-- XEP-XXX: MUC Push Notifications

-- Copyright (C) 2015-2016 Kim Alvefur

-- Copyright (C) 2017-2018 Thilo Molitor

--

-- This file is MIT/X11 licensed.

local s_match = string.match;

local s_sub = string.sub;

local os_time = os.time;

local next = next;

local st = require"util.stanza";

local jid = require"util.jid";

local dataform = require"util.dataforms".new;

local hashes = require"util.hashes";

local xmlns_push = "urn:xmpp:push:0";

-- configuration

local include_body = module:get_option_boolean("push_notification_with_body", false);

local include_sender = module:get_option_boolean("push_notification_with_sender", false);

local max_push_errors = module:get_option_number("push_max_errors", 16);

local max_push_devices = module:get_option_number("push_max_devices", 5);

local dummy_body = module:get_option_string("push_notification_important_body", "New Message!");

local host_sessions = prosody.hosts[module.host].sessions;

local push_errors = {};

local id2node = {};

module:depends("muc");

-- ordered table iterator, allow to iterate on the natural order of the keys of a table,

-- see http://lua-users.org/wiki/SortedIteration

local function __genOrderedIndex( t )

	local orderedIndex = {}

	for key in pairs(t) do

		table.insert( orderedIndex, key )

	end

	-- sort in reverse order (newest one first)

	table.sort( orderedIndex, function(a, b)

		if a == nil or t[a] == nil or b == nil or t[b] == nil then return false end

		-- only one timestamp given, this is the newer one

		if t[a].timestamp ~= nil and t[b].timestamp == nil then return true end

		if t[a].timestamp == nil and t[b].timestamp ~= nil then return false end

		-- both timestamps given, sort normally

		if t[a].timestamp ~= nil and t[b].timestamp ~= nil then return t[a].timestamp > t[b].timestamp end

		return false	-- normally not reached

	end)

	return orderedIndex

end

local function orderedNext(t, state)

	-- Equivalent of the next function, but returns the keys in timestamp

	-- order. We use a temporary ordered key table that is stored in the

	-- table being iterated.

	local key = nil

	--print("orderedNext: state = "..tostring(state) )

	if state == nil then

		-- the first time, generate the index

		t.__orderedIndex = __genOrderedIndex( t )

		key = t.__orderedIndex[1]

	else

		-- fetch the next value

		for i = 1, #t.__orderedIndex do

			if t.__orderedIndex[i] == state then

				key = t.__orderedIndex[i+1]

			end

		end

	end

	if key then

		return key, t[key]

	end

	-- no more value to return, cleanup

	t.__orderedIndex = nil

	return

end

local function orderedPairs(t)

	-- Equivalent of the pairs() function on tables. Allows to iterate

	-- in order

	return orderedNext, t, nil

end

-- small helper function to return new table with only "maximum" elements containing only the newest entries

local function reduce_table(table, maximum)

	local count = 0;

	local result = {};

	for key, value in orderedPairs(table) do

		count = count + 1;

		if count > maximum then break end

		result[key] = value;

	end

	return result;

end

-- For keeping state across reloads while caching reads

local push_store = (function()

	local store = module:open_store();

	local push_services = {};

	local api = {};

	function api:get(user)

		if not push_services[user] then

			local err;

			push_services[user], err = store:get(user);

			if not push_services[user] and err then

				module:log("warn", "Error reading push notification storage for user '%s': %s", user, tostring(err));

				push_services[user] = {};

				return push_services[user], false;

			end

		end

		if not push_services[user] then push_services[user] = {} end

		return push_services[user], true;

	end

	function api:set(user, data)

		push_services[user] = reduce_table(data, max_push_devices);

		local ok, err = store:set(user, push_services[user]);

		if not ok then

			module:log("error", "Error writing push notification storage for user '%s': %s", user, tostring(err));

			return false;

		end

		return true;

	end

	function api:set_identifier(user, push_identifier, data)

		local services = self:get(user);

		services[push_identifier] = data;

		return self:set(user, services);

	end

	return api;

end)();

-- Forward declarations, as both functions need to reference each other

local handle_push_success, handle_push_error;

function handle_push_error(event)

	local stanza = event.stanza;

	local error_type, condition = stanza:get_error();

	local node = id2node[stanza.attr.id];

	if node == nil then return false; end		-- unknown stanza? Ignore for now!

