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

module;

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

#include <ucl.h>

export module nihil.ucl:integer;

import nihil;
import :object;
import :type;

namespace nihil::ucl {

export struct integer final : object {
	using contained_type = std::int64_t;
	inline static constexpr object_type ucl_type = object_type::integer;

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

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

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

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

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

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

/*
 * Comparison operators.
 */

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

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

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

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

/*
 * Literal operator.
 */
inline namespace literals {
export constexpr auto operator""_ucl (unsigned long long i) -> integer
{
	if (std::cmp_greater(i, std::numeric_limits<std::int64_t>::max()))
		throw std::out_of_range("literal out of range");

	return integer(i);
}
} // namespace nihil::ucl::literals

} // namespace nihil::ucl

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

/*
 * std::formatter for an integer.  This provides the same format operations
 * as std::formatter<std::int64_t>.
 */
export template<>
struct std::formatter<nihil::ucl::integer, char>
{
	std::formatter<std::int64_t> base_formatter;

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

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