program {

	agents_ : [];

	main() {

		"Message Server starting...\n" >> stdout;
		
		while true do 
			receive {
				'register ->> {
					"Agent " ++ sender^0 ++ " registered\n" >> stdout;
					('message, self(), "Agent " ++ sender^0 ++ " has joined.") >>* agents_;
					('message, self(), "Welcome!") >> replyto;
					('message, self(), "Local agents: " ++ agents_^0 ) >> replyto;
					agents_ := [sender,..agents_];
				}
				|
				'unregister ->> {
					"Agent " ++ sender^0 ++ " unregistered\n" >> stdout;
					agents_ := agents_ reject sender;
					('message, self(), "Agent " ++ sender^0 ++ " has left.") >>* agents_;
				}
				|
				( 'broadcast, string?msg ) ->> {
					( 'message, sender, msg ) >>* agents_;
				}
			}
	};

} execute main;