/*
 * Copyright (c) 1996-2001
 * Logica Mobile Networks Limited
 * All rights reserved.
 *
 * This software is distributed under Logica Open Source License Version 1.0
 * ("Licence Agreement"). You shall use it and distribute only in accordance
 * with the terms of the License Agreement.
 *
 */
package org.smpp.smscsim;

import java.io.InterruptedIOException;
import java.io.IOException;

import org.smpp.SmppObject;
import org.smpp.Connection;

/**
 * This class accepts client connection on given port. When the connection
 * is accepted, the listener creates an instance of <code>SMSCSession</code>,
 * generates new <code>PDUProcessor</code> using object derived from
 * <code>PDUProcessorFactory</code>, passes the processor to the smsc session
 * and starts the session as a standalone thread.
 *
 * @author Logica Mobile Networks SMPP Open Source Team
 * @version $Revision: 1.2 $
 * @see SMSCSession
 * @see PDUProcessor
 * @see PDUProcessorFactory
 */
public class SMSCListenerImpl extends SmppObject implements Runnable, SMSCListener {
	private Connection serverConn = null;
	private int port;
	private long acceptTimeout = org.smpp.Data.ACCEPT_TIMEOUT;
	private PDUProcessorFactory processorFactory = null;
	private boolean keepReceiving = true;
	private boolean isReceiving = false;
	private boolean asynchronous = false;

	/**
	 * Construct synchronous listener listening on the given port.
	 * @param port the port to listen on
	 * @see #SMSCListenerImpl(int,boolean)
	 */
	public SMSCListenerImpl(int port) {
		this.port = port;
	}

	/**
	 * Constructor with control if the listener starts as a separate thread.
	 * If <code>asynchronous</code> is true, then the listener is started
	 * as a separate thread, i.e. the creating thread can continue after
	 * calling of method <code>start</code>. If it's false, then the
	 * caller blocks while the listener does it's work, i.e. listening.
	 * @param port the port to listen on
	 * @param asynchronous if the listening will be performed as separate thread
	 * @see #start()
	 */
	public SMSCListenerImpl(int port, boolean asynchronous) {
		this.port = port;
		this.asynchronous = asynchronous;
	}

	/**
	 * Starts the listening. If the listener is asynchronous (reccomended),
	 * then new thread is created which listens on the port and the
	 * <code>start</code> method returns to the caller. Otherwise
	 * the caller is blocked in the start method.
	 * @see #stop()
	 */
	public synchronized void start() throws IOException {
		debug.write("going to start SMSCListener on port " + port);
		if (!isReceiving) {
			serverConn = new org.smpp.TCPIPConnection(port);
			serverConn.setReceiveTimeout(getAcceptTimeout());
			serverConn.open();
			keepReceiving = true;
			if (asynchronous) {
				debug.write("starting listener in separate thread.");
				Thread serverThread = new Thread(this);
				serverThread.start();
				debug.write("listener started in separate thread.");
			} else {
				debug.write("going to listen in the context of current thread.");
				run();
			}
		} else {
			debug.write("already receiving, not starting the listener.");
		}
	}

	/**
	 * Signals the listener that it should stop listening and wait
	 * until the listener stops. Note that based on the timeout settings
	 * it can take some time befor this method is finished -- the listener
	 * can be blocked on i/o operation and only after exiting i/o
	 * it can detect that it should stop.
	 * @see #start()
	 */
	public synchronized void stop() throws IOException {
		debug.write("going to stop SMSCListener on port " + port);
		keepReceiving = false;
		while (isReceiving) {
			Thread.yield();
		}
		serverConn.close();
		debug.write("SMSCListener stopped on port " + port);
	}

	/**
	 * The actual listening code which is run either from the thread
	 * (for async listener) or called from <code>start</code> method
	 * (for sync listener). The method can be exited by calling of method
	 * <code>stop</code>.
	 * @see #start()
	 * @see #stop()
	 */
	public void run() {
		debug.enter(this, "run of SMSCListener on port " + port);
		isReceiving = true;
		try {
			while (keepReceiving) {
				listen();
				Thread.yield();
			}
		} finally {
			isReceiving = false;
		}
		debug.exit(this);
	}

	/**
	 * The "one" listen attempt called from <code>run</code> method.
	 * The listening is atomicised to allow contoled stopping of the listening.
	 * The length of the single listen attempt
	 * is defined by <code>acceptTimeout</code>.
	 * If a connection is accepted, then new session is created on this
	 * connection, new PDU processor is generated using PDU processor factory
	 * and the new session is started in separate thread.
	 * @see #run()
	 * @see com.logica.smpp.Connection
	 * @see SMSCSession
	 * @see PDUProcessor
	 * @see PDUProcessorFactory
	 */
	private void listen() {
		debug.enter(Simulator.DSIMD2, this, "SMSCListener listening on port " + port);
		try {
			Connection connection = null;
			serverConn.setReceiveTimeout(getAcceptTimeout());
			connection = serverConn.accept();

			if (connection != null) {
				debug.write("SMSCListener accepted a connection on port " + port);
				SMSCSession session = new SMSCSessionImpl(connection);
				PDUProcessor pduProcessor = null;
				if (processorFactory != null) {
					pduProcessor = processorFactory.createPDUProcessor(session);
				}
				session.setPDUProcessor(pduProcessor);
				Thread thread = new Thread(session);
				thread.start();
				debug.write("SMSCListener launched a session on the accepted connection.");
			} else {
				debug.write(Simulator.DSIMD2, "no connection accepted this time.");
			}
		} catch (InterruptedIOException e) {
			// thrown when the timeout expires => it's ok, we just didn't
			// receive anything
			debug.write("InterruptedIOException accepting, timeout? -> " + e);
		} catch (IOException e) {
			// accept can throw this from various reasons
			// and we don't want to continue then (?)
			event.write(e, "IOException accepting connection");
			keepReceiving = false;
		}
		debug.exit(Simulator.DSIMD2, this);
	}

	/**
	 * Sets a PDU processor factory to use for generating PDU processors.
	 * @param processorFactory the new PDU processor factory
	 */
	public void setPDUProcessorFactory(PDUProcessorFactory processorFactory) {
		this.processorFactory = processorFactory;
	}

	/**
	 * Sets new timeout for accepting new connection.
	 * The listening blocks the for maximum this time, then it
	 * exits regardless the connection was acctepted or not.
	 * @param value the new value for accept timeout
	 */
	public void setAcceptTimeout(int value) {
		acceptTimeout = value;
	}

	/**
	 * Returns the current setting of accept timeout.
	 * @return the current accept timeout
	 * @see #setAcceptTimeout(int)
	 */
	public long getAcceptTimeout() {
		return acceptTimeout;
	}
}
/*
 * $Log: SMSCListenerImpl.java,v $
 * Revision 1.2  2006/03/09 16:24:14  sverkera
 * Removed compiler and javadoc warnings
 *
 * Revision 1.1  2003/09/30 09:17:49  sverkera
 * Created an interface for SMSCListener and SMSCSession and implementations of them  so that it is possible to provide other implementations of these classes.
 *
 * Revision 1.1  2003/07/23 00:28:39  sverkera
 * Imported
 *
 * 
 * Old changelog:
 * 23-08-01 ticp@logica.com added yield() to run() to give chance to other
 *						    threads
 * 26-09-01 ticp@logica.com debug now in a group
 */