-module(gchess).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function]).

-export([perft/2]).

-spec perft(gleam@erlang@process:subject(game_server:message()), integer()) -> integer().
perft(Game_server_subject, Depth) ->
    case Depth of
        0 ->
            1;

        _ ->
            Moves = game_server:all_legal_moves(Game_server_subject),
            Nodes@2 = gleam@list:fold(
                Moves,
                0,
                fun(Nodes, Move) ->
                    game_server:apply_move(Game_server_subject, Move),
                    Nodes@1 = Nodes + perft(Game_server_subject, Depth - 1),
                    game_server:undo_move(Game_server_subject),
                    Nodes@1
                end
            ),
            Nodes@2
    end.