//
// System.Net.WebConnection
//
// Authors:
//	Gonzalo Paniagua Javier (gonzalo@ximian.com)
//
// (C) 2003 Ximian, Inc (http://www.ximian.com)
//

using System.Collections;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace System.Net
{
	enum ReadState
	{
		None,
		Status,
		Headers,
		Content
	}
	
	class WebConnection
	{
		ServicePoint sPoint;
		NetworkStream nstream;
		Socket socket;
		WebExceptionStatus status;
		WebConnectionGroup group;
		bool busy;
		ArrayList queue;
		WaitOrTimerCallback initConn;
		internal ManualResetEvent dataAvailable;
		bool keepAlive;
		bool aborted;
		byte [] buffer;
		internal static AsyncCallback readDoneDelegate = new AsyncCallback (ReadDone);
		EventHandler abortHandler;
		ReadState readState;
		internal WebConnectionData Data;
		WebConnectionStream prevStream;
		bool chunkedRead;
		ChunkStream chunkStream;
		AutoResetEvent waitForContinue;
		bool waitingForContinue;
		
		public WebConnection (WebConnectionGroup group, ServicePoint sPoint)
		{
			this.group = group;
			this.sPoint = sPoint;
			queue = new ArrayList (1);
			dataAvailable = new ManualResetEvent (true);
			buffer = new byte [4096];
			readState = ReadState.None;
			Data = new WebConnectionData ();
			initConn = new WaitOrTimerCallback (InitConnection);
			abortHandler = new EventHandler (Abort);
		}

		public void Connect ()
		{
			if (socket != null && socket.Connected && status == WebExceptionStatus.Success)
				return;

			lock (this) {
				if (socket != null && socket.Connected && status == WebExceptionStatus.Success)
					return;

				
				if (socket == null)
					socket = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);

				status = sPoint.Connect (socket);
				chunkStream = null;
			}
		}

		bool CreateStream (HttpWebRequest request)
		{
			//TODO: create stream for https
			try {
				nstream = new NetworkStream (socket, false);
			} catch (Exception e) {
				status = WebExceptionStatus.ConnectFailure;
				return false;
			}

			return true;
		}
		
		void HandleError (WebExceptionStatus st, Exception e)
		{
			status = st;
			Close ();
			if (e == null) { // At least we noe where it comes from
				try {
					throw new Exception ();
				} catch (Exception e2) {
					e = e2;
				}
			}

			if (Data != null && Data.request != null)
				Data.request.SetResponseError (st, e);
		}
		
		internal bool WaitForContinue (byte [] headers, int offset, int size)
		{
			Data.StatusCode = 0;
			if (sPoint.SendContinue == false)
				return false;

			if (waitForContinue == null)
				waitForContinue = new AutoResetEvent (false);

			Write (headers, offset, size);
			waitingForContinue = true;
			bool result = waitForContinue.WaitOne (2000, false);
			waitingForContinue = false;
			if (result) {
				Data.request.DoContinueDelegate (Data.StatusCode, Data.Headers);
				sPoint.SendContinue = true;
			} else {
				sPoint.SendContinue = false;
				waitForContinue = null;
			}

			return result;
		}
		
		static void ReadDone (IAsyncResult result)
		{
			WebConnection cnc = (WebConnection) result.AsyncState;
			NetworkStream ns = cnc.nstream;
			if (ns == null)
				return;

			int nread = -1;
			cnc.dataAvailable.Reset ();
			try {
				nread = ns.EndRead (result);
			} catch (Exception e) {
				cnc.status = WebExceptionStatus.ReceiveFailure;
				cnc.HandleError (cnc.status, e);
				cnc.dataAvailable.Set ();
				return;
			}

			if (nread == 0) {
				Console.WriteLine ("nread == 0");
				return;
			}

			if (nread < 0) {
				cnc.HandleError (WebExceptionStatus.ServerProtocolViolation, null);
				cnc.dataAvailable.Set ();
				return;
			}

			//Console.WriteLine (System.Text.Encoding.Default.GetString (cnc.buffer, 0, nread));
			int pos = -1;
			if (cnc.readState == ReadState.None) { 
				Exception exc = null;
				try {
					pos = cnc.GetResponse (cnc.buffer, nread);
				} catch (Exception e) {
					exc = e;
				}

				if (pos == -1 || exc != null) {
					cnc.HandleError (WebExceptionStatus.ServerProtocolViolation, exc);
					cnc.dataAvailable.Set ();
					return;
				}
			}

			if (cnc.readState != ReadState.Content) {
				cnc.HandleError (WebExceptionStatus.ServerProtocolViolation, null);
				cnc.dataAvailable.Set ();
				return;
			}

			if (cnc.waitingForContinue) {
				cnc.waitForContinue.Set ();
				if (cnc.Data.StatusCode == 100) {
					cnc.readState = ReadState.None;
					InitRead (cnc);
					return;
				}
			}
			
