
					post(on_reshape);
			}

			geom::box<float, 2> size_constraints() const override
			{
				return root->size_constraints();
			}

			void draw(painter &) const override {}

			std::shared_ptr<element> root;
			element * root_raw = nullptr;
			box_shape shape_;
			std::function<void()> on_reshape;
		};

	}

	struct controller::impl
	{
		async::event_loop * loop;
		painter_impl painter;
		std::shared_ptr<root_proxy> root;
		std::optional<geom::point<int, 2>> mouse;

		impl(async::event_loop * loop);

		template <typename E>
		bool event(E const & e);

		void update(float dt);
	};

	controller::impl::impl(async::event_loop * loop)
		: loop(loop)
		, root{std::make_shared<root_proxy>()}
	{
		root->set_loop(loop);
		root->on_reshape = [this]{
			if (mouse)
				event(mouse_move{*mouse});
		};
	}

	template <typename E>
	bool controller::impl::event(E const & e)
	{
		auto visitor = util::recursive([&](auto && self, element * elem) -> bool {
			if (elem->hidden()) return false;

			auto cs = elem->children();
			for (auto it = cs.rbegin(); it != cs.rend(); ++it)
				if (*it && self(*it)) return true;

			if (elem->enabled() && elem->on_event(e)) return true;
			return false;
		});

		if (root)
			return visitor(root.get());
		return false;
	}

	void controller::impl::update(float dt)
	{
		auto visitor = util::recursive([dt](auto && self, element * elem) -> void {
			if (elem->enabled()) elem->update(dt);
			for (auto c : elem->children())
				if (c) self(c);
		});

		if (root)
			visitor(root.get());
	}

	controller::controller(async::event_loop * loop)
		: pimpl_{make_impl(loop)}
	{}

	async::event_loop * controller::loop() const
	{
		return impl().loop;
	}

	controller::~controller() = default;

	std::shared_ptr<element> controller::set_root(std::shared_ptr<element> r)
	{
		auto old = std::move(impl().root->root);
		if (old)
			old->set_parent(nullptr);

		impl().root->root = std::move(r);
		impl().root->root_raw = impl().root->root.get();
		if (impl().root->root)
			impl().root->root->set_parent(impl().root.get());

		impl().root->reshape();

		return old;
	}

	element * controller::root()
	{
		return impl().root->root.get();
	}

	void controller::reshape(geom::box<float, 2> const & shape)
	{
		impl().root->reshape(shape);
	}

	bool controller::event(mouse_move const & e)
	{
		impl().mouse = e.position;
		return impl().event(e);
	}

	bool controller::event(mouse_click const & e)
	{
		return impl().event(e);
	}

	bool controller::event(mouse_wheel const & e)
	{
		return impl().event(e);
	}

	bool controller::event(key_press const & e)
	{
		return impl().event(e);
	}

	void controller::update(float dt)
	{
		impl().update(dt);
	}

	void controller::render(gfx::render_target const & rt)
	{
		impl().painter.start_frame(geom::cast<float>(rt.viewport));

		auto visitor = util::recursive([&](auto && self, element * elem) -> void {
			if (elem->hidden()) return;
			bool const visible = !(impl().painter.current_bbox() & elem->shape().bbox()).empty();
			if (visible)
				elem->draw(impl().painter);
			for (auto c : elem->children())
				if (c) self(c);
			if (visible)
				elem->post_draw(impl().painter);
		});

		visitor(impl().root.get());

		rt.bind();

		gl::Enable(gl::DEPTH_TEST);
		gl::DepthFunc(gl::LEQUAL);

		gl::Enable(gl::BLEND);
		gl::BlendFunc(gl::SRC_ALPHA, gl::ONE_MINUS_SRC_ALPHA);

		gl::Disable(gl::CULL_FACE);

		impl().painter.render(geom::window_camera{rt.viewport[0].length(), rt.viewport[1].length()}.transform());
	}

}