-module(gleam@iterator).
-compile([no_auto_import, nowarn_unused_vars]).

-export([step/1, empty/0, once/1, single/1, first/1, unfold/2, repeatedly/1, repeat/1, from_list/1, range/2, iterate/2, transform/3, fold/3, run/1, to_list/1, reduce/2, last/1, take/2, drop/2, at/2, map/2, group/2, each/2, append/2, flatten/1, flat_map/2, cycle/1, filter/2, find/2, index/1, take_while/2, drop_while/2, scan/3, zip/2, chunk/2, sized_chunk/2, intersperse/2, any/2, all/2, interleave/2, fold_until/3, try_fold/3, length/1]).
-export_type([action/1, iterator/1, step/2, chunk/2, sized_chunk/1]).

-type action(DEB) :: stop | {continue, DEB, fun(() -> action(DEB))}.

-opaque iterator(DEC) :: {iterator, fun(() -> action(DEC))}.

-type step(DED, DEE) :: {next, DED, DEE} | done.

-type chunk(DEF, DEG) :: {another_by,
        list(DEF),
        DEG,
        DEF,
        fun(() -> action(DEF))} |
    {last_by, list(DEF)}.

-type sized_chunk(DEH) :: {another, list(DEH), fun(() -> action(DEH))} |
    {last, list(DEH)} |
    no_more.

-spec stop() -> action(any()).
stop() ->
    stop.

-spec step(iterator(DGA)) -> step(DGA, iterator(DGA)).
step(Iterator) ->
    case (erlang:element(2, Iterator))() of
        stop ->
            done;

        {continue, E, A} ->
            {next, E, {iterator, A}}
    end.

-spec update_group_with(DLO) -> fun((gleam@option:option(list(DLO))) -> list(DLO)).
update_group_with(El) ->
    fun(Maybe_group) -> case Maybe_group of
            {some, Group} ->
                [El | Group];

            none ->
                [El]
        end end.

-spec empty() -> iterator(any()).
empty() ->
    {iterator, fun stop/0}.

-spec once(fun(() -> DMQ)) -> iterator(DMQ).
once(F) ->
    _pipe = fun() -> {continue, F(), fun stop/0} end,
    {iterator, _pipe}.

-spec single(DMS) -> iterator(DMS).
single(Elem) ->
    once(fun() -> Elem end).

-spec first(iterator(DOA)) -> {ok, DOA} | {error, nil}.
first(Iterator) ->
    case (erlang:element(2, Iterator))() of
        stop ->
            {error, nil};

        {continue, E, _} ->
            {ok, E}
    end.

-spec do_unfold(DEK, fun((DEK) -> step(DEL, DEK))) -> fun(() -> action(DEL)).
do_unfold(Initial, F) ->
    fun() -> case F(Initial) of
            {next, X, Acc} ->
                {continue, X, do_unfold(Acc, F)};

            done ->
                stop
        end end.

-spec unfold(DEP, fun((DEP) -> step(DEQ, DEP))) -> iterator(DEQ).
unfold(Initial, F) ->
    _pipe = Initial,
    _pipe@1 = do_unfold(_pipe, F),
    {iterator, _pipe@1}.

-spec repeatedly(fun(() -> DEU)) -> iterator(DEU).
repeatedly(F) ->
    unfold(nil, fun(_) -> {next, F(), nil} end).

-spec repeat(DEW) -> iterator(DEW).
repeat(X) ->
    repeatedly(fun() -> X end).

-spec from_list(list(DEY)) -> iterator(DEY).
from_list(List) ->
    Yield = fun(Acc) -> case Acc of
            [] ->
                done;

            [Head | Tail] ->
                {next, Head, Tail}
        end end,
    unfold(List, Yield).

