machi/src/machi_pb_translate.erl

%% -------------------------------------------------------------------
%%
%% Copyright (c) 2007-2015 Basho Technologies, Inc.  All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License.  You may obtain
%% a copy of the License at
%%
%%   http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied.  See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------

-module(machi_pb_translate).

%% @doc Adapt impedence mismatches between Erlang and Protocol Buffers.

-include("machi.hrl").
-include("machi_pb.hrl").
-include("machi_projection.hrl").

-export([from_pb_request/1,
         from_pb_response/1,
         to_pb_request/2,
         to_pb_response/3
        ]).

from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   echo=#mpb_echoreq{message=Msg}}) ->
    {ReqID, {low_echo, undefined, Msg}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   auth=#mpb_authreq{user=User, password=Pass}}) ->
    {ReqID, {low_auth, undefined, User, Pass}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   append_chunk=#mpb_ll_appendchunkreq{
                     epoch_id=PB_EpochID,
                     placement_key=PKey,
                     prefix=Prefix,
                     chunk=Chunk,
                     csum=#mpb_chunkcsum{type=CSum_type, csum=CSum},
                     chunk_extra=ChunkExtra}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    CSum_tag = conv_to_csum_tag(CSum_type),
    {ReqID, {low_append_chunk, EpochID, PKey, Prefix, Chunk, CSum_tag, CSum,
             ChunkExtra}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   write_chunk=#mpb_ll_writechunkreq{
                     epoch_id=PB_EpochID,
                     file=File,
                     offset=Offset,
                     chunk=Chunk,
                     csum=#mpb_chunkcsum{type=CSum_type, csum=CSum}}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    CSum_tag = conv_to_csum_tag(CSum_type),
    {ReqID, {low_write_chunk, EpochID, File, Offset, Chunk, CSum_tag, CSum}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   read_chunk=#mpb_ll_readchunkreq{
                     epoch_id=PB_EpochID,
                     file=File,
                     offset=Offset,
                     size=Size,
                     flag_get_checksum=PB_GetChecksum,
                     flag_no_chunk=PB_GetNoChunk}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    Opts = [{get_checksum, conv_to_boolean(PB_GetChecksum)},
            {no_chunk, conv_to_boolean(PB_GetNoChunk)}],
    {ReqID, {low_read_chunk, EpochID, File, Offset, Size, Opts}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   checksum_list=#mpb_ll_checksumlistreq{
                     epoch_id=PB_EpochID,
                     file=File}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    {ReqID, {low_checksum_list, EpochID, File}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   list_files=#mpb_ll_listfilesreq{
                     epoch_id=PB_EpochID}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    {ReqID, {low_list_files, EpochID}};
from_pb_request(#mpb_ll_request{
                   req_id=ReqID,
                   wedge_status=#mpb_ll_wedgestatusreq{}}) ->
    {ReqID, {low_wedge_status, undefined}};
%%qqq
from_pb_request(#mpb_request{req_id=ReqID,
                             echo=#mpb_echoreq{message=Msg}}) ->
    {ReqID, {high_echo, Msg}};
from_pb_request(#mpb_request{req_id=ReqID,
                             auth=#mpb_authreq{user=User, password=Pass}}) ->
    {ReqID, {high_auth, User, Pass}};
from_pb_request(#mpb_request{req_id=ReqID,
                             append_chunk=IR=#mpb_appendchunkreq{}}) ->
    #mpb_appendchunkreq{placement_key=__todoPK,
                        prefix=Prefix,
                        chunk=Chunk,
                        csum=CSum,
                        chunk_extra=ChunkExtra} = IR,
    TaggedCSum = make_tagged_csum(CSum, Chunk),
    {ReqID, {high_append_chunk, __todoPK, Prefix, Chunk, TaggedCSum,
             ChunkExtra}};
from_pb_request(#mpb_request{req_id=ReqID,
                             write_chunk=IR=#mpb_writechunkreq{}}) ->
    #mpb_writechunkreq{file=File,
                       offset=Offset,
                       chunk=Chunk,
                       csum=CSum} = IR,
    TaggedCSum = make_tagged_csum(CSum, Chunk),
    {ReqID, {high_write_chunk, File, Offset, Chunk, TaggedCSum}};
from_pb_request(#mpb_request{req_id=ReqID,
                             read_chunk=IR=#mpb_readchunkreq{}}) ->
    #mpb_readchunkreq{file=File,
                      offset=Offset,
                      size=Size} = IR,
    {ReqID, {high_read_chunk, File, Offset, Size}};
from_pb_request(#mpb_request{req_id=ReqID,
                             checksum_list=IR=#mpb_checksumlistreq{}}) ->
    #mpb_checksumlistreq{file=File} = IR,
    {ReqID, {high_checksum_list, File}};
from_pb_request(#mpb_request{req_id=ReqID,
                             list_files=_IR=#mpb_listfilesreq{}}) ->
    {ReqID, {high_list_files}};
from_pb_request(#mpb_request{req_id=ReqID}) ->
    {ReqID, {high_error, 999966, "Unknown request"}};
from_pb_request(_Else) ->
    io:format(user, "\nRRR from_pb_request(~p)\n", [_Else]), timer:sleep(2000),
    {<<>>, {high_error, 999667, "Unknown PB request"}}.

