%%%----------------------------------------------------------------------
%%% File    : mod_chatcommands.erl
%%% Author  : 
%%% Purpose : Executes commands received by chat, returns result
%%% Created : 30 July 2005
%%% Id      : 0.1.2
%%%----------------------------------------------------------------------

%%% INSTALL:
%%%   1. Copy mod_chatcommands.erl to ejabberd/src
%%%   2. Add on ejabberd.cfg:
%%%     {access, chatcommands, [{allow, admin}]}.
%%%   3. And add on 'modules' section:
%%%     {mod_chatcommands,       [{access, chatcommands}]},
%%%   4. Recompile ejabberd and restart it.
%%% 
%%% USAGE:
%%%   1. Login to your Jabber server with an admin account
%%%   2. Send a message to localhost/commands. Example: uname
%%%      If the message ends with a dot, it will be executed as an Erlang command.
%%%      Example: node().
%%%   3. The module will send the answer as a chat.
%%% 
%%% PROBLEMS:
%%%   - Since it waits for the proccess to end, don't start heavy proccesses.
%%%   - There's no check on input, so don't use that module on a production server
%%%      if you don't know what you are doing.

%%% CHANGELOG:
%%%   0.1.2 - 1 February 2006
%%%     * Added call to spawn()
%%%
%%%   0.1 - 30 July 2005
%%%     * Initial version

-module(mod_chatcommands).
-author('').

-behaviour(gen_mod).

-export([start/2,
	 init/0,
	 stop/1,
	 execute/1,
	 shell2/4,
	 shell/3]).

-include("ejabberd.hrl").
-include("jlib.hrl").

-define(PROCNAME, ejabberd_chatcommands).

start(Host, _) ->
    ejabberd_hooks:add(local_send_to_resource_hook, Host, ?MODULE, shell, 50),
    register(gen_mod:get_module_proc(Host, ?PROCNAME), proc_lib:spawn(?MODULE, init, [])).

init() ->
    loop().

loop() ->
    receive
	{shell, From, To, Packet, Host} ->
	    spawn(?MODULE, shell2, [From, To, Packet, Host]),
	    loop();
	_ ->
	    loop()
    end.

stop(Host) ->
    exit(whereis(gen_mod:get_module_proc(Host, ?PROCNAME)), stop).

shell(From, To, Packet) ->
    case To of
	#jid{luser = "", lresource = Res} ->
	    {xmlelement, Name, _Attrs, _Els} = Packet,
	    case {Res, Name} of
		{"commands", "message"} ->
		    Host = To#jid.server,
		    gen_mod:get_module_proc(Host, ?PROCNAME) 
		      ! {shell, From, To, Packet, Host},
		    stop;
		_ ->
		    ok
	    end;
	_ ->
	    ok
    end.

shell2(From, To, Packet, Host) ->
    Access = gen_mod:get_module_opt(Host, ?MODULE, access, none),
    case acl:match_rule(Host, Access, From) of
	deny ->
	    Err = jlib:make_error_reply(Packet, ?ERR_NOT_ALLOWED),
	    ejabberd_router:route(To, From, Err);
	allow ->
		SubEl1 = xml:get_subtag(Packet, "body"),
		Text1 = xml:get_tag_cdata(SubEl1),
		Text2 = execute(Text1),
		SubEl2 = [{xmlelement, "body", [], [{xmlcdata, Text2}]}],
		Re = {xmlelement, "message", [{"type", "chat"}], SubEl2},
		ejabberd_router:route(To, From, Re)
    end.

execute(C) ->
    case regexp:match(C, "^.*\\.$") of
	 {match, _, _} -> exece(C);
         nomatch -> exec(C)
    end.

exece(C) ->  
    {ok, A2, _} = erl_scan:string(C),
    {ok, A3} = erl_parse:parse_exprs(A2),
    {value, Res, _} = erl_eval:exprs(A3, []),
    io_lib:format("~w", [Res]).

exec(C) ->  
    Res = os:cmd(C),
    io_lib:format("~s", [Res]).