local async = require "util.async";

local promise = require "util.promise";

local http = require "net.http";

local st = require "util.stanza";

local xmlns_metadata = "xmpp:prosody.im/protocol/media-metadata#0"

local fetch_headers = {

	bytes = "content-length";

	type = "content-type";

	etag = "etag";

	blurhash = "blurhash";

};

local function fetch_media_metadata(url)

	return promise.new(function (resolve)

		http.request(url, { method = "HEAD" }, function (body, code, response) --luacheck: ignore 212/body

			if code == 200 then

				local metadata = {};

				for metadata_name, header_name in pairs(fetch_headers) do

					metadata[metadata_name] = response.headers[header_name];

				end

				resolve(metadata);

			else

				resolve(nil);

			end

		end);

	end);

end

local function metadata_to_tag(metadata)

	if not metadata then return; end

	local metadata_tag = st.stanza("metadata", { xmlns = xmlns_metadata });

	for k, v in pairs(metadata) do

		metadata_tag:text_tag(k, v)

	end

	return metadata_tag;

end

module:hook("muc-occupant-groupchat", function (event)

	local stanza = event.stanza;

	local promises;

	for oob in stanza:childtags("x", "jabber:x:oob") do

		if not promises then promises = {}; end

		local url = oob:get_child_text("url");

		local p = fetch_media_metadata(url)

			:next(metadata_to_tag)

			:next(function (metadata_tag)

				oob:add_child(metadata_tag);

			end);

		table.insert(promises, p);

	end

	if not promises then return; end

	async.wait(promise.all(promises));

end);