local add_filter = require "util.filters".add_filter;

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

local buffer_seconds = module:get_option_number("flush_presence_seconds");

local function throttle_session(data)

	local session = data.session;

	local buffer, flushing = {}, false;

	local timer_active = false;

	local function flush_buffer()

		module:log("debug", "Flushing buffer for %s", session.full_jid);

		flushing = true;

		for jid, presence in pairs(buffer) do

			session.send(presence);

		end

		flushing = false;

	end

	local function throttle_presence(stanza)

		if stanza.name ~= "presence" or (stanza.attr.type and stanza.attr.type ~= "unavailable") then

			module:log("debug", "Non-presence stanza for %s: %s", session.full_jid, tostring(stanza));

			flush_buffer();

		elseif not flushing then

			module:log("debug", "Buffering presence stanza from %s to %s", stanza.attr.from, session.full_jid);

			buffer[stanza.attr.from] = stanza;

			if not timer_active and buffer_seconds then

				timer_active = true;

				add_task(buffer_seconds, flush_buffer);

			end

			return nil; -- Drop this stanza (we've stored it for later)

		end

		return stanza;

	end

	add_filter(session, "stanzas/out", throttle_presence);

end

module:hook("resource-bind", throttle_session);