from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    echo=#mpb_echoresp{message=Msg}}) ->
    {ReqID, Msg};
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    auth=#mpb_authresp{code=Code}}) ->
    {ReqID, Code};
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    append_chunk=#mpb_ll_appendchunkresp{status=Status,
                                                        chunk_pos=ChunkPos}}) ->
    case Status of
        'OK' ->
            #mpb_chunkpos{offset=Offset,
                          chunk_size=Size,
                          file_name=File} = ChunkPos,
            {ReqID, {ok, {Offset, Size, File}}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    write_chunk=#mpb_ll_writechunkresp{status=Status}}) ->
    {ReqID, machi_pb_high_client:convert_general_status_code(Status)};
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    read_chunk=#mpb_ll_readchunkresp{status=Status,
                                                     chunk=Chunk}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, Chunk}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    checksum_list=#mpb_ll_checksumlistresp{
                      status=Status, chunk=Chunk}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, Chunk}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    list_files=#mpb_ll_listfilesresp{
                      status=Status, files=PB_Files}}) ->
    case Status of
        'OK' ->
            Files = [{Size, Name} ||
                        #mpb_fileinfo{file_size=Size,
                                      file_name=Name} <- PB_Files],
            {ReqID, {ok, Files}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    wedge_status=#mpb_ll_wedgestatusresp{
                      epoch_id=PB_EpochID, wedged_flag=PB_Wedged}}) ->
    EpochID = conv_to_epoch_id(PB_EpochID),
    Wedged_p = if PB_Wedged == 1 -> true;
                  PB_Wedged == 0 -> false
               end,
    {ReqID, {ok, {Wedged_p, EpochID}}};
%%qqq
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_gl=#mpb_ll_getlatestepochidresp{
                      status=Status, epoch_id=EID}}) ->
    case Status of
        'OK' ->
            #mpb_epochid{epoch_number=Epoch, epoch_csum=CSum} = EID,
            {ReqID, {ok, {Epoch, CSum}}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_rl=#mpb_ll_readlatestprojectionresp{
                      status=Status, proj=P}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, conv_to_projection_v1(P)}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_rp=#mpb_ll_readprojectionresp{
                      status=Status, proj=P}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, conv_to_projection_v1(P)}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_wp=#mpb_ll_writeprojectionresp{
                      status=Status}}) ->
    {ReqID, machi_pb_high_client:convert_general_status_code(Status)};
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_ga=#mpb_ll_getallprojectionsresp{
                      status=Status, projs=ProjsM}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, [conv_to_projection_v1(ProjM) || ProjM <- ProjsM]}};
        _ ->
            {ReqID, machi_pb_high_client:convert_general_status_code(Status)}
    end;
from_pb_response(#mpb_ll_response{
                    req_id=ReqID,
                    proj_la=#mpb_ll_listallprojectionsresp{
                      status=Status, epochs=Epochs}}) ->
    case Status of
        'OK' ->
            {ReqID, {ok, Epochs}};
        _ ->
            {ReqID< machi_pb_high_client:convert_general_status_code(Status)}
    end.

