From 7ac6005daff78fce414264685ec1fe4416fd06be Mon Sep 17 00:00:00 2001
From: Correl Roush <correl@gmail.com>
Date: Mon, 2 Jul 2012 22:05:05 -0400
Subject: [PATCH] Set and sequence detection

---
 include/riichi.hrl         |  5 +++++
 src/riichi_hand.erl        | 43 ++++++++++++++++++++++++++++++++++++++
 test/riichi_hand_tests.erl | 24 +++++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 src/riichi_hand.erl
 create mode 100644 test/riichi_hand_tests.erl

diff --git a/include/riichi.hrl b/include/riichi.hrl
index 9b45447..a8d044e 100644
--- a/include/riichi.hrl
+++ b/include/riichi.hrl
@@ -13,3 +13,8 @@
     tile,
     open=true
 }).
+
+-record(seq, {
+    tiles,
+    open=true
+}).
diff --git a/src/riichi_hand.erl b/src/riichi_hand.erl
new file mode 100644
index 0000000..c7419f1
--- /dev/null
+++ b/src/riichi_hand.erl
@@ -0,0 +1,43 @@
+-module(riichi_hand).
+
+-include("riichi.hrl").
+
+-compile([export_all]).
+
+
+find_sets(Tiles) ->
+    Unique = sets:to_list(sets:from_list(Tiles)),
+    [#set{count=length(lists:filter(fun(X) -> X == T end, Tiles)), tile=T, open=false}
+    || T <- Unique].
+
+reorder_seqs(Tiles) ->
+    Unique = sets:to_list(sets:from_list(Tiles)),
+    lists:sort(Unique) ++ (Tiles -- Unique).
+
+find_seqs(Tiles) ->
+    find_seqs(reorder_seqs(Tiles), {[], []}).
+
+find_seqs([], {Seqs, Rest}) ->
+    {lists:sort(Seqs), lists:sort(Rest)};
+
+find_seqs([T1 = #tile{suit=Suit}, T2 = #tile{suit=Suit}, T3  = #tile{suit=Suit} | Tiles], {Seqs, Rest})
+        when T2#tile.value =:= (T1#tile.value + 1)
+             andalso T3#tile.value =:= (T2#tile.value + 1) ->
+    find_seqs(reorder_seqs(Tiles), {[#seq{tiles=[T1, T2, T3], open=false} | Seqs], Rest});
+
+find_seqs([T | Tiles], {Seqs, Rest}) ->
+    find_seqs(Tiles, {Seqs, [T | Rest]}).
+
+perms([]) -> [[]];
+perms(L)  -> [[H|T] || H <- L, T <- perms(L--[H])].
+
+combinations(0, _) -> [[]];
+combinations(_, []) -> [];
+combinations(N, [X|XS]) -> [[X|YS] || YS <- combinations(N-1, XS)] ++ combinations(N, XS).
+
+find_hands(Tiles) ->
+    find_hands(Tiles, []).
+find_hands([], Hands) ->
+    Hands;
+find_hands([_T | _Remaining] = Tiles, Hands) ->
+    [#hand{tiles=Tiles} | Hands].
diff --git a/test/riichi_hand_tests.erl b/test/riichi_hand_tests.erl
new file mode 100644
index 0000000..1a8eb28
--- /dev/null
+++ b/test/riichi_hand_tests.erl
@@ -0,0 +1,24 @@
+-module(riichi_hand_tests).
+
+-include("riichi.hrl").
+-include_lib("eunit/include/eunit.hrl").
+
+find_sets_test() ->
+    Tiles = [#tile{suit=man, value=V} || V <- lists:seq(1,8)],
+    Expected = {[
+                 #seq{tiles=[#tile{suit=man, value=V} || V <- lists:seq(1,3)], open=false},
+                 #seq{tiles=[#tile{suit=man, value=V} || V <- lists:seq(4,6)], open=false}
+                ],
+                [#tile{suit=man, value=V} || V <- lists:seq(7,8)]
+               },
+    ?assertEqual(Expected, riichi_hand:find_seqs(Tiles)).  
+find_duplicate_sets_test() ->
+    Tiles = [#tile{suit=man, value=V} || V <- lists:seq(1,3), _ <- lists:seq(1,3)] ++
+            [#tile{suit=man, value=4} || _ <- [1,2]],
+    Expected = {[
+                 #seq{tiles=[#tile{suit=man, value=V} || V <- lists:seq(1,3)], open=false}
+                 || _ <- [1,2,3]
+                ],
+                [#tile{suit=man, value=4} || _ <- [1,2]]
+               },
+    ?assertEqual(Expected, riichi_hand:find_seqs(Tiles)).