local st = require "util.stanza";

local jid_bare = require "util.jid".bare;

-- advertise disco features

module:add_feature("urn:xmpp:sift:1");

-- supported features

module:add_feature("urn:xmpp:sift:stanzas:iq");

module:add_feature("urn:xmpp:sift:stanzas:message");

module:add_feature("urn:xmpp:sift:stanzas:presence");

module:add_feature("urn:xmpp:sift:recipients:all");

module:add_feature("urn:xmpp:sift:senders:all");

-- allowed values of 'sender' and 'recipient' attributes

local senders = {

	["all"] = true;

	["local"] = true;

	["others"] = true;

	["remote"] = true;

	["self"] = true;

};

local recipients = {

	["all"] = true;

	["bare"] = true;

	["full"] = true;

};

-- this function converts a <message/>, <presence/> or <iq/> element in

-- the SIFT namespace into a hashtable, for easy lookup

local function to_hashtable(element)

	if element ~= nil then

		local hash = {};

		-- make sure the sender and recipient attributes has a valid value

		hash.sender = element.attr.sender or "all";

		if not senders[hash.sender] then return false; end -- bad value, returning false

		hash.recipient = element.attr.recipient or "all";

		if not recipients[hash.recipient] then return false; end -- bad value, returning false

		-- next we loop over all <allow/> elements

		for _, tag in ipairs(element) do

			if tag.name == "allow" and tag.attr.xmlns == "urn:xmpp:sift:1" then

				-- make sure the element is valid

				if not tag.attr.name or not tag.attr.ns then return false; end -- missing required attributes, returning false

				hash[tag.attr.ns.."|"..tag.attr.name] = true;

				hash.allowed = true; -- just a flag indicating we have some elements allowed

			end

		end

		return hash;

	end

end

local data = {}; -- table with all our data

-- handle SIFT set

module:hook("iq/self/urn:xmpp:sift:1:sift", function(event)

	local origin, stanza = event.origin, event.stanza;

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

		local sifttag = stanza.tags[1]; -- <sift/>

		-- first, get the elements we are interested in

		local message = sifttag:get_child("message");

		local presence = sifttag:get_child("presence");

		local iq = sifttag:get_child("iq");

		-- for quick lookup, convert the elements into hashtables

		message = to_hashtable(message);

		presence = to_hashtable(presence);

		iq = to_hashtable(iq);

		-- make sure elements were valid

		if message == false or presence == false or iq == false then

			origin.send(st.error_reply(stanza, "modify", "bad-request"));

			return true;

		end

		local existing = data[origin.full_jid] or {}; -- get existing data, if any

		data[origin.full_jid] = { presence = presence, message = message, iq = iq }; -- store new data

		origin.send(st.reply(stanza)); -- send back IQ result

		if not existing.presence and not origin.presence and presence then

			-- TODO send probes

		end

		return true;

	end

end);

-- handle user disconnect

module:hook("resource-unbind", function(event)

	data[event.session.full_jid] = nil; -- discard data

end);

-- IQ handler

module:hook("iq/full", function(event)

	local origin, stanza = event.origin, event.stanza;

	local siftdata = data[stanza.attr.to];

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

		if siftdata and siftdata.iq then -- we seem to have an IQ filter

			local tag = stanza.tags[1]; -- the IQ child

			if not siftdata.iq[(tag.attr.xmlns or "jabber:client").."|"..tag.name] then

				-- element not allowed; sending back generic error

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

				return true;

			end

		end

	end

end, 50);

-- Message to full JID handler

module:hook("message/full", function(event)

	local origin, stanza = event.origin, event.stanza;

	local siftdata = data[stanza.attr.to];

	if siftdata and siftdata.message then -- we seem to have an message filter

		local allowed = false;

		for _, childtag in ipairs(stanza.tags) do

			if siftdata.message[(childtag.attr.xmlns or "jabber:client").."|"..childtag.name] then

				allowed = true;

			end

		end

		if not allowed then

			-- element not allowed; sending back generic error

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

			-- FIXME maybe send to offline storage

			return true;

		end

	end

end, 50);

-- Message to bare JID handler

module:hook("message/bare", function(event)

	local origin, stanza = event.origin, event.stanza;

	local user = bare_sessions[jid_bare(stanza.attr.to)];

	local allowed = false;

	for _, session in pairs(user and user.sessions or {}) do

		local siftdata = data[session.full_jid];

		if siftdata and siftdata.message then -- we seem to have an message filter

			for _, childtag in ipairs(stanza.tags) do

				if siftdata.message[(childtag.attr.xmlns or "jabber:client").."|"..childtag.name] then

					allowed = true;

				end

			end

		else

			allowed = true;

		end

	end

	if user and not allowed then

		-- element not allowed; sending back generic error

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

		-- FIXME maybe send to offline storage

		return true;

	end

end, 50);

-- Presence to full JID handler

module:hook("presence/full", function(event)

	local origin, stanza = event.origin, event.stanza;

	local siftdata = data[stanza.attr.to];

	if siftdata and siftdata.presence then -- we seem to have an presence filter

		local allowed = false;

		for _, childtag in ipairs(stanza.tags) do

			if siftdata.presence[(childtag.attr.xmlns or "jabber:client").."|"..childtag.name] then

				allowed = true;

			end

		end

		if not allowed then

			-- element not allowed; sending back generic error

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

			return true;

		end

	end

end, 50);

-- Presence to bare JID handler

module:hook("presence/bare", function(event)

	local origin, stanza = event.origin, event.stanza;

	local user = bare_sessions[jid_bare(stanza.attr.to)];

	local allowed = false;

	for _, session in pairs(user and user.sessions or {}) do

		local siftdata = data[session.full_jid];

		if siftdata and siftdata.presence then -- we seem to have an presence filter

			for _, childtag in ipairs(stanza.tags) do

				if siftdata.presence[(childtag.attr.xmlns or "jabber:client").."|"..childtag.name] then

					allowed = true;

				end

			end

		else

			allowed = true;

		end

	end

	if user and not allowed then

		-- element not allowed; sending back generic error

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

		return true;

	end

end, 50);