/*
 * DataChannelMux.java
 *
 *
 * Copyright (c) 1996 Chuck McManis, All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies.
 *
 * CHUCK MCMANIS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
 * SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. CHUCK MCMANIS
 * SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT
 * OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */

package util.comm;
import java.util.Vector;

/**
 * This class implements a simple Data Channel multiplexor. Normally, many writers
 * can write to the same channel, however they must all write the same type otherwise
 * the clients won't know what type of objects to expect out of the other end. A mux
 * channel can read from several channels simultaneously and write the output to an
 * output channel in the form of a MuxItem object. This object contains both the object
 * written and an identifier of the channel it came in on.
 */
public class DataChannelMux implements Runnable {
    Vector scythes = null;

    // private state variables for instances of the MUX
    private Thread DCM_TID = null;
    private String DCM_Channel;
    private int DCM_Index;
    private DataChannel DCM_Input;
    private DataChannel DCM_Output;

    public DataChannelMux(String inChans[], String outChan) {
	super();
	DCM_Output = DataChannel.getChannel(outChan);
	scythes = new Vector();
	for (int i = 0; i < inChans.length; i++) {
	    DataChannelMux dcm = new DataChannelMux(inChans[i], i, DCM_Output);
	    scythes.addElement(dcm);
	    dcm.start();
	}
    }

    DataChannelMux(String chanName, int userIndex, DataChannel outChan) {
	super();
	DCM_Channel = chanName;
	DCM_Index = userIndex;
	DCM_TID = new Thread(this);
	DCM_Input = DataChannel.getChannel(chanName, DCM_TID, 8);
	DCM_Output = outChan;
    }

    public boolean addChannel(String chanName, int userIndex) {
	if (scythes == null)
	    return false;

	DataChannelMux dcm = new DataChannelMux(chanName, userIndex, DCM_Output);


	scythes.addElement(dcm);
	dcm.start();
	return true;
    }

    public void start() {
    	DCM_TID.start();
    }

    public void run() {
	if ((DCM_Output == null) || (DCM_Input == null))
	    return;

	while (true) {
	    Object x = null;
	    try {
		x = DCM_Input.getValue();
	    } catch (DataChannelOverrun e1) {
		System.out.println("MUX overrun.");
	    } catch (DataChannelShutdown e2) {
		return; // time to exit.
	    } catch (DataChannelException e3) { } // ignore others
	    MuxItem m = new MuxItem(DCM_Channel, DCM_Index, x);
	    DCM_Output.putValue(m);
	}
    }
}