using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Collections.Generic;

namespace ConsoleChatServer
{
    static class IPSorter
    {
        /// <summary>
        /// Find the first IPv6 address for a given host
        /// </summary>
        /// <param name="host">URL of the host to lookup</param>
        /// <returns>IPAddress IPv6 or null if no IPv6 is associated</returns>
        public static IPAddress FindIPv6Address(string host)
        {
            IPAddress[] addressList = Dns.GetHostAddresses(host);

            foreach (IPAddress ip in addressList)
            {
                if (ip.AddressFamily == AddressFamily.InterNetworkV6)
                {
                    return ip;
                }
            }

            return null;
        }

        /// <summary>
        /// Find the first IPv4 on for a given host
        /// </summary>
        /// <param name="host">URL of the host to lookup</param>
        /// <returns>IPAddress IPv4 or null if no IPv4 address associated</returns>
        public static IPAddress FindIPv4Address(string host)
        {
            IPAddress[] addressList = Dns.GetHostAddresses(host);

            foreach (IPAddress ip in addressList)
            {
                if (ip.AddressFamily == AddressFamily.InterNetwork)
                {
                    return ip;
                }
            }

            return null;
        }

        /// <summary>
        /// Attempts to find an IPv6 for the host, if none is found, returns IPv4
        /// </summary>
        /// <param name="host"></param>
        /// <returns></returns>
        public static IPAddress GetBestAddress(string host)
        {
            IPAddress ip = FindIPv6Address(host);

            if (ip != null)
            {
                return ip;
            }

            return FindIPv4Address(host);
        }
    }
}