using System;
using System.Collections.Generic;
using System.Net.Sockets;
using System.IO;
using System.Diagnostics;
using System.Xml;
using System.Windows.Forms;

namespace GiantsLauncher
{
    class GiantsLauncher
    {
        [STAThread]
        static void Main(string[] args)
        {
            List<string> SERVERS = ReadServers();
            //string[] SERVERS = new string[] {"gckms.no-ip.org", "ahipstercat.fr"};
            string GIANTS_PATH = Microsoft.Win32.Registry.GetValue(@"HKEY_CURRENT_USER\Software\PlanetMoon\Giants", "DestDir", "").ToString();
            GIANTS_PATH += "\\Giants.exe";
            if (!File.Exists(GIANTS_PATH))
            {
                GIANTS_PATH = SetPath();
                GIANTS_PATH += "\\Giants.exe";
            }
            if (File.Exists(GIANTS_PATH))
            {
                Console.WriteLine("Giants path: {0}", GIANTS_PATH);
                // check version
                int version = GetGameBuild(GIANTS_PATH);
                if (version != 1497)
                {
                    // gtfo
                    Console.WriteLine("Game version is not 1.497. Found: {0}", version);
                    return;
                }
                string server_ok = "";
                foreach (string server in SERVERS)
                {
                    if (server.Length > 15)
                    {
                        Console.WriteLine("Server {0} has length > 15, skipping.", server);
                        continue;
                    }
                    Console.WriteLine("Testing {0}", server);
                    if (TestServer(server))
                    {
                        server_ok = server;
                        break;
                    }
                }

                if (server_ok != "")
                {
                    Console.WriteLine("Writing master server: {0}", server_ok);
                    using (BinaryWriter writer = new BinaryWriter(File.Open(GIANTS_PATH, FileMode.Open, FileAccess.ReadWrite)))
                    {
                        int offset = 0x157954; // position of master server in binary
                        Byte[] data = System.Text.Encoding.ASCII.GetBytes(server_ok);
                        writer.Seek(offset, SeekOrigin.Begin); //move cursor to the position
                        writer.Write(data);//write it
                        // add padding
                        for (int i = 0; i < 15 - data.Length; i++)
                        {
                            writer.Write((byte)0);//write it
                        }
                    }
                } else
                {
                    Console.WriteLine("No working master server found... RIP.");
                }
                Process.Start(GIANTS_PATH);
            }
        }

        static List<string> ReadServers()
        {
            // Loading from a file, you can also load from a stream
            try
            {
                XmlDocument xml = new XmlDocument();
                xml.Load("giantslauncher.xml");
                XmlNodeList elemList = xml.GetElementsByTagName("masterserver");
                List<string> array = new List<string>();
                for (int i = 0; i < elemList.Count; i++)
                {
                    array.Add(elemList[i].InnerXml);
                }

                if (array == null || array.Count < 1)
                {
                    WriteInitialConfig();
                    return ReadServers();
                }

                return array;
            }
            catch (System.IO.FileNotFoundException)
            {
                WriteInitialConfig();
                return ReadServers();
            }
        }

        static void WriteInitialConfig()
        {
            XmlDocument xmlDoc = new XmlDocument();
            XmlNode rootNode = xmlDoc.CreateElement("masterservers");
            xmlDoc.AppendChild(rootNode);

            XmlNode msNode = xmlDoc.CreateElement("masterserver");
            msNode.InnerText = "gckms.no-ip.org";
            rootNode.AppendChild(msNode);

            msNode = xmlDoc.CreateElement("masterserver");
            msNode.InnerText = "g.hipstercat.fr";
            rootNode.AppendChild(msNode);

            msNode = xmlDoc.CreateElement("masterserver");
            msNode.InnerText = "gm.vankerkom.be";
            rootNode.AppendChild(msNode);

            msNode = xmlDoc.CreateElement("masterserver");
            msNode.InnerText = "ms.giantswd.org";
            rootNode.AppendChild(msNode);

            xmlDoc.Save("giantslauncher.xml");
        }

        static bool TestServer(string ip)
        {
            try
            {
                // Create a TcpClient.
                // Note, for this client to work you need to have a TcpServer 
                // connected to the same address as specified by the server, port
                // combination.
                TcpClient client = new TcpClient();

                var result = client.BeginConnect(ip, 28900, null, null);

                var success = result.AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(2));

                if (!success)
                {
                    client.Close();
                    return false;
                }

                if (!client.Connected)
                {
                    return false;
                }

                NetworkStream stream = client.GetStream();

                // Buffer to store the response bytes.
                Byte[] data = new Byte[256];

                // String to store the response ASCII representation.
                String responseData = String.Empty;

                // Read the first batch of the TcpServer response bytes.
                Int32 bytes = stream.Read(data, 0, data.Length);
                responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
                Console.WriteLine("Received: {0}", responseData);

                // Close everything.
                stream.Close();
                //client.EndConnect(result);

                return true;
            }
            catch (SocketException e)
            {
                Console.WriteLine("SocketException: {0}", e);
                return false;
            }
        }

        static int GetGameBuild(string path)
        {
            using (BinaryReader reader = new BinaryReader(File.Open(path, FileMode.Open)))
            {
                int offset = 0x10da27; // position of game version as of 1497
                reader.BaseStream.Seek(offset, SeekOrigin.Begin); // move cursor to the position
                byte[] version = reader.ReadBytes(2); // read it
                return BitConverter.ToUInt16(version, 0);
            }
        }
        static string SetPath()
        {
            string path = "";
            while (!File.Exists(path + "\\Giants.exe"))
            {
                FolderBrowserDialog fbd = new FolderBrowserDialog();
                fbd.Description = "Select your Giants game directory";
                DialogResult dr = fbd.ShowDialog();
                if (dr == DialogResult.OK)
                {
                    path = fbd.SelectedPath;
                }
                else
                {
                    Environment.Exit(1);
                    return "";
                }
            }

            // add to registry
            Microsoft.Win32.Registry.SetValue(@"HKEY_CURRENT_USER\Software\PlanetMoon\Giants", "DestDir", path);
            return path;
        }
    }
}