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

-export([get_headers/1, get_header/2, parse/1, maildir_iterator/1, maildir_iterate/1, main/0]).
-export_type([m_box/0, mail/0]).

-type m_box() :: {m_box, gleam@dict:dict(binary(), binary()), binary()} |
    invalid_m_box.

-type mail() :: {mail,
        {ok, binary()} | {error, nil},
        {ok, binary()} | {error, nil},
        {ok, binary()} | {error, nil},
        {ok, binary()} | {error, nil},
        {ok, birl:time()} | {error, nil},
        {ok, binary()} | {error, nil},
        {ok, gleam@dict:dict(binary(), binary())} | {error, nil}} |
    invalid_mail.

-spec get_headers(m_box()) -> {ok, gleam@dict:dict(binary(), binary())} |
    {error, nil}.
get_headers(Mbox) ->
    case Mbox of
        invalid_m_box ->
            {error, nil};

        {m_box, Headers, _} ->
            {ok, Headers}
    end.

-spec get_header(m_box(), binary()) -> {ok, binary()} | {error, nil}.
get_header(Mbox, Key) ->
    case Mbox of
        {m_box, Headers, _} ->
            _pipe = Headers,
            gleam@dict:get(_pipe, Key);

        invalid_m_box ->
            {error, nil}
    end.

-spec parse_body(binary()) -> {ok, binary()} | {error, nil}.
parse_body(Mboxcontents) ->
    case gleam@string:split_once(Mboxcontents, <<"\n\n"/utf8>>) of
        {ok, Pair} ->
            _pipe = gleam@pair:second(Pair),
            {ok, _pipe};

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

-spec get_header_dict(binary()) -> {binary(), binary()}.
get_header_dict(S) ->
    _pipe = S,
    _pipe@1 = gleam@string:split_once(_pipe, <<": "/utf8>>),
    gleam@result:unwrap(_pipe@1, {<<""/utf8>>, <<""/utf8>>}).

-spec remove_dead_space(binary(), binary()) -> binary().
remove_dead_space(Acc, Matched_content) ->
    _assert_subject = gleam@regex:from_string(<<"\\s+"/utf8>>),
    {ok, Dead_space} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"gleambox"/utf8>>,
                        function => <<"remove_dead_space"/utf8>>,
                        line => 98})
    end,
    _pipe = Dead_space,
    _pipe@1 = gleam@regex:split(_pipe, Matched_content),
    _pipe@2 = gleam@string:join(_pipe@1, <<" "/utf8>>),
    gleam@string:replace(Acc, Matched_content, _pipe@2).

-spec fix_multiline_values(binary()) -> binary().
fix_multiline_values(S) ->
    _assert_subject = gleam@regex:compile(
        <<": [^\n]+\n\\s+[^\n]+$"/utf8>>,
        {options, true, true}
    ),
    {ok, Multi_line_value} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"gleambox"/utf8>>,
                        function => <<"fix_multiline_values"/utf8>>,
                        line => 86})
    end,
    _pipe = Multi_line_value,
    _pipe@1 = gleam@regex:scan(_pipe, S),
    _pipe@2 = gleam@list:map(
        _pipe@1,
        fun(Match) -> erlang:element(2, Match) end
    ),
    _pipe@3 = gleam@list:scan(_pipe@2, S, fun remove_dead_space/2),
    _pipe@4 = gleam@list:first(_pipe@3),
    gleam@result:unwrap(_pipe@4, <<"bar"/utf8>>).

-spec parse_headers(binary()) -> {ok, gleam@dict:dict(binary(), binary())} |
    {error, nil}.
parse_headers(Mboxcontents) ->
    case gleam@string:split_once(Mboxcontents, <<"\n\n"/utf8>>) of
        {ok, Pair} ->
            _pipe = gleam@pair:first(Pair),
            _pipe@1 = fix_multiline_values(_pipe),
            _pipe@2 = gleam@string:split(_pipe@1, <<"\n"/utf8>>),
            _pipe@3 = gleam@list:map(_pipe@2, fun get_header_dict/1),
            _pipe@4 = maps:from_list(_pipe@3),
            {ok, _pipe@4};

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

-spec parse(binary()) -> m_box().
parse(Mboxcontents) ->
    Headers = parse_headers(Mboxcontents),
    Body = parse_body(Mboxcontents),
    case {Headers, Body} of
        {{ok, Parsed_headers}, {ok, Parsed_body}} ->
            {m_box, Parsed_headers, Parsed_body};

        {_, _} ->
            invalid_m_box
    end.

-spec read_file(binary()) -> binary().
read_file(File_path) ->
    _pipe = File_path,
    _pipe@1 = simplifile:read(_pipe),
    gleam@result:unwrap(_pipe@1, <<""/utf8>>).

-spec maildir_iterator(binary()) -> gleam@iterator:iterator(binary()).
maildir_iterator(Mbox_path) ->
    _pipe = Mbox_path,
    _pipe@1 = simplifile:get_files(_pipe),
    _pipe@2 = gleam@result:lazy_unwrap(_pipe@1, fun gleam@list:new/0),
    _pipe@3 = gleam@iterator:from_list(_pipe@2),
    gleam@iterator:map(_pipe@3, fun read_file/1).

-spec maildir_iterate(binary()) -> gleam@iterator:iterator({binary(), binary()}).
maildir_iterate(Maildir_path) ->
    case simplifile:get_files(Maildir_path) of
        {ok, Maillist} ->
            _pipe = gleam@iterator:from_list(Maillist),
            gleam@iterator:map(_pipe, fun(Path) -> {Path, read_file(Path)} end);

        {error, _} ->
            _pipe@1 = {<<""/utf8>>, <<""/utf8>>},
            _pipe@2 = gleam@list:wrap(_pipe@1),
            gleam@iterator:from_list(_pipe@2)
    end.

-spec mbox_to_mail(m_box()) -> mail().
mbox_to_mail(Mbox) ->
    case Mbox of
        invalid_m_box ->
            invalid_mail;

        {m_box, Headers, Body} ->
            {mail,
                gleam@dict:get(Headers, <<"From"/utf8>>),
                gleam@dict:get(Headers, <<"To"/utf8>>),
                gleam@dict:get(Headers, <<"Subject"/utf8>>),
                gleam@dict:get(Headers, <<"Message-ID"/utf8>>),
                case gleam@dict:get(Headers, <<"Date"/utf8>>) of
                    {ok, Date_str} ->
                        birl:parse(Date_str);

                    {error, _} ->
                        {error, nil}
                end,
                {ok, Body},
                begin
                    _pipe = Mbox,
                    get_headers(_pipe)
                end}
    end.

-spec main() -> nil.
main() ->
    _pipe = maildir_iterate(
        <<"/home/payas/.mail/Gmail/[Gmail]/All Mail/cur"/utf8>>
    ),
    gleam@iterator:each(
        _pipe,
        fun(Mboxpair) -> case parse(gleam@pair:second(Mboxpair)) of
                invalid_m_box ->
                    gleam@io:debug(
                        <<"ERR MBOX: "/utf8,
                            (gleam@pair:first(Mboxpair))/binary>>
                    );

                {m_box, Headers, Body} ->
                    case mbox_to_mail({m_box, Headers, Body}) of
                        invalid_mail ->
                            gleam@io:debug(
                                <<"ERR MAIL: "/utf8,
                                    (gleam@pair:first(Mboxpair))/binary>>
                            );

                        _ ->
                            gleam@io:debug(
                                <<"SUCCESS: "/utf8,
                                    (gleam@pair:first(Mboxpair))/binary>>
                            )
                    end
            end end
    ).