riichi/src/yaku.erl

-module(yaku).

-include("../include/riichi.hrl").

-export([yakuhai/2,
        tanyao/2,
        pinfu/2,
        chiitoitsu/2,
        kokushi_musou/2]).

yakuhai(#game{round=Round}, #player{seat=Seat, hand=#hand{melds=Melds}}) ->
    length(lists:filter(fun(#meld{type=Type, tiles=[T|_]}) ->
                                case {Type, T} of
                                    {pair, _} ->
                                        false;
                                    {chii, _} ->
                                        false;
                                    {_, #tile{suit=wind, value=Round}} ->
                                        true;
                                    {_, #tile{suit=wind, value=Seat}} ->
                                        true;
                                    {_, #tile{suit=dragon}} ->
                                        true;
                                    _ ->
                                        false
                                end
                        end,
                        Melds)).

tanyao(#game{}, #player{hand=Hand}) ->
    not lists:any(fun(T = #tile{}) ->
                          case T#tile.suit of
                              dragon ->
                                  true;
                              wind ->
                                  true;
                              _ ->
                                  lists:member(T#tile.value, [1,9])
                          end
                  end,
                  riichi_hand:tiles(Hand)).

pinfu(#game{round=Round}, #player{seat=Seat, hand=Hand=#hand{melds=Melds}}) ->
    % TODO: Verify closed, open wait, and pair not round/seat wind
    Closed = lists:all(fun(T) -> T#tile.from =:= draw end, riichi_hand:tiles(Hand)),
    Chiis = length([M || M = #meld{type=chii} <- Melds]) =:= 4,
    #meld{type=pair, tiles=[HeadTile,HeadTile]} = riichi_hand:head(Hand),
    NonValuePair = HeadTile#tile.value =/= Round
        andalso HeadTile#tile.value =/= Seat
        andalso HeadTile#tile.suit =/= dragon,
    Closed and Chiis and NonValuePair.

% 7 Pairs
chiitoitsu(#game{}, #player{hand=#hand{tiles=[], melds=Melds}})
  when length(Melds) =:= 7 ->
    Pairs = [S || S <- Melds, S#meld.type =:= pair],
    length(Pairs) =:= 7 andalso sets:size(sets:from_list(Pairs)) =:= 7.

% 13 Orphans
kokushi_musou(#game{}, #player{hand=#hand{tiles=Tiles, melds=[#meld{type=pair, tiles=[T,T]}]}}) ->
    not lists:any(fun(#tile{value=V}) ->
                          lists:member(V, lists:seq(2,8))
                  end,
                  [T|Tiles])
        andalso sets:size(sets:from_list([T|Tiles])) =:= 13;
kokushi_musou(#game{}, #player{}) ->
    false.