-spec range(integer(), integer()) -> iterator(integer()).
range(Start, Stop) ->
    case gleam@int:compare(Start, Stop) of
        eq ->
            once(fun() -> Start end);

        gt ->
            unfold(Start, fun(Current) -> case Current < Stop of
                        false ->
                            {next, Current, Current - 1};

                        true ->
                            done
                    end end);

        lt ->
            unfold(Start, fun(Current@1) -> case Current@1 > Stop of
                        false ->
                            {next, Current@1, Current@1 + 1};

                        true ->
                            done
                    end end)
    end.

-spec iterate(DIS, fun((DIS) -> DIS)) -> iterator(DIS).
iterate(Initial, F) ->
    unfold(Initial, fun(Element) -> {next, Element, F(Element)} end).

-spec do_transform(
    fun(() -> action(DFB)),
    DFD,
    fun((DFD, DFB) -> step(DFE, DFD))
) -> fun(() -> action(DFE)).
do_transform(Continuation, State, F) ->
    fun() -> case Continuation() of
            stop ->
                stop;

            {continue, El, Next} ->
                case F(State, El) of
                    done ->
                        stop;

                    {next, Yield, Next_state} ->
                        {continue, Yield, do_transform(Next, Next_state, F)}
                end
        end end.

-spec transform(iterator(DFI), DFK, fun((DFK, DFI) -> step(DFL, DFK))) -> iterator(DFL).
transform(Iterator, Initial, F) ->
    _pipe = do_transform(erlang:element(2, Iterator), Initial, F),
    {iterator, _pipe}.

-spec do_fold(fun(() -> action(DFP)), fun((DFR, DFP) -> DFR), DFR) -> DFR.
do_fold(Continuation, F, Accumulator) ->
    case Continuation() of
        {continue, Elem, Next} ->
            do_fold(Next, F, F(Accumulator, Elem));

        stop ->
            Accumulator
    end.

-spec fold(iterator(DFS), DFU, fun((DFU, DFS) -> DFU)) -> DFU.
fold(Iterator, Initial, F) ->
    _pipe = erlang:element(2, Iterator),
    do_fold(_pipe, F, Initial).

-spec run(iterator(any())) -> nil.
run(Iterator) ->
    fold(Iterator, nil, fun(_, _) -> nil end).

-spec to_list(iterator(DFX)) -> list(DFX).
to_list(Iterator) ->
    _pipe = Iterator,
    _pipe@1 = fold(_pipe, [], fun(Acc, E) -> [E | Acc] end),
    gleam@list:reverse(_pipe@1).

-spec reduce(iterator(DMG), fun((DMG, DMG) -> DMG)) -> {ok, DMG} | {error, nil}.
reduce(Iterator, F) ->
    case (erlang:element(2, Iterator))() of
        stop ->
            {error, nil};

        {continue, E, Next} ->
            _pipe = do_fold(Next, F, E),
            {ok, _pipe}
    end.

-spec last(iterator(DMK)) -> {ok, DMK} | {error, nil}.
last(Iterator) ->
    _pipe = Iterator,
    reduce(_pipe, fun(_, Elem) -> Elem end).

-spec do_take(fun(() -> action(DGF)), integer()) -> fun(() -> action(DGF)).
do_take(Continuation, Desired) ->
    fun() -> case Desired > 0 of
            false ->
                stop;

            true ->
                case Continuation() of
                    stop ->
                        stop;

                    {continue, E, Next} ->
                        {continue, E, do_take(Next, Desired - 1)}
                end
        end end.

-spec take(iterator(DGI), integer()) -> iterator(DGI).
take(Iterator, Desired) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_take(_pipe, Desired),
    {iterator, _pipe@1}.

-spec do_drop(fun(() -> action(DGL)), integer()) -> action(DGL).
do_drop(Continuation, Desired) ->
    case Continuation() of
        stop ->
            stop;

        {continue, E, Next} ->
            case Desired > 0 of
                true ->
                    do_drop(Next, Desired - 1);

                false ->
                    {continue, E, Next}
            end
    end.

