using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Unosquare.Swan.Networking {
  /// <summary>
  /// Represents a network connection either on the server or on the client. It wraps a TcpClient
  /// and its corresponding network streams. It is capable of working in 2 modes. Typically on the server side
  /// you will need to enable continuous reading and events. On the client side you may want to disable continuous reading
  /// and use the Read methods available. In continuous reading mode Read methods are not available and will throw
  /// an invalid operation exceptions if they are used.
  /// Continuous Reading Mode: Subscribe to data reception events, it runs a background thread, don't use Read methods
  /// Manual Reading Mode: Data reception events are NEVER fired. No background threads are used. Use Read methods to receive data.
  /// </summary>
  /// <seealso cref="System.IDisposable" />
  /// <example>
  /// The following code explains how to create a TCP server.
  /// <code>
  /// using System.Text;
  /// using Unosquare.Swan.Networking;
  /// 
  /// class Example
  /// {
  ///     static void Main()
  ///     {
  ///         // create a new connection listener on a specific port
  ///         var connectionListener = new ConnectionListener(1337);
  ///         
  ///         // handle the OnConnectionAccepting event
  ///         connectionListener.OnConnectionAccepted += (s, e) =>
  ///         {
  ///              // create a new connection 
  ///              using (var con = new Connection(e.Client))
  ///              {               
  ///                 con.WriteLineAsync("Hello world!").Wait();
  ///              }
  ///         };
  ///         
  ///         connectionListener.Start();
  ///     }
  /// }
  /// </code>
  /// The following code describes how to create a TCP client.
  /// <code>
  /// using System.Net.Sockets;
  /// using System.Text;
  /// using System.Threading.Tasks;
  /// using Unosquare.Swan.Networking;
  /// 
  /// class Example
  /// {
  ///     static async Task Main()
  ///     {
  ///         // create a new TcpClient object
  ///         var client = new TcpClient();
  ///         
  ///         // connect to a specific address and port
  ///         client.Connect("localhost", 1337);
  ///         
  ///         //create a new connection with specific encoding,
  ///         //new line sequence and continuous reading disabled
  ///         using (var cn = new Connection(client, Encoding.UTF8, "\r\n", true, 0))
  ///         {               
  ///            var response = await cn.ReadTextAsync();
  ///         }
  ///     }
  /// }
  /// </code>
  /// </example>
  public sealed class Connection : IDisposable {
    // New Line definitions for reading. This applies to both, events and read methods
    private readonly String _newLineSequence;

    private readonly Byte[] _newLineSequenceBytes;
    private readonly Char[] _newLineSequenceChars;
    private readonly String[] _newLineSequenceLineSplitter;
    private readonly Byte[] _receiveBuffer;
    private readonly TimeSpan _continuousReadingInterval = TimeSpan.FromMilliseconds(5);
    private readonly Queue<String> _readLineBuffer = new Queue<String>();
    private readonly ManualResetEvent _writeDone = new ManualResetEvent(true);

    // Disconnect and Dispose
    private Boolean _hasDisposed;

    private Int32 _disconnectCalls;

    // Continuous Reading
    private Thread _continuousReadingThread;

    private Int32 _receiveBufferPointer;

    // Reading and writing
    private Task<Int32> _readTask;

    /// <summary>
    /// Initializes a new instance of the <see cref="Connection"/> class.
    /// </summary>
    /// <param name="client">The client.</param>
    /// <param name="textEncoding">The text encoding.</param>
    /// <param name="newLineSequence">The new line sequence used for read and write operations.</param>
    /// <param name="disableContinuousReading">if set to <c>true</c> [disable continuous reading].</param>
    /// <param name="blockSize">Size of the block. -- set to 0 or less to disable.</param>
    public Connection(
        TcpClient client,
        Encoding textEncoding,
        String newLineSequence,
        Boolean disableContinuousReading,
        Int32 blockSize) {
      // Setup basic properties
      this.Id = Guid.NewGuid();
      this.TextEncoding = textEncoding;

