%%%-------------------------------------------------------------------
%%% File    : mod_muc_mnesia.erl
%%% Author  : Evgeny Khramtsov <ekhramtsov@process-one.net>
%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2017   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(mod_muc_mnesia).

-behaviour(mod_muc).
-behaviour(mod_muc_room).

%% API
-export([init/2, import/3, store_room/4, restore_room/3, forget_room/3,
	 can_use_nick/4, get_rooms/2, get_nick/3, set_nick/4]).
-export([register_online_room/4, unregister_online_room/4, find_online_room/3,
	 get_online_rooms/3, count_online_rooms/2, rsm_supported/0,
	 register_online_user/4, unregister_online_user/4,
	 count_online_rooms_by_user/3, get_online_rooms_by_user/3]).
-export([set_affiliation/6, set_affiliations/4, get_affiliation/5,
	 get_affiliations/3, search_affiliation/4]).
%% gen_server callbacks
-export([start_link/2, init/1, handle_cast/2, handle_call/3, handle_info/2,
	 terminate/2, code_change/3]).

-include("mod_muc.hrl").
-include("logger.hrl").
-include("xmpp.hrl").
-include_lib("stdlib/include/ms_transform.hrl").

-record(state, {}).

%%%===================================================================
%%% API
%%%===================================================================
init(Host, Opts) ->
    Spec = {?MODULE, {?MODULE, start_link, [Host, Opts]},
	    transient, 5000, worker, [?MODULE]},
    case supervisor:start_child(ejabberd_backend_sup, Spec) of
	{ok, _Pid} -> ok;
	Err -> Err
    end.

start_link(Host, Opts) ->
    Name = gen_mod:get_module_proc(Host, ?MODULE),
    gen_server:start_link({local, Name}, ?MODULE, [Host, Opts], []).

store_room(_LServer, Host, Name, Opts) ->
    F = fun () ->
		mnesia:write(#muc_room{name_host = {Name, Host},
				       opts = Opts})
	end,
    mnesia:transaction(F).

restore_room(_LServer, Host, Name) ->
    case catch mnesia:dirty_read(muc_room, {Name, Host}) of
	[#muc_room{opts = Opts}] -> Opts;
	_ -> error
    end.

forget_room(_LServer, Host, Name) ->
    F = fun () -> mnesia:delete({muc_room, {Name, Host}})
	end,
    mnesia:transaction(F).

can_use_nick(_LServer, Host, JID, Nick) ->
    {LUser, LServer, _} = jid:tolower(JID),
    LUS = {LUser, LServer},
    case catch mnesia:dirty_select(muc_registered,
				   [{#muc_registered{us_host = '$1',
						     nick = Nick, _ = '_'},
				     [{'==', {element, 2, '$1'}, Host}],
				     ['$_']}])
	of
      {'EXIT', _Reason} -> true;
      [] -> true;
      [#muc_registered{us_host = {U, _Host}}] -> U == LUS
    end.

get_rooms(_LServer, Host) ->
    mnesia:dirty_select(muc_room,
			[{#muc_room{name_host = {'_', Host},
				    _ = '_'},
			  [], ['$_']}]).

get_nick(_LServer, Host, From) ->
    {LUser, LServer, _} = jid:tolower(From),
    LUS = {LUser, LServer},
    case mnesia:dirty_read(muc_registered, {LUS, Host}) of
	[] -> error;
	[#muc_registered{nick = Nick}] -> Nick
    end.

set_nick(_LServer, Host, From, Nick) ->
    {LUser, LServer, _} = jid:tolower(From),
    LUS = {LUser, LServer},
    F = fun () ->
		case Nick of
		    <<"">> ->
			mnesia:delete({muc_registered, {LUS, Host}}),
			ok;
		    _ ->
			Allow = case mnesia:select(
				       muc_registered,
				       [{#muc_registered{us_host =
							     '$1',
							 nick = Nick,
							 _ = '_'},
					 [{'==', {element, 2, '$1'},
					   Host}],
					 ['$_']}]) of
				    [] -> true;
				    [#muc_registered{us_host = {U, _Host}}] ->
					U == LUS
				end,
			if Allow ->
				mnesia:write(#muc_registered{
						us_host = {LUS, Host},
						nick = Nick}),
				ok;
			   true ->
				false
			end
		end
	end,
    mnesia:transaction(F).

set_affiliation(_ServerHost, _Room, _Host, _JID, _Affiliation, _Reason) ->
    {error, not_implemented}.

set_affiliations(_ServerHost, _Room, _Host, _Affiliations) ->
    {error, not_implemented}.

get_affiliation(_ServerHost, _Room, _Host, _LUser, _LServer) ->
    {error, not_implemented}.

get_affiliations(_ServerHost, _Room, _Host) ->
    {error, not_implemented}.

search_affiliation(_ServerHost, _Room, _Host, _Affiliation) ->
    {error, not_implemented}.

register_online_room(_ServerHost, Room, Host, Pid) ->
    F = fun() ->
		mnesia:write(
		  #muc_online_room{name_host = {Room, Host}, pid = Pid})
	end,
    mnesia:transaction(F).

