/******************************************************************************
 *                       ____    _    _____                                   *
 *                      / ___|  / \  |  ___|    C++                           *
 *                     | |     / _ \ | |_       Actor                         *
 *                     | |___ / ___ \|  _|      Framework                     *
 *                      \____/_/   \_|_|                                      *
 *                                                                            *
 * Copyright 2011-2018 Dominik Charousset                                     *
 *                                                                            *
 * Distributed under the terms and conditions of the BSD 3-Clause License or  *
 * (at your option) under the terms and conditions of the Boost Software      *
 * License 1.0. See accompanying files LICENSE and LICENSE_ALTERNATIVE.       *
 *                                                                            *
 * If you did not receive a copy of the license files, see                    *
 * http://opensource.org/licenses/BSD-3-Clause and                            *
 * http://www.boost.org/LICENSE_1_0.txt.                                      *
 ******************************************************************************/

#pragma once

#include <type_traits>

#include "caf/replies_to.hpp"

#include "caf/detail/type_list.hpp"
#include "caf/detail/typed_actor_util.hpp"

namespace caf::detail {

template <class T, class... Lists>
struct mpi_splice_by_input;

template <class T>
struct mpi_splice_by_input<T> {
  using type = T;
};

template <class T, class... Lists>
struct mpi_splice_by_input<T, type_list<>, Lists...> {
  // consumed an entire list without match -> fail
  using type = none_t;
};

// splice two MPIs if they have the same input
template <class Input, class... Xs, class... Ys, class... Ts, class... Lists>
struct mpi_splice_by_input<typed_mpi<Input, type_list<Xs...>>, type_list<typed_mpi<Input, type_list<Ys...>>, Ts...>, Lists...>
  : mpi_splice_by_input<typed_mpi<Input, type_list<Xs..., Ys...>>, Lists...> { };

// skip element in list until empty
template <class MPI, class MPI2, class... Ts, class... Lists>
struct mpi_splice_by_input<MPI, type_list<MPI2, Ts...>, Lists...>
  : mpi_splice_by_input<MPI, type_list<Ts...>, Lists...> { };

template <class Result, class CurrentNeedle, class... Lists>
struct input_mapped;

template <class... Rs, class... Lists>
struct input_mapped<type_list<Rs...>, none_t, type_list<>, Lists...> {
  using type = type_list<Rs...>;
};

template <class... Rs, class T, class... Ts, class... Lists>
struct input_mapped<type_list<Rs...>, none_t, type_list<T, Ts...>, Lists...>
    : input_mapped<type_list<Rs...>, T, type_list<Ts...>, Lists...> {};

template <class... Rs, class T, class FirstList, class... Lists>
struct input_mapped<type_list<Rs...>, T, FirstList, Lists...>
  : input_mapped<type_list<Rs..., typename mpi_splice_by_input<T, Lists...>::type>, none_t, FirstList, Lists...> { };

template <template <class...> class Target, class ListA, class ListB>
struct mpi_splice;

template <template <class...> class Target, class... Ts, class List>
struct mpi_splice<Target, type_list<Ts...>, List> {
  using spliced_list =
    typename input_mapped<type_list<>, none_t, type_list<Ts...>, List>::type;
  using filtered_list =
    typename tl_filter_not_type<
      spliced_list,
      none_t
    >::type;
  static_assert(tl_size<filtered_list>::value > 0,
                "cannot splice incompatible actor handles");
  using type = typename tl_apply<filtered_list, Target>::type;
};

} // namespace caf

