/*
 * Created on Nov 1, 2005
 * Created by Alon Rohter
 * Copyright (C) 2005, 2006 Aelitis, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 * AELITIS, SAS au capital de 46,603.30 euros
 * 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
 *
 */
package com.aelitis.azureus.core.networkmanager.impl.tcp;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketException;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.*;

import org.gudy.azureus2.core3.logging.*;
import org.gudy.azureus2.core3.util.*;

import com.aelitis.azureus.core.networkmanager.VirtualChannelSelector;
import com.aelitis.azureus.core.networkmanager.VirtualChannelSelector.VirtualSelectorListener;
import com.aelitis.azureus.core.networkmanager.impl.TransportHelper;



/**
 * 
 */
public class 
TCPTransportHelper 
	implements TransportHelper
{
	public static final int READ_TIMEOUT		= 10*1000;
	public static final int CONNECT_TIMEOUT		= 60*1000;
	  
	public static final int MAX_PARTIAL_WRITE_RETAIN	= 64;	// aim here is to catch headers
	
	private long remainingBytesToScatter = 0; 

	private static boolean enable_efficient_io = !Constants.JAVA_VERSION.startsWith("1.4");

	private	final SocketChannel	channel;
	
	private ByteBuffer	delayed_write;
	
	private Map	user_data;
	
	private boolean	trace;
	
	public TCPTransportHelper( SocketChannel _channel ) {
		channel = _channel;
	}
	
	public InetSocketAddress
	getAddress()
	{
		return( new InetSocketAddress( channel.socket().getInetAddress(), channel.socket().getPort()));
	}
	
	public String
	getName()
	{
			// default is TCP so don't clutter up views with this info
		
		return( "" );
	}
	
	public boolean
	minimiseOverheads()
	{
		return( false );
	}
	
	public int
	getConnectTimeout()
	{
		return( CONNECT_TIMEOUT );
	}
	
	public int
	getReadTimeout()
	{
		return( READ_TIMEOUT );
	}
	
	public boolean 
	delayWrite(
		ByteBuffer buffer) 
	{
		if ( delayed_write != null ){
			
			Debug.out( "secondary delayed write" );
			
			return( false );
		}
		
		delayed_write = buffer;
		
		return( true );
	}
	
	public boolean
	hasDelayedWrite()
	{
		return( delayed_write != null );
	}
	
	public int 
	write( 
		ByteBuffer 	buffer, 
		boolean 	partial_write ) 

		throws IOException 
	{  	
		if ( channel == null ){
			
			Debug.out( "channel == null" );
			
			return 0;
		}
		
			// partial-write means we are guaranteed to get hit with another write straight away
		
		if ( partial_write && delayed_write == null ){
			
			if ( buffer.remaining() < MAX_PARTIAL_WRITE_RETAIN ){
				
				ByteBuffer	copy = ByteBuffer.allocate( buffer.remaining());
				
				copy.put( buffer );
				
				copy.position( 0 );
				
				delayed_write = copy;
				
				return( copy.remaining());
			}
		}
		
		long	written = 0;
		
		if ( delayed_write != null ){
			
			// System.out.println( "delayed write: single" );
			
			ByteBuffer[]	buffers = new ByteBuffer[]{ delayed_write, buffer };
			
			int	delay_remaining = delayed_write.remaining();

			delayed_write = null;
			
			written = write( buffers, 0, 2 );
			
				// note that we can't report delayed bytes actually written as these have already been accounted for and confuse
				// the layers above if we report them now

			if ( buffers[0].hasRemaining()){
				
				delayed_write = buffers[0];
				
				written = 0;
				
				// System.out.println( "delayed write: single incomp" );
			}else{
				
				written -= delay_remaining;
			}
		}else{
			
			// log( buffer );
			
			written = channelWrite(buffer);
		}
		
		if ( trace ){
			
			TimeFormatter.milliTrace( "tcp: write " + written );
		}
		
		return((int)written );
	}
	
	public long 
	write( 
		ByteBuffer[] 	buffers, 
		int 			array_offset, 
		int 			length ) 
	
		throws IOException 
	{
		if( channel == null ){
			
			Debug.out( "channel == null" );
			
			return 0;
		}

		long written_sofar = 0;

		if ( delayed_write != null ){
			
			ByteBuffer[]	buffers2 = new ByteBuffer[length+1];
			
			buffers2[0] = delayed_write;
			
			int	pos = 1;

			for (int i=array_offset;i<array_offset+length;i++){
				
				buffers2[pos++] = buffers[i];
			}
			
			// System.out.println( "delayed write: mult (" + buffers2.length + ")" );

			int	delay_remaining = delayed_write.remaining();

			delayed_write = null;
			
			written_sofar = write( buffers2, 0, buffers2.length );
			
			if ( buffers2[0].hasRemaining()){
				
				delayed_write = buffers2[0];
				
				written_sofar = 0;
				