%% TODO: move the #mbp_* record making code from
%%       machi_pb_high_client:do_send_sync() clauses into to_pb_request().

to_pb_request(ReqID, {low_echo, _BogusEpochID, Msg}) ->
    #mpb_ll_request{
               req_id=ReqID,
               echo=#mpb_echoreq{message=Msg}};
to_pb_request(ReqID, {low_auth, _BogusEpochID, User, Pass}) ->
    #mpb_ll_request{req_id=ReqID,
                    auth=#mpb_authreq{user=User, password=Pass}};
to_pb_request(ReqID, {low_append_chunk, EpochID, PKey, Prefix, Chunk,
                      CSum_tag, CSum, ChunkExtra}) ->
    PB_EpochID = conv_from_epoch_id(EpochID),
    CSum_type = conv_from_csum_tag(CSum_tag),
    PB_CSum = #mpb_chunkcsum{type=CSum_type, csum=CSum},
    #mpb_ll_request{req_id=ReqID,
                    append_chunk=#mpb_ll_appendchunkreq{
                      epoch_id=PB_EpochID,
                      placement_key=PKey,
                      prefix=Prefix,
                      chunk=Chunk,
                      csum=PB_CSum,
                      chunk_extra=ChunkExtra}};
to_pb_request(ReqID, {low_write_chunk, EpochID, File, Offset, Chunk, CSum_tag, CSum}) ->
    PB_EpochID = conv_from_epoch_id(EpochID),
    CSum_type = conv_from_csum_tag(CSum_tag),
    PB_CSum = #mpb_chunkcsum{type=CSum_type, csum=CSum},
    #mpb_ll_request{req_id=ReqID,
                    write_chunk=#mpb_ll_writechunkreq{
                      epoch_id=PB_EpochID,
                      file=File,
                      offset=Offset,
                      chunk=Chunk,
                      csum=PB_CSum}};
to_pb_request(ReqID, {low_read_chunk, EpochID, File, Offset, Size, _Opts}) ->
    %% TODO: stop ignoring Opts ^_^
    PB_EpochID = conv_from_epoch_id(EpochID),
    #mpb_ll_request{
               req_id=ReqID,
               read_chunk=#mpb_ll_readchunkreq{
                 epoch_id=PB_EpochID,
                 file=File,
                 offset=Offset,
                 size=Size}};
to_pb_request(ReqID, {low_checksum_list, EpochID, File}) ->
    PB_EpochID = conv_from_epoch_id(EpochID),
    #mpb_ll_request{
                     req_id=ReqID,
                     checksum_list=#mpb_ll_checksumlistreq{epoch_id=PB_EpochID,
                                                           file=File}};
to_pb_request(ReqID, {low_list_files, EpochID}) ->
    PB_EpochID = conv_from_epoch_id(EpochID),
    #mpb_ll_request{req_id=ReqID,
                    list_files=#mpb_ll_listfilesreq{epoch_id=PB_EpochID}};
to_pb_request(ReqID, {low_wedge_status, _BogusEpochID}) ->
    #mpb_ll_request{req_id=ReqID,
                    wedge_status=#mpb_ll_wedgestatusreq{}}.
%%qqq

