#ifndef SPROUT_MATH_REMAINDER_HPP
#define SPROUT_MATH_REMAINDER_HPP

#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/signbit.hpp>
#include <sprout/math/rem_quo.hpp>
#include <sprout/type_traits/enabler_if.hpp>
#include <sprout/type_traits/float_promote.hpp>

namespace sprout {
	namespace math {
		namespace detail {
			template<
				typename FloatType,
				typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
			>
			inline SPROUT_CONSTEXPR FloatType
			remainder(FloatType x, FloatType y) {
				return y == 0 ? -std::numeric_limits<FloatType>::quiet_NaN()
					: sprout::math::isnan(y)
						? sprout::math::isnan(x)
							? sprout::math::signbit(y) && sprout::math::signbit(x) ? -std::numeric_limits<FloatType>::quiet_NaN()
								: std::numeric_limits<FloatType>::quiet_NaN()
							: y
					: sprout::math::isnan(x) ? x
					: x == std::numeric_limits<FloatType>::infinity() || x == -std::numeric_limits<FloatType>::infinity()
						? -std::numeric_limits<FloatType>::quiet_NaN()
					: x == 0 ? x
					: y == std::numeric_limits<FloatType>::infinity() || y == -std::numeric_limits<FloatType>::infinity() ? x
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
					: std::remainder(x, y)
#else
					: sprout::math::rem_quo(x, y).first
#endif
					;
			}
			template<
				typename ArithmeticType1,
				typename ArithmeticType2,
				typename sprout::enabler_if<
					std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
				>::type = sprout::enabler
			>
			inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
			remainder(ArithmeticType1 x, ArithmeticType2 y) {
				typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
				return sprout::math::detail::remainder(static_cast<type>(x), static_cast<type>(y));
			}
		}	// namespace detail
		//
		// issue:
		//	remainder(-NaN, -NaN) returns -NaN .
		//		# returns +NaN . ( same as remainder(+NaN, +NaN) )
		//
		using sprout::math::detail::remainder;
	}	// namespace math

	using sprout::math::remainder;
}	// namespace sprout

#endif	// #ifndef SPROUT_MATH_REMAINDER_HPP
