using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Net.Sockets;
using System.Threading;

namespace PullMyFinger {
    static class Finger {
        public static readonly int FINGER_PORT = 79;

        static readonly Regex r = new Regex(@"^(.*)@([a-zA-Z0-9.-]+)$");

        public delegate void FingerCallback(string response);

        public static string Get(string address) {
            Match m = r.Match(address);

            if (m.Success) {
                Byte[] data;
                int bytes;
                StringBuilder response = new StringBuilder();
                TcpClient client;

                client = new TcpClient(m.Groups[2].Value, FINGER_PORT);
                data = System.Text.Encoding.ASCII.GetBytes(m.Groups[1].Value + "\r\n");

                NetworkStream ns = client.GetStream();
                ns.Write(data, 0, data.Length);
                data = new Byte[4096];
                do {
                    bytes = ns.Read(data, 0, data.Length);
                    response.Append(System.Text.Encoding.ASCII.GetString(data, 0, bytes));
                } while (bytes > 0);

                return response.ToString();
            } else {
                throw new ArgumentException(address + " is not a valid finger address");
            }
        }

        public static void GetAsync(string address, FingerCallback fcb) {
            Thread t = new Thread((ThreadStart)delegate {
                // Since we can't really throw these exceptions across threads,
                // we just handle them here and return a sensible string result.
                string result;
                try {
                    result = Get(address);
                } catch (SocketException e) {
                    result = e.Message;
                } catch (ArgumentException e) {
                    result = e.Message;
                }
                fcb(result);
            });

            t.Start();
        }
    }
}