-module(puddle).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function]).

-export([shutdown/2, apply/4, start/2]).
-export_type([manager_message/2, resource_message/2]).

-opaque manager_message(HFI, HFJ) :: {manager_shutdown, fun((HFI) -> nil)} |
    {check_in, gleam@erlang@process:subject(resource_message(HFI, HFJ))} |
    {check_out,
        gleam@erlang@process:subject({ok,
                gleam@erlang@process:subject(resource_message(HFI, HFJ))} |
            {error, nil})}.

-opaque resource_message(HFK, HFL) :: {resource_usage,
        fun((HFK) -> HFL),
        gleam@erlang@process:subject({ok, HFL} | {error, nil})} |
    {resource_shutdown, fun((HFK) -> nil)}.

-spec shutdown(
    gleam@erlang@process:subject(manager_message(HIQ, any())),
    fun((HIQ) -> nil)
) -> nil.
shutdown(Manager, Shutdown_function) ->
    gleam@erlang@process:send(Manager, {manager_shutdown, Shutdown_function}).

-spec check_out(
    gleam@erlang@process:subject(manager_message(HGL, HGM)),
    integer()
) -> {ok,
        {ok, gleam@erlang@process:subject(resource_message(HGL, HGM))} |
            {error, nil}} |
    {error,
        gleam@erlang@process:call_error({ok,
                gleam@erlang@process:subject(resource_message(HGL, HGM))} |
            {error, nil})}.
check_out(Manager, Timeout) ->
    gleam@erlang@process:try_call(
        Manager,
        fun(Field@0) -> {check_out, Field@0} end,
        Timeout
    ).

-spec utilize(
    gleam@erlang@process:subject(resource_message(HGR, HGS)),
    fun((HGR) -> HGS),
    gleam@erlang@process:subject({ok, HGS} | {error, nil})
) -> nil.
utilize(Subject, Fun, Mine) ->
    gleam@erlang@process:send(Subject, {resource_usage, Fun, Mine}).

-spec check_in(
    gleam@erlang@process:subject(manager_message(HHA, HHB)),
    gleam@erlang@process:subject(resource_message(HHA, HHB))
) -> nil.
check_in(Manager, Subject) ->
    gleam@erlang@process:send(Manager, {check_in, Subject}).

-spec apply(
    gleam@erlang@process:subject(manager_message(HGB, HGC)),
    fun((HGB) -> HGC),
    integer(),
    fun(({ok, HGC} | {error, nil}) -> {ok, HJE} | {error, nil})
) -> {ok, HJE} | {error, nil}.
apply(Manager, Fun, Timeout, Rest) ->
    gleam@result:then(
        begin
            _pipe = check_out(Manager, Timeout),
            _pipe@1 = gleam@result:replace_error(_pipe, nil),
            gleam@result:flatten(_pipe@1)
        end,
        fun(Subject) ->
            Mine = gleam@erlang@process:new_subject(),
            utilize(Subject, Fun, Mine),
            Selector = begin
                _pipe@2 = gleam_erlang_ffi:new_selector(),
                gleam@erlang@process:selecting(_pipe@2, Mine, fun(R) -> R end)
            end,
            Result = begin
                _pipe@3 = gleam_erlang_ffi:select(Selector, Timeout),
                gleam@result:flatten(_pipe@3)
            end,
            check_in(Manager, Subject),
            Rest(Result)
        end
    ).

-spec handle_manager_message(
    manager_message(HHR, HHS),
    list({gleam@erlang@process:pid_(),
        gleam@erlang@process:subject(resource_message(HHR, HHS))})
) -> gleam@otp@actor:next(any(), list({gleam@erlang@process:pid_(),
    gleam@erlang@process:subject(resource_message(HHR, HHS))})).
handle_manager_message(Msg, Puddle) ->
    case Msg of
        {manager_shutdown, Shutdown_function} ->
            gleam@list:each(
                Puddle,
                fun(Item) ->
                    gleam@erlang@process:send(
                        erlang:element(2, Item),
                        {resource_shutdown, Shutdown_function}
                    )
                end
            ),
            {stop, normal};

        {check_in, Subject} ->
            Pid = gleam@erlang@process:subject_owner(Subject),
            gleam@otp@actor:continue(gleam@list:prepend(Puddle, {Pid, Subject}));

        {check_out, Client} ->
            case Puddle of
                [] ->
                    gleam@otp@actor:send(Client, {error, nil}),
                    gleam@otp@actor:continue(Puddle);

                [{_, Chosen} | New_puddle] ->
                    gleam@otp@actor:send(Client, {ok, Chosen}),
                    gleam@otp@actor:continue(New_puddle)
            end
    end.

-spec handle_resource_message(resource_message(HHY, any()), HHY) -> gleam@otp@actor:next(any(), HHY).
handle_resource_message(Msg, Resource) ->
    case Msg of
        {resource_usage, Fun, Client} ->
            Result = Fun(Resource),
            gleam@otp@actor:send(Client, {ok, Result}),
            gleam@otp@actor:continue(Resource);

        {resource_shutdown, Shutdown} ->
            Shutdown(Resource),
            {stop, normal}
    end.

-spec new(integer(), fun(() -> {ok, HHJ} | {error, nil})) -> {ok,
        list({gleam@erlang@process:pid_(),
            gleam@erlang@process:subject(resource_message(HHJ, any()))})} |
    {error, nil}.
new(Size, New_resource) ->
    _pipe = gleam@list:repeat(<<""/utf8>>, Size),
    gleam@list:try_map(_pipe, fun(_) -> case New_resource() of
                {ok, Initial_state} ->
                    _pipe@1 = gleam@otp@actor:start(
                        Initial_state,
                        fun handle_resource_message/2
                    ),
                    _pipe@2 = gleam@result:map(
                        _pipe@1,
                        fun(Subject) ->
                            Pid = gleam@erlang@process:subject_owner(Subject),
                            {Pid, Subject}
                        end
                    ),
                    gleam@result:nil_error(_pipe@2);

                {error, nil} ->
                    {error, nil}
            end end).

-spec start(integer(), fun(() -> {ok, HFS} | {error, nil})) -> {ok,
        gleam@erlang@process:subject(manager_message(HFS, any()))} |
    {error, gleam@otp@actor:start_error()}.
start(Size, New_resource) ->
    gleam@result:then(
        begin
            _pipe = new(Size, New_resource),
            gleam@result:map_error(
                _pipe,
                fun(_) ->
                    {init_failed,
                        {abnormal, <<"Failed to create new resource"/utf8>>}}
                end
            )
        end,
        fun(Puddle) ->
            gleam@otp@actor:start(Puddle, fun handle_manager_message/2)
        end
    ).