      // Setup new line sequence
      if(String.IsNullOrEmpty(newLineSequence)) {
        throw new ArgumentException("Argument cannot be null", nameof(newLineSequence));
      }

      this._newLineSequence = newLineSequence;
      this._newLineSequenceBytes = this.TextEncoding.GetBytes(this._newLineSequence);
      this._newLineSequenceChars = this._newLineSequence.ToCharArray();
      this._newLineSequenceLineSplitter = new[] { this._newLineSequence };

      // Setup Connection timers
      this.ConnectionStartTimeUtc = DateTime.UtcNow;
      this.DataReceivedLastTimeUtc = this.ConnectionStartTimeUtc;
      this.DataSentLastTimeUtc = this.ConnectionStartTimeUtc;

      // Setup connection properties
      this.RemoteClient = client;
      this.LocalEndPoint = client.Client.LocalEndPoint as IPEndPoint;
      this.NetworkStream = this.RemoteClient.GetStream();
      this.RemoteEndPoint = this.RemoteClient.Client.RemoteEndPoint as IPEndPoint;

      // Setup buffers
      this._receiveBuffer = new Byte[this.RemoteClient.ReceiveBufferSize * 2];
      this.ProtocolBlockSize = blockSize;
      this._receiveBufferPointer = 0;

      // Setup continuous reading mode if enabled
      if(disableContinuousReading) {
        return;
      }

#if NETSTANDARD1_3
            ThreadPool.QueueUserWorkItem(PerformContinuousReading, this);
#else
      ThreadPool.GetAvailableThreads(out Int32 availableWorkerThreads, out _);
      ThreadPool.GetMaxThreads(out Int32 maxWorkerThreads, out Int32 _);

      Int32 activeThreadPoolTreads = maxWorkerThreads - availableWorkerThreads;

      if(activeThreadPoolTreads < Environment.ProcessorCount / 4) {
        ThreadPool.QueueUserWorkItem(this.PerformContinuousReading, this);
      } else {
        new Thread(this.PerformContinuousReading) { IsBackground = true }.Start();
      }
#endif
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="Connection"/> class in continuous reading mode.
    /// It uses UTF8 encoding, CRLF as a new line sequence and disables a protocol block size.
    /// </summary>
    /// <param name="client">The client.</param>
    public Connection(TcpClient client)
        : this(client, Encoding.UTF8, "\r\n", false, 0) {
      // placeholder
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="Connection"/> class in continuous reading mode.
    /// It uses UTF8 encoding, disables line sequences, and uses a protocol block size instead.
    /// </summary>
    /// <param name="client">The client.</param>
    /// <param name="blockSize">Size of the block.</param>
    public Connection(TcpClient client, Int32 blockSize)
        : this(client, Encoding.UTF8, new String('\n', blockSize + 1), false, blockSize) {
      // placeholder
    }

    #region Events

    /// <summary>
    /// Occurs when the receive buffer has encounters a new line sequence, the buffer is flushed or the buffer is full.
    /// </summary>
    public event EventHandler<ConnectionDataReceivedEventArgs> DataReceived = (s, e) => { };

    /// <summary>
    /// Occurs when an error occurs while upgrading, sending, or receiving data in this client
    /// </summary>
    public event EventHandler<ConnectionFailureEventArgs> ConnectionFailure = (s, e) => { };

    /// <summary>
    /// Occurs when a client is disconnected
    /// </summary>
    public event EventHandler ClientDisconnected = (s, e) => { };

    #endregion

    #region Properties

    /// <summary>
    /// Gets the unique identifier of this connection.
    /// This field is filled out upon instantiation of this class.
    /// </summary>
    /// <value>
    /// The identifier.
    /// </value>
    public Guid Id {
      get;
    }

    /// <summary>
    /// Gets the active stream. Returns an SSL stream if the connection is secure, otherwise returns
    /// the underlying NetworkStream.
    /// </summary>
    /// <value>
    /// The active stream.
    /// </value>
    public Stream ActiveStream => this.SecureStream ?? this.NetworkStream as Stream;

    /// <summary>
    /// Gets a value indicating whether the current connection stream is an SSL stream.
    /// </summary>
    /// <value>
    ///   <c>true</c> if this instance is active stream secure; otherwise, <c>false</c>.
    /// </value>
    public Boolean IsActiveStreamSecure => this.SecureStream != null;

