local st = require "util.stanza";

local send = require "core.sessionmanager".send_to_session;

local sm_bind_resource = require "core.sessionmanager".bind_resource;

local jid

local usermanager_validate_credentials = require "core.usermanager".validate_credentials;

local t_concat, t_insert = table.concat, table.insert;

local tostring = tostring;

local jid_split = require "util.jid".split

local log = require "util.logger".init("mod_saslauth");

local xmlns_sasl ='urn:ietf:params:xml:ns:xmpp-sasl';

local xmlns_bind ='urn:ietf:params:xml:ns:xmpp-bind';

local xmlns_stanzas ='urn:ietf:params:xml:ns:xmpp-stanzas';

local new_sasl = require "util.sasl".new;

local function build_reply(status, ret, err_msg)

	local reply = st.stanza(status, {xmlns = xmlns_sasl});

	if status == "challenge" then

		reply:text(base64.encode(ret or ""));

	elseif status == "failure" then

		reply:tag(ret):up();

		if err_msg then reply:tag("text"):text(err_msg); end

	elseif status == "success" then

		reply:text(base64.encode(ret or ""));

	else

		error("Unknown sasl status: "..status);

	end

	return reply;

end

local function handle_status(session, status)

	if status == "failure" then

		session.sasl_handler = nil;

	elseif status == "success" then

		if not session.sasl_handler.username then error("SASL succeeded but we didn't get a username!"); end -- TODO move this to sessionmanager

		sessionmanager.make_authenticated(session, session.sasl_handler.username);

		session.sasl_handler = nil;

		session:reset_stream();

	end

end

local function password_callback(node, host, mechanism)

	local password = (datamanager.load(node, host, "accounts") or {}).password; -- FIXME handle hashed passwords

	local func = function(x) return x; end;

	if password then

		if mechanism == "PLAIN" then

			return func, password;

		elseif mechanism == "DIGEST-MD5" then

			return func, require "hashes".md5(node..":"..host..":"..password);

		end

	end

	return func, nil;

end

function do_sasl(session, stanza)

	local text = stanza[1];

	if text then

		text = base64.decode(text);

		if not text then

			session.sasl_handler = nil;

			session.send(build_reply("failure", "incorrect-encoding"));

			return;

		end

	end

	local status, ret, err_msg = session.sasl_handler:feed(text);

	handle_status(session, status);

	local s = build_reply(status, ret, err_msg); 

	log("debug", "sasl reply: "..tostring(s));

	session.send(s);

end

add_handler("c2s_unauthed", "auth", xmlns_sasl,

		function (session, stanza)

			if not session.sasl_handler then

				session.sasl_handler = new_sasl(stanza.attr.mechanism, session.host, password_callback);

				do_sasl(session, stanza);

			else

				error("Client tried to negotiate SASL again", 0);

			end

		end);

add_handler("c2s_unauthed", "abort", xmlns_sasl,

	function(session, stanza)

		if not session.sasl_handler then error("Attempt to abort when sasl has not started"); end

		do_sasl(session, stanza);

	end);

add_handler("c2s_unauthed", "response", xmlns_sasl,

	function(session, stanza)

		if not session.sasl_handler then error("Attempt to respond when sasl has not started"); end

		do_sasl(session, stanza);

	end);

add_event_hook("stream-features", 

					function (session, features)												

						if not session.username then

							t_insert(features, "<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>");

							-- TODO: Provide PLAIN only if TLS is active, this is a SHOULD from the introduction of RFC 4616. This behavior could be overridden via configuration but will issuing a warning or so.

								t_insert(features, "<mechanism>PLAIN</mechanism>");

							t_insert(features, "</mechanisms>");

						else

							t_insert(features, "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'><required/></bind>");

							t_insert(features, "<session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>");

						end

						--send [[<register xmlns="http://jabber.org/features/iq-register"/> ]]

					end);

add_iq_handler("c2s", "urn:ietf:params:xml:ns:xmpp-bind", 

		function (session, stanza)

			log("debug", "Client tried to bind to a resource");

			local resource;

			if stanza.attr.type == "set" then

				local bind = stanza.tags[1];

				if bind and bind.attr.xmlns == xmlns_bind then

					resource = bind:child_with_name("resource");

					if resource then

						resource = resource[1];

					end

				end

			end

			local success, err = sm_bind_resource(session, resource);

			if not success then

				local reply = st.reply(stanza);

				reply.attr.type = "error";

				if err == "conflict" then

					reply:tag("error", { type = "modify" })

						:tag("conflict", { xmlns = xmlns_stanzas });

				elseif err == "constraint" then

					reply:tag("error", { type = "cancel" })

						:tag("resource-constraint", { xmlns = xmlns_stanzas });

				elseif err == "auth" then

					reply:tag("error", { type = "cancel" })

						:tag("not-allowed", { xmlns = xmlns_stanzas });

				end

				send(session, reply);

			else

				local reply = st.reply(stanza);

				reply:tag("bind", { xmlns = xmlns_bind})

					:tag("jid"):text(session.full_jid);

				send(session, reply);

			end

		end);

add_iq_handler("c2s", "urn:ietf:params:xml:ns:xmpp-session", 

		function (session, stanza)

			log("debug", "Client tried to bind to a resource");

			send(session, st.reply(stanza));

		end);