-spec drop(iterator(DGO), integer()) -> iterator(DGO).
drop(Iterator, Desired) ->
    _pipe = fun() -> do_drop(erlang:element(2, Iterator), Desired) end,
    {iterator, _pipe}.

-spec at(iterator(DOE), integer()) -> {ok, DOE} | {error, nil}.
at(Iterator, Index) ->
    _pipe = Iterator,
    _pipe@1 = drop(_pipe, Index),
    first(_pipe@1).

-spec do_map(fun(() -> action(DGR)), fun((DGR) -> DGT)) -> fun(() -> action(DGT)).
do_map(Continuation, F) ->
    fun() -> case Continuation() of
            stop ->
                stop;

            {continue, E, Continuation@1} ->
                {continue, F(E), do_map(Continuation@1, F)}
        end end.

-spec map(iterator(DGV), fun((DGV) -> DGX)) -> iterator(DGX).
map(Iterator, F) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_map(_pipe, F),
    {iterator, _pipe@1}.

-spec group_updater(fun((DLS) -> DLT)) -> fun((gleam@map:map_(DLT, list(DLS)), DLS) -> gleam@map:map_(DLT, list(DLS))).
group_updater(F) ->
    fun(Groups, Elem) -> _pipe = Groups,
        gleam@map:update(_pipe, F(Elem), update_group_with(Elem)) end.

-spec group(iterator(DMA), fun((DMA) -> DMC)) -> gleam@map:map_(DMC, list(DMA)).
group(Iterator, Key) ->
    _pipe = Iterator,
    _pipe@1 = fold(_pipe, gleam@map:new(), group_updater(Key)),
    gleam@map:map_values(
        _pipe@1,
        fun(_, Group) -> gleam@list:reverse(Group) end
    ).

-spec each(iterator(DOM), fun((DOM) -> any())) -> nil.
each(Iterator, F) ->
    _pipe = Iterator,
    _pipe@1 = map(_pipe, F),
    run(_pipe@1).

-spec do_append(fun(() -> action(DGZ)), fun(() -> action(DGZ))) -> action(DGZ).
do_append(First, Second) ->
    case First() of
        {continue, E, First@1} ->
            {continue, E, fun() -> do_append(First@1, Second) end};

        stop ->
            Second()
    end.

-spec append(iterator(DHD), iterator(DHD)) -> iterator(DHD).
append(First, Second) ->
    _pipe = fun() ->
        do_append(erlang:element(2, First), erlang:element(2, Second))
    end,
    {iterator, _pipe}.

-spec do_flatten(fun(() -> action(iterator(DHH)))) -> action(DHH).
do_flatten(Flattened) ->
    case Flattened() of
        stop ->
            stop;

        {continue, It, Next_iterator} ->
            do_append(
                erlang:element(2, It),
                fun() -> do_flatten(Next_iterator) end
            )
    end.

-spec flatten(iterator(iterator(DHL))) -> iterator(DHL).
flatten(Iterator) ->
    _pipe = fun() -> do_flatten(erlang:element(2, Iterator)) end,
    {iterator, _pipe}.

-spec flat_map(iterator(DHP), fun((DHP) -> iterator(DHR))) -> iterator(DHR).
flat_map(Iterator, F) ->
    _pipe = Iterator,
    _pipe@1 = map(_pipe, F),
    flatten(_pipe@1).

-spec cycle(iterator(DIA)) -> iterator(DIA).
cycle(Iterator) ->
    _pipe = repeat(Iterator),
    flatten(_pipe).

-spec do_filter(fun(() -> action(DHU)), fun((DHU) -> boolean())) -> action(DHU).
do_filter(Continuation, Predicate) ->
    case Continuation() of
        stop ->
            stop;

        {continue, E, Iterator} ->
            case Predicate(E) of
                true ->
                    {continue, E, fun() -> do_filter(Iterator, Predicate) end};

                false ->
                    do_filter(Iterator, Predicate)
            end
    end.

