/*
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.mail;

import java.lang.*;

/**
 * The base class for all exceptions thrown by the Messaging classes
 *
 * @author John Mani
 */

public class MessagingException extends Exception {

    /**
     * The next exception in the chain.
     *
     * @serial
     */
    private Exception next;

    /**
     * Constructs a MessagingException with no detail message.
     */
    public MessagingException() {
	super();
    }

    /**
     * Constructs a MessagingException with the specified detail message.
     * @param s		the detail message
     */
    public MessagingException(String s) {
	super(s);
    }

    /**
     * Constructs a MessagingException with the specified 
     * Exception and detail message. The specified exception is chained
     * to this exception.
     * @param s		the detail message
     * @param e		the embedded exception
     * @see	#getNextException
     * @see	#setNextException
     */
    public MessagingException(String s, Exception e) {
	super(s);
	next = e;
    }

    /**
     * Get the next exception chained to this one. If the
     * next exception is a MessagingException, the chain
     * may extend further.
     *
     * @return	next Exception, null if none.
     */
    public Exception getNextException() {
	return next;
    }

    /**
     * Add an exception to the end of the chain. If the end
     * is <strong>not</strong> a MessagingException, this 
     * exception cannot be added to the end.
     *
     * @param	ex	the new end of the Exception chain
     * @return		<code>true</code> if the this Exception
     *			was added, <code>false</code> otherwise.
     */
    public synchronized boolean setNextException(Exception ex) {
	Exception theEnd = this;
	while (theEnd instanceof MessagingException &&
	       ((MessagingException)theEnd).next != null) {
	    theEnd = ((MessagingException)theEnd).next;
	}
	// If the end is a MessagingException, we can add this 
	// exception to the chain.
	if (theEnd instanceof MessagingException) {
	    ((MessagingException)theEnd).next = ex;
	    return true;
	} else
	    return false;
    }

    /**
     * Produce the message, include the message from the nested
     * exception if there is one.
     */
    public String getMessage() {
	if (next == null)
	    return super.getMessage();
	else
	    return super.getMessage() +
		";\n  nested exception is: \n\t" +
		next.toString();
    }
}