--- a/src/rps.erl	Mon Mar 03 22:17:50 2014 +0900
+++ b/src/rps.erl	Mon Mar 03 22:19:53 2014 +0900
@@ -4,11 +4,12 @@
     lobby/0, counter/0, printer/0]).
 
 -define(BOTS, [fool, copycat, gambler]).
--define(RULES, rps3).
+-define(RULES, rps5).
 
 go() ->
     rps_nickserv:start_link(),
     rps3:start_link(),
+    rps5:start_link(),
     register(lobby, spawn_link(?MODULE, lobby, [])),
     register(counter, spawn_link(?MODULE, counter, [])),
     register(printer, spawn_link(?MODULE, printer, [])),

--- a/src/rps5.erl	Mon Mar 03 22:17:50 2014 +0900
+++ b/src/rps5.erl	Mon Mar 03 22:19:53 2014 +0900
@@ -1,85 +1,38 @@
 -module(rps5).
--export([
-    get_hands/0,
-    beats/1, test_beats/0,
-    loses/1, test_loses/0,
-    winning_hand/1, test_winning_hand/0]).
-
-get_hands() -> [rock, paper, scissors, spock, lizard].
-
-beats(rock) ->
-    [scissors, lizard];
+-behaviour(gen_server).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+-export([start_link/0, get_hands/0, winning_hand/1, why/2]).
+-include("rps_rules.hrl").
 
-beats(paper) ->
-    [spock, rock];
-
-beats(scissors) ->
-    [lizard, paper];
+start_link() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 
-beats(spock) ->
-    [rock, scissors];
+init([]) ->
+    Text = "scissors cut paper covers rock crushes lizard poisons spock smashes scissors decapitate lizard eats paper disproves spock vaporizes rock crushes scissors",
+    {ok, rps_rules:parse(Text)}.
 
-beats(lizard) ->
-    [paper, spock].
-
-loses(lizard) ->
-    [scissors, rock];
+handle_call(get_hands, _From, State=#ruleinfo{hands=Hands}) ->
+    {reply, Hands, State};
 
-loses(spock) ->
-    [paper, lizard];
-
-loses(scissors) ->
-    [rock, spock];
+handle_call({winning_hand, Hands}, _From, State) ->
+    {reply, rps_rules:winning_hand(Hands, State), State};
 
-loses(paper) ->
-    [lizard, scissors];
+handle_call({why, H1, H2}, _From, State=#ruleinfo{why=Why}) ->
+    {reply, dict:fetch({H1, H2}, Why), State}.
 
-loses(rock) ->
-    [spock, paper].
+handle_cast(_Msg, State) -> {noreply, State}.
 
-test_beats() ->
-    lists:foreach(
-        fun(H) ->
-            io:format("~w beats ~w.~n", [H, beats(H)])
-        end,
-        get_hands()).
+handle_info(_Msg, State) -> {noreply, State}.
+
+terminate(_Reason, _State) -> ok.
 
-test_loses() ->
-    lists:foreach(
-        fun(H) ->
-            io:format("~w loses to ~w.~n", [H, loses(H)])
-        end,
-        get_hands()).
+code_change(_OldVersion, State, _Extra) -> {ok, State}.
 
-% winner for 3 hands is:
-% rock, rock, rock      -> rock
-% rock, paper, scissors -> undefined
-% rock, paper, paper    -> paper
-% rock, rock, paper     -> paper
+get_hands() ->
+    gen_server:call(?MODULE, get_hands).
 
 winning_hand(Hands) ->
-    HSet = sets:from_list(Hands),
-    sets:fold(
-        fun(Hand, Acc) ->
-            Loses = loses(Hand),
-            case sets:is_disjoint(sets:from_list(Loses), HSet) of
-                true -> Hand;
-                false -> Acc
-            end
-        end, undefined, HSet).
+    gen_server:call(?MODULE, {winning_hand, Hands}).
 
-test_winning_hand() ->
-    Exclude = fun(Hand) -> lists:delete(Hand, get_hands()) end,
-    Cases = [
-             [rock, rock, rock],
-             [rock, paper, scissors],
-             [rock, paper, paper],
-             [rock, rock, paper]
-             |lists:map(Exclude, get_hands())
-            ],
-    lists:foreach(
-        fun(Hands) ->
-            Winner = winning_hand(Hands),
-            io:format("~w wins in ~w.~n", [Winner, Hands])
-        end,
-        Cases).
+why(H1, H2) ->
+    gen_server:call(?MODULE, {why, H1, H2}).

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/rps5_tests.erl	Mon Mar 03 22:19:53 2014 +0900
@@ -0,0 +1,14 @@
+-module(rps5_tests).
+-include_lib("eunit/include/eunit.hrl").
+
+get_hands_test() ->
+    ?assertEqual(5, length(rps5:get_hands())).
+
+winning_hand_test() ->
+    ?assertEqual(paper,     rps5:winning_hand([rock, paper])),
+    ?assertEqual(scissors,  rps5:winning_hand([paper, scissors])),
+    ?assertEqual(rock,      rps5:winning_hand([scissors, rock])),
+    ?assertEqual(rock,      rps5:winning_hand([rock, rock, rock])),
+    ?assertEqual(undefined, rps5:winning_hand([rock, paper, scissors])),
+    ?assertEqual(paper,     rps5:winning_hand([rock, paper, paper])),
+    ?assertEqual(paper,     rps5:winning_hand([rock, rock, paper])).