using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;
using System.Text;
using ln.http.resources.session;
using ln.logging;
using ln.types.threads;


namespace ln.http
{
    public class HTTPServer
    {
        public static int backlog = 5;
        public static int defaultPort = 8080;
        public static bool exclusivePortListener = false;

        public HttpApplication DefaultApplication { get; set; }

        public SessionCache SessionCache { get; set; }

        public bool IsRunning => (currentListenerThreads.Count > 0) || (threadPool.CurrentPoolSize > 0);



        bool shutdown = false;

        Dictionary<IPEndPoint, TcpListener> tcpListeners = new Dictionary<IPEndPoint, TcpListener>();
        Dictionary<Uri, HttpApplication> applications = new Dictionary<Uri, HttpApplication>();

        Dictionary<TcpListener, Thread> currentListenerThreads = new Dictionary<TcpListener, Thread>();

        Pool threadPool = new Pool(32);

        public HTTPServer()
        {
            SessionCache = new SessionCache();
        }

        public void AddEndpoint(IPEndPoint endpoint)
        {
            if (this.tcpListeners.ContainsKey(endpoint))
            {
                throw new ArgumentOutOfRangeException(nameof(endpoint), "EndPoint already added");
            }

            this.tcpListeners.Add(endpoint, new TcpListener(endpoint));
        }
        public void RemoveEndpoint(IPEndPoint endpoint)
        {
            if (this.tcpListeners.ContainsKey(endpoint))
            {
                this.tcpListeners[endpoint].Stop();
                this.tcpListeners.Remove(endpoint);
            }
        }

        public void AddApplication(Uri BaseURI, HttpApplication application)
        {
            applications[BaseURI] = application;
        }

        public void Start()
        {
            foreach (TcpListener tcpListener in this.tcpListeners.Values)
            {
                tcpListener.Start(backlog);

                Thread listenerThread = new Thread(() => AcceptConnections(tcpListener));
                listenerThread.Start();
            }

        }

        public void Stop()
        {
            lock (this)
            {
                this.shutdown = true;
            }

            foreach (TcpListener tcpListener in tcpListeners.Values)
            {
                tcpListener.Stop();
            }

            threadPool.Close();

            while (IsRunning)
            {
                Thread.Sleep(50);
            }
        }

        private void AcceptConnections(TcpListener tcpListener)
        {
            lock (this)
            {
                if (currentListenerThreads.ContainsKey(tcpListener))
                {
                    throw new Exception("HTTP listener thread already running");
                }
                currentListenerThreads.Add(tcpListener, Thread.CurrentThread);
            }

            try
            {

                while (!this.shutdown)
                {
                    AcceptConnection(tcpListener);
                }

            }
            catch (Exception e)
            {
                Logging.Log(LogLevel.ERROR, "HTTPServer: Listener thread caught exception {0}", e);
                Logging.Log(e);
            }

            lock (this)
            {
                currentListenerThreads.Remove(tcpListener);
            }
        }

        private void AcceptConnection(TcpListener tcpListener)
        {
            TcpClient tcpClient = tcpListener.AcceptTcpClient();
            this.threadPool.Enqueue(() => HandleConnection(tcpClient));
        }

        private void HandleConnection(TcpClient tcpClient)
        {
            HttpReader httpReader = new HttpReader(tcpClient.GetStream());
            httpReader.Read();

            HttpRequest httpRequest = new HttpRequest(httpReader, (IPEndPoint)tcpClient.Client.LocalEndPoint);
            HttpResponse response = null;

            httpRequest.ApplySession(SessionCache);

            try
            {
                HttpApplication application = DefaultApplication;

                if (applications.ContainsKey(httpRequest.BaseURI))
                    application = applications[httpRequest.BaseURI];

                application.Authenticate(httpRequest);
                application.Authorize(httpRequest);

                response = application.GetResponse(httpRequest);
            }
            catch (Exception e)
            {
                response = new HttpResponse(httpRequest, "text/plain");
                response.StatusCode = 500;
                response.ContentWriter.WriteLine("Exception caught: {0}", e);
            }

            if (response == null)
            {
                Logging.Log(LogLevel.DEBUG, "Request {0} returned no Response", httpRequest);
            }
            else
            {
                if (!response.HasCustomContentStream)
                {
                    response.ContentWriter.Flush();
                    MemoryStream cstream = (MemoryStream)response.ContentStream;
                    cstream.Position = 0;

                    response.SetHeader("content-length", cstream.Length.ToString());
                }

                if (SessionCache != null)
                {
                    SessionCache.ApplySessionID(response, httpRequest.Session);
                }

                response.AddCookie("LN_SEEN", DateTime.Now.ToString());

                SendResponse(tcpClient.GetStream(), response);

                tcpClient.Close();
            }
        }



        public static void SendResponse(Stream stream, HttpResponse response)
        {
            StreamWriter streamWriter = new StreamWriter(stream);
            streamWriter.NewLine = "\r\n";

            streamWriter.WriteLine("{0} {1} {2}", response.HttpRequest.Protocol, response.StatusCode, response.StatusMessage);
            foreach (String headerName in response.GetHeaderNames())
            {
                streamWriter.WriteLine("{0}: {1}", headerName, response.GetHeader(headerName));
            }

            foreach (HttpCookie httpCookie in response.Cookies)
            {
                streamWriter.WriteLine("Set-Cookie: {0}", httpCookie.ToString());
            }

            streamWriter.WriteLine();
            streamWriter.Flush();

            response.ContentStream.CopyTo(stream);
            response.ContentStream.Close();
            response.ContentStream.Dispose();

            streamWriter.Flush();
        }
    }
}