//
// System.Net.ChunkedInputStream
//
// Authors:
//	Gonzalo Paniagua Javier (gonzalo@novell.com)
//
// Copyright (c) 2005 Novell, Inc (http://www.novell.com)
//
// 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.

using System.IO;
using System.Net.Sockets;
using System.Runtime.InteropServices;
namespace System.Net {
	class ChunkedInputStream : RequestStream {
		bool disposed;
		MonoChunkStream decoder;
		HttpListenerContext context;
		bool no_more_data;

		class ReadBufferState {
			public byte [] Buffer;
			public int Offset;
			public int Count;
			public int InitialCount;
			public HttpStreamAsyncResult Ares;
			public ReadBufferState (byte [] buffer, int offset, int count,
						HttpStreamAsyncResult ares)
			{
				Buffer = buffer;
				Offset = offset;
				Count = count;
				InitialCount = count;
				Ares = ares;
			}
		}

		public ChunkedInputStream (HttpListenerContext context, Stream stream,
						byte [] buffer, int offset, int length)
					: base (stream, buffer, offset, length)
		{
			this.context = context;
			WebHeaderCollection coll = (WebHeaderCollection) context.Request.Headers;
			decoder = new MonoChunkStream (coll);
		}

		public MonoChunkStream Decoder {
			get { return decoder; }
			set { decoder = value; }
		}

		public override int Read ([In,Out] byte [] buffer, int offset, int count)
		{
			IAsyncResult ares = BeginRead (buffer, offset, count, null, null);
			return EndRead (ares);
		}

		public override IAsyncResult BeginRead (byte [] buffer, int offset, int count,
							AsyncCallback cback, object state)
		{
			if (disposed)
				throw new ObjectDisposedException (GetType ().ToString ());

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

			int len = buffer.Length;
			if (offset < 0 || offset > len)
				throw new ArgumentOutOfRangeException ("offset exceeds the size of buffer");

			if (count < 0 || offset > len - count)
				throw new ArgumentOutOfRangeException ("offset+size exceeds the size of buffer");

			HttpStreamAsyncResult ares = new HttpStreamAsyncResult ();
			ares.Callback = cback;
			ares.State = state;
			if (no_more_data) {
				ares.Complete ();
				return ares;
			}
			int nread = decoder.Read (buffer, offset, count);
			offset += nread;
			count -= nread;
			if (count == 0) {
				// got all we wanted, no need to bother the decoder yet
				ares.Count = nread;
				ares.Complete ();
				return ares;
			}
			if (!decoder.WantMore) {
				no_more_data = nread == 0;
				ares.Count = nread;
				ares.Complete ();
				return ares;
			}
			ares.Buffer = new byte [8192];
			ares.Offset = 0;
			ares.Count = 8192;
			ReadBufferState rb = new ReadBufferState (buffer, offset, count, ares);
			rb.InitialCount += nread;
			base.BeginRead (ares.Buffer, ares.Offset, ares.Count, OnRead, rb);
			return ares;
		}

		void OnRead (IAsyncResult base_ares)
		{
			ReadBufferState rb = (ReadBufferState) base_ares.AsyncState;
			HttpStreamAsyncResult ares = rb.Ares;
			try {
				int nread = base.EndRead (base_ares);
				decoder.Write (ares.Buffer, ares.Offset, nread);
				nread = decoder.Read (rb.Buffer, rb.Offset, rb.Count);
				rb.Offset += nread;
				rb.Count -= nread;
				if (rb.Count == 0 || !decoder.WantMore || nread == 0) {
					no_more_data = !decoder.WantMore && nread == 0;
					ares.Count = rb.InitialCount - rb.Count;
					ares.Complete ();
					return;
				}
				ares.Offset = 0;
				ares.Count = Math.Min (8192, decoder.ChunkLeft + 6);
				base.BeginRead (ares.Buffer, ares.Offset, ares.Count, OnRead, rb);
			} catch (Exception e) {
				context.Connection.SendError (e.Message, 400);
				ares.Complete (e);
			}
		}

		public override int EndRead (IAsyncResult ares)
		{
			if (disposed)
				throw new ObjectDisposedException (GetType ().ToString ());

			HttpStreamAsyncResult my_ares = ares as HttpStreamAsyncResult;
			if (ares == null)
				throw new ArgumentException ("Invalid IAsyncResult", "ares");

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

			if (my_ares.Error != null)
				throw new HttpListenerException (400, "I/O operation aborted: " + my_ares.Error.Message);

			return my_ares.Count;
		}

		public override void Close ()
		{
			if (!disposed) {
				disposed = true;
				base.Close ();
			}
		}
	}
}