/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.commons.lang.exception;

import java.io.PrintStream;
import java.io.PrintWriter;

/**
 * The base class of all exceptions which can contain other exceptions.
 *
 * It is intended to ease the debugging by carrying on the information
 * about the exception which was caught and provoked throwing the
 * current exception. Catching and rethrowing may occur multiple
 * times, and provided that all exceptions except the first one
 * are descendands of <code>NestedException</code>, when the
 * exception is finally printed out using any of the <code>
 * printStackTrace()</code> methods, the stacktrace will contain
 * the information about all exceptions thrown and caught on
 * the way.
 * <p> Running the following program
 * <p><blockquote><pre>
 *  1 import org.apache.commons.lang.exception.NestableException;
 *  2
 *  3 public class Test {
 *  4     public static void main( String[] args ) {
 *  5         try {
 *  6             a();
 *  7         } catch(Exception e) {
 *  8             e.printStackTrace();
 *  9         }
 * 10      }
 * 11
 * 12      public static void a() throws Exception {
 * 13          try {
 * 14              b();
 * 15          } catch(Exception e) {
 * 16              throw new NestableException("foo", e);
 * 17          }
 * 18      }
 * 19
 * 20      public static void b() throws Exception {
 * 21          try {
 * 22              c();
 * 23          } catch(Exception e) {
 * 24              throw new NestableException("bar", e);
 * 25          }
 * 26      }
 * 27
 * 28      public static void c() throws Exception {
 * 29          throw new Exception("baz");
 * 30      }
 * 31 }
 * </pre></blockquote>
 * <p>Yields the following stacktrace:
 * <p><blockquote><pre>
 * org.apache.commons.lang.exception.NestableException: foo
 *         at Test.a(Test.java:16)
 *         at Test.main(Test.java:6)
 * Caused by: org.apache.commons.lang.exception.NestableException: bar
 *         at Test.b(Test.java:24)
 *         at Test.a(Test.java:14)
 *         ... 1 more
 * Caused by: java.lang.Exception: baz
 *         at Test.c(Test.java:29)
 *         at Test.b(Test.java:22)
 *         ... 2 more
 * </pre></blockquote><br>
 *
 * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
 * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
 * @author <a href="mailto:knielsen@apache.org">Kasper Nielsen</a>
 * @author <a href="mailto:steven@caswell.name">Steven Caswell</a>
 * @since 1.0
 * @version $Id: NestableException.java,v 1.9 2003/08/18 02:22:24 bayard Exp $
 */
public class NestableException extends Exception implements Nestable {
    
    /**
     * The helper instance which contains much of the code which we
     * delegate to.
     */
    protected NestableDelegate delegate = new NestableDelegate(this);

    /**
     * Holds the reference to the exception or error that caused
     * this exception to be thrown.
     */
    private Throwable cause = null;

    /**
     * Constructs a new <code>NestableException</code> without specified
     * detail message.
     */
    public NestableException() {
        super();
    }

    /**
     * Constructs a new <code>NestableException</code> with specified
     * detail message.
     *
     * @param msg The error message.
     */
    public NestableException(String msg) {
        super(msg);
    }

    /**
     * Constructs a new <code>NestableException</code> with specified
     * nested <code>Throwable</code>.
     *
     * @param cause the exception or error that caused this exception to be
     * thrown
     */
    public NestableException(Throwable cause) {
        super();
        this.cause = cause;
    }

    /**
     * Constructs a new <code>NestableException</code> with specified
     * detail message and nested <code>Throwable</code>.
     *
     * @param msg    the error message
     * @param cause  the exception or error that caused this exception to be
     * thrown
     */
    public NestableException(String msg, Throwable cause) {
        super(msg);
        this.cause = cause;
    }

    public Throwable getCause() {
        return cause;
    }

    /**
     * Returns the detail message string of this throwable. If it was
     * created with a null message, returns the following:
     * (cause==null ? null : cause.toString()).
     */
    public String getMessage() {
        if (super.getMessage() != null) {
            return super.getMessage();
        } else if (cause != null) {
            return cause.toString();
        } else {
            return null;
        }
    }

    public String getMessage(int index) {
        if (index == 0) {
            return super.getMessage();
        } else {
            return delegate.getMessage(index);
        }
    }

    public String[] getMessages() {
        return delegate.getMessages();
    }

    public Throwable getThrowable(int index) {
        return delegate.getThrowable(index);
    }

    public int getThrowableCount() {
        return delegate.getThrowableCount();
    }

    public Throwable[] getThrowables() {
        return delegate.getThrowables();
    }

    public int indexOfThrowable(Class type) {
        return delegate.indexOfThrowable(type, 0);
    }

    public int indexOfThrowable(Class type, int fromIndex) {
        return delegate.indexOfThrowable(type, fromIndex);
    }

    public void printStackTrace() {
        delegate.printStackTrace();
    }

    public void printStackTrace(PrintStream out) {
        delegate.printStackTrace(out);
    }

    public void printStackTrace(PrintWriter out) {
        delegate.printStackTrace(out);
    }

    public final void printPartialStackTrace(PrintWriter out) {
        super.printStackTrace(out);
    }

}