#include <psemek/ui/impl/frame_base.hpp>
#include <psemek/react/join.hpp>
#include <psemek/react/map.hpp>

namespace psemek::ui::impl
{

	namespace
	{

		size_constraints compute_size_constraints(size_constraints const & child_size_constraints, float margin)
		{
			return { child_size_constraints.box + geom::vector{2.f * margin, 2.f * margin} };
		}

		geom::box<float, 2> compute_child_shape(geom::box<float, 2> const & shape, float margin)
		{
			return geom::expand(shape, -margin);
		}

	}

	frame_base::frame_base()
		: margin_(0.f)
		, child_size_constraints_(size_constraints::max())
		, size_constraints_(react::map(compute_size_constraints, react::join(child_size_constraints_), react::join(margin_)))
	{}

	void frame_base::reshape(geom::box<float, 2> const & new_shape)
	{
		single_container::reshape(new_shape);

		if (auto child = this->child())
			child->reshape(compute_child_shape(new_shape, **margin_));
	}

	react::value<struct size_constraints> frame_base::size_constraints() const
	{
		return size_constraints_;
	}

	void frame_base::set_child(std::unique_ptr<component> child)
	{
		if (child)
			child_size_constraints_.set(child->size_constraints());
		else
			child_size_constraints_.set(size_constraints::max());
		single_container::set_child(std::move(child));
	}

	std::unique_ptr<component> frame_base::release_child()
	{
		child_size_constraints_.set(size_constraints::max());
		return single_container::release_child();
	}

	void frame_base::update(frame const & value)
	{
		margin_.set(value.margin);
	}

}