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

module;

#include <concepts>
#include <string>

#include <ucl.h>

export module nihil.ucl:type;

import :error;

namespace nihil::ucl {

// Our strongly-typed version of ::ucl_type.
export enum struct object_type {
	object		= UCL_OBJECT,
	array		= UCL_ARRAY,
	integer		= UCL_INT,
	real		= UCL_FLOAT,
	string		= UCL_STRING,
	boolean		= UCL_BOOLEAN,
	time		= UCL_TIME,
	userdata	= UCL_USERDATA,
	null		= UCL_NULL,
};

// Get the name of a type.
export auto str(object_type type) -> std::string_view {
	using namespace std::literals;

	switch (type) {
	case object_type::object:
		return "object"sv;
	case object_type::array:
		return "array"sv;
	case object_type::integer:
		return "integer"sv;
	case object_type::real:
		return "real"sv;
	case object_type::string:
		return "string"sv;
	case object_type::boolean:
		return "boolean"sv;
	case object_type::time:
		return "time"sv;
	case object_type::userdata:
		return "userdata"sv;
	case object_type::null:
		return "null"sv;
	default:
		// Don't fail here, since UCL might add more types that we
		// don't know about.
		return "unknown"sv;
	}
}

// Concept of a UCL data type.
export template<typename T>
concept datatype = requires(T o) {
	{ o.get_ucl_object() } -> std::convertible_to<::ucl_object_t const *>;
	{ o.type() } -> std::same_as<object_type>;
	{ T::ucl_type } -> std::convertible_to<object_type>;
};

// Exception thrown when a type assertion fails.
export struct type_mismatch : error {
	type_mismatch(object_type expected_type, object_type actual_type)
		: error("UCL type mismatch: expected type '{}' != actual type '{}'",
			str(expected_type), str(actual_type))
		, _expected_type(expected_type)
		, _actual_type(actual_type)
	{}

	// The type we expected.
	auto expected_type(this type_mismatch const &self) -> object_type
	{
		return self._expected_type;
	}

	// The type we got.
	auto actual_type(this type_mismatch const &self) -> object_type
	{
		return self._actual_type;
	}
	
private:
	object_type _expected_type;
	object_type _actual_type;
};

} // namespace nihil::ucl