using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Security;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading;
using XF;

namespace SslServer
{
    class Program
    {
        static X509Certificate serverCertificate;
        // The certificate parameter specifies the name of the file
        // containing the machine certificate.
        public static void RunServer(string certificate)
        {
            serverCertificate = X509Certificate.CreateFromCertFile(certificate);
            using (Network.AcceptAsync(new IPEndPoint(IPAddress.Any, 443), ProcessClient))
            {
                Console.WriteLine("Secure XF.Server is ready.");
                Console.WriteLine("Press any key to exit.");
                Console.ReadKey(true);
            }
        }

        private const string responseFormat =
            "HTTP/1.1 200 OK\r\n" +
            "Server: HTTPS Server using XF.Server\r\n" +
            "Content-Type: text/plain\r\n" +
            "Content-Length: {0}\r\n" +
            "Connection: Close\r\n\r\n{1}";

        static void ProcessClient(IConnection connection)
        {
            // A client has connected. Create the
            // SslStream using the client's network stream.
            var sslStream = new SslStream(new NetworkStream(connection), false);
            // Authenticate the server but don't require the client to authenticate.
            try
            {
                sslStream.AuthenticateAsServer(serverCertificate,
                    false, SslProtocols.Tls, true);

                // Read a message from the client.   
                var request = ReadMessage(sslStream);
                var responseContent = String.Format("REQUESTED:\r\n{0}\r\nCIPHER: {1} STRENGTH {2}",
                                          request, sslStream.CipherAlgorithm, sslStream.CipherStrength);
                var response = String.Format(responseFormat, responseContent.Length, responseContent);
                sslStream.Write(Encoding.UTF8.GetBytes(response));
            }
            catch (AuthenticationException e)
            {
                Console.WriteLine("Exception: {0}", e.Message);
                if (e.InnerException != null)
                {
                    Console.WriteLine("Inner exception: {0}", e.InnerException.Message);
                }
                Console.WriteLine("Authentication failed - closing the connection.");
            }
            catch(Exception e)
            {
                Console.WriteLine("Unknown error: {0}", e);
            }
            finally
            {
                // The client stream will be closed with the sslStream
                // because we specified this behavior when creating
                // the sslStream.
                sslStream.Close();
                connection.Close();
            }
        }

        static string ReadMessage(Stream sslStream)
        {
            var buffer = new byte[2048];
            var messageData = new StringBuilder();
            int bytes;
            do
            {
                // Read the client's test message.
                bytes = sslStream.Read(buffer, 0, buffer.Length);
                messageData.Append(Encoding.UTF8.GetString(buffer, 0, bytes));
                if (messageData.ToString().IndexOf(Environment.NewLine) != -1)
                {
                    break;
                }
            } while (bytes != 0);
            return messageData.ToString();
        }

        //specify path to cer file
        static void Main(string[] args)
        {
            if (args.Length != 1)
            {
                Console.WriteLine("Specify path to a certificate file(.cer)");
                return;
            }
            RunServer(args[0]);
        }
    }
}

namespace XF
{
    internal class NetworkStream : Stream
    {
        private readonly IConnection connection;
        private readonly ManualResetEvent readEvent = new ManualResetEvent(false);
        private readonly Queue<KeyValuePair<IMemoryBuffer, int>> buffers = new Queue<KeyValuePair<IMemoryBuffer, int>>();
        private bool disconnected;

        public NetworkStream(IConnection connection)
        {
            this.connection = connection;
            connection.ReadAsync((ignore, memoryBuffer, bytesReceived) =>
            {
                if (bytesReceived > 0)
                {
                    lock (buffers)
                    {
                        memoryBuffer.Acquire();
                        buffers.Enqueue(new KeyValuePair<IMemoryBuffer, int>(memoryBuffer, bytesReceived));
                    }
                }
                else disconnected = true;
                readEvent.Set();
            });
        }

        private int currentOffset;
        private KeyValuePair<IMemoryBuffer, int>? currentBufferData;

        public override int Read(byte[] buffer, int offset, int count)
        {
            readEvent.WaitOne();
            if (disconnected) return 0;

            if (currentBufferData == null)
            {
                lock(buffers)
                {
                    if (buffers.Count > 0)
                        currentBufferData = buffers.Dequeue();
                }
            }

            var memoryBuffer = currentBufferData.Value.Key;
            var dataSize = currentBufferData.Value.Value;
            var x = dataSize - currentOffset;
            if (x > count)
            {
                Buffer.BlockCopy(memoryBuffer.Data, memoryBuffer.Offset + currentOffset, buffer, offset, count);
                currentOffset += count;
                return count;
            }

            Buffer.BlockCopy(memoryBuffer.Data, memoryBuffer.Offset + currentOffset, buffer, offset, x);
            currentOffset = 0;
            memoryBuffer.Release();
            currentBufferData = null;
            if (buffers.Count == 0) readEvent.Reset();
            return x;
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            connection.WriteAsync(buffer, offset, count);
        }

        public override bool CanRead
        {
            get { return true; }
        }

        public override bool CanWrite
        {
            get { return true; }
        }

        public override long Length
        {
            get { throw new System.NotSupportedException(); }
        }
        public override long Position
        {
            get { throw new System.NotSupportedException(); }
            set { throw new System.NotSupportedException(); }
        }
        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new System.NotSupportedException();
        }
        public override bool CanSeek
        {
            get { return false; }
        }
        public override void Flush()
        {
            throw new System.NotSupportedException();
        }
        public override void SetLength(long value)
        {
            throw new System.NotSupportedException();
        }
    }
}