%%%-------------------------------------------------------------------
%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
%%% @copyright (C) 2016, Evgeny Khramtsov
%%% @doc
%%%
%%% @end
%%% Created :  2 Mar 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
%%%-------------------------------------------------------------------
-module(mod_mix).

-behaviour(gen_server).
-behaviour(gen_mod).

%% API
-export([start_link/2, start/2, stop/1, process_iq/3,
	 disco_items/5, disco_identity/5, disco_info/5,
	 disco_features/5, mod_opt_type/1]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).

-include("logger.hrl").
-include("jlib.hrl").
-include("pubsub.hrl").

-define(PROCNAME, ejabberd_mod_mix).
-define(NODES, [?NS_MIX_NODES_MESSAGES,
		?NS_MIX_NODES_PRESENCE,
		?NS_MIX_NODES_PARTICIPANTS,
		?NS_MIX_NODES_SUBJECT,
		?NS_MIX_NODES_CONFIG]).

-record(state, {server_host :: binary(),
		host :: binary()}).

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

start(Host, Opts) ->
    Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
    ChildSpec = {Proc, {?MODULE, start_link, [Host, Opts]},
		 temporary, 5000, worker, [?MODULE]},
    supervisor:start_child(ejabberd_sup, ChildSpec).

stop(Host) ->
    Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
    supervisor:terminate_child(ejabberd_sup, Proc),
    supervisor:delete_child(ejabberd_sup, Proc),
    ok.

disco_features(_Acc, _From, _To, _Node, _Lang) ->
    {result, [?NS_MIX_0]}.

disco_items(_Acc, _From, To, _Node, _Lang) when To#jid.luser /= <<"">> ->
    To_s = jid:to_string(jid:remove_resource(To)),
    {result, [#xmlel{name = <<"item">>,
		     attrs = [{<<"jid">>, To_s},
			      {<<"node">>, Node}]} || Node <- ?NODES]};
disco_items(_Acc, _From, _To, _Node, _Lang) ->
    {result, []}.

disco_identity(Acc, _From, To, _Node, _Lang) when To#jid.luser == <<"">> ->
    Acc ++ [#xmlel{name = <<"identity">>,
		   attrs =
		       [{<<"category">>, <<"conference">>},
			{<<"name">>, <<"MIX service">>},
			{<<"type">>, <<"text">>}]}];
disco_identity(Acc, _From, _To, _Node, _Lang) ->
    Acc ++ [#xmlel{name = <<"identity">>,
		   attrs =
		       [{<<"category">>, <<"conference">>},
			{<<"type">>, <<"mix">>}]}].

disco_info(_Acc, _From, To, _Node, _Lang) when is_atom(To) ->
    [#xmlel{name = <<"x">>,
	    attrs = [{<<"xmlns">>, ?NS_XDATA},
		     {<<"type">>, <<"result">>}],
	    children = [#xmlel{name = <<"field">>,
			       attrs = [{<<"var">>, <<"FORM_TYPE">>},
					{<<"type">>, <<"hidden">>}],
			       children = [#xmlel{name = <<"value">>,
						  children = [{xmlcdata,
							       ?NS_MIX_SERVICEINFO_0}]}]}]}];
disco_info(Acc, _From, _To, _Node, _Lang) ->
    Acc.

process_iq(From, To,
	   #iq{type = set, sub_el = #xmlel{name = <<"join">>} = SubEl} = IQ) ->
    Nodes = lists:flatmap(
	      fun(#xmlel{name = <<"subscribe">>, attrs = Attrs}) ->
		      Node = fxml:get_attr_s(<<"node">>, Attrs),
		      case lists:member(Node, ?NODES) of
			  true -> [Node];
			  false -> []
		      end;
		 (_) ->
		      []
	      end, SubEl#xmlel.children),
    case subscribe_nodes(From, To, Nodes) of
	{result, _} ->
	    case publish_participant(From, To) of
		{result, _} ->
		    LFrom_s = jid:to_string(jid:tolower(jid:remove_resource(From))),
		    Subscribe = [#xmlel{name = <<"subscribe">>,
					attrs = [{<<"node">>, Node}]} || Node <- Nodes],
		    IQ#iq{type = result,
			  sub_el = [#xmlel{name = <<"join">>,
					   attrs = [{<<"jid">>, LFrom_s},
						    {<<"xmlns">>, ?NS_MIX_0}],
					   children = Subscribe}]};
		{error, Err} ->
		    IQ#iq{type = error, sub_el = [SubEl, Err]}
	    end;
	{error, Err} ->
	    IQ#iq{type = error, sub_el = [SubEl, Err]}
    end;
process_iq(From, To,
	   #iq{type = set, sub_el = #xmlel{name = <<"leave">>} = SubEl} = IQ) ->
    case delete_participant(From, To) of
	{result, _} ->
	    case unsubscribe_nodes(From, To, ?NODES) of
		{result, _} ->
		    IQ#iq{type = result, sub_el = []};
		{error, Err} ->
		    IQ#iq{type = error, sub_el = [SubEl, Err]}
	    end;
	{error, Err} ->
	    IQ#iq{type = error, sub_el = [SubEl, Err]}
    end;
process_iq(_From, _To, #iq{sub_el = SubEl} = IQ) ->
    IQ#iq{type = error, sub_el = [SubEl, ?ERR_BAD_REQUEST]}.