    /// <summary>
    /// Gets the text encoding for send and receive operations.
    /// </summary>
    /// <value>
    /// The text encoding.
    /// </value>
    public Encoding TextEncoding {
      get;
    }

    /// <summary>
    /// Gets the remote end point of this TCP connection.
    /// </summary>
    /// <value>
    /// The remote end point.
    /// </value>
    public IPEndPoint RemoteEndPoint {
      get;
    }

    /// <summary>
    /// Gets the local end point of this TCP connection.
    /// </summary>
    /// <value>
    /// The local end point.
    /// </value>
    public IPEndPoint LocalEndPoint {
      get;
    }

    /// <summary>
    /// Gets the remote client of this TCP connection.
    /// </summary>
    /// <value>
    /// The remote client.
    /// </value>
    public TcpClient RemoteClient {
      get; private set;
    }

    /// <summary>
    /// When in continuous reading mode, and if set to greater than 0,
    /// a Data reception event will be fired whenever the amount of bytes
    /// determined by this property has been received. Useful for fixed-length message protocols.
    /// </summary>
    /// <value>
    /// The size of the protocol block.
    /// </value>
    public Int32 ProtocolBlockSize {
      get;
    }

    /// <summary>
    /// Gets a value indicating whether this connection is in continuous reading mode.
    /// Remark: Whenever a disconnect event occurs, the background thread is terminated
    /// and this property will return false whenever the reading thread is not active.
    /// Therefore, even if continuous reading was not disabled in the constructor, this property
    /// might return false.
    /// </summary>
    /// <value>
    ///   <c>true</c> if this instance is continuous reading enabled; otherwise, <c>false</c>.
    /// </value>
    public Boolean IsContinuousReadingEnabled => this._continuousReadingThread != null;

    /// <summary>
    /// Gets the start time at which the connection was started in UTC.
    /// </summary>
    /// <value>
    /// The connection start time UTC.
    /// </value>
    public DateTime ConnectionStartTimeUtc {
      get;
    }

    /// <summary>
    /// Gets the start time at which the connection was started in local time.
    /// </summary>
    /// <value>
    /// The connection start time.
    /// </value>
    public DateTime ConnectionStartTime => this.ConnectionStartTimeUtc.ToLocalTime();

    /// <summary>
    /// Gets the duration of the connection.
    /// </summary>
    /// <value>
    /// The duration of the connection.
    /// </value>
    public TimeSpan ConnectionDuration => DateTime.UtcNow.Subtract(this.ConnectionStartTimeUtc);

    /// <summary>
    /// Gets the last time data was received at in UTC.
    /// </summary>
    /// <value>
    /// The data received last time UTC.
    /// </value>
    public DateTime DataReceivedLastTimeUtc {
      get; private set;
    }

    /// <summary>
    /// Gets how long has elapsed since data was last received.
    /// </summary>
    public TimeSpan DataReceivedIdleDuration => DateTime.UtcNow.Subtract(this.DataReceivedLastTimeUtc);

    /// <summary>
    /// Gets the last time at which data was sent in UTC.
    /// </summary>
    /// <value>
    /// The data sent last time UTC.
    /// </value>
    public DateTime DataSentLastTimeUtc {
      get; private set;
    }

    /// <summary>
    /// Gets how long has elapsed since data was last sent.
    /// </summary>
    /// <value>
    /// The duration of the data sent idle.
    /// </value>
    public TimeSpan DataSentIdleDuration => DateTime.UtcNow.Subtract(this.DataSentLastTimeUtc);

