/******************************************************************************
 *                       ____    _    _____                                   *
 *                      / ___|  / \  |  ___|    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.                                      *
 ******************************************************************************/

#ifndef CAF_DETAIL_BEHAVIOR_IMPL_HPP
#define CAF_DETAIL_BEHAVIOR_IMPL_HPP

#include <tuple>
#include <type_traits>

#include "caf/none.hpp"
#include "caf/variant.hpp"
#include "caf/optional.hpp"
#include "caf/match_case.hpp"
#include "caf/make_counted.hpp"
#include "caf/intrusive_ptr.hpp"

#include "caf/atom.hpp"
#include "caf/message.hpp"
#include "caf/duration.hpp"
#include "caf/ref_counted.hpp"
#include "caf/skip.hpp"
#include "caf/response_promise.hpp"
#include "caf/timeout_definition.hpp"
#include "caf/typed_response_promise.hpp"

#include "caf/detail/int_list.hpp"
#include "caf/detail/apply_args.hpp"
#include "caf/detail/type_traits.hpp"
#include "caf/detail/tail_argument_token.hpp"
#include "caf/detail/invoke_result_visitor.hpp"

namespace caf {

class message_handler;

} // namespace caf

namespace caf {
namespace detail {

class behavior_impl : public ref_counted {
public:
  using pointer = intrusive_ptr<behavior_impl>;

  ~behavior_impl() override;

  behavior_impl(duration tout = duration{});

  virtual match_case::result invoke_empty(detail::invoke_result_visitor& f);

  virtual match_case::result invoke(detail::invoke_result_visitor& f,
                                    type_erased_tuple& xs);

  match_case::result invoke(detail::invoke_result_visitor& f, message& xs);

  optional<message> invoke(message&);

  optional<message> invoke(type_erased_tuple&);

  virtual void handle_timeout();

  inline const duration& timeout() const {
    return timeout_;
  }

  pointer or_else(const pointer& other);

protected:
  duration timeout_;
  match_case_info* begin_;
  match_case_info* end_;
};

template <class Tuple>
void call_timeout_handler(Tuple& tup, std::true_type) {
  auto& f = std::get<std::tuple_size<Tuple>::value - 1>(tup);
  f.handler();
}

template <class Tuple>
void call_timeout_handler(Tuple&, std::false_type) {
  // nop
}

template <class T, bool IsTimeout = is_timeout_definition<T>::value>
struct lift_behavior {
  using type = trivial_match_case<T>;
};

template <class T>
struct lift_behavior<T, true> {
  using type = T;
};

template <bool HasTimeout, class Tuple>
struct with_generic_timeout;

template <class... Ts>
struct with_generic_timeout<false, std::tuple<Ts...>> {
  using type = std::tuple<Ts..., generic_timeout_definition>;
};

template <class... Ts>
struct with_generic_timeout<true, std::tuple<Ts...>> {
  using type =
    typename tl_apply<
      typename tl_replace_back<
        type_list<Ts...>,
        generic_timeout_definition
      >::type,
      std::tuple
    >::type;
};

template <class Tuple>
class default_behavior_impl;

template <class... Ts>
class default_behavior_impl<std::tuple<Ts...>> : public behavior_impl {
public:
  using tuple_type = std::tuple<Ts...>;

  using back_type = typename tl_back<type_list<Ts...>>::type;

  static constexpr bool has_timeout = is_timeout_definition<back_type>::value;

  static constexpr size_t num_cases = sizeof...(Ts) - (has_timeout ? 1 : 0);

  using cases =
    typename std::conditional<
      has_timeout,
      typename tl_pop_back<type_list<Ts...>>::type,
      type_list<Ts...>
    >::type;

  default_behavior_impl(tuple_type&& tup) : cases_(std::move(tup)) {
    init();
  }

  template <class... Us>
  default_behavior_impl(Us&&... xs) : cases_(std::forward<Us>(xs)...) {
    init();
  }

  void handle_timeout() override {
    std::integral_constant<bool, has_timeout> token;
    call_timeout_handler(cases_, token);
  }

private:
  void init() {
    std::integral_constant<size_t, 0> first;
    std::integral_constant<size_t, num_cases> last;
    init(first, last);
  }

  template <size_t Last>
  void init(std::integral_constant<size_t, Last>,
            std::integral_constant<size_t, Last>) {
    this->begin_ = arr_.data();
    this->end_ = arr_.data() + arr_.size();
    std::integral_constant<bool, has_timeout> token;
    set_timeout(token);
  }

  template <size_t First, size_t Last>
  void init(std::integral_constant<size_t, First>,
            std::integral_constant<size_t, Last> last) {
    auto& element = std::get<First>(cases_);
    arr_[First] = match_case_info{element.type_token(), &element};
    init(std::integral_constant<size_t, First + 1>{}, last);
  }

  void set_timeout(std::true_type) {
    this->timeout_ = std::get<num_cases>(cases_).timeout;
  }

  void set_timeout(std::false_type) {
    // nop
  }

  tuple_type cases_;
  std::array<match_case_info, num_cases> arr_;
};

template <class Tuple>
struct behavior_factory {
  template <class... Ts>
  typename behavior_impl::pointer operator()(Ts&&... xs) const {
    return make_counted<default_behavior_impl<Tuple>>(std::forward<Ts>(xs)...);
  }
};

struct make_behavior_t {
  constexpr make_behavior_t() {
    // nop
  }

  template <class... Ts>
  intrusive_ptr<
    default_behavior_impl<std::tuple<typename lift_behavior<Ts>::type...>>>
  operator()(Ts... xs) const {
    using type =
      default_behavior_impl<std::tuple<typename lift_behavior<Ts>::type...>>;
    return make_counted<type>(std::move(xs)...);
  }
};

constexpr make_behavior_t make_behavior = make_behavior_t{};

using behavior_impl_ptr = intrusive_ptr<behavior_impl>;

// utility for getting a type-erased version of make_behavior
struct make_behavior_impl_t {
  constexpr make_behavior_impl_t() {
    // nop
  }

  template <class... Ts>
  behavior_impl_ptr operator()(Ts&&... xs) const {
    return make_behavior(std::forward<Ts>(xs)...);
  }
};

constexpr make_behavior_impl_t make_behavior_impl = make_behavior_impl_t{};

} // namespace detail
} // namespace caf

#endif // CAF_DETAIL_BEHAVIOR_IMPL_HPP