	local from = stanza.attr.from;

	local user_push_services = push_store:get(node);

	local changed = false;

	for push_identifier, _ in pairs(user_push_services) do

		local stanza_id = hashes.sha256(push_identifier, true);

		if stanza_id == stanza.attr.id then

			if user_push_services[push_identifier] and user_push_services[push_identifier].jid == from and error_type ~= "wait" then

				push_errors[push_identifier] = push_errors[push_identifier] + 1;

				module:log("info", "Got error of type '%s' (%s) for identifier '%s': "

					.."error count for this identifier is now at %s", error_type, condition, push_identifier,

					tostring(push_errors[push_identifier]));

				if push_errors[push_identifier] >= max_push_errors then

					module:log("warn", "Disabling push notifications for identifier '%s'", push_identifier);

					-- remove push settings from sessions

					if host_sessions[node] then

						for _, session in pairs(host_sessions[node].sessions) do

							if session.push_identifier == push_identifier then

								session.push_identifier = nil;

								session.push_settings = nil;

								session.first_hibernated_push = nil;

							end

						end

					end

					-- save changed global config

					changed = true;

					user_push_services[push_identifier] = nil

					push_errors[push_identifier] = nil;

					-- unhook iq handlers for this identifier (if possible)

					if module.unhook then

						module:unhook("iq-error/host/"..stanza_id, handle_push_error);

						module:unhook("iq-result/host/"..stanza_id, handle_push_success);

						id2node[stanza_id] = nil;

					end

				end

			elseif user_push_services[push_identifier] and user_push_services[push_identifier].jid == from and error_type == "wait" then

				module:log("debug", "Got error of type '%s' (%s) for identifier '%s': "

					.."NOT increasing error count for this identifier", error_type, condition, push_identifier);

			end

		end

	end

	if changed then

		push_store:set(node, user_push_services);

	end

	return true;

end

function handle_push_success(event)

	local stanza = event.stanza;

	local node = id2node[stanza.attr.id];

	if node == nil then return false; end		-- unknown stanza? Ignore for now!

	local from = stanza.attr.from;

	local user_push_services = push_store:get(node);

	for push_identifier, _ in pairs(user_push_services) do

		if hashes.sha256(push_identifier, true) == stanza.attr.id then

			if user_push_services[push_identifier] and user_push_services[push_identifier].jid == from and push_errors[push_identifier] > 0 then

				push_errors[push_identifier] = 0;

				module:log("debug", "Push succeeded, error count for identifier '%s' is now at %s again", push_identifier, tostring(push_errors[push_identifier]));

			end

		end

	end

	return true;

end

-- http://xmpp.org/extensions/xep-0357.html#disco

local function account_dico_info(event)

	(event.reply or event.stanza):tag("feature", {var=xmlns_push}):up();

end

module:hook("account-disco-info", account_dico_info);

-- http://xmpp.org/extensions/xep-0357.html#enabling

local function push_enable(event)

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

	local enable = stanza.tags[1];

	origin.log("debug", "Attempting to enable push notifications");

	-- MUST contain a 'jid' attribute of the XMPP Push Service being enabled

	local push_jid = enable.attr.jid;

	-- SHOULD contain a 'node' attribute

	local push_node = enable.attr.node;

	-- CAN contain a 'include_payload' attribute

	local include_payload = enable.attr.include_payload;

	if not push_jid then

		origin.log("debug", "MUC Push notification enable request missing the 'jid' field");

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

		return true;

	end

	local publish_options = enable:get_child("x", "jabber:x:data");

	if not publish_options then

		-- Could be intentional

		origin.log("debug", "No publish options in request");

	end

	local push_identifier = push_jid .. "<" .. (push_node or "");

	local push_service = {

		jid = push_jid;

		node = push_node;

		include_payload = include_payload;

		options = publish_options and st.preserialize(publish_options);

		timestamp = os_time();

	};

	local ok = push_store:set_identifier(origin.username.."@"..origin.host, push_identifier, push_service);

	if not ok then

		origin.send(st.error_reply(stanza, "wait", "internal-server-error"));

	else

		origin.push_identifier = push_identifier;

		origin.push_settings = push_service;

		origin.first_hibernated_push = nil;

		origin.log("info", "MUC Push notifications enabled for %s by %s (%s)",

			 tostring(stanza.attr.to),

			 tostring(stanza.attr.from),

			 tostring(origin.push_identifier)

			);

		origin.send(st.reply(stanza));

	end

	return true;

end

module:hook("iq-set/host/"..xmlns_push..":enable", push_enable);

-- http://xmpp.org/extensions/xep-0357.html#disabling

local function push_disable(event)