-spec filter(iterator(DHX), fun((DHX) -> boolean())) -> iterator(DHX).
filter(Iterator, Predicate) ->
    _pipe = fun() -> do_filter(erlang:element(2, Iterator), Predicate) end,
    {iterator, _pipe}.

-spec do_find(fun(() -> action(DIE)), fun((DIE) -> boolean())) -> {ok, DIE} |
    {error, nil}.
do_find(Continuation, F) ->
    case Continuation() of
        stop ->
            {error, nil};

        {continue, E, Next} ->
            case F(E) of
                true ->
                    {ok, E};

                false ->
                    do_find(Next, F)
            end
    end.

-spec find(iterator(DII), fun((DII) -> boolean())) -> {ok, DII} | {error, nil}.
find(Haystack, Is_desired) ->
    _pipe = erlang:element(2, Haystack),
    do_find(_pipe, Is_desired).

-spec do_index(fun(() -> action(DIM)), integer()) -> fun(() -> action({integer(),
    DIM})).
do_index(Continuation, Next) ->
    fun() -> case Continuation() of
            stop ->
                stop;

            {continue, E, Continuation@1} ->
                {continue, {Next, E}, do_index(Continuation@1, Next + 1)}
        end end.

-spec index(iterator(DIP)) -> iterator({integer(), DIP}).
index(Iterator) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_index(_pipe, 0),
    {iterator, _pipe@1}.

-spec do_take_while(fun(() -> action(DIU)), fun((DIU) -> boolean())) -> fun(() -> action(DIU)).
do_take_while(Continuation, Predicate) ->
    fun() -> case Continuation() of
            stop ->
                stop;

            {continue, E, Next} ->
                case Predicate(E) of
                    false ->
                        stop;

                    true ->
                        {continue, E, do_take_while(Next, Predicate)}
                end
        end end.

-spec take_while(iterator(DIX), fun((DIX) -> boolean())) -> iterator(DIX).
take_while(Iterator, Predicate) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_take_while(_pipe, Predicate),
    {iterator, _pipe@1}.

-spec do_drop_while(fun(() -> action(DJA)), fun((DJA) -> boolean())) -> action(DJA).
do_drop_while(Continuation, Predicate) ->
    case Continuation() of
        stop ->
            stop;

        {continue, E, Next} ->
            case Predicate(E) of
                false ->
                    {continue, E, Next};

                true ->
                    do_drop_while(Next, Predicate)
            end
    end.

-spec drop_while(iterator(DJD), fun((DJD) -> boolean())) -> iterator(DJD).
drop_while(Iterator, Predicate) ->
    _pipe = fun() -> do_drop_while(erlang:element(2, Iterator), Predicate) end,
    {iterator, _pipe}.

-spec do_scan(fun(() -> action(DJG)), fun((DJI, DJG) -> DJI), DJI) -> fun(() -> action(DJI)).
do_scan(Continuation, F, Accumulator) ->
    fun() -> case Continuation() of
            stop ->
                stop;

            {continue, El, Next} ->
                Accumulated = F(Accumulator, El),
                {continue, Accumulated, do_scan(Next, F, Accumulated)}
        end end.

-spec scan(iterator(DJK), DJM, fun((DJM, DJK) -> DJM)) -> iterator(DJM).
scan(Iterator, Initial, F) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_scan(_pipe, F, Initial),
    {iterator, _pipe@1}.

-spec do_zip(fun(() -> action(DJO)), fun(() -> action(DJQ))) -> fun(() -> action({DJO,
    DJQ})).
do_zip(Left, Right) ->
    fun() -> case Left() of
            stop ->
                stop;

            {continue, El_left, Next_left} ->
                case Right() of
                    stop ->
                        stop;

                    {continue, El_right, Next_right} ->
                        {continue,
                            {El_left, El_right},
                            do_zip(Next_left, Next_right)}
                end
        end end.

