-- The code in this file should be self-explanatory, though the logic is horrible

-- for more info on that, see doc/stanza_routing.txt, which attempts to condense

-- the rules from the RFCs (mainly 3921)

require "core.servermanager"

local log = require "util.logger".init("stanzarouter")

local st = require "util.stanza";

local send_s2s = require "core.s2smanager".send_to_host;

local user_exists = require "core.usermanager".user_exists;

local rostermanager = require "core.rostermanager";

local sessionmanager = require "core.sessionmanager";

local s2s_verify_dialback = require "core.s2smanager".verify_dialback;

local s2s_make_authenticated = require "core.s2smanager".make_authenticated;

local modules_handle_stanza = require "core.modulemanager".handle_stanza;

local format = string.format;

local tostring = tostring;

local jid_split = require "util.jid".split;

local print = print;

function core_process_stanza(origin, stanza)

	log("debug", "Received["..origin.type.."]: "..tostring(stanza))

	-- TODO verify validity of stanza (as well as JID validity)

	if stanza.name == "iq" and not(#stanza.tags == 1 and stanza.tags[1].attr.xmlns) then

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

			error("Invalid IQ");

		elseif #stanza.tags > 1 and not(stanza.attr.type == "error" or stanza.attr.type == "result") then

			error("Invalid IQ");

		end

	end

	if origin.type == "c2s" and not origin.full_jid

		and not(stanza.name == "iq" and stanza.tags[1].name == "bind"

				and stanza.tags[1].attr.xmlns == "urn:ietf:params:xml:ns:xmpp-bind") then

		error("Client MUST bind resource after auth");

	end

	local to = stanza.attr.to;

	-- TODO also, stazas should be returned to their original state before the function ends

	if origin.type == "c2s" then

		stanza.attr.from = origin.full_jid; -- quick fix to prevent impersonation (FIXME this would be incorrect when the origin is not c2s)

	end

	if not to then

		core_handle_stanza(origin, stanza);

	elseif origin.type == "c2s" and stanza.name == "presence" and stanza.attr.type ~= nil and stanza.attr.type ~= "unavailable" then

		local node, host = jid_split(stanza.attr.to);

		local to_bare = node and (node.."@"..host) or host; -- bare JID

		local from_node, from_host = jid_split(stanza.attr.from);

		local from_bare = from_node and (from_node.."@"..from_host) or from_host; -- bare JID

		handle_outbound_presence_subscriptions_and_probes(origin, stanza, from_bare, to_bare);

	elseif hosts[to] and hosts[to].type == "local" then

		core_handle_stanza(origin, stanza);

	elseif stanza.name == "iq" and not select(3, jid_split(to)) then

		core_handle_stanza(origin, stanza);

		modules_handle_stanza(origin, stanza);

	elseif origin.type == "c2s" or origin.type == "s2sin" then

		core_route_stanza(origin, stanza);

	end

end

-- This function handles stanzas which are not routed any further,

-- that is, they are handled by this server

function core_handle_stanza(origin, stanza)

	-- Handlers

	if modules_handle_stanza(origin, stanza) then return; end

	if origin.type == "c2s" or origin.type == "c2s_unauthed" then

		local session = origin;

		if stanza.name == "presence" and origin.roster then

			if stanza.attr.type == nil or stanza.attr.type == "unavailable" then

				for jid in pairs(origin.roster) do -- broadcast to all interested contacts

					local subscription = origin.roster[jid].subscription;

					if subscription == "both" or subscription == "from" then

						stanza.attr.to = jid;

						core_route_stanza(origin, stanza);

					end

				end

				local node, host = jid_split(stanza.attr.from);

				for _, res in pairs(hosts[host].sessions[node].sessions) do -- broadcast to all resources

					if res ~= origin and res.full_jid then -- to resource. FIXME is res.full_jid the correct check? Maybe it should be res.presence

						stanza.attr.to = res.full_jid;

						core_route_stanza(origin, stanza);

					end

				end

				if not origin.presence then -- presence probes on initial presence -- FIXME does unavailable qualify as initial presence?

					local probe = st.presence({from = origin.full_jid, type = "probe"});

					for jid in pairs(origin.roster) do -- probe all contacts we are subscribed to

						local subscription = origin.roster[jid].subscription;

						if subscription == "both" or subscription == "to" then

							probe.attr.to = jid;

							core_route_stanza(origin, probe);

						end

					end

					for _, res in pairs(hosts[host].sessions[node].sessions) do -- broadcast from all resources

						if res ~= origin and stanza.attr.type ~= "unavailable" and res.presence then -- FIXME does unavailable qualify as initial presence?

