Gitter Welcome Message Bot

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.Net;
using System.Collections.Specialized;
using System.IO;
using System.Xml;
using System.Xml.Linq;
using System.Text.RegularExpressions;

namespace ConsoleApplication3
{
    public class User
    {
        public string id { get; set; }
        public string username { get; set; }
        public string url { get; set; }
        public string avatarUrlSmall { get; set; }
        public string avatarUrlMedium { get; set; }
        public string role { get; set; }
    }
    public class Mention
    {
        public string screenName { get; set; }
        public string userId { get; set; }
    }
    public class issue
    {
        public string number { get; set; }
    }
    public class URL
    {
        public string url { get; set; }
    }
    public class Message
    {
        public string id { get; set; }
        public string text { get; set; }
        public string html { get; set; }
        public string sent { get; set; }
        public string editedAt { get; set; }
        public User fromUser { get; set; }
        public bool unread { get; set; }
        public int readBy { get; set; }
        public List<URL> urls { get; set; }
        public List<Mention> mentions { get; set; }
        public List<issue> issues { get; set; }
        public string meta { get;set; }
        public string v { get; set; }
    }
    class Program
    {
        static List<User> oldusers = new List<User>();
        static void Main(string[] args)
        {
           System.Threading.Thread th=new System.Threading.Thread (CheckCurrentUsers);
           th.Start();
           System.Threading.Thread th2 = new System.Threading.Thread(GetMessages);
           th2.Start();
        }
        static void GetMessages()
        {
            List<Message> postedids = new List<Message>();
            List<Message> mymessages;
            while (true)
            {
                System.Threading.Thread.Sleep(5000);
                using (var wb = new WebClient())
                {
                    //TODO:Send HTTP Get Request To Get The Last Messages.
                    wb.Headers.Add("Authorization", "Bearer 58e579a62047739c3839063d8b8e4c7d64588977"); //This is the Access Token I Got.
                    wb.Headers.Add("Host", "api.gitter.im");
                    var response = wb.DownloadString("https://api.gitter.im/v1/rooms/54577284db8155e6700d0a73/chatMessages?limit=1"); //I set the limit to 1 to get the last message ony , you can remove it and get the last 50 messages.
                    //TODO:Deserialize the Json Response To List Of Messages.
                    DataContractJsonSerializer contract = new DataContractJsonSerializer(typeof(List<Message>));
                    MemoryStream stream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(response));
                    mymessages = (List<Message>)contract.ReadObject(stream);
                }

                for (int i = 0; i < mymessages.Count; i++)
                {
                    //Check if there are any mentions in this message with the screenName "testbot23" which is the bot screen name.
                    if(mymessages[i].mentions.Count>0)
                    if (mymessages[i].mentions[0].screenName == "testbot23")
                    {
                        //Check if I posted this message before to not post it again.
                        bool posted = postedids.Any(x => x.id == mymessages[i].id);
                        if (!posted)
                        {
                            WebClient wb = new WebClient();
                            //Check if the user wanted the bot to tell him a quote, if he didn't the bot will just say "Yo".
                            if (mymessages[i].text.ToLower().Contains("compile"))
                            {
                                //Get Random quote from all-famous-quotes.com/quotes.generator.html
                                string[] langandcode = mymessages[i].text.ToLower().Split(' ');
                                var data = new NameValueCollection();
                                data["utf8"] = "%CE%BB";
                                try
                                {
                                    string code = mymessages[i].text.Replace(langandcode[0]+" " + langandcode[1]+" " + langandcode[2]+" " + langandcode[3], "").Remove(0,1);
                                    data["code"] = code;
                                }
                                catch { break; }
                                data["execute"] = "on";
                                switch (langandcode[3])
                                {
                                    case "c":
                                        data["lang"] = "c/gcc-4.9.1";
                                        break;
                                    case "c++":
                                        data["lang"] = "c++/c++11-gcc-4.9.1";
                                        break;
                                    case "coffescript":
                                        data["lang"] = "coffeescript/node-0.10.29-coffee-1.7.1";
                                        break;
                                    case "fortran":
                                        data["lang"] = "fortran/f95-4.4.3";
                                        break;
                                    case "haskell":
                                        data["lang"] = "haskell/hugs98-sep-2006";
                                        break;
                                    case "io":
                                        data["lang"] = "io/io-20131204";
                                        break;
                                    case "javascript":
                                        data["lang"] = "javascript/node-0.10.29";
                                        break;
                                    case "lua":
                                        data["lang"] = "lua/lua-5.2.3";
                                        break;
                                    case "ocaml":
                                        data["lang"] = "ocaml/ocaml-4.01.0";
                                        break;
                                    case "php":
                                        data["lang"] = "php/php-5.5.14";
                                        break;
                                    case "pascal":
                                        data["lang"] = "pascal/fpc-2.6.4";
                                        break;
                                    case "perl":
                                        data["lang"] = "perl/perl-5.20.0";
                                        break;
                                    case "python":
                                        data["lang"] = "python/cpython-3.4.1";
                                        break;
                                    case "ruby":
                                        data["lang"] = "ruby/mri-2.1";
                                        break;
                                    case "slash":
                                        data["lang"] = "slash/slash-head";
                                        break;
                                    case "assembly":
                                        data["lang"] = "assembly/nasm-2.07";
                                        break;
                                }
                                data["input"] = "";
                                wb.Headers.Add("Host", "eval.in");
                                wb.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 6.3; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0");
                                wb.Headers.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
                                wb.Headers.Add("Accept-Language", "en-US,en;q=0.5");
                                wb.Headers.Add("Referer", "https://eval.in/");
                                byte[] response;
                                try
                                {
                                     response = wb.UploadValues("https://eval.in", "POST", data);
                                }
                                catch { break; }
                                string htmlraw = System.Text.Encoding.UTF8.GetString(response);
                                string res1 = htmlraw.Substring(htmlraw.IndexOf("<h2>Program Output</h2>"));
                                string res2 = res1.Remove(res1.IndexOf("<h2>Fork</h2>"));
                                string finalres = Regex.Replace(res2, "<.*?>", string.Empty);
                                postMessage(finalres + "@" + mymessages[i].fromUser.username);          
                            }
                            else if (mymessages[i].text.ToLower().Contains("define"))
                            {
                                
