#include <psemek/audio/3d.hpp>
#include <psemek/util/not_implemented.hpp>

#include <optional>
#include <mutex>

namespace psemek::audio
{

	namespace
	{

		struct mono_effect_impl
			: listener_3d_mono::mono_effect
		{
			mono_effect_impl(geom::point<float, 3> const & source_position, geom::point<float, 3> & target_position, std::mutex & target_position_mutex, float distance_factor)
				: source_position_(source_position)
				, target_position_(target_position)
				, cached_target_position_(target_position)
				, target_position_mutex_(target_position_mutex)
				, distance_factor_(distance_factor)
			{}

			std::string_view name() const override
			{
				return "mono_3d";
			}

			void init(int, int) override
			{ }

			void operator()(sample * data, std::size_t count) override
			{
				{
					std::unique_lock lock{target_position_mutex_, std::try_to_lock};
					if (lock.owns_lock())
						cached_target_position_ = target_position_;
				}

				{
					std::unique_lock lock{source_position_mutex_, std::try_to_lock};
					if (lock.owns_lock())
						cached_source_position_ = source_position_;
				}

				float distance = geom::distance(cached_target_position_, cached_source_position_) / distance_factor_;
				float factor = std::min(1.f, 1.f / (1.f + distance * distance));

				for (std::size_t i = 0; i < count; ++i)
					data[i] = pack(unpack(data[i]) * factor);
			}

			void set_position(geom::point<float, 3> const & position) override
			{
				std::lock_guard lock{source_position_mutex_};
				source_position_ = position;
			}

		private:
			std::mutex source_position_mutex_;
			geom::point<float, 3> source_position_;
			geom::point<float, 3> cached_source_position_;

			geom::point<float, 3> & target_position_;
			geom::point<float, 3> cached_target_position_;
			std::mutex & target_position_mutex_;
			float distance_factor_;
		};

	}

	void listener_3d_mono::set_position(geom::point<float, 3> const & position)
	{
		std::lock_guard lock{position_mutex_};
		position_ = position;
	}

	std::shared_ptr<listener_3d_mono::mono_effect> listener_3d_mono::make_effect(const geom::point<float, 3> &position, float distance_factor)
	{
		return std::make_shared<mono_effect_impl>(position, position_, position_mutex_, distance_factor);
	}

}