    /// <summary>
    /// Gets a value indicating whether this connection is connected.
    /// Remarks: This property polls the socket internally and checks if it is available to read data from it.
    /// If disconnect has been called, then this property will return false.
    /// </summary>
    /// <value>
    ///   <c>true</c> if this instance is connected; otherwise, <c>false</c>.
    /// </value>
    public Boolean IsConnected {
      get {
        if(this._disconnectCalls > 0) {
          return false;
        }

        try {
          Socket socket = this.RemoteClient.Client;
          Boolean pollResult = !(socket.Poll(1000, SelectMode.SelectRead)
                              && this.NetworkStream.DataAvailable == false || !socket.Connected);

          if(pollResult == false) {
            this.Disconnect();
          }

          return pollResult;
        } catch {
          this.Disconnect();
          return false;
        }
      }
    }

    private NetworkStream NetworkStream {
      get; set;
    }

    private SslStream SecureStream {
      get; set;
    }

    #endregion

    #region Read Methods

    /// <summary>
    /// Reads data from the remote client asynchronously and with the given timeout.
    /// </summary>
    /// <param name="timeout">The timeout.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A byte array containing the results of encoding the specified set of characters.</returns>
    /// <exception cref="InvalidOperationException">Read methods have been disabled because continuous reading is enabled.</exception>
    /// <exception cref="TimeoutException">Reading data from {ActiveStream} timed out in {timeout.TotalMilliseconds} m.</exception>
    public async Task<Byte[]> ReadDataAsync(TimeSpan timeout, CancellationToken ct = default) {
      if(this.IsContinuousReadingEnabled) {
        throw new InvalidOperationException(
            "Read methods have been disabled because continuous reading is enabled.");
      }

      if(this.RemoteClient == null) {
        throw new InvalidOperationException("An open connection is required");
      }

      Byte[] receiveBuffer = new Byte[this.RemoteClient.ReceiveBufferSize * 2];
      List<Byte> receiveBuilder = new List<Byte>(receiveBuffer.Length);

      try {
        DateTime startTime = DateTime.UtcNow;

        while(receiveBuilder.Count <= 0) {
          if(DateTime.UtcNow.Subtract(startTime) >= timeout) {
            throw new TimeoutException(
                $"Reading data from {this.ActiveStream} timed out in {timeout.TotalMilliseconds} ms");
          }

          if(this._readTask == null) {
            this._readTask = this.ActiveStream.ReadAsync(receiveBuffer, 0, receiveBuffer.Length, ct);
          }

          if(this._readTask.Wait(this._continuousReadingInterval)) {
            Int32 bytesReceivedCount = this._readTask.Result;
            if(bytesReceivedCount > 0) {
              this.DataReceivedLastTimeUtc = DateTime.UtcNow;
              Byte[] buffer = new Byte[bytesReceivedCount];
              Array.Copy(receiveBuffer, 0, buffer, 0, bytesReceivedCount);
              receiveBuilder.AddRange(buffer);
            }

            this._readTask = null;
          } else {
            await Task.Delay(this._continuousReadingInterval, ct).ConfigureAwait(false);
          }
        }
      } catch(Exception ex) {
        ex.Error(typeof(Connection).FullName, "Error while reading network stream data asynchronously.");
        throw;
      }

      return receiveBuilder.ToArray();
    }

    /// <summary>
    /// Reads data asynchronously from the remote stream with a 5000 millisecond timeout.
    /// </summary>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A byte array containing the results the specified sequence of bytes.</returns>
    public Task<Byte[]> ReadDataAsync(CancellationToken ct = default)
        => this.ReadDataAsync(TimeSpan.FromSeconds(5), ct);

    /// <summary>
    /// Asynchronously reads data as text with the given timeout.
    /// </summary>
    /// <param name="timeout">The timeout.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A <see cref="System.String" /> that contains the results of decoding the specified sequence of bytes.</returns>
    public async Task<String> ReadTextAsync(TimeSpan timeout, CancellationToken ct = default) {
      Byte[] buffer = await this.ReadDataAsync(timeout, ct).ConfigureAwait(false);
      return buffer == null ? null : this.TextEncoding.GetString(buffer);
    }

    /// <summary>
    /// Asynchronously reads data as text with a 5000 millisecond timeout.
    /// </summary>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>When this method completes successfully, it returns the contents of the file as a text string.</returns>
    public Task<String> ReadTextAsync(CancellationToken ct = default)
        => this.ReadTextAsync(TimeSpan.FromSeconds(5), ct);