-spec zip(iterator(DJT), iterator(DJV)) -> iterator({DJT, DJV}).
zip(Left, Right) ->
    _pipe = do_zip(erlang:element(2, Left), erlang:element(2, Right)),
    {iterator, _pipe}.

-spec next_chunk(fun(() -> action(DJY)), fun((DJY) -> DKA), DKA, list(DJY)) -> chunk(DJY, DKA).
next_chunk(Continuation, F, Previous_key, Current_chunk) ->
    case Continuation() of
        stop ->
            {last_by, gleam@list:reverse(Current_chunk)};

        {continue, E, Next} ->
            Key = F(E),
            case Key =:= Previous_key of
                true ->
                    next_chunk(Next, F, Key, [E | Current_chunk]);

                false ->
                    {another_by,
                        gleam@list:reverse(Current_chunk),
                        Key,
                        E,
                        Next}
            end
    end.

-spec do_chunk(fun(() -> action(DKE)), fun((DKE) -> DKG), DKG, DKE) -> action(list(DKE)).
do_chunk(Continuation, F, Previous_key, Previous_element) ->
    case next_chunk(Continuation, F, Previous_key, [Previous_element]) of
        {last_by, Chunk} ->
            {continue, Chunk, fun stop/0};

        {another_by, Chunk@1, Key, El, Next} ->
            {continue, Chunk@1, fun() -> do_chunk(Next, F, Key, El) end}
    end.

-spec chunk(iterator(DKJ), fun((DKJ) -> any())) -> iterator(list(DKJ)).
chunk(Iterator, F) ->
    _pipe = fun() -> case (erlang:element(2, Iterator))() of
            stop ->
                stop;

            {continue, E, Next} ->
                do_chunk(Next, F, F(E), E)
        end end,
    {iterator, _pipe}.

-spec next_sized_chunk(fun(() -> action(DKO)), integer(), list(DKO)) -> sized_chunk(DKO).
next_sized_chunk(Continuation, Left, Current_chunk) ->
    case Continuation() of
        stop ->
            case Current_chunk of
                [] ->
                    no_more;

                Remaining ->
                    {last, gleam@list:reverse(Remaining)}
            end;

        {continue, E, Next} ->
            Chunk = [E | Current_chunk],
            case Left > 1 of
                false ->
                    {another, gleam@list:reverse(Chunk), Next};

                true ->
                    next_sized_chunk(Next, Left - 1, Chunk)
            end
    end.

-spec do_sized_chunk(fun(() -> action(DKS)), integer()) -> fun(() -> action(list(DKS))).
do_sized_chunk(Continuation, Count) ->
    fun() -> case next_sized_chunk(Continuation, Count, []) of
            no_more ->
                stop;

            {last, Chunk} ->
                {continue, Chunk, fun stop/0};

            {another, Chunk@1, Next_element} ->
                {continue, Chunk@1, do_sized_chunk(Next_element, Count)}
        end end.

-spec sized_chunk(iterator(DKW), integer()) -> iterator(list(DKW)).
sized_chunk(Iterator, Count) ->
    _pipe = erlang:element(2, Iterator),
    _pipe@1 = do_sized_chunk(_pipe, Count),
    {iterator, _pipe@1}.

-spec do_intersperse(fun(() -> action(DLA)), DLA) -> action(DLA).
do_intersperse(Continuation, Separator) ->
    case Continuation() of
        stop ->
            stop;

        {continue, E, Next} ->
            Next_interspersed = fun() -> do_intersperse(Next, Separator) end,
            {continue, Separator, fun() -> {continue, E, Next_interspersed} end}
    end.

-spec intersperse(iterator(DLD), DLD) -> iterator(DLD).
intersperse(Iterator, Elem) ->
    _pipe = fun() -> case (erlang:element(2, Iterator))() of
            stop ->
                stop;

            {continue, E, Next} ->
                {continue, E, fun() -> do_intersperse(Next, Elem) end}
        end end,
    {iterator, _pipe}.

