/*

 * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.io;

/**

 * This class is the superclass of all classes that filter output

 * streams. These streams sit on top of an already existing output

 * stream (the <i>underlying</i> output stream) which it uses as its

 * basic sink of data, but possibly transforming the data along the

 * way or providing additional functionality.

 * <p>

 * The class {@code FilterOutputStream} itself simply overrides

 * all methods of {@code OutputStream} with versions that pass

 * all requests to the underlying output stream. Subclasses of

 * {@code FilterOutputStream} may further override some of these

 * methods as well as provide additional methods and fields.

 *

 * @author  Jonathan Payne

 * @since   1.0

 */

public class FilterOutputStream extends OutputStream {

    /**

     * The underlying output stream to be filtered.

     */

    protected OutputStream out;

    /**

     * Whether the stream is closed; implicitly initialized to false.

     */

    private volatile boolean closed;

    /**

     * Object used to prevent a race on the 'closed' instance variable.

     */

    private final Object closeLock = new Object();

    /**

     * Creates an output stream filter built on top of the specified

     * underlying output stream.

     *

     * @param   out   the underlying output stream to be assigned to

     *                the field {@code this.out} for later use, or

     *                {@code null} if this instance is to be

     *                created without an underlying stream.

     */

    public FilterOutputStream(OutputStream out) {

        this.out = out;

    }

    /**

     * Writes the specified {@code byte} to this output stream.

     * <p>

     * The {@code write} method of {@code FilterOutputStream}

     * calls the {@code write} method of its underlying output stream,

     * that is, it performs {@code out.write(b)}.

     * <p>

     * Implements the abstract {@code write} method of {@code OutputStream}.

     *

     * @param      b   the {@code byte}.

     * @throws     IOException  if an I/O error occurs.

     */

    @Override

    public void write(int b) throws IOException {

        out.write(b);

    }

    /**

     * Writes {@code b.length} bytes to this output stream.

     * <p>

     * The {@code write} method of {@code FilterOutputStream}

     * calls its {@code write} method of three arguments with the

     * arguments {@code b}, {@code 0}, and

     * {@code b.length}.

     * <p>

     * Note that this method does not call the one-argument

     * {@code write} method of its underlying output stream with

     * the single argument {@code b}.

     *

     * @param      b   the data to be written.

     * @throws     IOException  if an I/O error occurs.

     * @see        java.io.FilterOutputStream#write(byte[], int, int)

     */

    @Override

    public void write(byte b[]) throws IOException {

        write(b, 0, b.length);

    }

    /**

     * Writes {@code len} bytes from the specified

     * {@code byte} array starting at offset {@code off} to

     * this output stream.

     * <p>

     * The {@code write} method of {@code FilterOutputStream}

     * calls the {@code write} method of one argument on each

     * {@code byte} to output.

     * <p>

     * Note that this method does not call the {@code write} method

     * of its underlying output stream with the same arguments. Subclasses

     * of {@code FilterOutputStream} should provide a more efficient

     * implementation of this method.

     *

     * @param      b     the data.

     * @param      off   the start offset in the data.

     * @param      len   the number of bytes to write.

     * @throws     IOException  if an I/O error occurs.

     * @see        java.io.FilterOutputStream#write(int)

     */

    @Override

    public void write(byte b[], int off, int len) throws IOException {

        if ((off | len | (b.length - (len + off)) | (off + len)) < 0)

            throw new IndexOutOfBoundsException();

        for (int i = 0 ; i < len ; i++) {

            write(b[off + i]);

        }

    }

    /**

     * Flushes this output stream and forces any buffered output bytes

     * to be written out to the stream.

     * <p>

     * The {@code flush} method of {@code FilterOutputStream}

     * calls the {@code flush} method of its underlying output stream.

     *

     * @throws     IOException  if an I/O error occurs.

     * @see        java.io.FilterOutputStream#out

     */

    @Override

    public void flush() throws IOException {

        out.flush();

    }

    /**

     * Closes this output stream and releases any system resources

     * associated with the stream.

     * <p>

     * When not already closed, the {@code close} method of {@code

     * FilterOutputStream} calls its {@code flush} method, and then

     * calls the {@code close} method of its underlying output stream.

     *

     * @throws     IOException  if an I/O error occurs.

     * @see        java.io.FilterOutputStream#flush()

     * @see        java.io.FilterOutputStream#out

     */

    @Override

    public void close() throws IOException {

        if (closed) {

            return;

        }

        synchronized (closeLock) {

            if (closed) {

                return;

            }

            closed = true;

        }

        Throwable flushException = null;

        try {

            flush();

        } catch (Throwable e) {

            flushException = e;

            throw e;

        } finally {

            if (flushException == null) {

                out.close();

            } else {

                try {

                    out.close();

                } catch (Throwable closeException) {

                   // evaluate possible precedence of flushException over closeException

                   if ((flushException instanceof ThreadDeath) &&

                       !(closeException instanceof ThreadDeath)) {

                       flushException.addSuppressed(closeException);

                       throw (ThreadDeath) flushException;

                   }

                    if (flushException != closeException) {

                        closeException.addSuppressed(flushException);

                    }

                    throw closeException;

                }

            }

        }

    }

}