-- Synthesize XEP-0156 JSON from DNS

local array = require "util.array";

local encodings = require "util.encodings";

local json = require "util.json";

local promise = require "util.promise";

local dns = require"net.adns".resolver();

local function check_dns(domain)

	return dns:lookup_promise("_xmppconnect." .. domain, "TXT");

end

local function check_domain(domain)

	return promise.resolve(domain):next(encodings.stringprep.nameprep):next(encodings.idna.to_ascii):next(

		function(domain_A)

			if not domain_A then

				return promise.reject(400);

			else

				return domain_A;

			end

		end):next(check_dns):next(function(txt)

		local uris = array();

		for _, cm in ipairs(txt) do

			local kind, uri = tostring(cm.txt):match("^_xmpp%-client%-(%w+)=([hpstw]+s?://.*)");

			if kind then

				uris:push({rel = "urn:xmpp:alt-connections:" .. kind, href = uri});

			end

		end

		if #uris == 0 then

			return promise.reject(404);

		end

		return {links=uris};

	end);

end

module:depends("http");

module:provides("http", {

	route = {

		["GET /*"] = function(_, domain)

			return check_domain(domain):next(function(altmethods)

				return {headers = {content_type = "application/json"}, body = json.encode(altmethods)};

			end);

		end,

	},

});

function module.command(args)

	local async = require "util.async";

	for _, domain in ipairs(args) do

		print(assert(async.wait_for(check_domain(domain):next(json.encode))));

	end

end