local is_contact_subscribed = require"core.rostermanager".is_contact_subscribed;

local jid_split = require"util.jid".split;

local jid_bare = require"util.jid".bare;

local st = require"util.stanza";

local datetime = require"util.datetime";

local presence_cache = {}; -- Reload to empty

local cache_full = module:get_option_boolean(module.name.."_full", false);

local function cache_hook(event)

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

	local typ = stanza.attr.type;

	module:log("debug", "Cache hook, got %s from a %s", stanza:top_tag(), origin.type);

	if origin.type:match"^s2s" and ( typ == nil or typ == "unavailable" ) then

		local from_jid = stanza.attr.from;

		local from_bare = jid_bare(from_jid);

		local username = jid_split(stanza.attr.to);

		if not is_contact_subscribed(username, module.host, from_bare) then

			module:log("debug", "Not in their roster", origin.username);

			return;

		end

		local user_presence_cache = presence_cache[username];

		if not user_presence_cache then

			user_presence_cache = {};

			presence_cache[username] = user_presence_cache;

		end

		local contact_presence_cache = user_presence_cache[from_bare];

		if not contact_presence_cache then

			contact_presence_cache = {};

			user_presence_cache[from_bare] = contact_presence_cache;

		end

		if typ == "unavailable" then

			contact_presence_cache[from_jid] = nil;

			if next(contact_presence_cache) == nil or from_jid == from_bare then

				user_presence_cache[from_bare] = nil;

				if next(user_presence_cache) == nil then

					presence_cache[username] = nil;

				end

			end

		elseif cache_full then

			stanza = st.clone(stanza);

			stanza:tag("delay", { xmlns = "urn:xmpp:delay", from = module.host, stamp = datetime.datetime() }):up();

			contact_presence_cache[from_jid] = stanza;

		else -- only cache binary state

			contact_presence_cache[from_jid] = datetime.datetime();

		end

	end

end

module:hook("presence/bare", cache_hook, 10);

-- module:hook("presence/full", cache_hook, 10);

local function answer_probe_from_cache(event)

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

	if stanza.attr.type ~= "probe" then return; end

	local contact_bare = stanza.attr.to;

	local user_presence_cache = presence_cache[origin.username];

	if not user_presence_cache then return; end

	local contact_presence_cache = user_presence_cache[contact_bare];

	if not contact_presence_cache then return; end

	local user_jid = stanza.attr.from;

	for jid, presence in pairs(contact_presence_cache) do

		module:log("debug", "Sending cached presence from %s", jid);

		if presence == true then

			presence = st.presence({ from = user_jid, from = jid });

		elseif type(presence) == "string" then -- a timestamp

			presence = st.presence({ from = user_jid, from = jid })

				:tag("delay", { xmlns = "urn:xmpp:delay", from = module.host, stamp = presence }):up();

		end

		origin.send(presence);

	end

	if cache_full then

		return true;

	end

end

module:hook("pre-presence/bare", answer_probe_from_cache, 10);

module:add_timer(3600, function (now)

	local older = datetime.datetime(now - 7200);

	for username, user_presence_cache in pairs(presence_cache) do

		for contact, contact_presence_cache in pairs(user_presence_cache) do

			for jid, presence in pairs(contact_presence_cache) do

				if presence == true or (type(presence) == "string" and presence < older) then

					contact_presence_cache[jid] = nil;

				end

			end

			if next(contact_presence_cache) == nil then

				user_presence_cache[contact] = nil;

			end

		end

		if next(user_presence_cache) == nil then

			presence_cache[username] = nil;

		end

	end

	return 3600;

end);