local st = require "util.stanza";

local uuid = require "util.uuid";

local mt = require "util.multitable";

local cache = require "util.cache";

local xmlns_pubsub = "http://jabber.org/protocol/pubsub";

local xmlns_pubsub_event = "http://jabber.org/protocol/pubsub#event";

-- TODO persist

-- TODO query known pubsub nodes to sync current subscriptions

-- TODO subscription ids per 'item' would be handy

local pending_subscription = cache.new(256); -- uuid → node

local pending_unsubscription = cache.new(256); -- uuid → node

local active_subscriptions = mt.new() -- service | node | uuid | { item }

function module.save()

	return { active_subscriptions = active_subscriptions.data }

end

function module.restore(data)

	if data and data.active_subscriptions then

		active_subscriptions.data = data.active_subscriptions

	end

end

local valid_events = {"subscribed"; "unsubscribed"; "error"; "item"; "retract"; "purge"; "delete"}

local function subscription_added(item_event)

	local item = item_event.item;

	assert(item.service, "pubsub subscription item MUST have a 'service' field.");

	assert(item.node, "pubsub subscription item MUST have a 'node' field.");

	local already_subscibed = false;

	for _ in active_subscriptions:iter(item.service, item.node, nil) do -- luacheck: ignore 512

		already_subscibed = true;

		break

	end

	item._id = uuid.generate();

	local iq_id = uuid.generate();

	pending_subscription:set(iq_id, item._id);

	active_subscriptions:set(item.service, item.node, item._id, item);

	if not already_subscibed then

		module:send(st.iq({ type = "set", id = iq_id, from = module.host, to = item.service })

			:tag("pubsub", { xmlns = xmlns_pubsub })

				:tag("subscribe", { jid = module.host, node = item.node }));

	end

end

for _, event_name in ipairs(valid_events) do

	module:hook("pubsub-event/host/"..event_name, function (event)

		for _, _, _, _, cb in active_subscriptions:iter(event.service, event.node, nil, "on_"..event_name) do

			pcall(cb, event);

		end

	end);

end

module:hook("iq/host", function (event)

	local stanza = event.stanza;

	local service = stanza.attr.from;

	if not stanza.attr.id then return end -- shouldn't be possible

	local subscribed_node = pending_subscription:get(stanza.attr.id);

	pending_subscription:set(stanza.attr.id, nil);

	local unsubscribed_node = pending_unsubscription:get(stanza.attr.id);

	pending_unsubscription:set(stanza.attr.id, nil);

	if stanza.attr.type == "result" then

		local pubsub_wrapper = stanza:get_child("pubsub", xmlns_pubsub);

		local subscription = pubsub_wrapper and pubsub_wrapper:get_child("subscription");

		if not subscription then return end

		local node = subscription.attr.node;

		local what;

		if subscription.attr.subscription == "subscribed" then

			what = "on_subscribed";

		elseif subscription.attr.subscription == "none" then

			what = "on_unsubscribed";

		end

		if not what then return end -- there are other states but we don't handle them

		for _, _, _, _, cb in active_subscriptions:iter(service, node, nil, what) do

			cb(event);

		end

		return true;

	elseif stanza.attr.type == "error" then

		local node = subscribed_node or unsubscribed_node;

		local error_type, error_condition, reason, pubsub_error = stanza:get_error();

		local err = { type = error_type, condition = error_condition, text = reason, extra = pubsub_error };

		if active_subscriptions:get(service) then

			for _, _, _, _, cb in active_subscriptions:iter(service, node, nil, "on_error") do

				cb(err);

			end

			return true;

		end

	end

end, 1);

local function subscription_removed(item_event)

	local item = item_event.item;

	active_subscriptions:set(item.service, item.node, item._id, nil);

	local node_subs = active_subscriptions:get(item.service, item.node);

	if node_subs and next(node_subs) then return end

	local iq_id = uuid.generate();

	pending_unsubscription:set(iq_id, item._id);

	module:send(st.iq({ type = "set", id = iq_id, from = module.host, to = item.service })

		:tag("pubsub", { xmlns = xmlns_pubsub })

			:tag("unsubscribe", { jid = module.host, node = item.node }))

end

module:handle_items("pubsub-subscription", subscription_added, subscription_removed, true);

module:hook("message/host", function(event)

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

	local ret = nil;

	local service = stanza.attr.from;

	module:log("debug", "Got message/host: %s", stanza:top_tag());

	for event_container in stanza:childtags("event", xmlns_pubsub_event) do

		for pubsub_event in event_container:childtags() do

			module:log("debug", "Got pubsub event %s", pubsub_event:top_tag());

			local node = pubsub_event.attr.node;

			module:fire_event("pubsub-event/host/"..pubsub_event.name, {

					stanza = stanza;

					origin = origin;

					event = pubsub_event;

					service = service;

					node = node;

				});

			ret = true;

		end

	end

	return ret;

end);

module:hook("pubsub-event/host/items", function (event)

	for item in event.event:childtags() do

		module:log("debug", "Got pubsub item event %s", item:top_tag());

		event.item = item;

		event.payload = item.tags[1];

		module:fire_event("pubsub-event/host/"..item.name, event);

	end

end);