to_pb_response(ReqID, {low_echo, _BogusEpochID, _Msg}, Resp) ->
    #mpb_ll_response{
                req_id=ReqID,
                echo=#mpb_echoresp{message=Resp}};
to_pb_response(ReqID, {low_auth, _, _, _}, Resp) ->
    #mpb_ll_response{
                req_id=ReqID,
                auth=#mpb_authresp{code=Resp}};
to_pb_response(ReqID, {low_append_chunk, _EID, _PKey, _Pfx, _Ch, _CST, _CS, _CE}, Resp)->
    case Resp of
        {ok, {Offset, Size, File}} ->
            Where = #mpb_chunkpos{offset=Offset,
                                  chunk_size=Size,
                                  file_name=File},
            #mpb_ll_response{req_id=ReqID,
                             append_chunk=#mpb_ll_appendchunkresp{status='OK',
                                                              chunk_pos=Where}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_ll_response{req_id=ReqID,
                           append_chunk=#mpb_ll_appendchunkresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {low_write_chunk, _EID, _Fl, _Off, _Ch, _CST, _CS},Resp)->
    Status = conv_from_status(Resp),
    #mpb_ll_response{req_id=ReqID,
                     write_chunk=#mpb_ll_writechunkresp{status=Status}};
to_pb_response(ReqID, {low_read_chunk, _EID, _Fl, _Off, _Sz, _Opts}, Resp)->
    case Resp of
        {ok, Chunk} ->
            CSum = undefined,                   % TODO not implemented
            #mpb_ll_response{req_id=ReqID,
                             read_chunk=#mpb_ll_readchunkresp{status='OK',
                                                              chunk=Chunk,
                                                              csum=CSum}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_ll_response{req_id=ReqID,
                             read_chunk=#mpb_ll_readchunkresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {low_checksum_list, _EpochID, _File}, Resp) ->
    case Resp of
        {ok, Chunk} ->
            #mpb_ll_response{req_id=ReqID,
                           checksum_list=#mpb_ll_checksumlistresp{status='OK',
                                                                  chunk=Chunk}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_ll_response{req_id=ReqID,
                         checksum_list=#mpb_ll_checksumlistresp{status=Status}};
        _Else ->
            make_ll_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {low_list_files, _EpochID}, Resp) ->
    case Resp of
        {ok, FileInfo} ->
            PB_Files = [#mpb_fileinfo{file_size=Size, file_name=Name} ||
                           {Size, Name} <- FileInfo],
            #mpb_ll_response{req_id=ReqID,
                             list_files=#mpb_ll_listfilesresp{status='OK',
                                                              files=PB_Files}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_ll_response{req_id=ReqID,
                         list_files=#mpb_ll_listfilesresp{status=Status}};
        _Else ->
            make_ll_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {low_wedge_status, _BogusEpochID}, Resp) ->
    {Wedged_p, EpochID} = Resp,
    PB_Wedged = conv_from_boolean(Wedged_p),
    PB_EpochID = conv_from_epoch_id(EpochID),
    #mpb_ll_response{req_id=ReqID,
                     wedge_status=#mpb_ll_wedgestatusresp{epoch_id=PB_EpochID,
                                                        wedged_flag=PB_Wedged}};
%%qqq
to_pb_response(ReqID, {high_echo, _Msg}, Resp) ->
    Msg = Resp,
    #mpb_response{req_id=ReqID,
                  echo=#mpb_echoresp{message=Msg}};
to_pb_response(ReqID, {high_auth, _User, _Pass}, _Resp) ->
    #mpb_response{req_id=ReqID,
                  generic=#mpb_errorresp{code=1,
                                         msg="AUTH not implemented"}};
to_pb_response(ReqID, {high_append_chunk, _TODO, _Prefix, _Chunk, _TSum, _CE}, Resp)->
    case Resp of
        {ok, {Offset, Size, File}} ->
            Where = #mpb_chunkpos{offset=Offset,
                                  chunk_size=Size,
                                  file_name=File},
            #mpb_response{req_id=ReqID,
                          append_chunk=#mpb_appendchunkresp{status='OK',
                                                            chunk_pos=Where}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_response{req_id=ReqID,
                          append_chunk=#mpb_appendchunkresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {high_write_chunk, _File, _Offset, _Chunk, _TaggedCSum}, Resp) ->
    case Resp of
        {ok, {_,_,_}} ->
            %% machi_cr_client returns ok 2-tuple, convert to simple ok.
            #mpb_response{req_id=ReqID,
                          write_chunk=#mpb_writechunkresp{status='OK'}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_response{req_id=ReqID,
                          write_chunk=#mpb_writechunkresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {high_read_chunk, _File, _Offset, _Size}, Resp) ->
    case Resp of
        {ok, Chunk} ->
            #mpb_response{req_id=ReqID,
                          read_chunk=#mpb_readchunkresp{status='OK',
                                                        chunk=Chunk}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_response{req_id=ReqID,
                          read_chunk=#mpb_readchunkresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {high_checksum_list, _File}, Resp) ->
    case Resp of
        {ok, Chunk} ->
            #mpb_response{req_id=ReqID,
                          checksum_list=#mpb_checksumlistresp{status='OK',
                                                              chunk=Chunk}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_response{req_id=ReqID,
                          checksum_list=#mpb_checksumlistresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {high_list_files}, Resp) ->
    case Resp of
        {ok, FileInfo} ->
            Files = [#mpb_fileinfo{file_size=Size, file_name=Name} ||
                        {Size, Name} <- FileInfo],
            #mpb_response{req_id=ReqID,
                          list_files=#mpb_listfilesresp{status='OK',
                                                        files=Files}};
        {error, _}=Error ->
            Status = conv_from_status(Error),
            #mpb_response{req_id=ReqID,
                          list_files=#mpb_listfilesresp{status=Status}};
        _Else ->
            make_error_resp(ReqID, 66, io_lib:format("err ~p", [_Else]))
    end;
to_pb_response(ReqID, {high_error, _, _}, {ErrCode, ErrMsg}) ->
    make_error_resp(ReqID, ErrCode, ErrMsg).

