# ----------------------------------------------------------------------------
# A server that handles sockets concurrently
#
# THIS IS EXPERIMENTAL WORK IN PROGRESS!!!
#
# Paul Griffioen 2012
# ----------------------------------------------------------------------------

module server

include channel, socket

public procedure main(args) =
  let
      port := "1234";
      host := "localhost";
      if args != [] then
          port := first(args);
          if rest(args) != [] then
              host := second(args)
          end
      end;
      socket := listen_on(host, port)
  in
      print_line(format("Running server on $x:$y.", x := host; y := port));
      serve_socket(socket);
      print_line("Bye")
  end

# ----------------------------------------------------------------------------
# The server
# ----------------------------------------------------------------------------

procedure serve_socket(socket) =
  let connection := accept(socket) in
      serve_socket(socket) |
      try
          print_line("Connection started");
          send_to(connection, "Welcome to the sleep server. Valid commands are 'sleep n' and 'bomb'");
          serve_connection_rec(connection);
          print_line("Connection terminated")
      catch(error)
          print_line(format("Connection aborted: $message", message := error))
      end 
  end

procedure serve_connection_rec(connection) = 
  let
      message := receive_from(connection);
      command := split_string(" ", message);
      print_line(format("Incoming command: $x ", x := message))
  in
      if command = [] then
          serve_connection_rec(connection)
      elsif command = ["bomb"] then
          send_to(connection, "Thanks a lot!");
          throw("bomb dropped!")
      elsif first(command) = "sleep" then
          let
              n := if rest(command) = [] then 1 else read_num(second(command)) end
           in
              sleep(n);
              send_to(connection, format("slept $x seconds", x := n))
          end |
          serve_connection_rec(connection)
      else
          send_to(connection, format("Invalid command: $message", message := first(command)));
          serve_connection_rec(connection)
      end
  end