/******************************************************************************
 *                       ____    _    _____                                   *
 *                      / ___|  / \  |  ___|    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_MESSAGE_BUILDER_HPP
#define CAF_MESSAGE_BUILDER_HPP

#include <vector>

#include "caf/fwd.hpp"
#include "caf/message.hpp"
#include "caf/message_handler.hpp"
#include "caf/type_erased_value.hpp"

namespace caf {

/// Provides a convenient interface for createing `message` objects
/// from a series of values using the member function `append`.
class message_builder {
public:
  friend class message;

  message_builder(const message_builder&) = delete;
  message_builder& operator=(const message_builder&) = delete;

  message_builder();
  ~message_builder();

  /// Creates a new instance and immediately calls `append(first, last)`.
  template <class Iter>
  message_builder(Iter first, Iter last) {
    init();
    append(first, last);
  }

  /// Appends all values in range [first, last).
  template <class Iter>
  message_builder& append(Iter first, Iter last) {
    for (; first != last; ++first)
      append(*first);
    return *this;
  }

  /// Adds `x` to the elements of the buffer.
  template <class T>
  message_builder& append(T&& x) {
    using type = typename unbox_message_element<
                   typename detail::implicit_conversions<
                    typename std::decay<T>::type
                   >::type
                 >::type;
    return emplace(make_type_erased_value<type>(std::forward<T>(x)));
  }

  inline message_builder& append_all() {
    return *this;
  }

  template <class T, class... Ts>
  message_builder& append_all(T&& x, Ts&&... xs) {
    append(std::forward<T>(x));
    return append_all(std::forward<Ts>(xs)...);
  }

  /// Converts the buffer to an actual message object without
  /// invalidating this message builder (nor clearing it).
  message to_message() const;

  /// Converts the buffer to an actual message object and transfers
  /// ownership of the data to it, leaving this object in an invalid state.
  /// @warning Calling *any*  member function on this object afterwards
  ///          is undefined behavior (dereferencing a `nullptr`)
  message move_to_message();

  /// @copydoc message::extract
  inline message extract(message_handler f) const {
    return to_message().extract(std::move(f));
  }

  /// @copydoc message::extract_opts
  inline message::cli_res extract_opts(std::vector<message::cli_arg> xs,
                                       message::help_factory f = nullptr,
                                       bool no_help = false) const {
    return to_message().extract_opts(std::move(xs), std::move(f), no_help);
  }

  /// @copydoc message::apply
  optional<message> apply(message_handler handler);

  /// Removes all elements from the buffer.
  void clear();

  /// Returns whether the buffer is empty.
  bool empty() const;

  /// Returns the number of elements in the buffer.
  size_t size() const;

private:
  void init();

  message_builder& emplace(type_erased_value_ptr);

  detail::dynamic_message_data* data();

  const detail::dynamic_message_data* data() const;

  intrusive_ptr<ref_counted> data_; // hide dynamic_message_data implementation
};

} // namespace caf

#endif // CAF_MESSAGE_BUILDER_HPP
