local st_iq = require "util.stanza".iq;

local uuid_gen = require "util.uuid".generate;

local calculate_hash = require "util.caps".calculate_hash;

-- Map of jid..node, to avoid querying the same client multiple times for the same value.

local in_flight_iqs = {}

-- Some clients (*ahem* poezio…) don’t include the @node in their result iq.

local iq_node_map = {}

assert(module.send_iq, "This module is not compatible with this version of Prosody.");

local function iq_result_handler(event)

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

	local query = stanza:get_child("query", "http://jabber.org/protocol/disco#info");

	if not query then

		origin.log("debug", "Wrong iq payload in disco#info result: %s", stanza);

		origin.caps_cache = nil;

		return;

	end

	local from = stanza.attr.from;

	local id = stanza.attr.id;

	local node_string = query.attr.node;

	local node_query = iq_node_map[from..id];

	if node_string == nil then

		node_string = node_query;

		query.attr.node = node_query;

	end

	iq_node_map[from..id] = nil;

	if node_string ~= node_query then

		origin.log("debug", "Wrong node for our disco#info query, expected %s, received %s", node_string, node_query);

		origin.caps_cache = nil;

		return;

	end

	local node, ver = node_query:match("([^#]+)#([^#]+)");

	local hash = calculate_hash(query)

	if ver ~= hash then

		origin.log("debug", "Wrong hash for disco#info: %s ~= %s", ver, hash);

		origin.caps_cache = nil;

		return;

	end

	origin.caps_cache = query;

	origin.log("info", "Stored caps %s", ver);

	module:fire_event("c2s-capabilities-changed", { origin = origin });

	return true;

end

local function iq_error_handler(err)

	local origin = err.context.origin;

	if origin ~= nil then

		origin.caps_cache = nil;

		module:fire_event("c2s-capabilities-changed", { origin = origin });

	end

end

local function presence_stanza_handler(event)

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

	local from = stanza.attr.from;

	if stanza.attr.to ~= nil then

		return;

	end

	local caps = stanza:get_child("c", "http://jabber.org/protocol/caps");

	if caps == nil then

		origin.log("debug", "Presence from %s without caps received, skipping", from);

		return;

	end

	local hash = caps.attr.hash;

	local node = caps.attr.node;

	local ver = caps.attr.ver;

	if not hash or not node or not ver then

		return;

	end

	if hash ~= "sha-1" then

		origin.log("warn", "Presence from %s with non-SHA-1 caps : %s", from, hash);

		return;

	end

	local node_query = node.."#"..ver;

	if (origin.caps_cache and origin.caps_cache.attr.node == node_query) or in_flight_iqs[from..node_query] ~= nil then

		origin.log("debug", "Already requested these caps, skipping");

		return;

	end

	origin.log("debug", "Presence from %s with SHA-1 caps %s, querying disco#info", from, node_query);

	local id = uuid_gen();

	iq_node_map[from..id] = node_query

	local iq = st_iq({ type = "get", from = module.host, to = from, id = id })

		:tag("query", { xmlns = "http://jabber.org/protocol/disco#info", node = node_query });

	in_flight_iqs[from..node_query] = true;

	module:send_iq(iq, origin)

		:next(iq_result_handler, iq_error_handler)

		:finally(function () in_flight_iqs[from..node_query] = nil; end)

end

-- Handle only non-directed presences for now.

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