    /// <summary>
    /// Performs the same task as this method's overload but it defaults to a read timeout of 30 seconds.
    /// </summary>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>
    /// A task that represents the asynchronous read operation. The value of the TResult parameter 
    /// contains the next line from the stream, or is null if all the characters have been read.
    /// </returns>
    public Task<String> ReadLineAsync(CancellationToken ct = default)
        => this.ReadLineAsync(TimeSpan.FromSeconds(30), ct);

    /// <summary>
    /// Reads the next available line of text in queue. Return null when no text is read.
    /// This method differs from the rest of the read methods because it keeps an internal
    /// queue of lines that are read from the stream and only returns the one line next in the queue.
    /// It is only recommended to use this method when you are working with text-based protocols
    /// and the rest of the read methods are not called.
    /// </summary>
    /// <param name="timeout">The timeout.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task with a string line from the queue.</returns>
    /// <exception cref="InvalidOperationException">Read methods have been disabled because continuous reading is enabled.</exception>
    public async Task<String> ReadLineAsync(TimeSpan timeout, CancellationToken ct = default) {
      if(this.IsContinuousReadingEnabled) {
        throw new InvalidOperationException(
            "Read methods have been disabled because continuous reading is enabled.");
      }

      if(this._readLineBuffer.Count > 0) {
        return this._readLineBuffer.Dequeue();
      }

      StringBuilder builder = new StringBuilder();

      while(true) {
        String text = await this.ReadTextAsync(timeout, ct).ConfigureAwait(false);
        if(text.Length == 0) {
          break;
        }

        _ = builder.Append(text);

        if(text.EndsWith(this._newLineSequence) == false) {
          continue;
        }

        String[] lines = builder.ToString().TrimEnd(this._newLineSequenceChars)
            .Split(this._newLineSequenceLineSplitter, StringSplitOptions.None);
        foreach(String item in lines) {
          this._readLineBuffer.Enqueue(item);
        }

        break;
      }

      return this._readLineBuffer.Count > 0 ? this._readLineBuffer.Dequeue() : null;
    }

    #endregion

    #region Write Methods

    /// <summary>
    /// Writes data asynchronously.
    /// </summary>
    /// <param name="buffer">The buffer.</param>
    /// <param name="forceFlush">if set to <c>true</c> [force flush].</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task that represents the asynchronous write operation.</returns>
    public async Task WriteDataAsync(Byte[] buffer, Boolean forceFlush, CancellationToken ct = default) {
      try {
        _ = this._writeDone.WaitOne();
        _ = this._writeDone.Reset();
        await this.ActiveStream.WriteAsync(buffer, 0, buffer.Length, ct).ConfigureAwait(false);
        if(forceFlush) {
          await this.ActiveStream.FlushAsync(ct).ConfigureAwait(false);
        }

        this.DataSentLastTimeUtc = DateTime.UtcNow;
      } finally {
        _ = this._writeDone.Set();
      }
    }

    /// <summary>
    /// Writes text asynchronously.
    /// </summary>
    /// <param name="text">The text.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task that represents the asynchronous write operation.</returns>
    public Task WriteTextAsync(String text, CancellationToken ct = default)
        => this.WriteTextAsync(text, this.TextEncoding, ct);

    /// <summary>
    /// Writes text asynchronously.
    /// </summary>
    /// <param name="text">The text.</param>
    /// <param name="encoding">The encoding.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task that represents the asynchronous write operation.</returns>
    public Task WriteTextAsync(String text, Encoding encoding, CancellationToken ct = default)
        => this.WriteDataAsync(encoding.GetBytes(text), true, ct);

    /// <summary>
    /// Writes a line of text asynchronously.
    /// The new line sequence is added automatically at the end of the line.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="encoding">The encoding.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task that represents the asynchronous write operation.</returns>
    public Task WriteLineAsync(String line, Encoding encoding, CancellationToken ct = default)
        => this.WriteDataAsync(encoding.GetBytes($"{line}{this._newLineSequence}"), true, ct);

    /// <summary>
    /// Writes a line of text asynchronously.
    /// The new line sequence is added automatically at the end of the line.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="ct">The cancellation token.</param>
    /// <returns>A task that represents the asynchronous write operation.</returns>
    public Task WriteLineAsync(String line, CancellationToken ct = default)
        => this.WriteLineAsync(line, this.TextEncoding, ct);

