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

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

-opaque non() :: any().

-opaque som() :: any().

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

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

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

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

-spec with_path(walk_builder(FWO, FWP, any()), binary()) -> walk_builder(FWO, FWP, som()).
with_path(Builder, Path) ->
    {walk_builder,
        erlang:element(2, Builder),
        erlang:element(3, Builder),
        {some, Path}}.

-spec with_entry_filter(
    walk_builder(any(), FWY, FWZ),
    fun((entry()) -> boolean())
) -> walk_builder(som(), FWY, FWZ).
with_entry_filter(Builder, Entry_filter) ->
    {walk_builder,
        {some,
            gleam@list:append(
                gleam@option:unwrap(erlang:element(2, Builder), []),
                [Entry_filter]
            )},
        erlang:element(3, Builder),
        erlang:element(4, Builder)}.

-spec with_traversal_filter(
    walk_builder(FXG, any(), FXI),
    fun((entry()) -> boolean())
) -> walk_builder(FXG, som(), FXI).
with_traversal_filter(Builder, Traversal_filter) ->
    {walk_builder,
        erlang:element(2, Builder),
        {some,
            gleam@list:append(
                gleam@option:unwrap(erlang:element(3, Builder), []),
                [Traversal_filter]
            )},
        erlang:element(4, Builder)}.

-spec to_entry(binary()) -> entry().
to_entry(Filename) ->
    {entry,
        Filename,
        {stat,
            begin
                _pipe = simplifile:verify_is_directory(Filename),
                gleam@result:unwrap(_pipe, false)
            end}}.

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

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

-spec filter_many(list(GBG), list(fun((GBG) -> boolean()))) -> list(GBG).
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(GBN)) -> gleam@iterator:iterator({ok, GBN} |
    {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())),
    list(fun((entry()) -> boolean()))
) -> gleam@iterator:iterator({ok, entry()} | {error, simplifile:file_error()}).
walk_path(Pth, Entry_filters, Traversal_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 begin
                                _pipe@1 = simplifile:verify_is_directory(
                                    gleam_community@path:to_string(Filepath)
                                ),
                                gleam@result:unwrap(_pipe@1, false)
                            end 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@2 = Filepaths,
                        _pipe@3 = gleam@list:map(_pipe@2, fun path_to_entry/1),
                        _pipe@4 = filter_many(_pipe@3, Entry_filters),
                        to_ok_iter(_pipe@4)
                    end,
                    Candidate_folder_entries = begin
                        _pipe@5 = Folderpaths,
                        gleam@list:map(_pipe@5, fun path_to_entry/1)
                    end,
                    Ok_filtered_folders = begin
                        _pipe@6 = Candidate_folder_entries,
                        _pipe@7 = filter_many(_pipe@6, Entry_filters),
                        to_ok_iter(_pipe@7)
                    end,
                    Traverse_folders = begin
                        _pipe@8 = Candidate_folder_entries,
                        filter_many(_pipe@8, Traversal_filters)
                    end,
                    gleam@iterator:concat(
                        [Ok_filtered_files,
                            Ok_filtered_folders |
                            gleam@list:map(
                                Traverse_folders,
                                fun(Ent) ->
                                    walk_path(
                                        gleam_community@path:from_string(
                                            erlang:element(2, Ent)
                                        ),
                                        Entry_filters,
                                        Traversal_filters
                                    )
                                end
                            )]
                    )
            end end).

-spec walk(walk_builder(any(), any(), som())) -> gleam@iterator:iterator({ok,
        entry()} |
    {error, simplifile:file_error()}).
walk(Builder) ->
    {walk_builder, Entry_filter_opt, Traversal_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 => 85})
    end,
    Entry_filters = case Entry_filter_opt of
        {some, Xs} ->
            Xs;

        _ ->
            []
    end,
    Traversal_filters = case Traversal_filter_opt of
        {some, Xs@1} ->
            Xs@1;

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

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

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

-spec fold(gleam@iterator:iterator(GDX), FYO, fun((FYO, GDX) -> FYO)) -> FYO.
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).