#region License
/*
 * ChunkedRequestStream.cs
 *
 * This code is derived from ChunkedInputStream.cs (System.Net) of Mono
 * (http://www.mono-project.com).
 *
 * The MIT License
 *
 * Copyright (c) 2005 Novell, Inc. (http://www.novell.com)
 * Copyright (c) 2012-2023 sta.blockhead
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#endregion

#region Authors
/*
 * Authors:
 * - Gonzalo Paniagua Javier <gonzalo@novell.com>
 */
#endregion

using System;
using System.IO;

namespace WebSocketSharp.Net
{
  internal class ChunkedRequestStream : RequestStream
  {
    #region Private Fields

    private static readonly int _bufferLength;
    private HttpListenerContext _context;
    private ChunkStream         _decoder;
    private bool                _disposed;
    private bool                _noMoreData;

    #endregion

    #region Static Constructor

    static ChunkedRequestStream ()
    {
      _bufferLength = 8192;
    }

    #endregion

    #region Internal Constructors

    internal ChunkedRequestStream (
      Stream innerStream,
      byte[] initialBuffer,
      int offset,
      int count,
      HttpListenerContext context
    )
      : base (innerStream, initialBuffer, offset, count, -1)
    {
      _context = context;

      _decoder = new ChunkStream (
                   (WebHeaderCollection) context.Request.Headers
                 );
    }

    #endregion

    #region Internal Properties

    internal bool HasRemainingBuffer {
      get {
        return _decoder.Count + Count > 0;
      }
    }

    internal byte[] RemainingBuffer {
      get {
        using (var buff = new MemoryStream ()) {
          var cnt = _decoder.Count;

          if (cnt > 0)
            buff.Write (_decoder.EndBuffer, _decoder.Offset, cnt);

          cnt = Count;

          if (cnt > 0)
            buff.Write (InitialBuffer, Offset, cnt);

          buff.Close ();

          return buff.ToArray ();
        }
      }
    }

    #endregion

    #region Private Methods

    private void onRead (IAsyncResult asyncResult)
    {
      var rstate = (ReadBufferState) asyncResult.AsyncState;
      var ares = rstate.AsyncResult;

      try {
        var nread = base.EndRead (asyncResult);

        _decoder.Write (ares.Buffer, ares.Offset, nread);

        nread = _decoder.Read (rstate.Buffer, rstate.Offset, rstate.Count);

        rstate.Offset += nread;
        rstate.Count -= nread;

        if (rstate.Count == 0 || !_decoder.WantsMore || nread == 0) {
          _noMoreData = !_decoder.WantsMore && nread == 0;

          ares.Count = rstate.InitialCount - rstate.Count;

          ares.Complete ();

          return;
        }

        base.BeginRead (ares.Buffer, ares.Offset, ares.Count, onRead, rstate);
      }
      catch (Exception ex) {
        _context.ErrorMessage = "I/O operation aborted";

        _context.SendError ();

        ares.Complete (ex);
      }
    }

    #endregion

    #region Public Methods

    public override IAsyncResult BeginRead (
      byte[] buffer,
      int offset,
      int count,
      AsyncCallback callback,
      object state
    )
    {
      if (_disposed)
        throw new ObjectDisposedException (ObjectName);

      if (buffer == null)
        throw new ArgumentNullException ("buffer");

      if (offset < 0) {
        var msg = "A negative value.";

        throw new ArgumentOutOfRangeException ("offset", msg);
      }

      if (count < 0) {
        var msg = "A negative value.";

        throw new ArgumentOutOfRangeException ("count", msg);
      }

      var len = buffer.Length;

      if (offset + count > len) {
        var msg = "The sum of offset and count is greater than the length of buffer.";

        throw new ArgumentException (msg);
      }

      var ares = new HttpStreamAsyncResult (callback, state);

      if (_noMoreData) {
        ares.Complete ();

        return ares;
      }

      var nread = _decoder.Read (buffer, offset, count);

      offset += nread;
      count -= nread;

      if (count == 0) {
        ares.Count = nread;

        ares.Complete ();

        return ares;
      }

      if (!_decoder.WantsMore) {
        _noMoreData = nread == 0;

        ares.Count = nread;

        ares.Complete ();

        return ares;
      }

      ares.Buffer = new byte[_bufferLength];
      ares.Offset = 0;
      ares.Count = _bufferLength;

      var rstate = new ReadBufferState (buffer, offset, count, ares);

      rstate.InitialCount += nread;

      base.BeginRead (ares.Buffer, ares.Offset, ares.Count, onRead, rstate);

      return ares;
    }

    public override void Close ()
    {
      if (_disposed)
        return;

      base.Close ();
      
      _disposed = true;
    }

    public override int EndRead (IAsyncResult asyncResult)
    {
      if (_disposed)
        throw new ObjectDisposedException (ObjectName);

      if (asyncResult == null)
        throw new ArgumentNullException ("asyncResult");

      var ares = asyncResult as HttpStreamAsyncResult;

      if (ares == null) {
        var msg = "A wrong IAsyncResult instance.";

        throw new ArgumentException (msg, "asyncResult");
      }

      if (!ares.IsCompleted)
        ares.AsyncWaitHandle.WaitOne ();

      if (ares.HasException) {
        var msg = "The I/O operation has been aborted.";

        throw new HttpListenerException (995, msg);
      }

      return ares.Count;
    }

    public override int Read (byte[] buffer, int offset, int count)
    {
      var ares = BeginRead (buffer, offset, count, null, null);

      return EndRead (ares);
    }

    #endregion
  }
}