    #endregion

    #region Socket Methods

    /// <summary>
    /// Upgrades the active stream to an SSL stream if this connection object is hosted in the server.
    /// </summary>
    /// <param name="serverCertificate">The server certificate.</param>
    /// <returns><c>true</c> if the object is hosted in the server; otherwise, <c>false</c>.</returns>
    public async Task<Boolean> UpgradeToSecureAsServerAsync(X509Certificate2 serverCertificate) {
      if(this.IsActiveStreamSecure) {
        return true;
      }

      _ = this._writeDone.WaitOne();

      SslStream secureStream = null;

      try {
        secureStream = new SslStream(this.NetworkStream, true);
        await secureStream.AuthenticateAsServerAsync(serverCertificate).ConfigureAwait(false);
        this.SecureStream = secureStream;
        return true;
      } catch(Exception ex) {
        ConnectionFailure(this, new ConnectionFailureEventArgs(ex));
        secureStream?.Dispose();

        return false;
      }
    }

    /// <summary>
    /// Upgrades the active stream to an SSL stream if this connection object is hosted in the client.
    /// </summary>
    /// <param name="hostname">The hostname.</param>
    /// <param name="callback">The callback.</param>
    /// <returns>A tasks with <c>true</c> if the upgrade to SSL was successful; otherwise, <c>false</c>.</returns>
    public async Task<Boolean> UpgradeToSecureAsClientAsync(
        String hostname = null,
        RemoteCertificateValidationCallback callback = null) {
      if(this.IsActiveStreamSecure) {
        return true;
      }

      SslStream secureStream = callback == null
          ? new SslStream(this.NetworkStream, true)
          : new SslStream(this.NetworkStream, true, callback);

      try {
        await secureStream.AuthenticateAsClientAsync(hostname ?? Network.HostName.ToLowerInvariant()).ConfigureAwait(false);
        this.SecureStream = secureStream;
      } catch(Exception ex) {
        secureStream.Dispose();
        ConnectionFailure(this, new ConnectionFailureEventArgs(ex));
        return false;
      }

      return true;
    }

    /// <summary>
    /// Disconnects this connection.
    /// </summary>
    public void Disconnect() {
      if(this._disconnectCalls > 0) {
        return;
      }

      this._disconnectCalls++;
      this._writeDone.WaitOne();

      try {
        ClientDisconnected(this, EventArgs.Empty);
      } catch {
        // ignore
      }

      try {
#if !NET452
                RemoteClient.Dispose();
                SecureStream?.Dispose();
                NetworkStream?.Dispose();
#else
        this.RemoteClient.Close();
        this.SecureStream?.Close();
        this.NetworkStream?.Close();
#endif
      } catch {
        // ignored
      } finally {
        this.NetworkStream = null;
        this.SecureStream = null;
        this.RemoteClient = null;
        this._continuousReadingThread = null;
      }
    }

    #endregion

    #region Dispose

    /// <summary>
    /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
    /// </summary>
    public void Dispose() {
      if(this._hasDisposed) {
        return;
      }

      // Release managed resources
      this.Disconnect();
      this._continuousReadingThread = null;
      this._writeDone.Dispose();

      this._hasDisposed = true;
    }

    #endregion

    #region Continuous Read Methods

    /// <summary>
    /// Raises the receive buffer events.
    /// </summary>
    /// <param name="receivedData">The received data.</param>
    /// <exception cref="Exception">Split function failed! This is terribly wrong.</exception>
    private void RaiseReceiveBufferEvents(Byte[] receivedData) {
      Boolean moreAvailable = this.RemoteClient.Available > 0;

      foreach(Byte data in receivedData) {
        this.ProcessReceivedBlock(data, moreAvailable);
      }

      // Check if we are left with some more stuff to handle
      if(this._receiveBufferPointer <= 0) {
        return;
      }

      // Extract the segments split by newline terminated bytes
      List<Byte[]> sequences = this._receiveBuffer.Skip(0).Take(this._receiveBufferPointer).ToArray()
          .Split(0, this._newLineSequenceBytes);