			WebConnectionStream stream = new WebConnectionStream (cnc);

			string contentType = cnc.Data.Headers ["Transfer-Encoding"];
			cnc.chunkedRead = (contentType != null && contentType.ToLower ().IndexOf ("chunked") != -1);
			if (!cnc.chunkedRead) {
				stream.ReadBuffer = cnc.buffer;
				stream.ReadBufferOffset = pos;
				stream.ReadBufferSize = nread;
				stream.CheckComplete ();
			} else if (cnc.chunkStream == null) {
				cnc.chunkStream = new ChunkStream (cnc.buffer, pos, nread, cnc.Data.Headers);
			} else {
				cnc.chunkStream.ResetBuffer ();
				cnc.chunkStream.Write (cnc.buffer, pos, nread);
			}

			cnc.prevStream = stream;
			cnc.Data.stream = stream;
			cnc.Data.request.SetResponseData (cnc.Data);
		}
		
		static void InitRead (object state)
		{
			WebConnection cnc = (WebConnection) state;
			NetworkStream ns = cnc.nstream;
			try {
				ns.BeginRead (cnc.buffer, 0, cnc.buffer.Length, readDoneDelegate, cnc);
			} catch (Exception e) {
				cnc.HandleError (WebExceptionStatus.ReceiveFailure, e);
				cnc.dataAvailable.Set ();
			}
		}
		
		int GetResponse (byte [] buffer, int max)
		{
			int pos = 0;
			string line = null;
			bool lineok = false;
			
			if (readState == ReadState.None) {
				lineok = ReadLine (buffer, ref pos, max, ref line);
				if (!lineok)
					return -1;

				readState = ReadState.Status;

				string [] parts = line.Split (' ');
				if (parts.Length < 3)
					return -1;

				if (String.Compare (parts [0], "HTTP/1.1", true) == 0) {
					Data.Version = HttpVersion.Version11;
				} else {
					Data.Version = HttpVersion.Version10;
				}

				Data.StatusCode = (int) UInt32.Parse (parts [1]);
				Data.StatusDescription = String.Join (" ", parts, 2, parts.Length - 2);
				if (pos >= max)
					return pos;
			}

			if (readState == ReadState.Status) {
				readState = ReadState.Headers;
				Data.Headers = new WebHeaderCollection ();
				ArrayList headers = new ArrayList ();
				bool finished = false;
				while (!finished) {
					if (ReadLine (buffer, ref pos, max, ref line) == false)
						break;
					
					if (line == null) {
						// Empty line: end of headers
						finished = true;
						continue;
					}
					
					if (line.Length > 0 && (line [0] == ' ' || line [0] == '\t')) {
						int count = headers.Count - 1;
						if (count < 0)
							break;

						string prev = (string) headers [count] + line;
						headers [count] = prev;
					} else {
						headers.Add (line);
					}
				}

				if (!finished) {
					// handle the error...
				} else {
					foreach (string s in headers)
						Data.Headers.Add (s);

					readState = ReadState.Content;
					return pos;
				}
			}

			return -1;
		}
		
		void InitConnection (object state, bool notUsed)
		{
			HttpWebRequest request = (HttpWebRequest) state;
			if (aborted) {
				status = WebExceptionStatus.RequestCanceled;
				request.SetWriteStreamError (status);
				return;
			}

			Connect ();
			if (status != WebExceptionStatus.Success) {
				request.SetWriteStreamError (status);
				Close ();
				return;
			}
			
			if (!CreateStream (request)) {
				request.SetWriteStreamError (status);
				Close ();
				return;
			}

			readState = ReadState.None;
			request.SetWriteStream (new WebConnectionStream (this, request));
			InitRead (this);
		}
		
		void BeginRequest (HttpWebRequest request)
		{
			lock (this) {
				keepAlive = request.KeepAlive;
				Data.Init ();
				Data.request = request;
			}