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

	local push_jid = stanza.tags[1].attr.jid; -- MUST include a 'jid' attribute

	local push_node = stanza.tags[1].attr.node; -- A 'node' attribute MAY be included

	if not push_jid then

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

		return true;

	end

	local user_push_services = push_store:get(origin.username);

	for key, push_info in pairs(user_push_services) do

		if push_info.jid == push_jid and (not push_node or push_info.node == push_node) then

			origin.log("info", "Push notifications disabled (%s)", tostring(key));

			if origin.push_identifier == key then

				origin.push_identifier = nil;

				origin.push_settings = nil;

				origin.first_hibernated_push = nil;

			end

			user_push_services[key] = nil;

			push_errors[key] = nil;

			if module.unhook then

				module:unhook("iq-error/host/"..key, handle_push_error);

				module:unhook("iq-result/host/"..key, handle_push_success);

				id2node[key] = nil;

			end

		end

	end

	local ok = push_store:set(origin.username, user_push_services);

	if not ok then

		origin.send(st.error_reply(stanza, "wait", "internal-server-error"));

	else

		origin.send(st.reply(stanza));

	end

	return true;

end

module:hook("iq-set/host/"..xmlns_push..":disable", push_disable);

-- Patched version of util.stanza:find() that supports giving stanza names

-- without their namespace, allowing for every namespace.

local function find(self, path)

	local pos = 1;

	local len = #path + 1;

	repeat

		local xmlns, name, text;

		local char = s_sub(path, pos, pos);

		if char == "@" then

			return self.attr[s_sub(path, pos + 1)];

		elseif char == "{" then

			xmlns, pos = s_match(path, "^([^}]+)}()", pos + 1);

		end

		name, text, pos = s_match(path, "^([^@/#]*)([/#]?)()", pos);

		name = name ~= "" and name or nil;

		if pos == len then

			if text == "#" then

				local child = xmlns ~= nil and self:get_child(name, xmlns) or self:child_with_name(name);

				return child and child:get_text() or nil;

			end

			return xmlns ~= nil and self:get_child(name, xmlns) or self:child_with_name(name);

		end

		self = xmlns ~= nil and self:get_child(name, xmlns) or self:child_with_name(name);

	until not self

	return nil;

end

-- is this push a high priority one (this is needed for ios apps not using voip pushes)

local function is_important(stanza)

	local st_name = stanza and stanza.name or nil;

	if not st_name then return false; end	-- nonzas are never important here

	if st_name == "presence" then

		return false;						-- same for presences

	elseif st_name == "message" then

		-- unpack carbon copies

		local stanza_direction = "in";

		local carbon;

		local st_type;

		-- support carbon copied message stanzas having an arbitrary message-namespace or no message-namespace at all

		if not carbon then carbon = find(stanza, "{urn:xmpp:carbons:2}/forwarded/message"); end

		if not carbon then carbon = find(stanza, "{urn:xmpp:carbons:1}/forwarded/message"); end

		stanza_direction = carbon and stanza:child_with_name("sent") and "out" or "in";

		if carbon then stanza = carbon; end

		st_type = stanza.attr.type;

		-- headline message are always not important

		if st_type == "headline" then return false; end

		-- carbon copied outgoing messages are not important

		if carbon and stanza_direction == "out" then return false; end

		-- We can't check for body contents in encrypted messages, so let's treat them as important

		-- Some clients don't even set a body or an empty body for encrypted messages

		-- check omemo https://xmpp.org/extensions/inbox/omemo.html

		if stanza:get_child("encrypted", "eu.siacs.conversations.axolotl") or stanza:get_child("encrypted", "urn:xmpp:omemo:0") then return true; end

		-- check xep27 pgp https://xmpp.org/extensions/xep-0027.html

		if stanza:get_child("x", "jabber:x:encrypted") then return true; end

		-- check xep373 pgp (OX) https://xmpp.org/extensions/xep-0373.html

		if stanza:get_child("openpgp", "urn:xmpp:openpgp:0") then return true; end

		local body = stanza:get_child_text("body");

		if st_type == "groupchat" and stanza:get_child_text("subject") then return false; end		-- groupchat subjects are not important here

		return body ~= nil and body ~= "";			-- empty bodies are not important

	end

	return false;		-- this stanza wasn't one of the above cases --> it is not important, too

end

local push_form = dataform {

	{ name = "FORM_TYPE"; type = "hidden"; value = "urn:xmpp:push:summary"; };

	{ name = "message-count"; type = "text-single"; };

	{ name = "pending-subscription-count"; type = "text-single"; };