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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
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 * "Portions Copyrighted [year] [name of copyright owner]"
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 * Contributor(s):
 *
 * The Original Software is NetBeans. The Initial Developer of the Original
 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
 * Microsystems, Inc. All Rights Reserved.
 *
 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
 * single choice of license, a recipient has the option to distribute
 * your version of this file under either the CDDL, the GPL Version 2 or
 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
 * Version 2 license, then the option applies only if the new code is
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 */
package org.freezedry.persistence.readers;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.io.Reader;

/**
 * This class converts {@link PersistenceReader} to {@link InputStream}. It works by converting the
 * characters to the encoding specified in constructor parameter.
 * 
 * @author Petr Hamernik, David Strupl
 */
public class ReaderInputStream extends InputStream {

	private Reader reader;
	private PipedOutputStream pos;
	private PipedInputStream pis;
	private OutputStreamWriter osw;

	/**
	 * Creates new input stream from the given reader. Uses the platform default
	 * encoding.
	 * 
	 * @param reader Input reader
	 */
	public ReaderInputStream( final Reader reader ) throws IOException
	{
		this.reader = reader;
		pos = new PipedOutputStream();
		pis = new PipedInputStream( pos );
		osw = new OutputStreamWriter( pos );
	}

	/**
	 * Creates new input stream from the given reader and encoding.
	 * 
	 * @param reader Input reader
	 * @param encoding
	 */
	public ReaderInputStream( final Reader reader, final String encoding ) throws IOException
	{
		this.reader = reader;
		pos = new PipedOutputStream();
		pis = new PipedInputStream( pos );
		osw = new OutputStreamWriter( pos, encoding );
	}

	/*
	 * (non-Javadoc)
	 * @see java.io.InputStream#read()
	 */
	@Override
	public int read() throws IOException
	{
		if( pis.available() > 0 ) { return pis.read(); }

		int c = reader.read();

		if( c == -1 ) { return c; }

		osw.write( c );
		osw.flush();
		pos.flush();

		return pis.read();
	}

	/*
	 * (non-Javadoc)
	 * @see java.io.InputStream#read(byte[], int, int)
	 */
	@Override
	public int read( byte[] b, int off, int len ) throws IOException
	{
		if( len == 0 ) { return 0; }

		int c = read();

		if( c == -1 ) { return -1; }

		b[ off ] = (byte) c;

		int i = 1;

		// Don't try to fill up the buffer if the reader is waiting.
		for( ; (i < len) && reader.ready(); i++ )
		{
			c = read();

			if( c == -1 ) { return i; }

			b[ off + i ] = (byte) c;
		}

		return i;
	}

	/*
	 * (non-Javadoc)
	 * @see java.io.InputStream#available()
	 */
	@Override
	public int available() throws IOException
	{
		int i = pis.available();

		if( i > 0 ) { return i; }

		if( reader.ready() )
		{
			// Char must produce at least one byte.
			return 1;
		}
		else
		{
			return 0;
		}
	}

	/*
	 * (non-Javadoc)
	 * @see java.io.InputStream#close()
	 */
	@Override
	public void close() throws IOException
	{
		reader.close();
		osw.close();
		pis.close();
	}
}