//
// System.Net.WebConnectionStream
//
// Authors:
//	Gonzalo Paniagua Javier (gonzalo@ximian.com)
//
// (C) 2003 Ximian, Inc (http://www.ximian.com)
// (C) 2004 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.Text;
using System.Threading;

namespace System.Net
{
	class WebConnectionStream : Stream
	{
		static byte [] crlf = new byte [] { 13, 10 };
		bool isRead;
		WebConnection cnc;
		HttpWebRequest request;
		byte [] readBuffer;
		int readBufferOffset;
		int readBufferSize;
		int contentLength;
		int totalRead;
		bool nextReadCalled;
		int pendingReads;
		int pendingWrites;
		ManualResetEvent pending;
		bool allowBuffering;
		bool sendChunked;
		MemoryStream writeBuffer;
		bool requestWritten;
		byte [] headers;
		bool disposed;
		bool headersSent;

		public WebConnectionStream (WebConnection cnc)
		{
			isRead = true;
			pending = new ManualResetEvent (true);
			this.cnc = cnc;
			string clength = cnc.Data.Headers ["Content-Length"];
			if (clength != null && clength != "") {
				try {
					contentLength = Int32.Parse (clength);
				} catch {
					contentLength = Int32.MaxValue;
				}
			} else {
				contentLength = Int32.MaxValue;
			}
		}

		public WebConnectionStream (WebConnection cnc, HttpWebRequest request)
		{
			isRead = false;
			this.cnc = cnc;
			this.request = request;
			allowBuffering = request.InternalAllowBuffering;
			sendChunked = request.SendChunked;
			if (allowBuffering)
				writeBuffer = new MemoryStream ();

			if (sendChunked)
				pending = new ManualResetEvent (true);
		}

		internal bool SendChunked {
			set { sendChunked = value; }
		}

		internal byte [] ReadBuffer {
			set { readBuffer = value; }
		}

		internal int ReadBufferOffset {
			set { readBufferOffset = value;}
		}
		
		internal int ReadBufferSize {
			set { readBufferSize = value; }
		}
		
		internal byte[] WriteBuffer {
			get { return writeBuffer.GetBuffer (); }
		}

		internal int WriteBufferLength {
			get { return (int) writeBuffer.Length; }
		}

		internal void ForceCompletion ()
		{
			nextReadCalled = true;
			cnc.NextRead ();
		}
		
		internal void CheckComplete ()
		{
			bool nrc = nextReadCalled;
			if (!nrc && readBufferSize - readBufferOffset == contentLength) {
				nextReadCalled = true;
				cnc.NextRead ();
			}
		}

		internal void ReadAll ()
		{
			if (!isRead || totalRead >= contentLength || nextReadCalled) {
				if (!nextReadCalled) {
					nextReadCalled = true;
					cnc.NextRead ();
				}
				return;
			}

			pending.WaitOne ();
			lock (this) {
				if (totalRead >= contentLength)
					return;
				
				byte [] b = null;
				int diff = readBufferSize - readBufferOffset;
				int new_size;

				if (contentLength == Int32.MaxValue) {
					MemoryStream ms = new MemoryStream ();
					byte [] buffer = null;
					if (readBuffer != null && diff > 0) {
						ms.Write (readBuffer, readBufferOffset, diff);
						if (readBufferSize >= 8192)
							buffer = readBuffer;
					}

					if (buffer == null)
						buffer = new byte [8192];

					int read;
					while ((read = cnc.Read (buffer, 0, buffer.Length)) != 0)
						ms.Write (buffer, 0, read);

					b = ms.GetBuffer ();
					new_size = (int) ms.Length;
					contentLength = new_size;
				} else {
					new_size = contentLength - totalRead;
					b = new byte [new_size];
					if (readBuffer != null && diff > 0) {
						if (diff > new_size)
							diff = new_size;