      // Something really wrong happened
      if(sequences.Count == 0) {
        throw new InvalidOperationException("Split function failed! This is terribly wrong!");
      }

      // We only have one sequence and it is not newline-terminated
      // we don't have to do anything.
      if(sequences.Count == 1 && sequences[0].EndsWith(this._newLineSequenceBytes) == false) {
        return;
      }

      // Process the events for each sequence
      for(Int32 i = 0; i < sequences.Count; i++) {
        Byte[] sequenceBytes = sequences[i];
        Boolean isNewLineTerminated = sequences[i].EndsWith(this._newLineSequenceBytes);
        Boolean isLast = i == sequences.Count - 1;

        if(isNewLineTerminated) {
          ConnectionDataReceivedEventArgs eventArgs = new ConnectionDataReceivedEventArgs(
              sequenceBytes,
              ConnectionDataReceivedTrigger.NewLineSequenceEncountered,
              isLast == false);
          DataReceived(this, eventArgs);
        }

        // Depending on the last segment determine what to do with the receive buffer
        if(!isLast) {
          continue;
        }

        if(isNewLineTerminated) {
          // Simply reset the buffer pointer if the last segment was also terminated
          this._receiveBufferPointer = 0;
        } else {
          // If we have not received the termination sequence, then just shift the receive buffer to the left
          // and adjust the pointer
          Array.Copy(sequenceBytes, this._receiveBuffer, sequenceBytes.Length);
          this._receiveBufferPointer = sequenceBytes.Length;
        }
      }
    }

    private void ProcessReceivedBlock(Byte data, Boolean moreAvailable) {
      this._receiveBuffer[this._receiveBufferPointer] = data;
      this._receiveBufferPointer++;

      // Block size reached
      if(this.ProtocolBlockSize > 0 && this._receiveBufferPointer >= this.ProtocolBlockSize) {
        this.SendBuffer(moreAvailable, ConnectionDataReceivedTrigger.BlockSizeReached);
        return;
      }

      // The receive buffer is full. Time to flush
      if(this._receiveBufferPointer >= this._receiveBuffer.Length) {
        this.SendBuffer(moreAvailable, ConnectionDataReceivedTrigger.BufferFull);
      }
    }

    private void SendBuffer(Boolean moreAvailable, ConnectionDataReceivedTrigger trigger) {
      Byte[] eventBuffer = new Byte[this._receiveBuffer.Length];
      Array.Copy(this._receiveBuffer, eventBuffer, eventBuffer.Length);

      DataReceived(this,
          new ConnectionDataReceivedEventArgs(
              eventBuffer,
              trigger,
              moreAvailable));
      this._receiveBufferPointer = 0;
    }

    private void PerformContinuousReading(Object threadContext) {
      this._continuousReadingThread = Thread.CurrentThread;

      // Check if the RemoteClient is still there
      if(this.RemoteClient == null) {
        return;
      }

      Byte[] receiveBuffer = new Byte[this.RemoteClient.ReceiveBufferSize * 2];

      while(this.IsConnected && this._disconnectCalls <= 0) {
        Boolean doThreadSleep = false;

        try {
          if(this._readTask == null) {
            this._readTask = this.ActiveStream.ReadAsync(receiveBuffer, 0, receiveBuffer.Length);
          }

          if(this._readTask.Wait(this._continuousReadingInterval)) {
            Int32 bytesReceivedCount = this._readTask.Result;
            if(bytesReceivedCount > 0) {
              this.DataReceivedLastTimeUtc = DateTime.UtcNow;
              Byte[] buffer = new Byte[bytesReceivedCount];
              Array.Copy(receiveBuffer, 0, buffer, 0, bytesReceivedCount);
              this.RaiseReceiveBufferEvents(buffer);
            }

            this._readTask = null;
          } else {
            doThreadSleep = this._disconnectCalls <= 0;
          }
        } catch(Exception ex) {
          ex.Log(nameof(Connection), "Continuous Read operation errored");
        } finally {
          if(doThreadSleep) {
            Thread.Sleep(this._continuousReadingInterval);
          }
        }
      }
    }

    #endregion
  }
}