# HG changeset patch
# User marc0s <marcos.devera@quobis.com>
# Date 1582761557 -3600
# Node ID 3e19c25ff93ecbd766eef93ebb373f2ac6703eb5
# Parent  f1e28dcb37915187b8c9522613ad3863703e691f
mod_reminders: Initial commit for supporting Reminders ProtoXEP

See https://tenak.net/marcos/xeps/reminders.html

diff -r f1e28dcb3791 -r 3e19c25ff93e mod_reminders/README.md
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_reminders/README.md	Thu Feb 27 00:59:17 2020 +0100
@@ -0,0 +1,18 @@
+---
+labels:
+- 'Stage-alpha'
+summary: Enable ProtoXEP: Reminders support'
+...
+
+
+Introduction
+============
+
+`mod_reminders` implements ProtoXEP: Reminders.
+
+Usage
+=====
+
+Place the sibling `mod_reminders.lua` somewhere under your
+`plugins_path`.
+
diff -r f1e28dcb3791 -r 3e19c25ff93e mod_reminders/mod_reminders.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_reminders/mod_reminders.lua	Thu Feb 27 00:59:17 2020 +0100
@@ -0,0 +1,178 @@
+-- mod_reminders
+--
+-- Copyright (C) 2020 Marcos de Vera Piquero <marcos@tenak.net>
+--
+-- This file is MIT/X11 licensed.
+--
+-- A module to support ProtoXEP: Reminders
+--
+
+local id = require "util.id"
+local datetime = require"util.datetime";
+local errors = require"util.error";
+local jid = require"util.jid";
+local st = require"util.stanza";
+local os_time = os.time;
+
+local xmlns_reminders = "urn:xmpp:reminders:0";
+
+local reminders_store = module:open_store(xmlns_reminders, "keyval");
+
+local reminders_errors = {
+	missing_fields = {
+		type = "modify";
+		condition = "bad-request";
+		text = "Missing required value for date or text";
+	};
+	invalid_dateformat = {
+		type = "modify";
+		condition = "bad-request";
+		text = "Invalid date format";
+	};
+	past_date = {
+		type = "modify";
+		condition = "gone";
+		text = "Reminder date is in the past";
+	};
+	store_error = {
+		type = "cancel";
+		condition = "internal-server-error";
+		text = "Unable to persist data";
+	};
+};
+
+local function reminder_error (name)
+	return errors.new(name, nil, reminders_errors);
+end
+
+local function store_reminder (reminder)
+	-- pushes the reminder to the store, and nothing else
+	return reminders_store:set(reminder.id, reminder);
+end
+
+local function delete_reminder (reminder_id)
+	-- empties the store for the given reminder_id
+	return reminders_store:set(reminder_id, nil);
+end
+
+local function get_reminder (reminder_id)
+	return reminders_store:get(reminder_id);
+end
+
+local function send_reminder (reminder)
+	-- actually delivers the <message /> with the reminder to the user
+	local bare = jid.bare(reminder.jid);
+	module:log("debug", "Sending reminder %s to %s", reminder.id, bare);
+	local message = st.message({ from = "localhost"; to = bare; id = id.short() })
+		:tag("reminder", {xmlns = xmlns_reminders})
+		:add_child(reminder.text)
+		:tag("date"):text(datetime.datetime(reminder.date)):up();
+	module:send(message);
+	return delete_reminder(reminder.id)
+end
+
+local function schedule_reminder (reminder)
+	-- schedule a module:add_timer for the given reminder
+	module:log("debug", "Scheduling reminder to datetime %s", reminder.date);
+	local now = os_time();
+	local when = reminder.date;
+	local delay = when - now;
+	module:log("debug", "Reminder text: %s", reminder.text);
+	local function callback ()
+		send_reminder(reminder)
+	end
+	module:add_timer(delay, callback);
+end
+
+local function process_reminders_store ()
+	-- retrieve all reminders in the store and schedule them
+	for reminder_id in reminders_store:users() do
+		module:log("debug", "Found stored reminder %s", reminder_id);
+		local reminder = get_reminder(reminder_id);
+		if reminder.date and reminder.text then
+			local text = st.deserialize(reminder.text)
+			module:log("debug", "Read reminder %s", reminder.id);
+			-- cleanup missed reminders
+			if reminder.date < os_time() then
+				module:log("debug", "Deleting outdated reminder %s", reminder.id)
+				delete_reminder(reminder.id)
+			end
+			schedule_reminder({
+					date = reminder.date;
+					id = reminder.id;
+					jid = reminder.jid;
+					text = text;	
+			})
+		else
+			delete_reminder(reminder_id);
+		end
+	end
+end
+
+local function create_reminder (jid, reminder)
+	local rem = st.clone(reminder);
+	local date = reminder:get_child("date");
+	local text = reminder:get_child("text");
+	if date == nil or text == nil then
+		return nil, reminder_error("missing_fields")
+	end
+	local now = os_time();
+	local _, parsed_date = pcall(datetime.parse, date:get_text());
+	if parsed_date == nil then
+		return nil, reminder_error("invalid_dateformat")
+	end
+	if parsed_date < now then
+		return nil, reminder_error("past_date"), nil
+	end	
+	rem.attr.id = id.medium();
+	local data = {
+		id = rem.attr.id;
+		jid = jid;
+		text = text;
+		date = parsed_date;
+	}
+	local stored = store_reminder(data);
+	if not stored then
+		return nil, reminder_error("store_error")
+	end
+	schedule_reminder(data);
+	return rem
+end
+
+local function handle_set (event)
+	local origin, stanza = event.origin, event.stanza
+	local reminder = stanza:get_child("reminder", xmlns_reminders);
+	if reminder.attr.id ~= nil and reminder:get_child("date") == nil then
+		-- delete existing reminder
+		local ok = delete_reminder(reminder.attr.id);
+		if ok then
+			module:log("debug", "reminder %s deleted", reminder.attr.id);
+			origin.send(st.reply(stanza):add_child(reminder));
+		else
+			module:log("debug", "failed to delete reminder %s", reminder.attr.id);
+			origin.send(st.error_reply(stanza, "cancel", "internal-server-error"));
+		end
+		return true;
+	else
+		-- create new reminder
+		local jid = stanza.attr.from
+		local created, err = create_reminder(jid, reminder);
+		if err ~= nil then
+			origin.send(st.error_reply(stanza, err))
+			return true;
+		else
+			origin.send(st.reply(stanza):add_child(created))
+			return true;
+		end		
+	end
+	origin.send(st.error_reply(stanza, "modify", "bad-request"));
+	return true;
+end
+
+
+-- load saved reminders and set timers
+process_reminders_store();
+
+module:hook("iq-set/host/"..xmlns_reminders..":reminder", handle_set)
+module:add_feature(xmlns_reminders);
+module:log("debug", "Module loaded");