%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
init([ServerHost, Opts]) ->
    Host = gen_mod:get_opt_host(ServerHost, Opts, <<"mix.@HOST@">>),
    IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                             one_queue),
    ConfigTab = gen_mod:get_module_proc(Host, config),
    ets:new(ConfigTab, [named_table]),
    ets:insert(ConfigTab, {plugins, [<<"mix">>]}),
    ejabberd_hooks:add(disco_local_items, Host, ?MODULE, disco_items, 100),
    ejabberd_hooks:add(disco_local_features, Host, ?MODULE, disco_features, 100),
    ejabberd_hooks:add(disco_local_identity, Host, ?MODULE, disco_identity, 100),
    ejabberd_hooks:add(disco_sm_items, Host, ?MODULE, disco_items, 100),
    ejabberd_hooks:add(disco_sm_features, Host, ?MODULE, disco_features, 100),
    ejabberd_hooks:add(disco_sm_identity, Host, ?MODULE, disco_identity, 100),
    ejabberd_hooks:add(disco_info, Host, ?MODULE, disco_info, 100),
    gen_iq_handler:add_iq_handler(ejabberd_local, Host,
				  ?NS_DISCO_ITEMS, mod_disco,
				  process_local_iq_items, IQDisc),
    gen_iq_handler:add_iq_handler(ejabberd_local, Host,
				  ?NS_DISCO_INFO, mod_disco,
				  process_local_iq_info, IQDisc),
    gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
				  ?NS_DISCO_ITEMS, mod_disco,
				  process_local_iq_items, IQDisc),
    gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
				  ?NS_DISCO_INFO, mod_disco,
				  process_local_iq_info, IQDisc),
    gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
				  ?NS_PUBSUB, mod_pubsub, iq_sm, IQDisc),
    gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
				  ?NS_MIX_0, ?MODULE, process_iq, IQDisc),
    ejabberd_router:register_route(Host, ServerHost),
    {ok, #state{server_host = ServerHost, host = Host}}.

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

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

handle_info({route, From, To, Packet}, State) ->
    case catch do_route(State, From, To, Packet) of
	{'EXIT', _} = Err ->
	    try
		?ERROR_MSG("failed to route packet ~p from '~s' to '~s': ~p",
			   [Packet, jid:to_string(From), jid:to_string(To), Err]),
		ErrPkt = jlib:make_error_reply(Packet, ?ERR_INTERNAL_SERVER_ERROR),
		ejabberd_router:route_error(To, From, ErrPkt, Packet)
	    catch _:_ ->
		    ok
	    end;
	_ ->
	    ok
    end,
    {noreply, State};
handle_info(_Info, State) ->
    {noreply, State}.

terminate(_Reason, #state{host = Host}) ->
    ejabberd_hooks:delete(disco_local_items, Host, ?MODULE, disco_items, 100),
    ejabberd_hooks:delete(disco_local_features, Host, ?MODULE, disco_features, 100),
    ejabberd_hooks:delete(disco_local_identity, Host, ?MODULE, disco_identity, 100),
    ejabberd_hooks:delete(disco_sm_items, Host, ?MODULE, disco_items, 100),
    ejabberd_hooks:delete(disco_sm_features, Host, ?MODULE, disco_features, 100),
    ejabberd_hooks:delete(disco_sm_identity, Host, ?MODULE, disco_identity, 100),
    ejabberd_hooks:delete(disco_info, Host, ?MODULE, disco_info, 100),
    gen_iq_handler:remove_iq_handler(ejabberd_local, Host, ?NS_DISCO_ITEMS),
    gen_iq_handler:remove_iq_handler(ejabberd_local, Host, ?NS_DISCO_INFO),
    gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_DISCO_ITEMS),
    gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_DISCO_INFO),
    gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_PUBSUB),
    gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_MIX_0),
    ejabberd_router:unregister_route(Host),
    ok.

