/*=============================================================================
  Copyright (c) 2011-2019 Bolero MURAKAMI
  https://github.com/bolero-MURAKAMI/Sprout

  Distributed under the Boost Software License, Version 1.0. (See accompanying
  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_NUMERIC_DFT_DFT_ELEMENT_HPP
#define SPROUT_NUMERIC_DFT_DFT_ELEMENT_HPP

#include <iterator>
#include <sprout/config.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/numeric/dft/detail/dft_element_gen.hpp>

namespace sprout {
	namespace detail {
		template<typename InputIterator, typename Size>
		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::value_type
		dft_element_impl(
			InputIterator const& first, InputIterator const& last, typename std::iterator_traits<InputIterator>::difference_type i,
			Size size
			)
		{
			typedef typename std::iterator_traits<InputIterator>::value_type value_type;
			typedef typename value_type::value_type elem_type;
			return sprout::detail::dft_element_gen(
				first, last,
				-(sprout::math::two_pi<elem_type>() * i / size)
				);
		}
	}	// namespace detail
	//
	// dft_element
	//
	template<typename InputIterator>
	inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::value_type
	dft_element(InputIterator first, InputIterator last, typename std::iterator_traits<InputIterator>::difference_type i) {
		return sprout::detail::dft_element_impl(
			first, last, i,
			sprout::distance(first, last)
			);
	}
}	// namespace sprout

#endif	// #ifndef SPROUT_NUMERIC_DFT_DFT_ELEMENT_HPP