// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project

#ifndef MPD_SERVER_SOCKET_HXX
#define MPD_SERVER_SOCKET_HXX

#include "config.h"

#include <cassert>
#include <list>

class SocketAddress;
class AllocatedSocketAddress;
class UniqueSocketDescriptor;
class EventLoop;
class Path;

/**
 * A socket that accepts incoming stream connections (e.g. TCP).
 */
class ServerSocket {
	class OneServerSocket;

	EventLoop &loop;

	std::list<OneServerSocket> sockets;

#ifdef HAVE_TCP
	/**
	 * A non-negative value sets the IPPROTO_IP/IP_TOS or
	 * IPPROTO_IPV6/IPV6_TCLASS socket option.
	 */
	int dscp_class = -1;
#endif

	unsigned next_serial = 1;

public:
	ServerSocket(EventLoop &_loop) noexcept;
	~ServerSocket() noexcept;

	EventLoop &GetEventLoop() const noexcept {
		return loop;
	}

#ifdef HAVE_TCP
	void SetDscpClass(int _dscp_class) noexcept {
		assert(sockets.empty());

		dscp_class = _dscp_class;
	}

	/**
	 * Determine to which TCP port the socket was effectively
	 * bound.  Returns 0 if none (or error).
	 */
	[[gnu::pure]]
	unsigned GetEffectivePort() const noexcept;
#endif // HAVE_TCP

private:
	template<typename A>
	OneServerSocket &AddAddress(A &&address) noexcept;

	/**
	 * Add a listener on a port on all IPv4 interfaces.
	 *
	 * @param port the TCP port
	 */
	void AddPortIPv4(unsigned port) noexcept;

	/**
	 * Add a listener on a port on all IPv6 interfaces.
	 *
	 * @param port the TCP port
	 */
	void AddPortIPv6(unsigned port) noexcept;

public:
	/**
	 * Add a listener on a port on all interfaces.
	 *
	 * Throws #std::runtime_error on error.
	 *
	 * @param port the TCP port
	 */
	void AddPort(unsigned port);

	/**
	 * Resolves a host name, and adds listeners on all addresses in the
	 * result set.
	 *
	 * Throws #std::runtime_error on error.
	 *
	 * @param hostname the host name to be resolved
	 * @param port the TCP port
	 */
	void AddHost(const char *hostname, unsigned port);

	/**
	 * Add a listener on a local socket.
	 *
	 * Throws #std::runtime_error on error.
	 *
	 * @param path the absolute socket path
	 */
	void AddPath(Path path);

	/**
	 * Add a listener on an abstract local socket (Linux specific).
	 *
	 * Throws on error.
	 *
	 * @param name the abstract socket name, starting with a '@'
	 * instead of a null byte
	 */
	void AddAbstract(const char *name);

	/**
	 * Add a socket descriptor that is accepting connections.  After this
	 * has been called, don't call server_socket_open(), because the
	 * socket is already open.
	 *
	 * Throws #std::runtime_error on error.
	 */
	void AddFD(UniqueSocketDescriptor fd);

	void AddFD(UniqueSocketDescriptor fd,
		   AllocatedSocketAddress &&address) noexcept;

	bool IsEmpty() const noexcept {
		return sockets.empty();
	}

	/**
	 * Throws #std::runtime_error on error.
	 */
	void Open();

	void Close() noexcept;

protected:
	virtual void OnAccept(UniqueSocketDescriptor fd,
			      SocketAddress address) noexcept = 0;
};

#endif
