using AspNetTools;
using FxSsh;
using FxSsh.Services;
using MiniTerm;
using System;
using System.Configuration;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Reflection;
using System.Web;

namespace WebTerminalServer
{
    public class SshWsModule : IHttpModule
    {
        private SshServer _server;
        private IPEndPoint _listenEndPoint;

        private static void Log(string info)
        {
            File.AppendAllText(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "logs.log"), info + Environment.NewLine);
        }

        public void Init(HttpApplication context)
        {
            Log("SshWsModule Init, OS:" + Environment.OSVersion.ToString());

            AppDomain.CurrentDomain.UnhandledException += (sender, args) =>
            {
                Log(args.ExceptionObject?.ToString());
            };

            //Create ssh server with available port
            _server = new SshServer(new StartingInfo(IPAddress.Loopback, 0, "SSH-2"));
            _server.AddHostKey("ssh-rsa", ConfigurationManager.AppSettings["SshHostKey"]);
            _server.ConnectionAccepted += (s2, e2) =>
            {
                e2.ServiceRegistered += (s1, e1) =>
                {
                    if (e1 is UserauthService)
                    {
                        var service = (UserauthService)e1;
                        service.Userauth += (s, e) =>
                        {
                            e.Result = true;
                        };
                    }
                    else if (e1 is ConnectionService service)
                    {
                        int w = 0, h = 0;
                        Terminal terminal = null;
                        service.EnvReceived += (s, e) => Console.WriteLine("Received environment variable {0}:{1}", e.Name, e.Value); ;
                        service.PtyReceived += (s, e) =>
                        {
                            w = (int)e.WidthChars;
                            h = (int)e.HeightRows;
                        };

                        service.WindowChange += (sender, args) =>
                        {
                            terminal?.ChangeWindowSize((short)args.WidthColumns, (short)args.HeightRows);
                        };

                        service.CommandOpened += (s, e) =>
                        {
                            Console.WriteLine($"Channel {e.Channel.ServerChannelId} runs {e.ShellType}: \"{e.CommandText}\".");

                            var allow = true;  // func(e.ShellType, e.CommandText, e.AttachedUserauthArgs);

                            if (!allow) return;

                            if (e.ShellType == "shell")
                            {
                                // requirements: Windows 10 RedStone 5, 1809
                                // also, you can call powershell.exe
                                Log("Pending Create Terminal");
                                try
                                {
                                    terminal = new Terminal("cmd.exe", w, h);
                                }
                                catch (Exception exception)
                                {
                                    Log(exception.ToString());
                                    return;
                                }
                                Log("Terminal Created");

                                e.Channel.DataReceived += (ss, ee) => terminal.OnInput(ee);
                                e.Channel.CloseReceived += (ss, ee) => terminal.OnClose();
                                terminal.DataReceived += (ss, ee) => e.Channel.SendData(ee);
                                terminal.CloseReceived += (ss, ee) => e.Channel.SendClose(ee);

                                terminal.Run();
                            }
                        };
                    }
                };
            };

            _server.Start();

            var field = _server.GetType().GetField("_listenser", BindingFlags.Instance | BindingFlags.NonPublic);
            var listener = (TcpListener)field.GetValue(_server);
            _listenEndPoint = (IPEndPoint)listener.Server.LocalEndPoint;

            context.PostMapRequestHandler += delegate
            {
                WebSocketForwardModule.ForwardCurrentContext("terminal", ConfigurationManager.AppSettings["PassCode"], _listenEndPoint);
            };
        }

        public void Dispose()
        {
            _server?.Stop();
        }
    }
}