using System;
using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace MelonVPNCore
{
    public static class DaemonSocketServer
    {
        private static Process currentVpnProcess = null;
        private static bool shouldBeRunning = false;
        private static bool shouldRestart = false;
        private static bool isRestarting = false;
        private static int startingTime = 3000;
        private static int restartDelay = 250;
        private static DaemonServer _srv;
        private static DaemonClientMultiplexor _mlt;
        private static string lastClientUpdate = Messages.EOF;

        public static void StartServer()
        {
            _srv = new DaemonServer();
            _mlt = new DaemonClientMultiplexor(_srv);
            _mlt.clientMessageReceived += clientMessageReceived;
            _srv.start();
        }

        public static bool isProcessOnline(Process p)
        {
            if (p == null)
            {
                return false;
            }
            else
            {
                if (p.HasExited)
                {
                    return false;
                }
                else
                {
                    return true;
                }
            }
        }

        static void clientMessageReceived(object sender, string data)
        {
            try
            {
                if (data.StartsWith(Messages.ClientListStartMsg, StringComparison.CurrentCulture) && shouldBeRunning)
                {
                    lastClientUpdate = data;
                    _mlt.SendCustomMessage(lastClientUpdate);
                }
                else if (data == Messages.RestartOnMsg)
                {
                    shouldRestart = true;
                    _mlt.SendDataMessage(DataMessage.RestartOn);
                }
                else if (data == Messages.RestartOffMsg)
                {
                    shouldRestart = false;
                    _mlt.SendDataMessage(DataMessage.RestartOff);
                }
                else if (data == Messages.StatusMsg)
                {
                    Console.WriteLine("Status requested");
                    if (isProcessOnline(currentVpnProcess) || shouldBeRunning)
                    {
                        if (isRestarting)
                        {
                            Console.WriteLine("Sending response: restarting");
                            _mlt.SendDataMessage(DataMessage.Restarting);
                            _mlt.SendCustomMessage(lastClientUpdate);
                        }
                        else
                        {
                            Console.WriteLine("Sending response: online");
                            _mlt.SendDataMessage(DataMessage.Online);
                            _mlt.SendCustomMessage(lastClientUpdate);
                        }
                    }
                    else
                    {
                        Console.WriteLine("Sending response: offline");
                        _mlt.SendDataMessage(DataMessage.Offline);
                        _mlt.SendCustomMessage(Messages.ClientListEmptyMsg);
                    }
                    _mlt.SendDataMessage((shouldRestart) ? DataMessage.RestartOn : DataMessage.RestartOff);
                }
                else if (data == Messages.StartMsg)
                {
                    if (!isProcessOnline(currentVpnProcess))
                    {
                        shouldBeRunning = true;
                        Console.WriteLine("Starting VPN");
                        try
                        {
                            Console.WriteLine("Starting embedded process");
                            Console.WriteLine("Sending starting reply");
                            _mlt.SendDataMessage(DataMessage.Starting);
                            if (StartEProcess(true))
                            {
                                Console.WriteLine("Sending online reply");
                                _mlt.SendDataMessage(DataMessage.Online);
                                currentVpnProcess.EnableRaisingEvents = true;
                            }
                            else { throw new InvalidOperationException("Client crashed!"); }
                        }
                        catch (Exception e)
                        {
                            shouldBeRunning = false;
                            Console.WriteLine("There was an error. But I fixed it.");
                            Console.WriteLine("It looked like this: " + e);
                            currentVpnProcess.Dispose();
                            currentVpnProcess = null;
                            _mlt.SendDataMessage(DataMessage.Error);
                            _mlt.SendCustomMessage(Messages.ClientListEmptyMsg);
                        }
                    }
                    else
                    {
                        Console.WriteLine("VPN already started");
                    }
                }
                else if (data == Messages.StopMsg)
                {
                    shouldBeRunning = false;
                    bool haderr = false;
                    if (isProcessOnline(currentVpnProcess))
                    {
                        Console.WriteLine("Stopping VPN");
                        try
                        {
                            currentVpnProcess.EnableRaisingEvents = false;
                            Console.WriteLine("Stopping embedded process");
                            currentVpnProcess.Kill();
                            currentVpnProcess = null;
                        }
                        catch (Exception e)
                        {
                            Console.WriteLine("There was an error. But I fixed it.");
                            Console.WriteLine("It looked like this: " + e);
                            currentVpnProcess = null;
                            _mlt.SendDataMessage(DataMessage.Error);
                            _mlt.SendCustomMessage(Messages.ClientListEmptyMsg);
                            haderr = true;
                        }
                    }
                    else
                    {
                        Console.WriteLine("VPN already stopped");
                    }
                    if (!haderr)
                    {
                        Console.WriteLine("Sending offline reply");
                        _mlt.SendDataMessage(DataMessage.Offline);
                        _mlt.SendCustomMessage(Messages.ClientListEmptyMsg);
                    }
                }

                _mlt.SendDataMessage(DataMessage.Blank);

            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }


        static void CurrentVpnProcess_Exited(object sender, EventArgs e)
        {
            Console.WriteLine("Restarting embedded process");
            currentVpnProcess.Dispose();
            currentVpnProcess = null;
            Thread.Sleep(restartDelay);
            bool imonline = false;
            isRestarting = true;
            while (shouldRestart && shouldBeRunning)
            {
                Console.WriteLine("Sending restarting reply");
                _mlt.SendDataMessage(DataMessage.Restarting);
                if (StartEProcess(false))
                {
                    Console.WriteLine("Sending online reply");
                    _mlt.SendDataMessage(DataMessage.Online);
                    currentVpnProcess.EnableRaisingEvents = true;
                    imonline = true;
                    break;
                }
                else
                {
                    currentVpnProcess.Dispose();
                    currentVpnProcess = null;
                    Thread.Sleep(restartDelay);
                }
            }
            isRestarting = false;
            if (! imonline)
            {
                shouldBeRunning = false;
                Console.WriteLine("Sending offline reply");
                _mlt.SendDataMessage(DataMessage.Offline);
                _mlt.SendCustomMessage(Messages.ClientListEmptyMsg);
            }
        }

        static bool StartEProcess(bool reraisee)
        {
            if (shouldBeRunning)
            {
                try
                {
                    currentVpnProcess = new Process
                    {
                        StartInfo = new ProcessStartInfo("simple-vpn", "client /etc/melon-vpn/client.cfg"),
                        EnableRaisingEvents = false
                    };
                    currentVpnProcess.Exited += CurrentVpnProcess_Exited;
                    currentVpnProcess.Start();
                    Thread.Sleep(startingTime);
                    return !currentVpnProcess.HasExited;
                }
                catch (Exception e)
                {
                    //Not really fixed is it?
                    Console.WriteLine("There was an error. But I fixed it.");
                    Console.WriteLine("It looked like this: " + e);
                    if (reraisee) { throw e; }
                }
            }
            return false;
        }
    }
}