// This source code is released into the public domain.
export module nihil.core:errc;

import nihil.std;

namespace nihil {

export enum struct errc : std::uint8_t {
	no_error = 0,

	///////////////////////////////////////////////////////////////
	// nihil.command

	incomplete_command,

	///////////////////////////////////////////////////////////////
	// nihil.ucl

	failed_to_create_object,
	type_mismatch,

	///////////////////////////////////////////////////////////////
	// nihil.util

	// Empty string is not allowed.
	empty_string,

	// Invalid unit, e.g. in parse_size()
	invalid_unit,
};

struct nihil_error_category final : std::error_category
{
	[[nodiscard]] auto name() const noexcept -> char const * override
	{
		return "nihil";
	}

	[[nodiscard]] auto message(int err) const -> std::string override
	{
		switch (static_cast<errc>(err)) {
		case errc::no_error:
			return "No error";
		case errc::incomplete_command:
			return "Incomplete command";
		case errc::empty_string:
			return "Empty string is not permitted";
		case errc::invalid_unit:
			return "Invalid unit specifier";
		case errc::failed_to_create_object:
			return "Failed to create UCL object";
		case errc::type_mismatch:
			return "UCL type does not match expected type";
		default:
			return "Undefined error";
		}
	}
};

export [[nodiscard]] auto nihil_category() noexcept -> std::error_category &
{
	static auto category = nihil_error_category();
	return category;
}

export [[nodiscard]] auto make_error_condition(errc ec) -> std::error_condition
{
	return {static_cast<int>(ec), nihil_category()};
}

} // namespace nihil

export template <>
struct std::is_error_condition_enum<nihil::errc> : std::true_type
{
};