-module(dining3).

-export([start/1,stickDown/0,phil/3]).


start(N) when N>=2 ->
    Sticks = createSticks(N),
    startPhils(lists:last(Sticks),Sticks,0).

createSticks(0) ->
    [];
createSticks(N) when N>0 ->
    [spawn(dining3,stickDown,[])|createSticks(N-1)].

startPhils(SL,[],_) ->
    ok;
startPhils(SL,[SR|Sticks],N) ->
    spawn(dining3,phil,[SL,SR,N]),
    startPhils(SR,Sticks,N+1).

stickDown() ->
    receive
	{take,P} ->
	    P!took,
	    stickUp();
	{getState,P} ->
	    P!down,
	    stickDown()
    end.

stickUp() ->
    receive
	put ->
	    stickDown();
	{getState,P} ->
	    P!up,
	    stickUp()
    end.

take(Stick) ->
    Stick!{take,self()},
    receive
	took -> ok
    end.

phil(SL,SR,N) ->
    io:format("~w is thinking~n",[N]),
    %timer:sleep(100*N),
    io:format("~w is getting hungry~n",[N]),
    take(SL),
    io:format("~w took left stick~n",[N]),
    SR!{getState,self()},
    receive
	up -> SL!put,
	      io:format("~w returned left stick~n",[N]),
	      phil(SL,SR,N);
	down -> 
	    take(SR),
	    io:format("~w took right stick~n",[N]),
	    io:format("~w is eating~n",[N]),
	    %timer:sleep(100*N),
	    SL!put,
	    io:format("~w put left stick~n",[N]),
	    SR!put,
	    io:format("~w put right stick~n",[N]),
	    phil(SL,SR,N)
    end.