			ThreadPool.RegisterWaitForSingleObject (dataAvailable, initConn, request, -1, true);
		}

		internal EventHandler SendRequest (HttpWebRequest request)
		{
			Monitor.Enter (this);

			if (prevStream != null && socket != null && socket.Connected) {
				prevStream.ReadAll ();
				prevStream = null;
			}
				
			if (!busy) {
				busy = true;
				Monitor.Exit (this);
				BeginRequest (request);
			} else {
				queue.Add (request);
				Monitor.Exit (this);
			}

			return abortHandler;
		}
		
		internal void NextRead ()
		{
			Monitor.Enter (this);
			string cncHeader = (Data.Headers != null) ? Data.Headers ["Connection"] : null;
			// Bug in xsp...? It does not send Connection: close. Well. it's 1.0
			if (Data.Version == HttpVersion.Version10 || (socket != null && !socket.Connected) || (!keepAlive ||
			    (cncHeader != null && cncHeader.IndexOf ("close") != -1))) {
				Close ();
			}

			if (queue.Count > 0) {
				HttpWebRequest request = (HttpWebRequest) queue [0];
				queue.RemoveAt (0);
				Monitor.Exit (this);
				SendRequest (request);
			} else {
				busy = false;
				Monitor.Exit (this);
			}
		}
		
		static bool ReadLine (byte [] buffer, ref int start, int max, ref string output)
		{
			bool foundCR = false;
			StringBuilder text = new StringBuilder ();

			int c = 0;
			while (start < max) {
				c = (int) buffer [start++];

				if (c == '\n') {			// newline
					if ((text.Length > 0) && (text [text.Length - 1] == '\r'))
						text.Length--;

					foundCR = false;
					break;
				} else if (foundCR) {
					text.Length--;
					break;
				}

				if (c == '\r')
					foundCR = true;
					

				text.Append ((char) c);
			}

			if (c != '\n' && c != '\r')
				return false;

			if (text.Length == 0) {
				output = null;
				return (c == '\n' || c == '\r');
			}

			if (foundCR)
				text.Length--;

			output = text.ToString ();
			return true;
		}

		internal IAsyncResult BeginRead (byte [] buffer, int offset, int size, AsyncCallback cb, object state)
		{
			if (nstream == null)
				return null;

			IAsyncResult result = null;
			if (!chunkedRead || chunkStream.WantMore) {
				try {
					result = nstream.BeginRead (buffer, offset, size, cb, state);
				} catch (Exception e) {
					status = WebExceptionStatus.ReceiveFailure;
					throw;
				}
			}

			if (chunkedRead) {
				WebAsyncResult wr = new WebAsyncResult (null, null, buffer, offset, size);
				wr.InnerAsyncResult = result;
				return wr;
			}

			return result;
		}
		
		internal int EndRead (IAsyncResult result)
		{
			if (nstream == null)
				return 0;

			if (chunkedRead) {
				WebAsyncResult wr = (WebAsyncResult) result;
				int nbytes = 0;
				if (wr.InnerAsyncResult != null)
					nbytes = nstream.EndRead (wr.InnerAsyncResult);

				chunkStream.WriteAndReadBack (wr.Buffer, wr.Offset, wr.Size, ref nbytes);
				return nbytes;
			}

			return nstream.EndRead (result);
		}

		internal IAsyncResult BeginWrite (byte [] buffer, int offset, int size, AsyncCallback cb, object state)
		{
			IAsyncResult result = null;
			if (nstream == null)
				return null;

			try {
				result = nstream.BeginWrite (buffer, offset, size, cb, state);
			} catch (Exception e) {
				status = WebExceptionStatus.SendFailure;
				throw;
			}

			return result;
		}

		internal void EndWrite (IAsyncResult result)
		{
			if (nstream != null)
				nstream.EndWrite (result);
		}

		internal int Read (byte [] buffer, int offset, int size)
		{
			if (nstream == null)
				return 0;

			int result = 0;
			try {
				if (!chunkedRead || chunkStream.WantMore)
					result = nstream.Read (buffer, offset, size);

				if (chunkedRead)
					chunkStream.WriteAndReadBack (buffer, offset, size, ref result);
			} catch (Exception e) {
				status = WebExceptionStatus.ReceiveFailure;
				HandleError (status, e);
			}

			return result;
		}

		internal void Write (byte [] buffer, int offset, int size)
		{
			if (nstream == null)
				return;

			try {
				nstream.Write (buffer, offset, size);
			} catch (Exception e) {
				status = WebExceptionStatus.SendFailure;
				HandleError (status, e);
			}
		}

		void Close ()
		{
			if (nstream != null) {
				try {
					nstream.Close ();
				} catch {}
				nstream = null;
			}

			if (socket != null) {
				try {
					socket.Close ();
				} catch {}
				socket = null;
			}
		}

		void Abort (object sender, EventArgs args)
		{
			HandleError (WebExceptionStatus.RequestCanceled, null);
		}
	}
}