				// System.out.println( "delayed write: mult incomp" );

			}else{
				
				written_sofar -= delay_remaining;
			}
		}else{
			
			// log( buffers, array_offset, length );
			
			if ( enable_efficient_io && remainingBytesToScatter < 1 ){
				
				try{
					written_sofar = channel.write( buffers, array_offset, length );
					
				}catch( IOException ioe ) {
					
					//a bug only fixed in Tiger (1.5 series):
					//http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4854354
					String msg = ioe.getMessage();
					if( msg != null && msg.equals( "A non-blocking socket operation could not be completed immediately" ) ) {
						enable_efficient_io = false;
						Logger.log(new LogAlert(LogAlert.UNREPEATABLE, LogAlert.AT_WARNING,
								"WARNING: Multi-buffer socket write failed; "
								+ "switching to single-buffer mode.\n"
								+ "Upgrade to JRE 1.5 (5.0) series to fix this problem!"));
					}
					throw ioe;
				}
			}else{
	
					//single-buffer mode
							
				for( int i=array_offset; i < (array_offset + length); i++ ) {
					
					int data_length = buffers[ i ].remaining();
					
					int written = channelWrite(buffers[i]);
					
					written_sofar += written;
					
					if( written < data_length ) {
						
						break;
					}
				}
			}
		}

	
		if ( trace ){
			TimeFormatter.milliTrace( "tcp: write " + written_sofar );
		}
		
		return written_sofar;
	}
	
	private static final Random rnd = new Random();
	
	private int channelWrite(ByteBuffer buf) throws IOException
	{
		int written = 0;
		while(remainingBytesToScatter > 0 && buf.remaining() > 0)
		{
			int currentWritten = channel.write((ByteBuffer)(buf.slice().limit(Math.min(50+rnd.nextInt(100),buf.remaining()))));
			if(currentWritten == 0)
				break;
			buf.position(buf.position()+currentWritten);
			remainingBytesToScatter -= currentWritten;
			if(remainingBytesToScatter <= 0)
			{
				remainingBytesToScatter = 0;
				try
				{
					channel.socket().setTcpNoDelay(false);
				} catch (SocketException e)
				{
					Debug.printStackTrace(e);
				}
			}
			written += currentWritten;
		}
		
		if(buf.remaining() > 0)
			written += channel.write(buf);
	
		return written;		
	}
	
	public int 
	read( 
		ByteBuffer buffer ) 
	
		throws IOException 
	{  	
		if( channel == null ) {
			
			Debug.out( "channel == null" );
			
			return 0;
		}
		
		int	res = channel.read( buffer );
		
		if ( trace ){
			TimeFormatter.milliTrace( "tcp: read " + res );
		}
		
		return( res );
	}

	public long 
	read( 
		ByteBuffer[] 	buffers, 
		int 			array_offset, 
		int 			length ) 
	
		throws IOException 
	{  	
		if( channel == null ) {
			Debug.out( "channel == null" );
			return 0;
		}

		if( buffers == null ) {
			Debug.out( "read: buffers == null" );
			return 0;
		}

		long bytes_read = 0;

		if( enable_efficient_io ) {
			try{
				bytes_read = channel.read( buffers, array_offset, length );
			}
			catch( IOException ioe ) {
				//a bug only fixed in Tiger (1.5 series):
				//http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4854354
				String msg = ioe.getMessage();
				if( msg != null && msg.equals( "A non-blocking socket operation could not be completed immediately" ) ) {
					enable_efficient_io = false;
					Logger.log(new LogAlert(LogAlert.UNREPEATABLE, LogAlert.AT_WARNING,
							"WARNING: Multi-buffer socket read failed; switching to single-buffer mode.\n"
							+ "Upgrade to JRE 1.5 (5.0) series to fix this problem!"));
				}

				throw ioe;
			}
		}else{
				//single-buffer mode
			
			for( int i=array_offset; i < (array_offset + length); i++ ) {
				
				int data_length = buffers[ i ].remaining();
				
				int read = channel.read( buffers[ i ] );
				
				bytes_read += read;
				
				if( read < data_length ) {
					
					break;
				}
			}
		}    

		if ( bytes_read < 0 ){
			
			throw new IOException( "end of stream on socket read" );
		}

		if ( trace ){
			TimeFormatter.milliTrace( "tcp: read " + bytes_read );
		}
		
		return bytes_read;
	}

	public void
	registerForReadSelects(
		final selectListener		listener,
		Object						attachment )
	{
		TCPNetworkManager.getSingleton().getReadSelector().register(
				channel,
				new VirtualSelectorListener()
				{
					public boolean 
					selectSuccess(
							VirtualChannelSelector	selector, 
							SocketChannel			sc, 
							Object 					attachment )
					{
						return( listener.selectSuccess( TCPTransportHelper.this, attachment ));
					}

