local server = require "net.server";

local log = require "util.logger".init("net.connect");

local new_id = require "util.id".short;

-- TODO #1246 Happy Eyeballs

-- FIXME RFC 6724

-- FIXME Error propagation from resolvers doesn't work

-- FIXME #1428 Reuse DNS resolver object between service and basic resolver

-- FIXME #1429 Close DNS resolver object when done

local pending_connection_methods = {};

local pending_connection_mt = {

	__name = "pending_connection";

	__index = pending_connection_methods;

	__tostring = function (p)

		return "<pending connection "..p.id.." to "..tostring(p.target_resolver.hostname)..">";

	end;

};

function pending_connection_methods:log(level, message, ...)

	log(level, "[pending connection %s] "..message, self.id, ...);

end

-- pending_connections_map[conn] = pending_connection

local pending_connections_map = {};

local pending_connection_listeners = {};

local function attempt_connection(p)

	p:log("debug", "Checking for targets...");

	if p.conn then

		pending_connections_map[p.conn] = nil;

		p.conn = nil;

	end

	p.target_resolver:next(function (conn_type, ip, port, extra)

		if not conn_type then

			-- No more targets to try

			p:log("debug", "No more connection targets to try", p.target_resolver.last_error);

			if p.listeners.onfail then

				p.listeners.onfail(p.data, p.last_error or p.target_resolver.last_error or "unable to resolve service");

			end

			return;

		end

		p:log("debug", "Next target to try is %s:%d", ip, port);

		local conn, err = server.addclient(ip, port, pending_connection_listeners, p.options.pattern or "*a",

			extra and extra.sslctx or p.options.sslctx, conn_type, extra);

		if not conn then

			log("debug", "Connection attempt failed immediately: %s", err);

			p.last_error = err or "unknown reason";

			return attempt_connection(p);

		end

		p.conn = conn;

		pending_connections_map[conn] = p;

	end);

end

function pending_connection_listeners.onconnect(conn)

	local p = pending_connections_map[conn];

	if not p then

		log("warn", "Successful connection, but unexpected! Closing.");

		conn:close();

		return;

	end

	pending_connections_map[conn] = nil;

	p:log("debug", "Successfully connected");

	conn:setlistener(p.listeners, p.data);

	return p.listeners.onconnect(conn);

end

function pending_connection_listeners.ondisconnect(conn, reason)

	local p = pending_connections_map[conn];

	if not p then

		log("warn", "Failed connection, but unexpected!");

		return;

	end

	p.last_error = reason or "unknown reason";

	p:log("debug", "Connection attempt failed: %s", p.last_error);

	attempt_connection(p);

end

local function connect(target_resolver, listeners, options, data)

	local p = setmetatable({

		id = new_id();

		target_resolver = target_resolver;

		listeners = assert(listeners);

		options = options or {};

		data = data;

	}, pending_connection_mt);

	p:log("debug", "Starting connection process");

	attempt_connection(p);

end

return {

	connect = connect;

};