/*
 * Copyright (C) 2023  Christopher J. Howard
 *
 * This file is part of Antkeeper source code.
 *
 * Antkeeper source code 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.
 *
 * Antkeeper source code 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 Antkeeper source code.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef ANTKEEPER_EVENT_PUBLISHER_HPP
#define ANTKEEPER_EVENT_PUBLISHER_HPP

#include <algorithm>
#include <execution>
#include <engine/event/channel.hpp>

namespace event {

/**
 * Publishes messages to subscribers.
 *
 * @tparam T Message type.
 */
template <class T>
class publisher
{
public:
	/// Message type.
	typedef T message_type;
	
	/// Channel type.
	typedef channel<message_type> channel_type;
	
	/**
	 * Publishes a message.
	 *
	 * @tparam ExecutionPolicy Execution policy type.
	 *
	 * @param policy Execution policy to use.
	 * @param message Message to publish.
	 */
	/// @{
	template <class ExecutionPolicy>
	void publish(ExecutionPolicy&& policy, const message_type& message) const
	{
		std::for_each
		(
			policy,
			std::begin(m_channel.subscribers),
			std::end(m_channel.subscribers),
			[&](const auto& subscriber)
			{
				(*subscriber)(message);
			}
		);
	}
	
	void publish(const message_type& message) const
	{
		publish(std::execution::seq, message);
	}
	/// @}
	
	/**
	 * Returns the channel through which messages are published.
	 */
	/// @{
	[[nodiscard]] inline const channel_type& channel() const noexcept
	{
		return m_channel;
	}
	
	[[nodiscard]] inline channel_type& channel() noexcept
	{
		return m_channel;
	}
	/// @}
	
private:
	channel_type m_channel;
};

} // namespace event

#endif // ANTKEEPER_EVENT_PUBLISHER_HPP