%%%----------------------------------------------------------------------
%%% File    : ejd2sql.erl
%%% Author  : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Export some mnesia tables to SQL DB
%%% Created : 22 Aug 2005 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2019   ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%----------------------------------------------------------------------

-module(ejd2sql).

-author('alexey@process-one.net').

-include("logger.hrl").
-include("ejabberd_sql_pt.hrl").

-export([export/2, export/3, import/3, import/4, delete/1, import_info/1]).


-define(MAX_RECORDS_PER_TRANSACTION, 100).

-record(sql_dump, {fd, type}).

%%%----------------------------------------------------------------------
%%% API
%%%----------------------------------------------------------------------
%%% How to use:
%%% A table can be converted from Mnesia to an ODBC database by calling
%%% one of the API function with the following parameters:
%%% - Server is the server domain you want to convert
%%% - Output can be either sql to export to the configured relational
%%%   database or "Filename" to export to text file.

modules() ->
    [ejabberd_auth,
     mod_announce,
     mod_caps,
     mod_last,
     mod_mam,
     mod_muc,
     mod_offline,
     mod_privacy,
     mod_private,
     mod_pubsub,
     mod_push,
     mod_roster,
     mod_shared_roster,
     mod_vcard].

export(Server, Output) ->
    LServer = jid:nameprep(iolist_to_binary(Server)),
    Modules = modules(),
    IO = prepare_output(Output),
    lists:foreach(
      fun(Module) ->
              export(LServer, IO, Module)
      end, Modules),
    close_output(Output, IO).

export(Server, Output, Module1) ->
    Module = case Module1 of
		 mod_pubsub -> pubsub_db;
		 _ -> Module1
	     end,
    SQLMod = gen_mod:db_mod(sql, Module),
    LServer = jid:nameprep(iolist_to_binary(Server)),
    IO = prepare_output(Output),
    lists:foreach(
      fun({Table, ConvertFun}) ->
              case export(LServer, Table, IO, ConvertFun) of
                  {atomic, ok} -> ok;
		  {aborted, {no_exists, _}} ->
		      ?WARNING_MSG("Ignoring export for module ~ts: "
				   "Mnesia table ~ts doesn't exist (most likely "
				   "because the module is unused)",
				   [Module1, Table]);
                  {aborted, Reason} ->
                      ?ERROR_MSG("Failed export for module ~p and table ~p: ~p",
                                 [Module, Table, Reason])
              end
      end, SQLMod:export(Server)),
    close_output(Output, IO).

delete(Server) ->
    Modules = modules(),
    lists:foreach(
      fun(Module) ->
              delete(Server, Module)
      end, Modules).

delete(Server, Module) ->
    LServer = jid:nameprep(iolist_to_binary(Server)),
    lists:foreach(
      fun({Table, ConvertFun}) ->
              delete(LServer, Table, ConvertFun)
      end, Module:export(Server)).

import(Server, Dir, ToType) ->
    lists:foreach(
      fun(Mod) ->
              ?INFO_MSG("Importing ~p...", [Mod]),
              import(Mod, Server, Dir, ToType)
      end, modules()).

import(Mod, Server, Dir, ToType) ->
    LServer = jid:nameprep(iolist_to_binary(Server)),
    try Mod:import_start(LServer, ToType)
    catch error:undef -> ok end,
    lists:foreach(
      fun({File, Tab, _Mod, FieldsNumber}) ->
              FileName = filename:join([Dir, File]),
              case open_sql_dump(FileName) of
                  {ok, #sql_dump{type = FromType} = Dump} ->
                      import_rows(LServer, {sql, FromType}, ToType,
                                  Tab, Mod, Dump, FieldsNumber),
                      close_sql_dump(Dump);
                  {error, enoent} ->
                      ok;
                  eof ->
                      ?INFO_MSG("It seems like SQL dump ~ts is empty", [FileName]);
                  Err ->
                      ?ERROR_MSG("Failed to open SQL dump ~ts: ~ts",
                                 [FileName, format_error(Err)])
              end
      end, import_info(Mod)),
    try Mod:import_stop(LServer, ToType)
    catch error:undef -> ok end.

import_info(Mod) ->
    Info = Mod:import_info(),
    lists:map(
      fun({Tab, FieldsNum}) ->
              FileName = <<Tab/binary, ".txt">>,
              {FileName, Tab, Mod, FieldsNum}
      end, Info).

