xo

-module(xo@internal@referee).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([decide/2]).
-export_type([outcome/0, location/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(false).

-type outcome() :: {win, xo@internal@mark:mark(), list(location())} |
    {draw, xo@internal@mark:mark()}.

-type location() :: r1 | r2 | r3 | c1 | c2 | c3 | d1 | d2.

-file("src/xo/internal/referee.gleam", 44).
?DOC(false).
-spec to_winning_arrangements(
    list(gleam@option:option(xo@internal@mark:mark()))
) -> list({{gleam@option:option(xo@internal@mark:mark()),
        gleam@option:option(xo@internal@mark:mark()),
        gleam@option:option(xo@internal@mark:mark())},
    location()}).
to_winning_arrangements(Tiles) ->
    case Tiles of
        [A, B, C, D, E, F, G, H, I] ->
            [{{A, B, C}, r1},
                {{D, E, F}, r2},
                {{G, H, I}, r3},
                {{A, D, G}, c1},
                {{B, E, H}, c2},
                {{C, F, I}, c3},
                {{A, E, I}, d1},
                {{C, E, G}, d2}];

        _ ->
            []
    end.

-file("src/xo/internal/referee.gleam", 36).
?DOC(false).
-spec find_win(
    list(gleam@option:option(xo@internal@mark:mark())),
    xo@internal@mark:mark()
) -> list(location()).
find_win(Tiles, Mark) ->
    T = {some, Mark},
    _pipe = Tiles,
    _pipe@1 = to_winning_arrangements(_pipe),
    gleam@list:key_filter(_pipe@1, {T, T, T}).

-file("src/xo/internal/referee.gleam", 63).
?DOC(false).
-spec is_draw(list(gleam@option:option(xo@internal@mark:mark()))) -> boolean().
is_draw(Tiles) ->
    _pipe = Tiles,
    gleam@list:all(_pipe, fun(T) -> T /= none end).

-file("src/xo/internal/referee.gleam", 22).
?DOC(false).
-spec decide(
    list({{integer(), integer()}, xo@internal@mark:mark()}),
    xo@internal@mark:mark()
) -> gleam@option:option(outcome()).
decide(Board, Mark) ->
    Tiles = xo@internal@board:to_tiles(Board),
    case find_win(Tiles, Mark) of
        [] ->
            case is_draw(Tiles) of
                true ->
                    {some, {draw, Mark}};

                false ->
                    none
            end;

        Locations ->
            {some, {win, Mark, Locations}}
    end.