package org.apache.maven.util;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 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 acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Maven" 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",
 *    "Apache Maven", nor may "Apache" appear in their name, 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/>.
 *
 * ====================================================================
 */

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;

/**
 * A class to asynchronously read the provided InputStream and
 * provide the output as a String
 *
 * @author <a href="mailto:dion@multitask.com.au">dIon Gillard</a>
 * @version $Id: AsyncStreamReader.java,v 1.1 2003/01/24 03:44:56 jvanzyl Exp $
 */
public class AsyncStreamReader extends Thread
{
    /** buffer to dump output to */
    private StringBuffer streamBuffer = new StringBuffer();
    
    /** stream to read from */
    private BufferedReader stream;

    /**
     * Create a reader to process the provided stream
     * @param anInputStream any input stream
     */
    public AsyncStreamReader(InputStream anInputStream)
    {
        if (anInputStream == null)
        {
            throw new NullPointerException("input stream parameter is null");
        }
        stream = new BufferedReader(new InputStreamReader(anInputStream));
    }

    /**
     * Read lines from the input stream provided, appending to a buffer
     * for retrieval via the toString() method 
     */
    public void run()
    {
        String line;
        try
        {
            while ((line = stream.readLine()) != null)
            {
                if (okToConsume(line))
                {
                    streamBuffer.append(line);
                    streamBuffer.append('\n');
                }
            }
        }
        catch (IOException ioe) 
        {
            ioe.printStackTrace();
        }
    }

    /**
     * @return the contents of the buffer
     */
    public String toString()
    {
        return streamBuffer.toString();
    }

    /**
     * Indicate if its ok to consume (add to the buffer) this line.  This
     * implementation always returns <code>true</code>.
     *
     * @param line the line to check.
     * @return if its ok to add this line to the buffer.
     */
    protected boolean okToConsume(String line)
    {
        return true;
    }
    
} // end of AsyncStreamReader