						Buffer.BlockCopy (readBuffer, readBufferOffset, b, 0, diff);
					}
					
					int remaining = new_size - diff;
					int r = -1;
					while (remaining > 0 && r != 0) {
						r = cnc.Read (b, diff, remaining);
						remaining -= r;
						diff += r;
					}
				}

				readBuffer = b;
				readBufferOffset = 0;
				readBufferSize = new_size;
				totalRead = 0;
				nextReadCalled = true;
			}

			cnc.NextRead ();
		}
		
	   	static void CallbackWrapper (IAsyncResult r)
		{
			WebAsyncResult result = (WebAsyncResult) r.AsyncState;
			result.InnerAsyncResult = r;
			result.DoCallback ();
		}

		public override int Read (byte [] buffer, int offset, int size)
		{
			if (!isRead)
				throw new NotSupportedException ("this stream does not allow reading");

			if (totalRead >= contentLength)
				return 0;

			IAsyncResult res = BeginRead (buffer, offset, size, null, null);
			return EndRead (res);
		}

		public override IAsyncResult BeginRead (byte [] buffer, int offset, int size,
							AsyncCallback cb, object state)
		{
			if (!isRead)
				throw new NotSupportedException ("this stream does not allow reading");

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

			int length = buffer.Length;
			if (size < 0 || offset < 0 || length < offset || length - offset < size)
				throw new ArgumentOutOfRangeException ();

			lock (this) {
				pendingReads++;
				pending.Reset ();
			}

			WebAsyncResult result = new WebAsyncResult (cb, state, buffer, offset, size);
			if (totalRead >= contentLength) {
				result.SetCompleted (true, -1);
				result.DoCallback ();
				return result;
			}
			
			int remaining = readBufferSize - readBufferOffset;
			if (remaining > 0) {
				int copy = (remaining > size) ? size : remaining;
				Buffer.BlockCopy (readBuffer, readBufferOffset, buffer, offset, copy);
				readBufferOffset += copy;
				offset += copy;
				size -= copy;
				totalRead += copy;
				if (size == 0 || totalRead >= contentLength) {
					result.SetCompleted (true, copy);
					result.DoCallback ();
					return result;
				}
				result.NBytes = copy;
			}

			if (cb != null)
				cb = new AsyncCallback (CallbackWrapper);

			if (contentLength != Int32.MaxValue && contentLength - totalRead < size)
				size = contentLength - totalRead;

			result.InnerAsyncResult = cnc.BeginRead (buffer, offset, size, cb, result);
			return result;
		}

		public override int EndRead (IAsyncResult r)
		{
			WebAsyncResult result = (WebAsyncResult) r;

			if (!result.IsCompleted) {
				int nbytes = cnc.EndRead (result.InnerAsyncResult);
				bool finished = (nbytes == -1);
				if (finished && result.NBytes > 0)
					nbytes = 0;

				result.SetCompleted (false, nbytes + result.NBytes);
				totalRead += nbytes;
				if (finished || nbytes == 0)
					contentLength = totalRead;
			}

			lock (this) {
				pendingReads--;
				if (pendingReads == 0)
					pending.Set ();
			}

			if (totalRead >= contentLength && !nextReadCalled)
				ReadAll ();

			return result.NBytes;
		}
		
		public override IAsyncResult BeginWrite (byte [] buffer, int offset, int size,
							AsyncCallback cb, object state)
		{
			if (isRead)
				throw new NotSupportedException ("this stream does not allow writing");

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

			int length = buffer.Length;
			if (size < 0 || offset < 0 || length < offset || length - offset < size)
				throw new ArgumentOutOfRangeException ();

			if (sendChunked) {
				lock (this) {
					pendingWrites++;
					pending.Reset ();
				}
			}

			WebAsyncResult result = new WebAsyncResult (cb, state);
			if (allowBuffering) {
				writeBuffer.Write (buffer, offset, size);
				if (!sendChunked) {
					result.SetCompleted (true, 0);
					result.DoCallback ();
					return result;
				}
			}

