-module(string_width_ffi).
-export([
    fold_bytes/3,
    fold_codepoints/3,
    utf_codepoint_to_string/1,
    get_terminal_size/0
]).

fold_bytes(<<Byte/integer, Rest/binary>>, State, Fun) -> fold_bytes(Rest, Fun(State, Byte), Fun);
fold_bytes(_Binary, State, _Fun) -> State.

fold_codepoints(<<Cp/utf8, Rest/binary>>, State, Fun) -> fold_codepoints(Rest, Fun(State, Cp), Fun);
fold_codepoints(_Binary, State, _Fun) -> State.

utf_codepoint_to_string(Cp) -> <<Cp/utf8>>.

get_terminal_size() ->
    case {io:rows(), io:columns()} of
        {{ok, Rows}, {ok, Cols}} -> {ok, {Rows, Cols}};
        _ -> case {os:getenv("LINES"), os:getenv("COLUMNS")} of
            {false, _} -> {error, nil};
            {_, false} -> {error, nil};
            {LinesStr, ColumnsStr} ->
                case catch {list_to_integer(LinesStr), list_to_integer(ColumnsStr)} of
                    {EnvRows, EnvCols} when is_integer(EnvRows) andalso is_integer(EnvCols) ->
                        {ok, {EnvRows, EnvCols}};
                    _ -> {error, nil}
                end
        end
    end.