make_tagged_csum(#mpb_chunkcsum{type='CSUM_TAG_NONE'}, Chunk) ->
    C = machi_util:checksum_chunk(Chunk),
    machi_util:make_tagged_csum(server_sha, C);
make_tagged_csum(#mpb_chunkcsum{type='CSUM_TAG_CLIENT_SHA', csum=CSum}, _CB) ->
    machi_util:make_tagged_csum(client_sha, CSum).

make_ll_error_resp(ReqID, Code, Msg) ->
    #mpb_ll_response{req_id=ReqID,
                     generic=#mpb_errorresp{code=Code,
                                            msg=Msg}}.    

make_error_resp(ReqID, Code, Msg) ->
    #mpb_response{req_id=ReqID,
                  generic=#mpb_errorresp{code=Code,
                                         msg=Msg}}.    

conv_from_epoch_id({Epoch, EpochCSum}) ->
    #mpb_epochid{epoch_number=Epoch,
                 epoch_csum=EpochCSum}.

conv_to_epoch_id(#mpb_epochid{epoch_number=Epoch,
                              epoch_csum=EpochCSum}) ->
    {Epoch, EpochCSum}.

conv_to_projection_v1(#mpb_projectionv1{epoch_number=Epoch,
                                        epoch_csum=CSum,
                                        author_server=Author,
                                        all_members=AllMembers,
                                        creation_time=CTime,
                                        mode=Mode,
                                        upi=UPI,
                                        repairing=Repairing,
                                        down=Down,
                                        opaque_flap=Flap,
                                        opaque_inner=Inner,
                                        opaque_dbg=Dbg,
                                        opaque_dbg2=Dbg2,
                                        members_dict=MembersDict}) ->
    #projection_v1{epoch_number=Epoch,
                   epoch_csum=CSum,
                   author_server=to_atom(Author),
                   all_members=[to_atom(X) || X <- AllMembers],
                   creation_time=conv_to_now(CTime),
                   mode=conv_to_mode(Mode),
                   upi=[to_atom(X) || X <- UPI],
                   repairing=[to_atom(X) || X <- Repairing],
                   down=[to_atom(X) || X <- Down],
                   flap=dec_optional_sexp(Flap),
                   inner=dec_optional_sexp(Inner),
                   dbg=dec_sexp(Dbg),
                   dbg2=dec_sexp(Dbg2),
                   members_dict=conv_to_members_dict(MembersDict)}.

enc_sexp(T) ->
    term_to_binary(T).

dec_sexp(Bin) when is_binary(Bin) ->
    binary_to_term(Bin).

enc_optional_sexp(undefined) ->
    undefined;
enc_optional_sexp(T) ->
    enc_sexp(T).

dec_optional_sexp(undefined) ->
    undefined;
dec_optional_sexp(T) ->
    dec_sexp(T).

conv_from_members_dict(D) ->
    %% Use list_to_binary() here to "flatten" the serialized #p_srvr{}
    [#mpb_membersdictentry{key=to_list(K), val=conv_from_p_srvr(V)} ||
        {K, V} <- orddict:to_list(D)].

conv_to_members_dict(List) ->
    orddict:from_list([{to_atom(K), conv_to_p_srvr(V)} ||
                          #mpb_membersdictentry{key=K, val=V} <- List]).

