local array = require "util.array";

local hashes = require "util.hashes";

local it = require "util.iterators";

local base64_enc = require "util.encodings".base64.encode;

local hash_functions = {

	["SCRAM-SHA-1"] = hashes.sha1;

	["SCRAM-SHA-1-PLUS"] = hashes.sha1;

	["SCRAM-SHA-256"] = hashes.sha256;

	["SCRAM-SHA-256-PLUS"] = hashes.sha256;

};

function add_ssdp_info(event)

	local sasl_handler = event.session.sasl_handler;

	local hash = hash_functions[sasl_handler.selected];

	if not hash then

		module:log("debug", "Not enabling SSDP for unsupported mechanism: %s", sasl_handler.selected);

		return;

	end

	local mechanism_list = array.collect(it.keys(sasl_handler:mechanisms())):sort();

	local cb = sasl_handler.profile.cb;

	local cb_list = cb and array.collect(it.keys(cb)):sort();

	local ssdp_string;

	if cb_list then

		ssdp_string = mechanism_list:concat(",").."|"..cb_list:concat(",");

	else

		ssdp_string = mechanism_list:concat(",");

	end

	module:log("debug", "Calculated SSDP string: %s", ssdp_string);

	event.message = event.message..",d="..base64_enc(hash(ssdp_string));

	sasl_handler.state.server_first_message = event.message;

end

module:hook("sasl/c2s/challenge", add_ssdp_info, 1);

module:hook("sasl2/c2s/challenge", add_ssdp_info, 1);