#pragma once

#include <memory>

namespace OpenVic {
	// Based on https://github.com/think-cell/think-cell-library/blob/b9c84dd7fc926fad80829ed49705fa51afe36e87/tc/base/ref.h
	//     Boost Software License - Version 1.0 - August 17th, 2003

	// Permission is hereby granted, free of charge, to any person or organization
	// obtaining a copy of the software and accompanying documentation covered by
	// this license (the "Software") to use, reproduce, display, distribute,
	// execute, and transmit the Software, and to prepare derivative works of the
	// Software, and to permit third-parties to whom the Software is furnished to
	// do so, all subject to the following:

	// The copyright notices in the Software and this entire statement, including
	// the above license grant, this restriction and the following disclaimer,
	// must be included in all copies of the Software, in whole or in part, and
	// all derivative works of the Software, unless such copies or derivative
	// works are solely in the form of machine-executable object code generated by
	// a source language processor.

	// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
	// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
	// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
	// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
	// DEALINGS IN THE SOFTWARE.
	union AnyRef {
		// Any pointer to function can be converted to a pointer to a different function type. Calling the
		// function through a pointer to a different function type is undefined, but converting such pointer
		// back to pointer to the original function type yields the pointer to the original function.
		// https://en.cppreference.com/w/cpp/language/reinterpret_cast

		template<typename T>
		[[nodiscard]] static constexpr T* as_mutable_ptr(T const* pt) noexcept {
			return const_cast<T*>(pt);
		}

		template<typename RefT>
		explicit AnyRef(RefT& ref) noexcept : m_pvRef(std::addressof(ref)) {}

		template<typename RefT>
		requires std::is_function<RefT>::value
		explicit AnyRef(RefT& ref) noexcept : m_fpvRef(reinterpret_cast<void (*)()>(std::addressof(ref))) {}

		template<typename RefT> // may be const and/or volatile
		RefT& get_ref() const& noexcept {
			static_assert(!std::is_reference<RefT>::value);
			if constexpr (std::is_function<RefT>::value) {
				return *reinterpret_cast<RefT*>(m_fpvRef);
			} else {
				return *static_cast<RefT*>(as_mutable_ptr(m_pvRef));
			}
		}

		void const* m_pvRef;
		void (*m_fpvRef)();
	};
}