/*=============================================================================
  Copyright (c) 2011-2017 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_ALGORITHM_FIXED_RECURRENCE_HPP
#define SPROUT_ALGORITHM_FIXED_RECURRENCE_HPP

#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/container/traits.hpp>
#include <sprout/container/functions.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/algorithm/fixed/results.hpp>
#include <sprout/pit/pit.hpp>
#include <sprout/detail/container_complate.hpp>

namespace sprout {
	namespace fixed {
		namespace detail {
			template<std::size_t InitSize, typename Container, typename Generator, typename... Args>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				InitSize == 0,
				typename sprout::container_traits<Container>::value_type
			>::type
			call_gen(Generator const& gen, Args const&...) {
				return gen();
			}
			template<std::size_t InitSize, typename Container, typename Generator, typename Head, typename... Args>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				InitSize != 0 && InitSize == sizeof...(Args) + 1,
				typename sprout::container_traits<Container>::value_type
			>::type
			call_gen(Generator const& gen, Head const& head, Args const&... args) {
				return gen(head, args...);
			}
			template<std::size_t InitSize, typename Container, typename Generator, typename Head, typename... Args>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				InitSize != 0 && InitSize != sizeof...(Args) + 1,
				typename sprout::container_traits<Container>::value_type
			>::type
			call_gen(Generator const& gen, Head const&, Args const&... args) {
				return call_gen<InitSize, Container>(gen, args...);
			}
			template<typename Container, typename Generator>
			inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
			recurrence_impl_drop(
				Container const& cont, Generator const&,
				typename sprout::container_traits<Container>::size_type
				)
			{
				return sprout::detail::container_complate(cont);
			}
			template<typename Container, typename Generator, typename Head, typename... Inits>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				(sprout::container_traits<Container>::static_size >= sizeof...(Inits) + 1),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl_drop(
				Container const& cont, Generator const& gen,
				typename sprout::container_traits<Container>::size_type size,
				Head const& head, Inits const&... inits
				)
			{
				return size < sizeof...(Inits) + 1
					? sprout::fixed::detail::recurrence_impl_drop(cont, gen, size, inits...)
					: sprout::detail::container_complate(cont, head, inits...)
					;
			}
			template<typename Container, typename Generator, typename Head, typename... Inits>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				(sprout::container_traits<Container>::static_size < sizeof...(Inits) + 1),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl_drop(
				Container const& cont, Generator const& gen,
				typename sprout::container_traits<Container>::size_type size,
				Head const&, Inits const&... inits
				)
			{
				return sprout::fixed::detail::recurrence_impl_drop(cont, gen, size, inits...);
			}
			template<std::size_t InitSize, typename Container, typename Generator, typename... Args>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				sprout::container_traits<Container>::static_size == sizeof...(Args),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl_1(
				Container const& cont, Generator const&,
				typename sprout::container_traits<Container>::size_type,
				Args const&... args
				)
			{
				return sprout::remake<Container>(cont, sprout::size(cont), args...);
			}
			template<std::size_t InitSize, typename Container, typename Generator, typename... Args>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				sprout::container_traits<Container>::static_size != sizeof...(Args),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl_1(
				Container const& cont, Generator const& gen,
				typename sprout::container_traits<Container>::size_type size,
				Args const&... args
				)
			{
				return sizeof...(Args) < size
					? sprout::fixed::detail::recurrence_impl_1<InitSize>(
						cont, gen,
						size,
						args..., sprout::fixed::detail::call_gen<InitSize, Container>(gen, args...)
						)
					: sprout::detail::container_complate(cont, args...)
					;
			}
			template<typename Container, typename Generator, typename... Inits>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				(sprout::container_traits<Container>::static_size > sizeof...(Inits)),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl(
				Container const& cont, Generator const& gen,
				typename sprout::container_traits<Container>::size_type size,
				Inits const&... inits
				)
			{
				return sizeof...(Inits) < size
					? sprout::fixed::detail::recurrence_impl_1<sizeof...(Inits)>(cont, gen, size, inits...)
					: sprout::fixed::detail::recurrence_impl_drop(cont, gen, size, inits...)
					;
			}
			template<typename Container, typename Generator, typename... Inits>
			inline SPROUT_CONSTEXPR typename std::enable_if<
				(sprout::container_traits<Container>::static_size <= sizeof...(Inits)),
				typename sprout::fixed::results::algorithm<Container>::type
			>::type
			recurrence_impl(
				Container const& cont, Generator const& gen,
				typename sprout::container_traits<Container>::size_type size,
				Inits const&... inits
				)
			{
				return sprout::fixed::detail::recurrence_impl_drop(cont, gen, size, inits...);
			}
		}	// namespace detail
		//
		// recurrence
		//
		template<typename Container, typename Generator, typename... Inits>
		inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
		recurrence(Container const& cont, Generator const& gen, Inits const&... inits) {
			return sprout::fixed::detail::recurrence_impl(cont, gen, sprout::size(cont), inits...);
		}

		template<typename Container, typename Generator, typename... Inits>
		inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
		recurrence(Generator const& gen, Inits const&... inits) {
			return sprout::fixed::recurrence(sprout::pit<Container>(), gen, inits...);
		}
	}	// namespace fixed

	using sprout::fixed::recurrence;
}	// namespace sprout

#endif	// #ifndef SPROUT_ALGORITHM_FIXED_RECURRENCE_HPP