unregister_online_room(_ServerHost, Room, Host, Pid) ->
    F = fun () ->
		mnesia:delete_object(
		  #muc_online_room{name_host = {Room, Host}, pid = Pid})
	end,
    mnesia:transaction(F).

find_online_room(_ServerHost, Room, Host) ->
    find_online_room(Room, Host).

find_online_room(Room, Host) ->
    case mnesia:dirty_read(muc_online_room, {Room, Host}) of
	[] -> error;
	[#muc_online_room{pid = Pid}] -> {ok, Pid}
    end.

count_online_rooms(_ServerHost, Host) ->
    ets:select_count(
      muc_online_room,
      ets:fun2ms(
	fun(#muc_online_room{name_host = {_, H}}) ->
		H == Host
	end)).

get_online_rooms(_ServerHost, Host,
		 #rsm_set{max = Max, 'after' = After, before = undefined})
  when is_binary(After), After /= <<"">> ->
    lists:reverse(get_online_rooms(next, {After, Host}, Host, 0, Max, []));
get_online_rooms(_ServerHost, Host,
		 #rsm_set{max = Max, 'after' = undefined, before = Before})
  when is_binary(Before), Before /= <<"">> ->
    get_online_rooms(prev, {Before, Host}, Host, 0, Max, []);
get_online_rooms(_ServerHost, Host,
		 #rsm_set{max = Max, 'after' = undefined, before = <<"">>}) ->
    get_online_rooms(last, {<<"">>, Host}, Host, 0, Max, []);
get_online_rooms(_ServerHost, Host, #rsm_set{max = Max}) ->
    lists:reverse(get_online_rooms(first, {<<"">>, Host}, Host, 0, Max, []));
get_online_rooms(_ServerHost, Host, undefined) ->
    mnesia:dirty_select(
      muc_online_room,
      ets:fun2ms(
	fun(#muc_online_room{name_host = {Name, H}, pid = Pid})
	      when H == Host -> {Name, Host, Pid}
	end)).

-spec get_online_rooms(prev | next | last | first,
		       {binary(), binary()}, binary(),
		       non_neg_integer(), non_neg_integer() | undefined,
		       [{binary(), binary(), pid()}]) ->
			      [{binary(), binary(), pid()}].
get_online_rooms(_Action, _Key, _Host, Count, Max, Items) when Count >= Max ->
    Items;
get_online_rooms(Action, Key, Host, Count, Max, Items) ->
    Call = fun() ->
		   case Action of
		       prev -> mnesia:dirty_prev(muc_online_room, Key);
		       next -> mnesia:dirty_next(muc_online_room, Key);
		       last -> mnesia:dirty_last(muc_online_room);
		       first -> mnesia:dirty_first(muc_online_room)
		   end
	   end,
    NewAction = case Action of
		    last -> prev;
		    first -> next;
		    _ -> Action
		end,
    try Call() of
	'$end_of_table' ->
	    Items;
	{Room, Host} = NewKey ->
	    case find_online_room(Room, Host) of
		{ok, Pid} ->
		    get_online_rooms(NewAction, NewKey, Host,
				     Count + 1, Max, [{Room, Host, Pid}|Items]);
		error ->
		    get_online_rooms(NewAction, NewKey, Host,
				     Count, Max, Items)
	    end;
	NewKey ->
	    get_online_rooms(NewAction, NewKey, Host, Count, Max, Items)
    catch _:{aborted, {badarg, _}} ->
	    Items
    end.

rsm_supported() ->
    true.

register_online_user(_ServerHost, {U, S, R}, Room, Host) ->
    ets:insert(muc_online_users,
	       #muc_online_users{us = {U, S}, resource = R,
				 room = Room, host = Host}).

unregister_online_user(_ServerHost, {U, S, R}, Room, Host) ->
    ets:delete_object(muc_online_users,
		      #muc_online_users{us = {U, S}, resource = R,
					room = Room, host = Host}).

count_online_rooms_by_user(_ServerHost, U, S) ->
    ets:select_count(
      muc_online_users,
      ets:fun2ms(
	fun(#muc_online_users{us = {U1, S1}}) ->
		U == U1 andalso S == S1
	end)).

get_online_rooms_by_user(_ServerHost, U, S) ->
    ets:select(
      muc_online_users,
      ets:fun2ms(
	fun(#muc_online_users{us = {U1, S1}, room = Room, host = Host})
	      when U == U1 andalso S == S1 -> {Room, Host}
	end)).

import(_LServer, <<"muc_room">>,
       [Name, RoomHost, SOpts, _TimeStamp]) ->
    Opts = mod_muc:opts_to_binary(ejabberd_sql:decode_term(SOpts)),
    mnesia:dirty_write(
      #muc_room{name_host = {Name, RoomHost},
                opts = Opts});
import(_LServer, <<"muc_registered">>,
       [J, RoomHost, Nick, _TimeStamp]) ->
    #jid{user = U, server = S} = jid:decode(J),
    mnesia:dirty_write(
      #muc_registered{us_host = {{U, S}, RoomHost},
                      nick = Nick}).

