/*
 * This source code is released into the public domain.
 */

module;

#include <compare>
#include <expected>
#include <format>
#include <utility>

#include <ucl.h>

export module nihil.ucl:real;

import :object;
import :type;

namespace nihil::ucl {

export struct real final : object {
	using contained_type = double;

	inline static constexpr object_type ucl_type = object_type::real;

	/*
	 * Create a real holding the value 0.  Throws std::system_error
	 * on failure.
	 */
	real();

	/*
	 * Create a real holding a specific value.  Throws std::system_error
	 * on failure.
	 */
	explicit real(contained_type value);

	/*
	 * Create a new real from a UCL object.  Throws type_mismatch
	 * on failure.
	 */
	real(ref_t, ::ucl_object_t const *uobj);
	real(noref_t, ::ucl_object_t *uobj);

	// Return the value of this real.
	[[nodiscard]] auto value(this real const &self) -> contained_type;
};

/*
 * Real constructors.  These return an error instead of throwing.
 */

export [[nodiscard]] auto
make_real(real::contained_type = 0) -> std::expected<real, error>;

/*
 * Comparison operators.
 */

export [[nodiscard]] auto operator== (real const &a, real const &b) -> bool;

export [[nodiscard]] auto operator== (real const &a,
				      real::contained_type b) -> bool;

export [[nodiscard]] auto operator<=> (real const &a, real const &b)
	-> std::partial_ordering;

export [[nodiscard]] auto operator<=> (real const &a, real::contained_type b)
	-> std::partial_ordering;

/*
 * Literal operator.
 */
inline namespace literals {
export constexpr auto operator""_ucl (long double d) -> real
{
	if (d > static_cast<long double>(std::numeric_limits<double>::max()) ||
	    d < static_cast<long double>(std::numeric_limits<double>::min()))
		throw std::out_of_range("literal out of range");

	return real(static_cast<double>(d));
}
} // namespace nihil::ucl::literals

} // namespace nihil::ucl

namespace nihil { inline namespace literals {
	export using namespace ::nihil::ucl::literals;
}} // namespace nihil::literals

/*
 * std::formatter for a real.  This provides the same format operations
 * as std::formatter<double>;
 */
export template<>
struct std::formatter<nihil::ucl::real, char>
{
	std::formatter<double> base_formatter;

	template<class ParseContext>
	constexpr ParseContext::iterator parse(ParseContext& ctx)
	{
		return base_formatter.parse(ctx);
	}

	template<class FmtContext>
	FmtContext::iterator format(nihil::ucl::real const &o,
				    FmtContext& ctx) const
	{
		return base_formatter.format(o.value(), ctx);
	}
};