%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
export(LServer, Table, IO, ConvertFun) ->
    F = fun () ->
                mnesia:read_lock_table(Table),
                {_N, SQLs} =
                    mnesia:foldl(
                      fun(R, {N, SQLs} = Acc) ->
                              case ConvertFun(LServer, R) of
                                  [] ->
                                      Acc;
                                  SQL1 ->
                                      SQL = format_queries(SQL1),
                                      if N < (?MAX_RECORDS_PER_TRANSACTION) - 1 ->
                                              {N + 1, [SQL | SQLs]};
                                         true ->
                                              output(LServer,
                                                     Table, IO,
                                                     flatten([SQL | SQLs])),
                                              {0, []}
                                      end
                              end
                      end,
                      {0, []}, Table),
                output(LServer, Table, IO, flatten(SQLs))
        end,
    mnesia:transaction(F).

output(_LServer, _Table, _IO, []) ->
    ok;
output(LServer, _Table, sql, SQLs) ->
    {atomic, ok} = ejabberd_sql:sql_transaction(LServer, SQLs),
    ok;
output(_LServer, Table, Fd, SQLs) ->
    file:write(Fd, ["-- \n-- Mnesia table: ", atom_to_list(Table),
                    "\n--\n", SQLs]).

delete(LServer, Table, ConvertFun) ->
    F = fun () ->
                mnesia:write_lock_table(Table),
                {_N, SQLs} =
                    mnesia:foldl(
                      fun(R, Acc) ->
                              case ConvertFun(LServer, R) of
                                  [] ->
                                      Acc;
                                  _SQL ->
				      mnesia:delete_object(R),
                                      Acc
                              end
                      end,
                      {0, []}, Table),
                delete(LServer, Table, SQLs)
        end,
    mnesia:transaction(F).

prepare_output(FileName) ->
    prepare_output(FileName, normal).

prepare_output(FileName, Type) when is_binary(FileName) ->
    prepare_output(binary_to_list(FileName), Type);
prepare_output(FileName, normal) when is_list(FileName) ->
    case file:open(FileName, [write, raw]) of
        {ok, Fd} ->
            Fd;
        {error, eacces} ->
            exit({"Not enough permission to the file or path", FileName});
        {error, enoent} ->
            exit({"Path does not exist", FileName});
        Err ->
            exit(Err)
    end;
prepare_output(Output, _Type) ->
    Output.

close_output(FileName, Fd) when FileName /= Fd ->
    file:close(Fd),
    ok;
close_output(_, _) ->
    ok.

flatten(SQLs) ->
    flatten(SQLs, []).

flatten([L|Ls], Acc) ->
    flatten(Ls, flatten1(lists:reverse(L), Acc));
flatten([], Acc) ->
    Acc.

flatten1([H|T], Acc) ->
    flatten1(T, [[H, $\n]|Acc]);
flatten1([], Acc) ->
    Acc.

import_rows(LServer, FromType, ToType, Tab, Mod, Dump, FieldsNumber) ->
    case read_row_from_sql_dump(Dump, FieldsNumber) of
        {ok, Fields} ->
            case catch Mod:import(LServer, FromType, ToType, Tab, Fields) of
                ok ->
                    ok;
                Err ->
                    ?ERROR_MSG("Failed to import fields ~p for tab ~p: ~p",
                               [Fields, Tab, Err])
            end,
            import_rows(LServer, FromType, ToType,
                        Tab, Mod, Dump, FieldsNumber);
        eof ->
            ok;
        Err ->
            ?ERROR_MSG("Failed to read row from SQL dump: ~ts",
                       [format_error(Err)])
    end.

