-module(cmd).
-compile(no_auto_import).

-export([exec/4]).
-export_type([timing/0, undef_run/0]).

-type timing() :: endless | {ending, integer()}.

-type undef_run() :: undef | run.

-spec exec(
    list(integer()),
    timing(),
    fun((integer()) -> {ok, FYA} | {error, snag:snag()}),
    fun(({{ok, FYA} | {error, snag:snag()}, integer()}) -> binary())
) -> list(binary()).
exec(Days, Timing, Do, Collect) ->
    _pipe = Days,
    _pipe@1 = task_map(_pipe, Do),
    _pipe@2 = try_await_many(_pipe@1, Timing),
    _pipe@3 = gleam@iterator:from_list(_pipe@2),
    _pipe@4 = gleam@iterator:map(_pipe@3, fun gleam@result:flatten/1),
    _pipe@5 = gleam@iterator:zip(_pipe@4, gleam@iterator:from_list(Days)),
    _pipe@6 = gleam@iterator:map(_pipe@5, Collect),
    gleam@iterator:to_list(_pipe@6).

-spec now_ms() -> integer().
now_ms() ->
    gleam@erlang:system_time(millisecond).

-spec task_map(list(FYF), fun((FYF) -> FYH)) -> list(gleam@otp@task:task(FYH)).
task_map(L, F) ->
    gleam@list:map(L, fun(X) -> gleam@otp@task:async(fun() -> F(X) end) end).

-spec try_await_many(list(gleam@otp@task:task(FYK)), timing()) -> list({ok, FYK} |
    {error, snag:snag()}).
try_await_many(Tasks, Timing) ->
    Await = case Timing of
        endless ->
            fun(T) ->
                _pipe = T,
                _pipe@1 = gleam@otp@task:try_await(_pipe, 600000),
                gleam@result:map_error(_pipe@1, fun snag_task_error/1)
            end;

        {ending, Timeout} ->
            End = now_ms() + Timeout,
            fun(T@1) ->
                _pipe@2 = End
                - now_ms(),
                _pipe@3 = gleam@int:clamp(_pipe@2, 0, Timeout),
                _pipe@4 = gleam@otp@task:try_await(T@1, _pipe@3),
                gleam@result:map_error(_pipe@4, fun snag_task_error/1)
            end
    end,
    gleam@list:map(Tasks, Await).

-spec snag_task_error(gleam@otp@task:await_error()) -> snag:snag().
snag_task_error(Err) ->
    _pipe = case Err of
        timeout ->
            <<"task timed out"/utf8>>;

        {exit, Dyn} ->
            case gleam@dynamic:unsafe_coerce(Dyn) of
                {undef, [{_@1, run, _@2, _@3} | _@4]} ->
                    <<"Run function missing"/utf8>>;

                _@5 ->
                    <<"task exited for some reason"/utf8>>
            end
    end,
    snag:new(_pipe).