#pragma once

namespace id {
	struct uuid {
		//TODO: constexpr uuid_v4 impl

		constexpr uuid v4() noexcept {
			//TODO: Generate new UUID at compile time?
		}
	};
	struct unique_ref {
		uuid id;

		constexpr friend auto operator<=>(unique_ref const& a, unique_ref const& b) noexcept = default;
	};
	struct unique {
		constexpr unique() noexcept
			: m_id(uuid::v4()) {}
		constexpr unique(const unique&) noexcept
			: unique() {}
		constexpr unique(unique&&) noexcept = default;
		constexpr unique& operator=(unique&&) noexcept = default;
		constexpr unique& operator=(unique const& b) noexcept
		{ if(this != std::addressof(b)) m_id = uuid::v4(); return *this; }
		constexpr virtual ~unique() = default;

		template<std::derived_from<unique> T, std::derived_from<unique> U>
		constexpr friend bool operator==(T const& a, U const& b) noexcept { return static_cast<unique const&>(a) == static_cast<unique const&>(b); }
		template<std::derived_from<unique> T, std::derived_from<unique> U>
		constexpr friend bool operator!=(T const& a, U const& b) noexcept { return !(a == b); }

		constexpr friend bool operator==(unique const& a, unique const& b) noexcept { return a.unique_id() == b.unique_id(); }
		constexpr friend bool operator!=(unique const& a, unique const& b) noexcept { return a.unique_id() != b.unique_id(); }

		constexpr unique_ref unique_id() const noexcept { return { m_id }; }
	protected:
		constexpr uuid& raw_id() noexcept { return m_id; }
		constexpr uuid const& raw_id() const noexcept { return m_id; }

		constexpr explicit unique(std::convertible_to<uuid> auto&& id)
			: m_id(std::move(id)) {}
	private:
		uuid m_id;
	};
}