hotp

-module(hotp_secret).

-export(
    [ new/0
    , new/1
    ]).

-spec new() ->
    binary().
new() ->
    new(sha).

-spec new(hotp_hmac:hash_algo()) ->
    binary().
new(HashAlgo) ->
    NumOfBytes = num_of_bytes_needed_for_hash_algo(HashAlgo),
    crypto:strong_rand_bytes(NumOfBytes).

num_of_bytes_needed_for_hash_algo(HashAlgo) ->
    case HashAlgo
    of  sha    -> 20
    ;   sha256 -> 32
    ;   sha512 -> 64
    end.

-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").

all_test_() ->
    Tests =
        [
            ?_assertNotEqual(new(), new())
        |
            [?_assertNotEqual(new(H), new(H)) || H <- hotp_hmac:hash_algos_supported()]
        ],
    {inparallel, Tests}.

-endif.