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

-export([start/0, gen/1, is_cuid/1, slug/1, is_slug/1]).
-export_type([message/0, state/0, char_list/0]).

-opaque message() :: {generate, gleam@otp@process:sender(binary())} |
    {generate_slug, gleam@otp@process:sender(binary())}.

-opaque state() :: {state, integer(), binary()}.

-type char_list() :: any().

-spec start() -> {ok, gleam@otp@process:sender(message())} |
    {error, gleam@otp@actor:start_error()}.
start() ->
    gleam@otp@actor:start({state, 0, get_fingerprint()}, fun handle_msg/2).

-spec gen(gleam@otp@process:sender(message())) -> binary().
gen(Channel) ->
    gleam@otp@actor:call(Channel, fun(A) -> {generate, A} end, 1000).

-spec is_cuid(binary()) -> boolean().
is_cuid(Id) ->
    gleam@string:starts_with(Id, <<"c"/utf8>>).

-spec slug(gleam@otp@process:sender(message())) -> binary().
slug(Channel) ->
    gleam@otp@actor:call(Channel, fun(A) -> {generate_slug, A} end, 1000).

-spec is_slug(binary()) -> boolean().
is_slug(Slug) ->
    Slug_length = gleam@string:length(Slug),
    (Slug_length >= 7) andalso (Slug_length =< 10).

-spec handle_msg(message(), state()) -> gleam@otp@actor:next(state()).
handle_msg(Msg, State) ->
    case Msg of
        {generate, Reply} ->
            Id = format_id(
                [<<"c"/utf8>>,
                 timestamp(),
                 format_count(erlang:element(2, State)),
                 erlang:element(3, State),
                 random_block(),
                 random_block()]
            ),
            gleam@otp@actor:send(Reply, Id),
            {continue,
             erlang:setelement(2, State, new_count(erlang:element(2, State)))};

        {generate_slug, Reply@1} ->
            Slug = format_id(
                [gleam@string:slice(timestamp(), -2, 2),
                 gleam@string:slice(
                     format_count(erlang:element(2, State)),
                     -4,
                     4
                 ),
                 gleam@string:concat(
                     [gleam@string:slice(erlang:element(3, State), 0, 1),
                      gleam@string:slice(erlang:element(3, State), -1, 1)]
                 ),
                 gleam@string:slice(random_block(), -2, 2)]
            ),
            gleam@otp@actor:send(Reply@1, Slug),
            {continue,
             erlang:setelement(2, State, new_count(erlang:element(2, State)))}
    end.

-spec format_id(list(binary())) -> binary().
format_id(Id_data) ->
    gleam@string:lowercase(gleam@string:concat(Id_data)).

-spec new_count(integer()) -> integer().
new_count(Count) ->
    case Count < 1679616 of
        true ->
            Count + 1;

        false ->
            0
    end.

-spec timestamp() -> binary().
timestamp() ->
    Secs = gleam@os:system_time(millisecond),
    gleam@int:to_base_string(Secs, 36).

-spec format_count(integer()) -> binary().
format_count(Num) ->
    gleam@string:pad_left(gleam@int:to_base_string(Num, 36), 4, <<"0"/utf8>>).

-spec get_fingerprint() -> binary().
get_fingerprint() ->
    Operator = 36 * 36,
    {ok, Pid} = gleam@int:parse(erlang:list_to_binary(os:getpid())),
    Id = (case Operator of
        0 -> 0;
        Gleam@denominator -> Pid rem Gleam@denominator
    end) * Operator,
    Localhost = net_adm:localhost(),
    Sum = gleam@list:fold(Localhost, 0, fun(Char, Acc) -> Char + Acc end),
    Hostid = case Operator of
        0 -> 0;
        Gleam@denominator@1 -> ((Sum + gleam@list:length(Localhost)) + 36) rem Gleam@denominator@1
    end,
    gleam@int:to_base_string(Id + Hostid, 36).

-spec random_block() -> binary().
random_block() ->
    gleam@string:pad_left(
        gleam@int:to_base_string(rand:uniform(1679616 - 1), 36),
        4,
        <<"0"/utf8>>
    ).