local dt = require "util.datetime";

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

local hashes = require "util.hashes";

local st = require "util.stanza";

local jid = require "util.jid";

local array = require "util.array";

local set = require "util.set";

local default_host = module:get_option_string("external_service_host", module.host);

local default_port = module:get_option_number("external_service_port");

local default_secret = module:get_option_string("external_service_secret");

local default_ttl = module:get_option_number("external_service_ttl", 86400);

local configured_services = module:get_option_array("external_services", {});

local access = module:get_option_set("external_service_access", {});

-- https://tools.ietf.org/html/draft-uberti-behave-turn-rest-00

local function behave_turn_rest_credentials(srv, item, secret)

	local ttl = default_ttl;

	if type(item.ttl) == "number" then

		ttl = item.ttl;

	end

	local expires = srv.expires or os.time() + ttl;

	local username;

	if type(item.username) == "string" then

		username = string.format("%d:%s", expires, item.username);

	else

		username = string.format("%d", expires);

	end

	srv.username = username;

	srv.password = base64.encode(hashes.hmac_sha1(secret, srv.username));

end

local algorithms = {

	turn = behave_turn_rest_credentials;

}

-- filter config into well-defined service records

local function prepare(item)

	if type(item) ~= "table" then

		module:log("error", "Service definition is not a table: %q", item);

		return nil;

	end

	local srv = {

		type = nil;

		transport = nil;

		host = default_host;

		port = default_port;

		username = nil;

		password = nil;

		restricted = nil;

		expires = nil;

	};

	if type(item.type) == "string" then

		srv.type = item.type;

	else

		module:log("error", "Service missing mandatory 'type' field: %q", item);

		return nil;

	end

	if type(item.transport) == "string" then

		srv.transport = item.transport;

	end

	if type(item.host) == "string" then

		srv.host = item.host;

	end

	if type(item.port) == "number" then

		srv.port = item.port;

	end

	if type(item.username) == "string" then

		srv.username = item.username;

	end

	if type(item.password) == "string" then

		srv.password = item.password;

		srv.restricted = true;

	end

	if item.restricted == true then

		srv.restricted = true;

	end

	if type(item.expires) == "number" then

		srv.expires = item.expires;

	elseif type(item.ttl) == "number" then

		srv.expires = os.time() + item.ttl;

	end

	if (item.secret == true and default_secret) or type(item.secret) == "string" then

		local secret_cb = item.credentials_cb or algorithms[item.algorithm] or algorithms[srv.type];

		local secret = item.secret;

		if secret == true then

			secret = default_secret;

		end

		if secret_cb then

			secret_cb(srv, item, secret);

			srv.restricted = true;

		end

	end

	return srv;

end

function module.load()

	-- Trigger errors on startup

	local services = configured_services / prepare;

	if #services == 0 then

		module:log("warn", "No services configured or all had errors");

	end

end

-- Ensure only valid items are added in events

local services_mt = {

	__index = getmetatable(array()).__index;

	__newindex = function (self, i, v)

		rawset(self, i, assert(prepare(v), "Invalid service entry added"));

	end;

}

function get_services()

	local extras = module:get_host_items("external_service");

	local services = ( configured_services + extras ) / prepare;

	setmetatable(services, services_mt);

	return services;

end

function services_xml(services, name, namespace)

	local reply = st.stanza(name or "services", { xmlns = namespace or "urn:xmpp:extdisco:2" });

	for _, srv in ipairs(services) do

		reply:tag("service", {

				type = srv.type;

				transport = srv.transport;

				host = srv.host;

				port = srv.port and string.format("%d", srv.port) or nil;

				username = srv.username;

				password = srv.password;

				expires = srv.expires and dt.datetime(srv.expires) or nil;

				restricted = srv.restricted and "1" or nil;

			}):up();

	end

	return reply;

end

local function handle_services(event)

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

	local action = stanza.tags[1];

	local user_bare = jid.bare(stanza.attr.from);

	local user_host = jid.host(user_bare);

	if not ((access:empty() and origin.type == "c2s") or access:contains(user_bare) or access:contains(user_host)) then

		origin.send(st.error_reply(stanza, "auth", "forbidden"));

		return true;

	end

	local services = get_services();

	local requested_type = action.attr.type;

	if requested_type then

		services:filter(function(item)

			return item.type == requested_type;

		end);

	end

	module:fire_event("external_service/services", {

			origin = origin;

			stanza = stanza;

			requested_type = requested_type;

			services = services;

		});

	local reply = st.reply(stanza):add_child(services_xml(services, action.name, action.attr.xmlns));

	origin.send(reply);

	return true;

end

local function handle_credentials(event)

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

	local action = stanza.tags[1];

	if origin.type ~= "c2s" then

		origin.send(st.error_reply(stanza, "auth", "forbidden", "The 'port' and 'type' attributes are required."));

		return true;

	end

	local services = get_services();

	services:filter(function (item)

		return item.restricted;

	end)

	local requested_credentials = set.new();

	for service in action:childtags("service") do

		if not service.attr.type or not service.attr.host then

			origin.send(st.error_reply(stanza, "modify", "bad-request"));

			return true;

		end

		requested_credentials:add(string.format("%s:%s:%d", service.attr.type, service.attr.host,

			tonumber(service.attr.port) or 0));

	end

	module:fire_event("external_service/credentials", {

			origin = origin;

			stanza = stanza;

			requested_credentials = requested_credentials;

			services = services;

		});

	services:filter(function (srv)

		local port_key = string.format("%s:%s:%d", srv.type, srv.host, srv.port or 0);

		local portless_key = string.format("%s:%s:%d", srv.type, srv.host, 0);

		return requested_credentials:contains(port_key) or requested_credentials:contains(portless_key);

	end);

	local reply = st.reply(stanza):add_child(services_xml(services, action.name, action.attr.xmlns));

	origin.send(reply);

	return true;

end

-- XEP-0215 v0.7

module:add_feature("urn:xmpp:extdisco:2");

module:hook("iq-get/host/urn:xmpp:extdisco:2:services", handle_services);

module:hook("iq-get/host/urn:xmpp:extdisco:2:credentials", handle_credentials);

-- COMPAT XEP-0215 v0.6

-- Those still on the old version gets to deal with undefined attributes until they upgrade.

module:add_feature("urn:xmpp:extdisco:1");

module:hook("iq-get/host/urn:xmpp:extdisco:1:services", handle_services);

module:hook("iq-get/host/urn:xmpp:extdisco:1:credentials", handle_credentials);