-module(telephone).
-compile(export_all).

start(N) when is_integer(N), N > 1 ->
  First = spawn( fun() -> loop() end ),
  First ! {set_recipient, start(N-1, First)},
  register(game_master, First).

start(1, Neighbor) ->
  spawn( fun() -> loop(Neighbor) end );
start(N, Neighbor) ->
  start(N-1, spawn( fun() -> loop(Neighbor) end )).

play(Message) ->
  game_master ! {send, Message}.

loop(WhoToTell) ->
  MyPid = self(),
  receive
    {send, Message} ->
      io:format("(~p) Whispering to my neighbor: ~p~n", [MyPid, Message]),
      WhoToTell ! {MyPid, Message},
      loop(WhoToTell);

    {MyPid, Message} ->
      io:format("(~p) Got my message back: ~p~n", [MyPid, Message]),
      loop(WhoToTell);

    {_Sender, Message}=X ->
      io:format("(~p) Passing message along: ~p~n", [MyPid, Message]),
      WhoToTell ! X,
      loop(WhoToTell)
  end.

loop() ->
  receive
    {set_recipient, Pid} -> loop(Pid)
  end.