                                string after=mymessages[i].text.Substring(mymessages[i].text.IndexOf("define")).Replace("define", "").Replace(" ","");
                                string response="";
                                try
                                {
                                    response = wb.DownloadString("http://www.merriam-webster.com/dictionary/" + after);
                                }
                                catch {
                                    postMessage("Sorry,There is no definition for this world. " + "@" + mymessages[i].fromUser.username);
                                    break;
                                }
                                int cutIndex = response.IndexOf("<div class=\"ld_on_collegiate\">");
                                if (cutIndex<0)
                                {
                                    postMessage("Sorry,There is no definition for this world. " + "@"+mymessages[i].fromUser.username);
                                    break;
                                }
                                string raw1 = response.Substring(cutIndex);
                                string definition = raw1.Remove(raw1.IndexOf("<p class=\"bottom_entry\">")).Replace("<div class=\"ld_on_collegiate\">", "").Replace("<p>","").Replace("</p>","").Replace("\r","").Replace("\n","");
                                postMessage("The definition for " + after + " is " + definition + "\nSource:http://www.merriam-webster.com/dictionary/"+after+" @" + mymessages[i].fromUser.username);    
                            }
                            else if (mymessages[i].text.ToLower().Contains("quote"))
                            {
                                //Get Random quote from all-famous-quotes.com/quotes.generator.html
                                string response = wb.DownloadString("http://www.all-famous-quotes.com/quotes_generator.html");
                                string raw1 = response.Substring(response.IndexOf("<blockquote class=\"new\">"));
                                string quote=raw1.Remove(raw1.IndexOf("- <a href=\"http://www.all-famous-quotes.com")).Replace("<blockquote class=\"new\">", "");
                                postMessage(quote + "@"+mymessages[i].fromUser.username);                                
                            }
                            else if(mymessages[i].text.ToLower().Contains("joke"))
                            {
                                //Get Random Joke
                                string rawhtml = wb.DownloadString("http://www.ajokeaday.com/ChisteAlAzar.asp");
                                string raw1 = rawhtml.Substring(rawhtml.IndexOf(("<div class=\"chiste\">")));
                                string raw2 = raw1.Remove(raw1.IndexOf("<div class=\"opciones\">"));
                                string joke = Regex.Replace(raw2, "<.*?>", string.Empty);
                                postMessage(joke + " @" + mymessages[i].fromUser.username);                                
                            }
                            else
                            {
                                postMessage("Yo, @" + mymessages[i].fromUser.username);                                
                            }
                        }
                        //Mark this message as posted.
                        postedids.Add(mymessages[i]);
                    }
                }
            }
        }
        static void CheckCurrentUsers()
        {
            while (true)
            {
                System.Threading.Thread.Sleep(5000);
                List<User> myusers;
                using (var wb = new WebClient())
                {
                    //TODO:Send HTTP Get Request To Get The Current Users.
                    wb.Headers.Add("Authorization", "Bearer 87eaf739c5c4c90707df73a938d435c5f9e5cca3"); //This is the Access Token I Got.
                    wb.Headers.Add("Host", "api.gitter.im");
                    var response = wb.DownloadString("https://api.gitter.im/v1/rooms/54577284db8155e6700d0a73/users");
                    //TODO:Deserialize the Json Response To List Of Users.
                    DataContractJsonSerializer contract = new DataContractJsonSerializer(typeof(List<User>));
                    MemoryStream stream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(response));
                    myusers = (List<User>)contract.ReadObject(stream);
                }
                bool newUser = false;
                //Check There are any new users with this O(n^2) horrible algorithm.
                for (int i = 0; i < myusers.Count; i++)
                {
                    newUser = false;
                    for (int j = 0; j < oldusers.Count; j++)
                    {
                        if (myusers[i].id != oldusers[j].id)
                        {
                            newUser = true;
                        }
                        else
                        {
                            newUser = false;
                            break;
                        }
                    }
                    if (newUser)
                    {
                        //If There is a new user post a welcome Message
                        postMessage("Welcome @" + myusers[i].username + "\n `You can ask me to say a quote, define a word or compile some code. Just mention me`");
                    }
                }
                oldusers = myusers;

            }
        }
        static void postMessage(string msg)
        {
            WebClient wb = new WebClient();
            var data = new NameValueCollection();
            wb.Headers.Add("Authorization", "Bearer 58e579a62047739c3839063d8b8e4c7d64588977");
            wb.Headers.Add("Accept", "application/json");
            data["text"] = msg;
            wb.UploadValues("https://api.gitter.im/v1/rooms/54577284db8155e6700d0a73/chatMessages", "POST", data);
        }

    }
}