/**
 * @file common/utils/Multithreading.hpp
 * @author The ARTIS Development Team
 * See the AUTHORS or Authors.txt file
 */

/*
 * ARTIS - the multimodeling and simulation environment
 * This file is a part of the ARTIS environment
 *
 * Copyright (C) 2013-2019 ULCO http://www.univ-littoral.fr
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef COMMON_UTILS_MULTITHREADING
#define COMMON_UTILS_MULTITHREADING

#include <condition_variable>
#include <queue>
#include <mutex>

namespace artis {
namespace common {

struct BaseMessage
{
  virtual ~BaseMessage()
  {}
};

template<typename Msg>
struct Message : BaseMessage
{
  explicit Message(Msg const &content)
      : _content(content)
  {}

  Msg _content;
};

class Close
{
};

class MessageQueue
{
public:
  MessageQueue() = default;

  template<typename T>
  void push(T const &msg)
  {
    std::lock_guard<std::mutex> lock(_mutex);

    _queue.push(std::make_shared<Message<T> >(msg));
    _condition.notify_all();
  }

  std::shared_ptr<BaseMessage> wait_and_pop()
  {
    std::unique_lock<std::mutex> lock(_mutex);

    _condition.wait(lock, [&] { return not _queue.empty(); });
    auto res = _queue.front();
    _queue.pop();
    return res;
  }

private:
  std::mutex _mutex;
  std::condition_variable _condition;
  std::queue<std::shared_ptr<BaseMessage> > _queue;
};

class Sender
{
public:
  Sender()
      : _queue(0)
  {}

  explicit Sender(MessageQueue *queue)
      : _queue(queue)
  {}

  template<typename Message>
  void send(Message const &msg)
  {
    if (_queue) {
      _queue->push(msg);
    }
  }

private:
  MessageQueue *_queue;
};

template<typename PreviousDispatcher, typename Msg, typename Func>
class TemplateDispatcher
{
  template<typename Dispatcher, typename OtherMsg, typename OtherFunc>
  friend
  class TemplateDispatcher;

public:
  TemplateDispatcher(TemplateDispatcher &&other)
      : _queue(other._queue),
        _previous(other._previous),
        _function(
            std::move(
                other._function)),
        _chained(other._chained)
  { other._chained = true; }

  TemplateDispatcher(MessageQueue *queue,
                     PreviousDispatcher *previous,
                     Func &&function)
      :
      _queue(queue), _previous(previous),
      _function(std::forward<Func>(function)),
      _chained(false)
  { previous->_chained = true; }

  bool dispatch(std::shared_ptr<BaseMessage> const &msg)
  {
    Message<Msg> *message =
        dynamic_cast < Message<Msg> * >(msg.get());

    if (message) {
      _function(message->_content);
      return true;
    } else {
      return _previous->dispatch(msg);
    }
  }

  template<typename OtherMsg, typename OtherFunc>
  TemplateDispatcher<TemplateDispatcher<PreviousDispatcher, Msg, Func>,
                     OtherMsg, OtherFunc>
  handle(OtherFunc &&of)
  {
    return TemplateDispatcher<TemplateDispatcher<PreviousDispatcher,
                                                 Msg, Func>,
                              OtherMsg, OtherFunc>(
        _queue, this, std::forward<OtherFunc>(of));
  }

  ~TemplateDispatcher() noexcept(false)
  {
    if (not _chained) {
      wait_and_dispatch();
    }
  }

private:
  TemplateDispatcher(TemplateDispatcher const &) = delete;

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

  void wait_and_dispatch()
  {
    for (;;) {
      auto msg = _queue->wait_and_pop();

      if (dispatch(msg)) {
        break;
      }
    }
  }

  MessageQueue *_queue;
  PreviousDispatcher *_previous;
  Func _function;
  bool _chained;
};

class Dispatcher
{
  template<typename Dispatcher, typename Msg, typename Func>
  friend
  class TemplateDispatcher;

public:
  Dispatcher(Dispatcher &&other)
      : _queue(other._queue),
        _chained(other._chained)
  { other._chained = true; }

  explicit Dispatcher(MessageQueue *queue)
      : _queue(queue), _chained(false)
  {}

  template<typename Message, typename Func>
  TemplateDispatcher<Dispatcher, Message, Func>
  handle(Func &&function)
  {
    return TemplateDispatcher<Dispatcher, Message, Func>(
        _queue, this, std::forward<Func>(function));
  }

  ~Dispatcher() noexcept(false)
  {
    if (not _chained) {
      wait_and_dispatch();
    }
  }

private:
  Dispatcher(Dispatcher const &) = delete;

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

  void wait_and_dispatch()
  {
    for (;;) {
      auto msg = _queue->wait_and_pop();

      dispatch(msg);
    }
  }

  bool dispatch(std::shared_ptr<BaseMessage> const &msg)
  {
    if (dynamic_cast < Message<Close> * >(msg.get())) {
      throw Close();
    }
    return false;
  }

  MessageQueue *_queue;
  bool _chained;
};

class Receiver
{
public:
  Receiver() : _queue(new MessageQueue)
  {}

  ~Receiver()
  { delete _queue; }

  Sender get_sender()
  { return Sender(_queue); }

  Dispatcher wait()
  { return Dispatcher(_queue); }

private:
  MessageQueue *_queue;
};

}
}  // namespace artis common

#endif