open_sql_dump(FileName) ->
    case file:open(FileName, [raw, read, binary, read_ahead]) of
        {ok, Fd} ->
            case file:read(Fd, 11) of
                {ok, <<"PGCOPY\n", 16#ff, "\r\n", 0>>} ->
                    case skip_pgcopy_header(Fd) of
                        ok ->
                            {ok, #sql_dump{fd = Fd, type = pgsql}};
                        Err ->
                            Err
                    end;
                {ok, _} ->
                    file:position(Fd, 0),
                    {ok, #sql_dump{fd = Fd, type = mysql}};
                Err ->
                    Err
            end;
        Err ->
            Err
    end.

close_sql_dump(#sql_dump{fd = Fd}) ->
    file:close(Fd).

read_row_from_sql_dump(#sql_dump{fd = Fd, type = pgsql}, _) ->
    case file:read(Fd, 2) of
        {ok, <<(-1):16/signed>>} ->
            eof;
        {ok, <<FieldsNum:16>>} ->
            read_fields(Fd, FieldsNum, []);
        {ok, _} ->
            {error, eof};
        eof ->
            {error, eof};
        {error, _} = Err ->
            Err
    end;
read_row_from_sql_dump(#sql_dump{fd = Fd, type = mysql}, FieldsNum) ->
    read_lines(Fd, FieldsNum, <<"">>, []).

skip_pgcopy_header(Fd) ->
    try
        {ok, <<_:4/binary, ExtSize:32>>} = file:read(Fd, 8),
        {ok, <<_:ExtSize/binary>>} = file:read(Fd, ExtSize),
        ok
    catch error:{badmatch, {error, _} = Err} ->
            Err;
          error:{badmatch, _} ->
            {error, eof}
    end.

read_fields(_Fd, 0, Acc) ->
    {ok, lists:reverse(Acc)};
read_fields(Fd, N, Acc) ->
    case file:read(Fd, 4) of
        {ok, <<(-1):32/signed>>} ->
            read_fields(Fd, N-1, [null|Acc]);
        {ok, <<ValSize:32>>} ->
            case file:read(Fd, ValSize) of
                {ok, <<Val:ValSize/binary>>} ->
                    read_fields(Fd, N-1, [Val|Acc]);
                {ok, _} ->
                    {error, eof};
                Err ->
                    Err
            end;
        {ok, _} ->
            {error, eof};
        eof ->
            {error, eof};
        {error, _} = Err ->
            Err
    end.

read_lines(_Fd, 0, <<"">>, Acc) ->
    {ok, lists:reverse(Acc)};
read_lines(Fd, N, Buf, Acc) ->
    case file:read_line(Fd) of
        {ok, Data} when size(Data) >= 2 ->
            Size = size(Data) - 2,
            case Data of
                <<Val:Size/binary, 0, $\n>> ->
                    NewBuf = <<Buf/binary, Val/binary>>,
                    read_lines(Fd, N-1, <<"">>, [NewBuf|Acc]);
                _ ->
                    NewBuf = <<Buf/binary, Data/binary>>,
                    read_lines(Fd, N, NewBuf, Acc)
            end;
        {ok, Data} ->
            NewBuf = <<Buf/binary, Data/binary>>,
            read_lines(Fd, N, NewBuf, Acc);
        eof when Buf == <<"">>, Acc == [] ->
            eof;
        eof ->
            {error, eof};
        {error, _} = Err ->
            Err
    end.

format_error({error, eof}) ->
    "unexpected end of file";
format_error({error, Posix}) ->
    file:format_error(Posix).

format_queries(SQLs) ->
    lists:map(
      fun(#sql_query{} = SQL) ->
              ejabberd_sql:sql_query_to_iolist(SQL);
         (SQL) ->
              SQL
      end, SQLs).