conv_from_p_srvr(#p_srvr{name=Name,
                         proto_mod=ProtoMod,
                         address=Address,
                         port=Port,
                         props=Props}) ->
    #mpb_p_srvr{name=to_list(Name),
                proto_mod=to_list(ProtoMod),
                address=to_list(Address),
                port=to_list(Port),
                opaque_props=enc_sexp(Props)}.

conv_to_p_srvr(#mpb_p_srvr{name=Name,
                           proto_mod=ProtoMod,
                           address=Address,
                           port=Port,
                           opaque_props=Props}) ->
    #p_srvr{name=to_atom(Name),
            proto_mod=to_atom(ProtoMod),
            address=to_list(Address),
            port=to_integer(Port),
            props=dec_sexp(Props)}.

to_list(X) when is_atom(X) ->
    atom_to_list(X);
to_list(X) when is_binary(X) ->
    binary_to_list(X);
to_list(X) when is_integer(X) ->
    integer_to_list(X);
to_list(X) when is_list(X) ->
    X.

to_atom(X) when is_list(X) ->
    list_to_atom(X);
to_atom(X) when is_binary(X) ->
    erlang:binary_to_atom(X, latin1);
to_atom(X) when is_atom(X) ->
    X.

to_integer(X) when is_list(X) ->
    list_to_integer(X);
to_integer(X) when is_binary(X) ->
    list_to_binary(binary_to_list(X));
to_integer(X) when is_integer(X) ->
    X.

conv_from_csum_tag(CSum_tag) ->
    case CSum_tag of
        ?CSUM_TAG_NONE -> 'CSUM_TAG_NONE';
        ?CSUM_TAG_CLIENT_SHA -> 'CSUM_TAG_CLIENT_SHA';
        ?CSUM_TAG_SERVER_SHA -> 'CSUM_TAG_SERVER_SHA';
        ?CSUM_TAG_SERVER_REGEN_SHA -> 'CSUM_TAG_SERVER_REGEN_SHA'
    end.

conv_to_csum_tag(Type) ->
    case Type of
        'CSUM_TAG_NONE' -> ?CSUM_TAG_NONE;
        'CSUM_TAG_CLIENT_SHA' -> ?CSUM_TAG_CLIENT_SHA;
        'CSUM_TAG_SERVER_SHA' -> ?CSUM_TAG_SERVER_SHA;
        'CSUM_TAG_SERVER_REGEN_SHA' -> ?CSUM_TAG_SERVER_REGEN_SHA
    end.

conv_from_now({A,B,C}) ->
    #mpb_now{sec=(1000000 * A) + B,
             usec=C}.

conv_to_now(#mpb_now{sec=Sec, usec=USec}) ->
    {Sec div 1000000, Sec rem 1000000, USec}.

conv_from_mode(ap_mode) -> 'AP_MODE';
conv_from_mode(cp_mode) -> 'CP_MODE'.

conv_to_mode('AP_MODE') -> ap_mode;
conv_to_mode('CP_MODE') -> cp_mode.

conv_from_type(private) -> 'PRIVATE';
conv_from_type(public)  -> 'PUBLIC'.

conv_to_type('PRIVATE') -> private;
conv_to_type('PUBLIC')  -> public.

conv_from_status(ok) ->
    'OK';
conv_from_status({error, bad_arg}) ->
    'BAD_ARG';
conv_from_status({error, wedged}) ->
    'WEDGED';
conv_from_status({error, bad_checksum}) ->
    'BAD_CHECKSUM';
conv_from_status({error, partition}) ->
    'PARTITION';
conv_from_status({error, not_written}) ->
    'NOT_WRITTEN';
conv_from_status({error, written}) ->
    'WRITTEN';
conv_from_status({error, no_such_file}) ->
    'NO_SUCH_FILE';
conv_from_status({error, partial_read}) ->
    'PARTIAL_READ';
conv_from_status(_OOPS) ->
    io:format(user, "HEY, ~s:~w got ~w\n", [?MODULE, ?LINE, _OOPS]),
    'BAD_JOSS'.

conv_to_boolean(undefined) ->
    false;
conv_to_boolean(0) ->
    false;
conv_to_boolean(N) when is_integer(N) ->
    true.

conv_from_boolean(false) ->
    0;
conv_from_boolean(true) ->
    1.