					public void 
					selectFailure(
							VirtualChannelSelector	selector, 
							SocketChannel 			sc, 
							Object 					attachment, 
							Throwable 				msg)
					{
						listener.selectFailure( TCPTransportHelper.this, attachment, msg );
					}
				},
				attachment );
	}

	public void
	registerForWriteSelects(
		final selectListener		listener,
		Object						attachment )
	{
		TCPNetworkManager.getSingleton().getWriteSelector().register(
				channel,
				new VirtualSelectorListener()
				{
					public boolean 
					selectSuccess(
							VirtualChannelSelector	selector, 
							SocketChannel			sc, 
							Object 					attachment )
					{
						if ( trace ){
							TimeFormatter.milliTrace( "tcp: write select" );
						}

						return( listener.selectSuccess( TCPTransportHelper.this, attachment ));
					}

					public void 
					selectFailure(
							VirtualChannelSelector	selector, 
							SocketChannel 			sc, 
							Object 					attachment, 
							Throwable 				msg)
					{
						listener.selectFailure( TCPTransportHelper.this, attachment, msg );
					}
				},
				attachment );
	}

	public void
	cancelReadSelects()
	{
		TCPNetworkManager.getSingleton().getReadSelector().cancel( channel );
	}

	public void
	cancelWriteSelects()
	{
		if ( trace ){
			TimeFormatter.milliTrace( "tcp: cancel write selects" );
		}
		
		TCPNetworkManager.getSingleton().getWriteSelector().cancel( channel );
	}

	public void
	resumeReadSelects()
	{
		TCPNetworkManager.getSingleton().getReadSelector().resumeSelects( channel );
	}

	public void
	resumeWriteSelects()
	{
		if ( trace ){
			TimeFormatter.milliTrace( "tcp: resume write selects" );
		}
		
		TCPNetworkManager.getSingleton().getWriteSelector().resumeSelects( channel );
	}

	public void
	pauseReadSelects()
	{
		TCPNetworkManager.getSingleton().getReadSelector().pauseSelects( channel );
	}

	public void
	pauseWriteSelects()
	{
		if ( trace ){
			TimeFormatter.milliTrace( "tcp: pause write selects" );
		}
		
		TCPNetworkManager.getSingleton().getWriteSelector().pauseSelects( channel );
	}

	public void
	close( String reason )
	{
		TCPNetworkManager.getSingleton().getReadSelector().cancel( channel );
		TCPNetworkManager.getSingleton().getWriteSelector().cancel( channel );
		TCPNetworkManager.getSingleton().getConnectDisconnectManager().closeConnection( channel );
	}

	public void
	failed(
		Throwable	reason )
	{
		close( Debug.getNestedExceptionMessage( reason ));
	}

	public SocketChannel getSocketChannel(){  return channel; }

	public synchronized void
	setUserData(
		Object	key,
		Object	data )
	{
		if ( user_data == null ){

			user_data = new HashMap();
		}

		user_data.put( key, data );
	}

	public synchronized Object
	getUserData(
		Object	key )
	{
		if ( user_data == null ){

			return(null);

		}

		return( user_data.get( key ));
	}

	/*
	protected void 
	log( 
		ByteBuffer[] 	buffers, 
		int 			array_offset, 
		int 			length ) 
	{
		System.out.println( "Writing group of " + length );
		
		for( int i=array_offset; i < (array_offset + length); i++ ) {
	
			log( buffers[i]);
		}
	}

	protected void
	log(
		ByteBuffer	buffer )
	{
		int position = buffer.position();
		
		int	rem = buffer.remaining();
		
		byte[]	temp = new byte[rem>64?64:rem];
		
		buffer.get( temp );
		
		buffer.position( position );
		
		System.out.println( "    writing " + rem + ": " + new String(temp));
	}
	*/
	
	public void
	setTrace(
		boolean	on )
	{
		trace	= on;
	}
	
	public void setScatteringMode(long forBytes) {
		if(forBytes > 0)
		{
			if(remainingBytesToScatter == 0)
				try
			{
				channel.socket().setTcpNoDelay(true);
			} catch (SocketException e)
			{
				Debug.printStackTrace(e);
			}
			remainingBytesToScatter = forBytes;
		} else
		{
			if(remainingBytesToScatter > 0)
				try
			{
				channel.socket().setTcpNoDelay(false);
			} catch (SocketException e)
			{
				Debug.printStackTrace(e);
			}
			remainingBytesToScatter = 0;
		}
			

	}
}
