1-- mod_reminders
2--
3-- Copyright (C) 2020 Marcos de Vera Piquero <marcos@tenak.net>
4--
5-- This file is MIT/X11 licensed.
6--
7-- A module to support ProtoXEP: Reminders
8--
9
10local id = require "util.id"
11local datetime = require"util.datetime";
12local errors = require"util.error";
13local jid = require"util.jid";
14local st = require"util.stanza";
15local os_time = os.time;
16
17local xmlns_reminders = "urn:xmpp:reminders:0";
18
19local reminders_store = module:open_store(xmlns_reminders, "keyval");
20
21local reminders_errors = {
22	missing_fields = {
23		type = "modify";
24		condition = "bad-request";
25		text = "Missing required value for date or text";
26	};
27	invalid_dateformat = {
28		type = "modify";
29		condition = "bad-request";
30		text = "Invalid date format";
31	};
32	past_date = {
33		type = "modify";
34		condition = "gone";
35		text = "Reminder date is in the past";
36	};
37	store_error = {
38		type = "cancel";
39		condition = "internal-server-error";
40		text = "Unable to persist data";
41	};
42};
43
44local function reminder_error (name)
45	return errors.new(name, nil, reminders_errors);
46end
47
48local function store_reminder (reminder)
49	-- pushes the reminder to the store, and nothing else
50	return reminders_store:set(reminder.id, reminder);
51end
52
53local function delete_reminder (reminder_id)
54	-- empties the store for the given reminder_id
55	return reminders_store:set(reminder_id, nil);
56end
57
58local function get_reminder (reminder_id)
59	return reminders_store:get(reminder_id);
60end
61
62local function send_reminder (reminder)
63	-- actually delivers the <message /> with the reminder to the user
64	local bare = jid.bare(reminder.jid);
65	module:log("debug", "Sending reminder %s to %s", reminder.id, bare);
66	local message = st.message({ from = "localhost"; to = bare; id = id.short() })
67		:tag("reminder", {id = reminder.id; xmlns = xmlns_reminders})
68		:add_child(reminder.text)
69		:tag("date"):text(datetime.datetime(reminder.date)):up();
70	module:send(message);
71	return delete_reminder(reminder.id)
72end
73
74local function schedule_reminder (reminder)
75	-- schedule a module:add_timer for the given reminder
76	module:log("debug", "Scheduling reminder to datetime %s", reminder.date);
77	local now = os_time();
78	local when = reminder.date;
79	local delay = when - now;
80	module:log("debug", "Reminder text: %s", reminder.text);
81	local function callback ()
82		send_reminder(reminder)
83	end
84	module:add_timer(delay, callback);
85end
86
87local function process_reminders_store ()
88	-- retrieve all reminders in the store and schedule them
89	for reminder_id in reminders_store:users() do
90		module:log("debug", "Found stored reminder %s", reminder_id);
91		local reminder = get_reminder(reminder_id);
92		if reminder.date and reminder.text then
93			local text = st.deserialize(reminder.text)
94			module:log("debug", "Read reminder %s", reminder.id);
95			-- cleanup missed reminders
96			if reminder.date < os_time() then
97				module:log("debug", "Deleting outdated reminder %s", reminder.id)
98				delete_reminder(reminder.id)
99			end
100			schedule_reminder({
101					date = reminder.date;
102					id = reminder.id;
103					jid = reminder.jid;
104					text = text;
105			})
106		else
107			delete_reminder(reminder_id);
108		end
109	end
110end
111
112local function create_reminder (jid, reminder)
113	local date = reminder:get_child("date");
114	local text = reminder:get_child("text");
115	if date == nil or text == nil then
116		return nil, reminder_error("missing_fields")
117	end
118	local now = os_time();
119	local _, parsed_date = pcall(datetime.parse, date:get_text());
120	if parsed_date == nil then
121		return nil, reminder_error("invalid_dateformat")
122	end
123	if parsed_date < now then
124		return nil, reminder_error("past_date"), nil
125	end
126	local reminder_id = id.medium();
127	local rem = st.stanza("reminder", {xmlns = xmlns_reminders; id = reminder_id});
128	local data = {
129		id = reminder_id;
130		jid = jid;
131		text = text;
132		date = parsed_date;
133	}
134	local stored = store_reminder(data);
135	if not stored then
136		return nil, reminder_error("store_error")
137	end
138	schedule_reminder(data);
139	return rem
140end
141
142local function handle_set (event)
143	local origin, stanza = event.origin, event.stanza
144	local reminder = stanza:get_child("reminder", xmlns_reminders);
145	if reminder.attr.id ~= nil and reminder:get_child("date") == nil then
146		-- delete existing reminder
147		local ok = delete_reminder(reminder.attr.id);
148		if ok then
149			module:log("debug", "reminder %s deleted", reminder.attr.id);
150			origin.send(st.reply(stanza):add_child(reminder));
151		else
152			module:log("debug", "failed to delete reminder %s", reminder.attr.id);
153			origin.send(st.error_reply(stanza, "cancel", "internal-server-error"));
154		end
155		return true;
156	else
157		-- create new reminder
158		local jid = stanza.attr.from
159		local created, err = create_reminder(jid, reminder);
160		if err ~= nil then
161			origin.send(st.error_reply(stanza, err))
162			return true;
163		else
164			origin.send(st.reply(stanza):add_child(created))
165			return true;
166		end
167	end
168	origin.send(st.error_reply(stanza, "modify", "bad-request"));
169	return true;
170end
171
172
173-- load saved reminders and set timers
174process_reminders_store();
175
176module:hook("iq-set/host/"..xmlns_reminders..":reminder", handle_set)
177module:add_feature(xmlns_reminders);
178module:log("debug", "Module loaded");
179