%%%-------------------------------------------------------------------
%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
%%% @copyright (C) 2016, Evgeny Khramtsov
%%% @doc
%%%
%%% @end
%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
%%%-------------------------------------------------------------------
-module(mod_shared_roster_mnesia).

-behaviour(mod_shared_roster).

%% API
-export([init/2, list_groups/1, groups_with_opts/1, create_group/3,
	 delete_group/2, get_group_opts/2, set_group_opts/3,
	 get_user_groups/2, get_group_explicit_users/2,
	 get_user_displayed_groups/3, is_user_in_group/3,
	 add_user_to_group/3, remove_user_from_group/3, import/2]).

-include("jlib.hrl").
-include("mod_roster.hrl").
-include("mod_shared_roster.hrl").
-include("logger.hrl").

%%%===================================================================
%%% API
%%%===================================================================
init(_Host, _Opts) ->
    mnesia:create_table(sr_group,
			[{disc_copies, [node()]},
			 {attributes, record_info(fields, sr_group)}]),
    mnesia:create_table(sr_user,
			[{disc_copies, [node()]}, {type, bag},
			 {attributes, record_info(fields, sr_user)}]),
    update_tables(),
    mnesia:add_table_index(sr_user, group_host).

list_groups(Host) ->
    mnesia:dirty_select(sr_group,
			[{#sr_group{group_host = {'$1', '$2'}, _ = '_'},
			  [{'==', '$2', Host}], ['$1']}]).

groups_with_opts(Host) ->
    Gs = mnesia:dirty_select(sr_group,
			     [{#sr_group{group_host = {'$1', Host}, opts = '$2',
					 _ = '_'},
			       [], [['$1', '$2']]}]),
    lists:map(fun ([G, O]) -> {G, O} end, Gs).

create_group(Host, Group, Opts) ->
    R = #sr_group{group_host = {Group, Host}, opts = Opts},
    F = fun () -> mnesia:write(R) end,
    mnesia:transaction(F).

delete_group(Host, Group) ->
    GroupHost = {Group, Host},
    F = fun () ->
		mnesia:delete({sr_group, GroupHost}),
		Users = mnesia:index_read(sr_user, GroupHost,
					  #sr_user.group_host),
		lists:foreach(fun (UserEntry) ->
				      mnesia:delete_object(UserEntry)
			      end,
			      Users)
	end,
    mnesia:transaction(F).

get_group_opts(Host, Group) ->
    case catch mnesia:dirty_read(sr_group, {Group, Host}) of
	[#sr_group{opts = Opts}] -> Opts;
	_ -> error
    end.

set_group_opts(Host, Group, Opts) ->
    R = #sr_group{group_host = {Group, Host}, opts = Opts},
    F = fun () -> mnesia:write(R) end,
    mnesia:transaction(F).

get_user_groups(US, Host) ->
    case catch mnesia:dirty_read(sr_user, US) of
	Rs when is_list(Rs) ->
	    [Group || #sr_user{group_host = {Group, H}} <- Rs, H == Host];
	_ ->
	    []
    end.

get_group_explicit_users(Host, Group) ->
    Read = (catch mnesia:dirty_index_read(sr_user,
					  {Group, Host}, #sr_user.group_host)),
    case Read of
	Rs when is_list(Rs) -> [R#sr_user.us || R <- Rs];
	_ -> []
    end.

get_user_displayed_groups(LUser, LServer, GroupsOpts) ->
    case catch mnesia:dirty_read(sr_user, {LUser, LServer}) of
	Rs when is_list(Rs) ->
	    [{Group, proplists:get_value(Group, GroupsOpts, [])}
	     || #sr_user{group_host = {Group, H}} <- Rs,
		H == LServer];
	_ ->
	    []
    end.

is_user_in_group(US, Group, Host) ->
    case mnesia:dirty_match_object(
	   #sr_user{us = US, group_host = {Group, Host}}) of
	[] -> false;
	_ -> true
    end.

add_user_to_group(Host, US, Group) ->
    R = #sr_user{us = US, group_host = {Group, Host}},
    F = fun () -> mnesia:write(R) end,
    mnesia:transaction(F).

remove_user_from_group(Host, US, Group) ->
    R = #sr_user{us = US, group_host = {Group, Host}},
    F = fun () -> mnesia:delete_object(R) end,
    mnesia:transaction(F).

import(_LServer, #sr_group{} = G) ->
    mnesia:dirty_write(G);
import(_LServer, #sr_user{} = U) ->
    mnesia:dirty_write(U).

%%%===================================================================
%%% Internal functions
%%%===================================================================
update_tables() ->
    update_sr_group_table(),
    update_sr_user_table().

update_sr_group_table() ->
    Fields = record_info(fields, sr_group),
    case mnesia:table_info(sr_group, attributes) of
        Fields ->
            ejabberd_config:convert_table_to_binary(
              sr_group, Fields, set,
              fun(#sr_group{group_host = {G, _}}) -> G end,
              fun(#sr_group{group_host = {G, H},
                            opts = Opts} = R) ->
                      R#sr_group{group_host = {iolist_to_binary(G),
                                               iolist_to_binary(H)},
                                 opts = mod_shared_roster:opts_to_binary(Opts)}
              end);
        _ ->
            ?INFO_MSG("Recreating sr_group table", []),
            mnesia:transform_table(sr_group, ignore, Fields)
    end.

update_sr_user_table() ->
    Fields = record_info(fields, sr_user),
    case mnesia:table_info(sr_user, attributes) of
        Fields ->
            ejabberd_config:convert_table_to_binary(
              sr_user, Fields, bag,
              fun(#sr_user{us = {U, _}}) -> U end,
              fun(#sr_user{us = {U, S}, group_host = {G, H}} = R) ->
                      R#sr_user{us = {iolist_to_binary(U), iolist_to_binary(S)},
                                group_host = {iolist_to_binary(G),
                                              iolist_to_binary(H)}}
              end);
        _ ->
            ?INFO_MSG("Recreating sr_user table", []),
            mnesia:transform_table(sr_user, ignore, Fields)
    end.