#pragma once

#include <string_view>
#include <utility>
#include <array>

#include "exopt.h"

#define _EO_CONSTANT_VALUE(X) ([]() { \
	struct { \
		typedef decltype(X) comptime_constant_t; \
		consteval operator comptime_constant_t() const noexcept { return (X); } \
	} inner; \
	return inner; \
})()

namespace exopt { namespace util [[gnu::visibility("internal")]] {
	template<typename T, typename U>
	concept comptime = std::convertible_to<T, U> and requires{
		typename T::comptime_constant_t;
	};

	constexpr auto comptime_value(auto value) noexcept {
		using U = decltype(value);
		struct inner {
			typedef U comptime_constant_t;
			consteval operator comptime_constant_t() const noexcept { return std::move(value); }
			U value;

			constexpr inner(std::add_rvalue_reference_t<U> m) noexcept : value(std::move(m)) {}
			constexpr ~inner() = default;
		};
		return inner{ std::move(value) };
	}

	static_assert(comptime_value(std::string_view{"hello"}.size()) == 5, "Bad comptime_value()");
	static_assert(_EO_CONSTANT_VALUE(std::string_view{"hello world"}) == std::string_view{"hello world"}, "Bad CONSTANT_VALUE()");


	template<typename T, size_t N, typename Array= std::array<T, N>, typename _I = std::make_index_sequence<N>>
	constexpr auto array_literal(const T (&a)[N]) noexcept 
		-> Array
	{
		constexpr decltype(auto) _array_create = []<size_t... I>(auto const& a, std::index_sequence<I...>) noexcept 
		{
			return Array { a[I]... };
		};
		return _array_create(std::move(a), _I{});
	}
	template<typename T, size_t N, typename Array= std::array<T, N>, typename _I = std::make_index_sequence<N>>
	constexpr auto array_literal(T (&&a)[N]) noexcept 
		-> Array
	{
		constexpr decltype(auto) _array_create = []<size_t... I>(auto&& a, std::index_sequence<I...>) noexcept 
		{
			return Array { std::move(a[I])... };
		};
		return _array_create(std::move(a), _I{});
	}
} }