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

%%%===================================================================
%%% Internal functions
%%%===================================================================
do_route(_State, From, To, #xmlel{name = <<"iq">>} = Packet) ->
    if To#jid.luser == <<"">> ->
	    ejabberd_local:process_iq(From, To, Packet);
       true ->
	    ejabberd_sm:process_iq(From, To, Packet)
    end;
do_route(_State, From, To, #xmlel{name = <<"presence">>} = Packet)
  when To#jid.luser /= <<"">> ->
    case fxml:get_tag_attr_s(<<"type">>, Packet) of
	<<"unavailable">> ->
	    delete_presence(From, To);
	_ ->
	    ok
    end;
do_route(_State, _From, _To, _Packet) ->
    ok.

subscribe_nodes(From, To, Nodes) ->
    LTo = jid:tolower(jid:remove_resource(To)),
    LFrom = jid:tolower(jid:remove_resource(From)),
    From_s = jid:to_string(LFrom),
    lists:foldl(
      fun(_Node, {error, _} = Err) ->
	      Err;
	 (Node, {result, _}) ->
	      case mod_pubsub:subscribe_node(LTo, Node, From, From_s, []) of
		  {error, _} = Err ->
		      case is_item_not_found(Err) of
			  true ->
			      case mod_pubsub:create_node(
				     LTo, To#jid.lserver, Node, LFrom, <<"mix">>) of
				  {result, _} ->
				      mod_pubsub:subscribe_node(LTo, Node, From, From_s, []);
				  Error ->
				      Error
			      end;
			  false ->
			      Err
		      end;
		  {result, _} = Result ->
		      Result
	      end
      end, {result, []}, Nodes).

unsubscribe_nodes(From, To, Nodes) ->
    LTo = jid:tolower(jid:remove_resource(To)),
    LFrom = jid:tolower(jid:remove_resource(From)),
    From_s = jid:to_string(LFrom),
    lists:foldl(
      fun(_Node, {error, _} = Err) ->
	      Err;
	 (Node, {result, _} = Result) ->
	      case mod_pubsub:unsubscribe_node(LTo, Node, From, From_s, <<"">>) of
		  {error, _} = Err ->
		      case is_not_subscribed(Err) of
			  true -> Result;
			  _ -> Err
		      end;
		  {result, _} = Res ->
		      Res
	      end
      end, {result, []}, Nodes).

publish_participant(From, To) ->
    LFrom = jid:tolower(jid:remove_resource(From)),
    LTo = jid:tolower(jid:remove_resource(To)),
    Participant = #xmlel{name = <<"participant">>,
			 attrs = [{<<"xmlns">>, ?NS_MIX_0},
				  {<<"jid">>, jid:to_string(LFrom)}]},
    ItemID = p1_sha:sha(jid:to_string(LFrom)),
    mod_pubsub:publish_item(
      LTo, To#jid.lserver, ?NS_MIX_NODES_PARTICIPANTS,
      From, ItemID, [Participant]).

delete_presence(From, To) ->
    LFrom = jid:tolower(From),
    LTo = jid:tolower(jid:remove_resource(To)),
    case mod_pubsub:get_items(LTo, ?NS_MIX_NODES_PRESENCE) of
	Items when is_list(Items) ->
	    lists:foreach(
	      fun(#pubsub_item{modification = {_, LJID},
			       itemid = {ItemID, _}}) when LJID == LFrom ->
		      delete_item(From, To, ?NS_MIX_NODES_PRESENCE, ItemID);
		 (_) ->
		      ok
	      end, Items);
	_ ->
	    ok
    end.

delete_participant(From, To) ->
    LFrom = jid:tolower(jid:remove_resource(From)),
    ItemID = p1_sha:sha(jid:to_string(LFrom)),
    delete_presence(From, To),
    delete_item(From, To, ?NS_MIX_NODES_PARTICIPANTS, ItemID).

delete_item(From, To, Node, ItemID) ->
    LTo = jid:tolower(jid:remove_resource(To)),
    case mod_pubsub:delete_item(
	   LTo, Node, From, ItemID, true) of
	{result, _} = Res ->
	    Res;
	{error, _} = Err ->
	    case is_item_not_found(Err) of
		true -> {result, []};
		false -> Err
	    end
    end.

is_item_not_found({error, ErrEl}) ->
    case fxml:get_subtag_with_xmlns(
	   ErrEl, <<"item-not-found">>, ?NS_STANZAS) of
	#xmlel{} -> true;
	_ -> false
    end.

is_not_subscribed({error, ErrEl}) ->
    case fxml:get_subtag_with_xmlns(
	   ErrEl, <<"not-subscribed">>, ?NS_PUBSUB_ERRORS) of
	#xmlel{} -> true;
	_ -> false
    end.

mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
mod_opt_type(host) -> fun iolist_to_binary/1;
mod_opt_type(_) -> [host, iqdisc].