-- util to easily merge multiple sets of LuaSec context options

-- All "handlers" behave like extended rawset(table, key, value) with extra

-- processing usually merging the new value with the old in some reasonable

-- way

-- If a field does not have a defined handler then a new value simply

-- replaces the old.

-- Convert either a list or a set into a special type of set where each

-- item is either positive or negative in order for a later set of options

-- to be able to remove options from this set by filtering out the negative ones

function handlers.options(config, field, new)

	local options = config[field] or { };

	if type(new) ~= "table" then new = { new } end

	for key, value in pairs(new) do

			options[key] = value;

		else -- list item

			options[value] = true;

	config[field] = options;

-- finalisers take something produced by handlers and return what luasec

-- expects it to be

-- Produce a list of "positive" options from the set

function finalisers.options(options)

	local output = {};

	for opt, enable in pairs(options) do

			output[#output+1] = opt;

	return output;

-- We allow ciphers to be a list

function finalisers.ciphers(cipherlist)

	if type(cipherlist) == "table" then

		return t_concat(cipherlist, ":");

	return cipherlist;

-- protocol = "x" should enable only that protocol

-- protocol = "x+" should enable x and later versions

-- this interacts with ssl.options as well to add no_x

local function protocol(config)

	local min_protocol = protocols[config.protocol];

		config.protocol = "sslv23";

			t_insert(config.options, "no_"..protocols[i]);

-- Merge options from 'new' config into 'config'

local function apply(config, new)

	if type(new) == "table" then

		for field, value in pairs(new) do

			(handlers[field] or rawset)(config, field, value);

-- Finalize the config into the form LuaSec expects

local function final(config)

	local output = { };

	for field, value in pairs(config) do

		output[field] = (finalisers[field] or id)(value);

	-- Need to handle protocols last because it adds to the options list

	protocol(output);

	return output;