							res.presence.attr.to = origin.full_jid;

							core_route_stanza(res, res.presence);

							res.presence.attr.to = nil;

						end

					end

					-- TODO resend subscription requests

				end

				origin.presence = stanza;

				stanza.attr.to = nil; -- reset it

			else

				-- TODO error, bad type

			end

		end

	else

		log("warn", "Unhandled origin: %s", origin.type);

	end

end

function send_presence_of_available_resources(user, host, jid, recipient_session)

	local h = hosts[host];

	local count = 0;

	if h and h.type == "local" then

		local u = h.sessions[user];

		if u then

			for k, session in pairs(u.sessions) do

				local pres = session.presence;

				if pres then

					pres.attr.to = jid;

					pres.attr.from = session.full_jid;

					recipient_session.send(pres);

					pres.attr.to = nil;

					pres.attr.from = nil;

					count = count + 1;

				end

			end

		end

	end

	return count;

end

function handle_outbound_presence_subscriptions_and_probes(origin, stanza, from_bare, to_bare)

	local node, host = jid_split(from_bare);

	local st_from, st_to = stanza.attr.from, stanza.attr.to;

	stanza.attr.from, stanza.attr.to = from_bare, to_bare;

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

		log("debug", "outbound subscribe from "..from_bare.." for "..to_bare);

		-- 1. route stanza

		-- 2. roster push (subscription = none, ask = subscribe)

		if rostermanager.set_contact_pending_out(node, host, to_bare) then

			rostermanager.roster_push(node, host, to_bare);

		end -- else file error

		core_route_stanza(origin, stanza);

	elseif stanza.attr.type == "unsubscribe" then

		log("debug", "outbound unsubscribe from "..from_bare.." for "..to_bare);

		-- 1. route stanza

		-- 2. roster push (subscription = none or from)

		if rostermanager.unsubscribe(node, host, to_bare) then

			rostermanager.roster_push(node, host, to_bare); -- FIXME do roster push when roster has in fact not changed?

		end -- else file error

		core_route_stanza(origin, stanza);

	elseif stanza.attr.type == "subscribed" then

		log("debug", "outbound subscribed from "..from_bare.." for "..to_bare);

		-- 1. route stanza

		-- 2. roster_push ()

		-- 3. send_presence_of_available_resources

		if rostermanager.subscribed(node, host, to_bare) then

			rostermanager.roster_push(node, host, to_bare);

			core_route_stanza(origin, stanza);

			send_presence_of_available_resources(node, host, to_bare, origin);

		end

	elseif stanza.attr.type == "unsubscribed" then

		log("debug", "outbound unsubscribed from "..from_bare.." for "..to_bare);

		-- 1. route stanza

		-- 2. roster push (subscription = none or to)

		if rostermanager.unsubscribed(node, host, to_bare) then

			rostermanager.roster_push(node, host, to_bare);

			core_route_stanza(origin, stanza);

		end

	end

	stanza.attr.from, stanza.attr.to = st_from, st_to;

end

function handle_inbound_presence_subscriptions_and_probes(origin, stanza, from_bare, to_bare)

	local node, host = jid_split(to_bare);

	local st_from, st_to = stanza.attr.from, stanza.attr.to;

	stanza.attr.from, stanza.attr.to = from_bare, to_bare;

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

		if rostermanager.is_contact_subscribed(node, host, from_bare) then

			if 0 == send_presence_of_available_resources(node, host, from_bare, origin) then

				-- TODO send last recieved unavailable presence (or we MAY do nothing, which is fine too)

			end

		else

			core_route_stanza(origin, st.presence({from=to_bare, to=from_bare, type="unsubscribed"}));

		end

	elseif stanza.attr.type == "subscribe" then

		log("debug", "inbound subscribe from "..from_bare.." for "..to_bare);

		if rostermanager.is_contact_subscribed(node, host, from_bare) then

			core_route_stanza(origin, st.presence({from=to_bare, to=from_bare, type="subscribed"})); -- already subscribed

		else

			if not rostermanager.is_contact_pending_in(node, host, from_bare) then

				if rostermanager.set_contact_pending_in(node, host, from_bare) then

					sessionmanager.send_to_available_resources(node, host, stanza);

