//
// RequestStream.cs
//	Copied from System.Net.RequestStream.cs
//
// Author:
//	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;
using System.IO;
using System.Runtime.InteropServices;

namespace WebSocketSharp.Net {

	class RequestStream : Stream {

		#region Fields

		byte [] buffer;
		bool    disposed;
		int     length;
		int     offset;
		long    remaining_body;
		Stream  stream;

		#endregion

		#region Constructors

		internal RequestStream (Stream stream, byte [] buffer, int offset, int length)
			: this (stream, buffer, offset, length, -1)
		{
		}

		internal RequestStream (Stream stream, byte [] buffer, int offset, int length, long contentlength)
		{
			this.stream = stream;
			this.buffer = buffer;
			this.offset = offset;
			this.length = length;
			this.remaining_body = contentlength;
		}

		#endregion

		#region Properties

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

		public override bool CanSeek {
			get { return false; }
		}

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

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

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

		#endregion

		#region Private Method

		// Returns 0 if we can keep reading from the base stream,
		// > 0 if we read something from the buffer.
		// -1 if we had a content length set and we finished reading that many bytes.
		int FillFromBuffer (byte [] buffer, int offset, int count)
		{
			if (buffer == null)
				throw new ArgumentNullException ("buffer");

			if (offset < 0)
				throw new ArgumentOutOfRangeException ("offset", "< 0");

			if (count < 0)
				throw new ArgumentOutOfRangeException ("count", "< 0");

			int len = buffer.Length;
			if (offset > len)
				throw new ArgumentException ("Destination offset is beyond array size.");

			if (offset > len - count)
				throw new ArgumentException ("Reading would overrun buffer.");

			if (this.remaining_body == 0)
				return -1;

			if (this.length == 0)
				return 0;

			int size = Math.Min (this.length, count);
			if (this.remaining_body > 0)
				size = (int) Math.Min (size, this.remaining_body);

			if (this.offset > this.buffer.Length - size) {
				size = Math.Min (size, this.buffer.Length - this.offset);
			}

			if (size == 0)
				return 0;

			Buffer.BlockCopy (this.buffer, this.offset, buffer, offset, size);
			this.offset += size;
			this.length -= size;
			if (this.remaining_body > 0)
				remaining_body -= size;

			return size;
		}

		#endregion

		#region Public Methods

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

			int nread = FillFromBuffer (buffer, offset, count);
			if (nread > 0 || nread == -1) {
				var ares = new HttpStreamAsyncResult ();
				ares.Buffer = buffer;
				ares.Offset = offset;
				ares.Count = count;
				ares.Callback = cback;
				ares.State = state;
				ares.SyncRead = nread;
				ares.Complete ();
				return ares;
			}

			// Avoid reading past the end of the request to allow
			// for HTTP pipelining
			if (remaining_body >= 0 && count > remaining_body)
				count = (int) Math.Min (Int32.MaxValue, remaining_body);

			return stream.BeginRead (buffer, offset, count, cback, state);
		}

		public override IAsyncResult BeginWrite (
			byte [] buffer, int offset, int count, AsyncCallback cback, object state)
		{
			throw new NotSupportedException ();
		}

		public override void Close ()
		{
			disposed = true;
		}

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

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

			if (ares is HttpStreamAsyncResult) {
				var ares_ = (HttpStreamAsyncResult) ares;
				if (!ares.IsCompleted)
					ares.AsyncWaitHandle.WaitOne ();

				return ares_.SyncRead;
			}

			// Close on exception?
			int nread = stream.EndRead (ares);
			if (remaining_body > 0 && nread > 0)
				remaining_body -= nread;

			return nread;
		}

		public override void EndWrite (IAsyncResult async_result)
		{
			throw new NotSupportedException ();
		}

		public override void Flush ()
		{
		}

		public override int Read ([In,Out] byte[] buffer, int offset, int count)
		{
			if (disposed)
				throw new ObjectDisposedException (GetType () .ToString ());

			// Call FillFromBuffer to check for buffer boundaries even when remaining_body is 0
			int nread = FillFromBuffer (buffer, offset, count);
			if (nread == -1) { // No more bytes available (Content-Length)
				return 0;
			} else if (nread > 0) {
				return nread;
			}

			nread = stream.Read (buffer, offset, count);
			if (nread > 0 && remaining_body > 0)
				remaining_body -= nread;

			return nread;
		}

		public override long Seek (long offset, SeekOrigin origin)
		{
			throw new NotSupportedException ();
		}

		public override void SetLength (long value)
		{
			throw new NotSupportedException ();
		}

		public override void Write (byte[] buffer, int offset, int count)
		{
			throw new NotSupportedException ();
		}

		#endregion
	}
}