# TCPServer represents a TCP/IP server socket.
#
# A simple TCP server may look like:
#
#     require 'socket'
#
#     server = TCPServer.new 2000 # Server bind to port 2000
#     loop do
#       client = server.accept    # Wait for a client to connect
#       client.puts "Hello !"
#       client.puts "Time is #{Time.now}"
#       client.close
#     end
#
# A more usable server (serving multiple clients):
#
#     require 'socket'
#
#     server = TCPServer.new 2000
#     loop do
#       Thread.start(server.accept) do |client|
#         client.puts "Hello !"
#         client.puts "Time is #{Time.now}"
#         client.close
#       end
#     end
class TCPServer < TCPSocket
  public

  # Accepts an incoming connection. It returns a new TCPSocket object.
  #
  #     TCPServer.open("127.0.0.1", 14641) {|serv|
  #       s = serv.accept
  #       s.puts Time.now
  #       s.close
  #     }
  #
  def accept: () -> TCPSocket

  # Accepts an incoming connection using accept(2) after O_NONBLOCK is set for the
  # underlying file descriptor. It returns an accepted TCPSocket for the incoming
  # connection.
  #
  # ### Example
  #     require 'socket'
  #     serv = TCPServer.new(2202)
  #     begin # emulate blocking accept
  #       sock = serv.accept_nonblock
  #     rescue IO::WaitReadable, Errno::EINTR
  #       IO.select([serv])
  #       retry
  #     end
  #     # sock is an accepted socket.
  #
  # Refer to Socket#accept for the exceptions that may be thrown if the call to
  # TCPServer#accept_nonblock fails.
  #
  # TCPServer#accept_nonblock may raise any error corresponding to accept(2)
  # failure, including Errno::EWOULDBLOCK.
  #
  # If the exception is Errno::EWOULDBLOCK, Errno::EAGAIN, Errno::ECONNABORTED,
  # Errno::EPROTO, it is extended by IO::WaitReadable. So IO::WaitReadable can be
  # used to rescue the exceptions for retrying accept_nonblock.
  #
  # By specifying a keyword argument *exception* to `false`, you can indicate that
  # accept_nonblock should not raise an IO::WaitReadable exception, but return the
  # symbol `:wait_readable` instead.
  #
  # ### See
  # *   TCPServer#accept
  # *   Socket#accept
  #
  #
  def accept_nonblock: (?exception: boolish) -> (TCPSocket | :wait_readable)

  # Listens for connections, using the specified `int` as the backlog. A call to
  # *listen* only applies if the `socket` is of type SOCK_STREAM or
  # SOCK_SEQPACKET.
  #
  # ### Parameter
  # *   `backlog` - the maximum length of the queue for pending connections.
  #
  #
  # ### Example 1
  #     require 'socket'
  #     include Socket::Constants
  #     socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
  #     sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
  #     socket.bind( sockaddr )
  #     socket.listen( 5 )
  #
  # ### Example 2 (listening on an arbitrary port, unix-based systems only):
  #     require 'socket'
  #     include Socket::Constants
  #     socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
  #     socket.listen( 1 )
  #
  # ### Unix-based Exceptions
  # On unix based systems the above will work because a new `sockaddr` struct is
  # created on the address ADDR_ANY, for an arbitrary port number as handed off by
  # the kernel. It will not work on Windows, because Windows requires that the
  # `socket` is bound by calling *bind* before it can *listen*.
  #
  # If the *backlog* amount exceeds the implementation-dependent maximum queue
  # length, the implementation's maximum queue length will be used.
  #
  # On unix-based based systems the following system exceptions may be raised if
  # the call to *listen* fails:
  # *   Errno::EBADF - the *socket* argument is not a valid file descriptor
  # *   Errno::EDESTADDRREQ - the *socket* is not bound to a local address, and
  #     the protocol does not support listening on an unbound socket
  # *   Errno::EINVAL - the *socket* is already connected
  # *   Errno::ENOTSOCK - the *socket* argument does not refer to a socket
  # *   Errno::EOPNOTSUPP - the *socket* protocol does not support listen
  # *   Errno::EACCES - the calling process does not have appropriate privileges
  # *   Errno::EINVAL - the *socket* has been shut down
  # *   Errno::ENOBUFS - insufficient resources are available in the system to
  #     complete the call
  #
  #
  # ### Windows Exceptions
  # On Windows systems the following system exceptions may be raised if the call
  # to *listen* fails:
  # *   Errno::ENETDOWN - the network is down
  # *   Errno::EADDRINUSE - the socket's local address is already in use. This
  #     usually occurs during the execution of *bind* but could be delayed if the
  #     call to *bind* was to a partially wildcard address (involving ADDR_ANY)
  #     and if a specific address needs to be committed at the time of the call to
  #     *listen*
  # *   Errno::EINPROGRESS - a Windows Sockets 1.1 call is in progress or the
  #     service provider is still processing a callback function
  # *   Errno::EINVAL - the `socket` has not been bound with a call to *bind*.
  # *   Errno::EISCONN - the `socket` is already connected
  # *   Errno::EMFILE - no more socket descriptors are available
  # *   Errno::ENOBUFS - no buffer space is available
  # *   Errno::ENOTSOC - `socket` is not a socket
  # *   Errno::EOPNOTSUPP - the referenced `socket` is not a type that supports
  #     the *listen* method
  #
  #
  # ### See
  # *   listen manual pages on unix-based systems
  # *   listen function in Microsoft's Winsock functions reference
  #
  #
  def listen: (Integer backlog) -> void

  # Returns a file descriptor of a accepted connection.
  #
  #     TCPServer.open("127.0.0.1", 28561) {|serv|
  #       fd = serv.sysaccept
  #       s = IO.for_fd(fd)
  #       s.puts Time.now
  #       s.close
  #     }
  #
  def sysaccept: () -> Integer

  private

  def __accept_nonblock: (untyped) -> untyped

  # Creates a new server socket bound to *port*.
  #
  # If *hostname* is given, the socket is bound to it.
  #
  #     serv = TCPServer.new("127.0.0.1", 28561)
  #     s = serv.accept
  #     s.puts Time.now
  #     s.close
  #
  # Internally, TCPServer.new calls getaddrinfo() function to obtain addresses. If
  # getaddrinfo() returns multiple addresses, TCPServer.new tries to create a
  # server socket for each address and returns first one that is successful.
  #
  def initialize: (?String host, Integer port) -> untyped
end