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

-export([builder/0, with_path/2, with_filter/2, walk/1, each/2, map/2, fold/3, only_dirs/1, only_files/1]).
-export_type([non/0, som/0, walk_builder/2, stat/0, entry/0]).

-opaque non() :: any().

-opaque som() :: any().

-opaque walk_builder(FYT, FYU) :: {walk_builder,
        gleam@option:option(list(fun((entry()) -> boolean()))),
        gleam@option:option(binary())} |
    {gleam_phantom, FYT, FYU}.

-type stat() :: {stat, boolean()}.

-type entry() :: {entry, binary(), stat()}.

-spec builder() -> walk_builder(non(), non()).
builder() ->
    {walk_builder, none, none}.

-spec with_path(walk_builder(FYX, any()), binary()) -> walk_builder(FYX, som()).
with_path(Builder, Path) ->
    {walk_builder, erlang:element(2, Builder), {some, Path}}.

-spec with_filter(walk_builder(any(), FZE), fun((entry()) -> boolean())) -> walk_builder(som(), FZE).
with_filter(Builder, Filter) ->
    {walk_builder,
        {some,
            gleam@list:append(
                gleam@option:unwrap(erlang:element(2, Builder), []),
                [Filter]
            )},
        erlang:element(3, Builder)}.

-spec to_entry(binary()) -> entry().
to_entry(Filename) ->
    {entry, Filename, {stat, simplifile:is_directory(Filename)}}.

-spec path_to_entry(gleam_community@path:path()) -> entry().
path_to_entry(Pth) ->
    to_entry(gleam_community@path:to_string(Pth)).

-spec ok(FZN) -> {ok, FZN} | {error, any()}.
ok(X) ->
    {ok, X}.

-spec filter_many(list(GBN), list(fun((GBN) -> boolean()))) -> list(GBN).
filter_many(Xs, Filters) ->
    _pipe = Xs,
    gleam@list:filter(
        _pipe,
        fun(Entry) -> gleam@list:all(Filters, fun(F) -> F(Entry) end) end
    ).

-spec to_ok_iter(list(GBU)) -> gleam@iterator:iterator({ok, GBU} |
    {error, any()}).
to_ok_iter(Xs) ->
    _pipe = Xs,
    _pipe@1 = gleam@list:map(_pipe, fun ok/1),
    gleam@iterator:from_list(_pipe@1).

-spec walk_path(gleam_community@path:path(), list(fun((entry()) -> boolean()))) -> gleam@iterator:iterator({ok,
        entry()} |
    {error, simplifile:file_error()}).
walk_path(Pth, Filters) ->
    _pipe = gleam@iterator:once(
        fun() ->
            simplifile:read_directory(gleam_community@path:to_string(Pth))
        end
    ),
    gleam@iterator:flat_map(_pipe, fun(Readdir_result) -> case Readdir_result of
                {error, X} ->
                    gleam@iterator:once(fun() -> {error, X} end);

                {ok, Filenames} ->
                    {Filepaths, Folderpaths} = gleam@list:fold(
                        Filenames,
                        {[], []},
                        fun(Acc, F) ->
                            Filepath = gleam_community@path:append_string(
                                Pth,
                                F
                            ),
                            case simplifile:is_directory(
                                gleam_community@path:to_string(Filepath)
                            ) of
                                true ->
                                    {erlang:element(1, Acc),
                                        [Filepath | erlang:element(2, Acc)]};

                                false ->
                                    {[Filepath | erlang:element(1, Acc)],
                                        erlang:element(2, Acc)}
                            end
                        end
                    ),
                    Ok_filtered_files = begin
                        _pipe@1 = Filepaths,
                        _pipe@2 = gleam@list:map(_pipe@1, fun path_to_entry/1),
                        _pipe@3 = filter_many(_pipe@2, Filters),
                        to_ok_iter(_pipe@3)
                    end,
                    Filtered_folders = begin
                        _pipe@4 = Folderpaths,
                        _pipe@5 = gleam@list:map(_pipe@4, fun path_to_entry/1),
                        filter_many(_pipe@5, Filters)
                    end,
                    Ok_filtered_folders = to_ok_iter(Filtered_folders),
                    gleam@iterator:concat(
                        [Ok_filtered_files,
                            Ok_filtered_folders |
                            gleam@list:map(
                                Filtered_folders,
                                fun(Ent) ->
                                    walk_path(
                                        gleam_community@path:from_string(
                                            erlang:element(2, Ent)
                                        ),
                                        Filters
                                    )
                                end
                            )]
                    )
            end end).

-spec walk(walk_builder(any(), som())) -> gleam@iterator:iterator({ok, entry()} |
    {error, simplifile:file_error()}).
walk(Builder) ->
    {walk_builder, Filter_opt, Path_opt} = Builder,
    {some, Root_path} = case Path_opt of
        {some, _} -> Path_opt;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"fswalk"/utf8>>,
                        function => <<"walk"/utf8>>,
                        line => 52})
    end,
    Filters = case Filter_opt of
        {some, Xs} ->
            Xs;

        _ ->
            []
    end,
    walk_path(gleam_community@path:from_string(Root_path), Filters).

-spec each(gleam@iterator:iterator(GDR), fun((GDR) -> any())) -> nil.
each(It, Fun) ->
    _pipe = It,
    gleam@iterator:each(_pipe, Fun).

-spec map(gleam@iterator:iterator(GDT), fun((GDT) -> GDU)) -> gleam@iterator:iterator(GDU).
map(It, Fun) ->
    _pipe = It,
    gleam@iterator:map(_pipe, Fun).

-spec fold(gleam@iterator:iterator(GDV), GAF, fun((GAF, GDV) -> GAF)) -> GAF.
fold(It, Init, Fun) ->
    _pipe = It,
    gleam@iterator:fold(_pipe, Init, Fun).

-spec only_dirs(entry()) -> boolean().
only_dirs(Ent) ->
    erlang:element(2, erlang:element(3, Ent)).

-spec only_files(entry()) -> boolean().
only_files(Ent) ->
    not only_dirs(Ent).