%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
init([Host, Opts]) ->
    MyHost = proplists:get_value(host, Opts),
    case gen_mod:db_mod(Host, Opts, mod_muc) of
	?MODULE ->
	    ejabberd_mnesia:create(?MODULE, muc_room,
				   [{disc_copies, [node()]},
				    {attributes,
				     record_info(fields, muc_room)}]),
	    ejabberd_mnesia:create(?MODULE, muc_registered,
				   [{disc_copies, [node()]},
				    {attributes,
				     record_info(fields, muc_registered)},
				    {index, [nick]}]),
	    update_tables(MyHost);
	_ ->
	    ok
    end,
    case gen_mod:ram_db_mod(Host, Opts, mod_muc) of
	?MODULE ->
	    update_muc_online_table(),
	    ejabberd_mnesia:create(?MODULE, muc_online_room,
				   [{ram_copies, [node()]},
				    {type, ordered_set},
				    {attributes, record_info(fields, muc_online_room)}]),
	    mnesia:add_table_copy(muc_online_room, node(), ram_copies),
	    catch ets:new(muc_online_users, [bag, named_table, public, {keypos, 2}]),
	    clean_table_from_bad_node(node(), MyHost),
	    mnesia:subscribe(system);
	_ ->
	    ok
    end,
    {ok, #state{}}.

handle_call(_Request, _From, State) ->
    Reply = ok,
    {reply, Reply, State}.

handle_cast(_Msg, State) ->
    {noreply, State}.

handle_info({mnesia_system_event, {mnesia_down, Node}}, State) ->
    clean_table_from_bad_node(Node),
    {noreply, State};
handle_info(Info, State) ->
    ?ERROR_MSG("unexpected info: ~p", [Info]),
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%%===================================================================
%%% Internal functions
%%%===================================================================
clean_table_from_bad_node(Node) ->
    F = fun() ->
		Es = mnesia:select(
		       muc_online_room,
		       [{#muc_online_room{pid = '$1', _ = '_'},
			 [{'==', {node, '$1'}, Node}],
			 ['$_']}]),
		lists:foreach(fun(E) ->
				      mnesia:delete_object(E)
			      end, Es)
        end,
    mnesia:async_dirty(F).

clean_table_from_bad_node(Node, Host) ->
    F = fun() ->
		Es = mnesia:select(
		       muc_online_room,
		       [{#muc_online_room{pid = '$1',
					  name_host = {'_', Host},
					  _ = '_'},
			 [{'==', {node, '$1'}, Node}],
			 ['$_']}]),
		lists:foreach(fun(E) ->
				      mnesia:delete_object(E)
			      end, Es)
        end,
    mnesia:async_dirty(F).

update_tables(Host) ->
    update_muc_room_table(Host),
    update_muc_registered_table(Host).

update_muc_room_table(_Host) ->
    Fields = record_info(fields, muc_room),
    case mnesia:table_info(muc_room, attributes) of
      Fields ->
          ejabberd_config:convert_table_to_binary(
            muc_room, Fields, set,
            fun(#muc_room{name_host = {N, _}}) -> N end,
            fun(#muc_room{name_host = {N, H},
                          opts = Opts} = R) ->
                    R#muc_room{name_host = {iolist_to_binary(N),
                                            iolist_to_binary(H)},
                               opts = mod_muc:opts_to_binary(Opts)}
            end);
      _ ->
	  ?INFO_MSG("Recreating muc_room table", []),
	  mnesia:transform_table(muc_room, ignore, Fields)
    end.

update_muc_registered_table(_Host) ->
    Fields = record_info(fields, muc_registered),
    case mnesia:table_info(muc_registered, attributes) of
      Fields ->
          ejabberd_config:convert_table_to_binary(
            muc_registered, Fields, set,
            fun(#muc_registered{us_host = {_, H}}) -> H end,
            fun(#muc_registered{us_host = {{U, S}, H},
                                nick = Nick} = R) ->
                    R#muc_registered{us_host = {{iolist_to_binary(U),
                                                 iolist_to_binary(S)},
                                                iolist_to_binary(H)},
                                     nick = iolist_to_binary(Nick)}
            end);
      _ ->
	  ?INFO_MSG("Recreating muc_registered table", []),
	  mnesia:transform_table(muc_registered, ignore, Fields)
    end.

update_muc_online_table() ->
    try
	case mnesia:table_info(muc_online_room, type) of
	    ordered_set -> ok;
	    _ ->
		case mnesia:delete_table(muc_online_room) of
		    {atomic, ok} -> ok;
		    Err -> erlang:error(Err)
		end
	end
    catch _:{aborted, {no_exists, muc_online_room}} -> ok;
	  _:{aborted, {no_exists, muc_online_room, type}} -> ok;
	  E:R ->
	    ?ERROR_MSG("failed to update mnesia table '~s': ~p",
		       [muc_online_room, {E, R, erlang:get_stacktrace()}])
    end.