-- Fetches Atom feeds and publishes to PubSub nodes

--

-- Config:

-- Component "pubsub.example.com" "pubsub"

-- modules_enabled = {

--   "pubsub_feed";

-- }

-- feeds = { -- node -> url

-- }

-- feed_pull_interval = 20 -- minutes

local modules = hosts[module.host].modules;

if not modules.pubsub then

	module:log("warn", "Pubsub needs to be loaded on this host");

end

local add_task = require "util.timer".add_task;

local date, time = os.date, os.time;

local http = require "net.http";

local parse_feed = require "feeds".feed_from_string;

local config = module:get_option("feeds") or {

	planet_jabber = "http://planet.jabber.org/atom.xml";

	prosody_blog = "http://blog.prosody.im/feed/atom.xml";

};

local refresh_interval = (module:get_option("feed_pull_interval") or 15) * 60;

local feed_list = { }

for node, url in pairs(config) do

	feed_list[node] = { url = url };

end

local function update(item, callback)

	local headers = { };

	if item.data and item.last_update then

		headers["If-Modified-Since"] = date("!%a, %d %b %Y %T %Z", item.last_update);

	end

	http.request(item.url, {headers = headers}, function(data, code, req) 

		if code == 200 then

			item.data = data;

			callback(item)

			item.last_update = time();

		end

		if code == 304 then

			item.last_update = time();

		end

	end);

end

local actor = module.host.."/"..module.name;

local function refresh_feeds()

	for node, item in pairs(feed_list) do

		update(item, function(item)

			local feed = parse_feed(item.data);

			module:log("debug", "node: %s", node);

			for _, entry in ipairs(feed) do

				entry.attr.xmlns = "http://www.w3.org/2005/Atom";

				local e_published = entry:get_child("published");

				e_published = e_published and e_published[1];

				e_published = e_published and dt_parse(e_published);

				local e_updated = entry:get_child("updated");

				e_updated = e_updated and e_updated[1];

				e_updated = e_updated and dt_parse(e_updated);

				local timestamp = e_published or e_updated or nil;

				module:log("debug", "timestamp is %s, item.last_update is %s", tostring(timestamp), tostring(item.last_update));

				if not timestamp or not item.last_update or timestamp > item.last_update then

					local id = entry:get_child("id");

					module:log("debug", "publishing to %s, id %s", node, id);

				end

			end

		end);

	end

	return refresh_interval;

end

function init()

	add_task(0, refresh_feeds);

end

if prosody.start_time then -- already started

	init();

else

	prosody.events.add_handler("server-started", init);

end