/*
 * Copyright (C) 2008-2017, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.juick.components.s2s;

import org.apache.commons.lang3.math.NumberUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.util.Hashtable;
import java.util.Random;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

/**
 *
 * @author ugnich
 */
public class DNSQueries {

    private static final Logger logger = LoggerFactory.getLogger(DNSQueries.class);

    private static Random rand = new Random();

    public static InetSocketAddress getServerAddress(String hostname) {

        String host = hostname;
        int port = 5269;

        Hashtable<String, String> env = new Hashtable<>(5);
        env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
        try {
            DirContext ctx = new InitialDirContext(env);
            Attribute att = ctx.getAttributes("_xmpp-server._tcp." + hostname, new String[]{"SRV"}).get("SRV");

            if (att != null && att.size() > 0) {
                int i = rand.nextInt(att.size());
                String srv[] = att.get(i).toString().split(" ");
                port = NumberUtils.toInt(srv[2], 5269);
                host = srv[3];
            }
            ctx.close();
        } catch (NamingException e) {
            logger.info("SRV record for {} is not resolved, falling back to A record", hostname);
        }
        return new InetSocketAddress(host, port);
    }
}