ids

-module(ids@uuid).
-compile(no_auto_import).

-export([v4/0]).

-spec v4() -> {ok, binary()} | {error, nil}.
v4() ->
    <<U0:48, _@1:4, U1:12, _@2:2, U2:62>> = crypto:strong_rand_bytes(16),
    <<A1:4,
      A2:4,
      A3:4,
      A4:4,
      A5:4,
      A6:4,
      A7:4,
      A8:4,
      B1:4,
      B2:4,
      B3:4,
      B4:4,
      C1:4,
      C2:4,
      C3:4,
      C4:4,
      D1:4,
      D2:4,
      D3:4,
      D4:4,
      E1:4,
      E2:4,
      E3:4,
      E4:4,
      E5:4,
      E6:4,
      E7:4,
      E8:4,
      E9:4,
      E10:4,
      E11:4,
      E12:4>> = <<U0:48, 4:4, U1:12, 2:2, U2:62>>,
    Id = <<(e(A1)),
           (e(A2)),
           (e(A3)),
           (e(A4)),
           (e(A5)),
           (e(A6)),
           (e(A7)),
           (e(A8)),
           45,
           (e(B1)),
           (e(B2)),
           (e(B3)),
           (e(B4)),
           45,
           (e(C1)),
           (e(C2)),
           (e(C3)),
           (e(C4)),
           45,
           (e(D1)),
           (e(D2)),
           (e(D3)),
           (e(D4)),
           45,
           (e(E1)),
           (e(E2)),
           (e(E3)),
           (e(E4)),
           (e(E5)),
           (e(E6)),
           (e(E7)),
           (e(E8)),
           (e(E9)),
           (e(E10)),
           (e(E11)),
           (e(E12))>>,
    gleam@bit_string:to_string(Id).

-spec e(integer()) -> integer().
e(N) ->
    case N of
        0 ->
            48;

        1 ->
            49;

        2 ->
            50;

        3 ->
            51;

        4 ->
            52;

        5 ->
            53;

        6 ->
            54;

        7 ->
            55;

        8 ->
            56;

        9 ->
            57;

        10 ->
            97;

        11 ->
            98;

        12 ->
            99;

        13 ->
            100;

        14 ->
            101;

        15 ->
            102
    end.