-spec do_any(fun(() -> action(DLG)), fun((DLG) -> boolean())) -> boolean().
do_any(Continuation, Predicate) ->
    case Continuation() of
        stop ->
            false;

        {continue, E, Next} ->
            case Predicate(E) of
                true ->
                    true;

                false ->
                    do_any(Next, Predicate)
            end
    end.

-spec any(iterator(DLI), fun((DLI) -> boolean())) -> boolean().
any(Iterator, Predicate) ->
    _pipe = erlang:element(2, Iterator),
    do_any(_pipe, Predicate).

-spec do_all(fun(() -> action(DLK)), fun((DLK) -> boolean())) -> boolean().
do_all(Continuation, Predicate) ->
    case Continuation() of
        stop ->
            true;

        {continue, E, Next} ->
            case Predicate(E) of
                true ->
                    do_all(Next, Predicate);

                false ->
                    false
            end
    end.

-spec all(iterator(DLM), fun((DLM) -> boolean())) -> boolean().
all(Iterator, Predicate) ->
    _pipe = erlang:element(2, Iterator),
    do_all(_pipe, Predicate).

-spec do_interleave(fun(() -> action(DMU)), fun(() -> action(DMU))) -> action(DMU).
do_interleave(Current, Next) ->
    case Current() of
        stop ->
            Next();

        {continue, E, Next_other} ->
            {continue, E, fun() -> do_interleave(Next, Next_other) end}
    end.

-spec interleave(iterator(DMY), iterator(DMY)) -> iterator(DMY).
interleave(Left, Right) ->
    _pipe = fun() ->
        do_interleave(erlang:element(2, Left), erlang:element(2, Right))
    end,
    {iterator, _pipe}.

-spec do_fold_until(
    fun(() -> action(DNC)),
    fun((DNE, DNC) -> gleam@list:continue_or_stop(DNE)),
    DNE
) -> DNE.
do_fold_until(Continuation, F, Accumulator) ->
    case Continuation() of
        stop ->
            Accumulator;

        {continue, Elem, Next} ->
            case F(Accumulator, Elem) of
                {continue, Accumulator@1} ->
                    do_fold_until(Next, F, Accumulator@1);

                {stop, Accumulator@2} ->
                    Accumulator@2
            end
    end.

-spec fold_until(
    iterator(DNG),
    DNI,
    fun((DNI, DNG) -> gleam@list:continue_or_stop(DNI))
) -> DNI.
fold_until(Iterator, Initial, F) ->
    _pipe = erlang:element(2, Iterator),
    do_fold_until(_pipe, F, Initial).

-spec do_try_fold(
    fun(() -> action(DNK)),
    fun((DNM, DNK) -> {ok, DNM} | {error, DNN}),
    DNM
) -> {ok, DNM} | {error, DNN}.
do_try_fold(Continuation, F, Accumulator) ->
    case Continuation() of
        stop ->
            {ok, Accumulator};

        {continue, Elem, Next} ->
            gleam@result:'try'(
                F(Accumulator, Elem),
                fun(Accumulator@1) -> do_try_fold(Next, F, Accumulator@1) end
            )
    end.

-spec try_fold(iterator(DNS), DNU, fun((DNU, DNS) -> {ok, DNU} | {error, DNV})) -> {ok,
        DNU} |
    {error, DNV}.
try_fold(Iterator, Initial, F) ->
    _pipe = erlang:element(2, Iterator),
    do_try_fold(_pipe, F, Initial).

-spec do_length(fun(() -> action(any())), integer()) -> integer().
do_length(Continuation, Length) ->
    case Continuation() of
        stop ->
            Length;

        {continue, _, Next} ->
            do_length(Next, Length + 1)
    end.

-spec length(iterator(any())) -> integer().
length(Iterator) ->
    _pipe = erlang:element(2, Iterator),
    do_length(_pipe, 0).