			AsyncCallback callback = null;
			if (cb != null)
				callback = new AsyncCallback (CallbackWrapper);

			if (sendChunked) {
				WriteRequest ();

				string cSize = String.Format ("{0:X}\r\n", size);
				byte [] head = Encoding.ASCII.GetBytes (cSize);
				int chunkSize = 2 + size + head.Length;
				byte [] newBuffer = new byte [chunkSize];
				Buffer.BlockCopy (head, 0, newBuffer, 0, head.Length);
				Buffer.BlockCopy (buffer, offset, newBuffer, head.Length, size);
				Buffer.BlockCopy (crlf, 0, newBuffer, head.Length + size, crlf.Length);

				buffer = newBuffer;
				offset = 0;
				size = chunkSize;
			}

			result.InnerAsyncResult = cnc.BeginWrite (buffer, offset, size, callback, result);
			return result;
		}

		public override void EndWrite (IAsyncResult r)
		{
			if (r == null)
				throw new ArgumentNullException ("r");

			if (allowBuffering && !sendChunked)
				return;

			WebAsyncResult result = r as WebAsyncResult;
			if (result == null)
				throw new ArgumentException ("Invalid IAsyncResult");

			if (result.GotException)
				throw result.Exception;

			cnc.EndWrite (result.InnerAsyncResult);
			if (sendChunked) {
				lock (this) {
					pendingWrites--;
					if (pendingWrites == 0)
						pending.Set ();
				}
			}
		}
		
		public override void Write (byte [] buffer, int offset, int size)
		{
			if (isRead)
				throw new NotSupportedException ("This stream does not allow writing");

			IAsyncResult res = BeginWrite (buffer, offset, size, null, null);
			EndWrite (res);
		}

		public override void Flush ()
		{
		}

		internal void SetHeaders (byte [] buffer, int offset, int size)
		{
			if (headersSent)
				return;

			if (!allowBuffering || sendChunked) {
				headersSent = true;
				if (!cnc.Connected)
					throw new WebException ("Not connected", null, WebExceptionStatus.SendFailure, null);

				cnc.Write (buffer, offset, size);
			} else {
				headers = new byte [size];
				Buffer.BlockCopy (buffer, offset, headers, 0, size);
			}
		}

		internal bool RequestWritten {
			get { return requestWritten; }
		}

		internal void WriteRequest ()
		{
			if (requestWritten)
				return;

			if (sendChunked) {
				request.SendRequestHeaders ();
				requestWritten = true;
				return;
			}

			if (!allowBuffering || writeBuffer == null)
				return;

			byte [] bytes = writeBuffer.GetBuffer ();
			int length = (int) writeBuffer.Length;
			if (request.ContentLength != -1 && request.ContentLength < length) {
				throw new WebException ("Specified Content-Length is less than the number of bytes to write", null,
							WebExceptionStatus.ServerProtocolViolation, null);
			}

			request.InternalContentLength = length;
			request.SendRequestHeaders ();
			requestWritten = true;
			cnc.Write (headers, 0, headers.Length);
			if (!cnc.Connected)
				throw new WebException ("Error writing request.", null, WebExceptionStatus.SendFailure, null);

			headersSent = true;
			if (cnc.Data.StatusCode != 0 && cnc.Data.StatusCode != 100)
				return;

			cnc.Write (bytes, 0, length);
		}

		internal void InternalClose ()
		{
			disposed = true;
		}
		
		public override void Close ()
		{
			if (sendChunked) {
				pending.WaitOne ();
				byte [] chunk = Encoding.ASCII.GetBytes ("0\r\n\r\n");
				cnc.Write (chunk, 0, chunk.Length);
				return;
			}

			if (isRead) {
				if (!nextReadCalled) {
					CheckComplete ();
					// If we have not read all the contents
					if (!nextReadCalled)
						cnc.Close (true);
				}
				return;
			}

			if (!allowBuffering || disposed)
				return;

			disposed = true;

			long length = request.ContentLength;
			if (length != -1 && length > writeBuffer.Length)
				throw new IOException ("Cannot close the stream until all bytes are written");

			WriteRequest ();
		}

		public override long Seek (long a, SeekOrigin b)
		{
			throw new NotSupportedException ();
		}
		
		public override void SetLength (long a)
		{
			throw new NotSupportedException ();
		}
		
		public override bool CanSeek {
			get { return false; }
		}

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

		public override bool CanWrite {
			get { return !isRead; }
		}

		public override long Length {
			get { throw new NotSupportedException (); }
		}

		public override long Position {
			get { throw new NotSupportedException (); }
			set { throw new NotSupportedException (); }
		}
	}
}