				end -- TODO else return error, unable to save

			end

		end

	elseif stanza.attr.type == "unsubscribe" then

		log("debug", "inbound unsubscribe from "..from_bare.." for "..to_bare);

		if rostermanager.process_inbound_unsubscribe(node, host, from_bare) then

			rostermanager.roster_push(node, host, from_bare);

		end

	elseif stanza.attr.type == "subscribed" then

		log("debug", "inbound subscribed from "..from_bare.." for "..to_bare);

		if rostermanager.process_inbound_subscription_approval(node, host, from_bare) then

			rostermanager.roster_push(node, host, from_bare);

		end

	elseif stanza.attr.type == "unsubscribed" then

		log("debug", "inbound unsubscribed from "..from_bare.." for "..to_bare);

		if rostermanager.process_inbound_subscription_approval(node, host, from_bare) then

			rostermanager.roster_push(node, host, from_bare);

		end

	end -- discard any other type

	stanza.attr.from, stanza.attr.to = st_from, st_to;

end

function core_route_stanza(origin, stanza)

	-- Hooks

	--- ...later

	-- Deliver

	local to = stanza.attr.to;

	local node, host, resource = jid_split(to);

	local to_bare = node and (node.."@"..host) or host; -- bare JID

	local from = stanza.attr.from;

	local from_node, from_host, from_resource = jid_split(from);

	local from_bare = from_node and (from_node.."@"..from_host) or from_host; -- bare JID

	if stanza.name == "presence" and (stanza.attr.type ~= nil and stanza.attr.type ~= "unavailable") then resource = nil; end

	local host_session = hosts[host]

	if host_session and host_session.type == "local" then

		-- Local host

		local user = host_session.sessions[node];

		if user then

			local res = user.sessions[resource];

			if not res then

				-- if we get here, resource was not specified or was unavailable

				if stanza.name == "presence" then

					if stanza.attr.type ~= nil and stanza.attr.type ~= "unavailable" then

						handle_inbound_presence_subscriptions_and_probes(origin, stanza, from_bare, to_bare);

					else -- sender is available or unavailable

						for k in pairs(user.sessions) do -- presence broadcast to all user resources. FIXME should this be just for available resources? Do we need to check subscription?

							if user.sessions[k].full_jid then

								stanza.attr.to = user.sessions[k].full_jid; -- reset at the end of function

								user.sessions[k].send(stanza);

							end

						end

					end

				elseif stanza.name == "message" then -- select a resource to recieve message

					for k in pairs(user.sessions) do

						if user.sessions[k].full_jid then

							res = user.sessions[k];

							break;

						end

					end

					-- TODO find resource with greatest priority

					res.send(stanza);

				else

					-- TODO send IQ error

				end

			else

				-- User + resource is online...

				stanza.attr.to = res.full_jid; -- reset at the end of function

				res.send(stanza); -- Yay \o/

			end

		else

			-- user not online

			if user_exists(node, host) then

				if stanza.name == "presence" then

					if stanza.attr.type ~= nil and stanza.attr.type ~= "unavailable" then

						handle_inbound_presence_subscriptions_and_probes(origin, stanza, from_bare, to_bare);

					else

						-- TODO send unavailable presence or unsubscribed

					end

				elseif stanza.name == "message" then

					-- TODO send message error, or store offline messages

				elseif stanza.name == "iq" then

					-- TODO send IQ error

				end

			else -- user does not exist

				-- TODO we would get here for nodeless JIDs too. Do something fun maybe? Echo service? Let plugins use xmpp:server/resource addresses?

				if stanza.name == "presence" then

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

						origin.send(st.presence({from = to_bare, to = from_bare, type = "unsubscribed"}));

					end

					-- else ignore

				else

					origin.send(st.error_reply(stanza, "cancel", "service-unavailable"));

				end

			end

		end

	elseif origin.type == "c2s" then

		-- Remote host

		local xmlns = stanza.attr.xmlns;

		--stanza.attr.xmlns = "jabber:server";

		stanza.attr.xmlns = nil;

		log("debug", "sending s2s stanza: %s", tostring(stanza));

		send_s2s(origin.host, host, stanza); -- TODO handle remote routing errors

		stanza.attr.xmlns = xmlns; -- reset

	else

		log("warn", "received stanza from unhandled connection type: %s", origin.type);

	end

	stanza.attr.to = to; -- reset

end

function handle_stanza_toremote(stanza)

	log("error", "Stanza bound for remote host, but s2s is not implemented");

end