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	/*
	* Copyright (c) 2000, 2006, 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 javax.imageio.stream;

	import java.io.IOException;
	import java.io.OutputStream;

	/**
	* An implementation of <code>ImageOutputStream</code> that writes its
	* output to a regular <code>OutputStream</code>. A memory buffer is
	* used to cache at least the data between the discard position and
	* the current write position. The only constructor takes an
	* <code>OutputStream</code>, so this class may not be used for
	* read/modify/write operations. Reading can occur only on parts of
	* the stream that have already been written to the cache and not
	* yet flushed.
	*
	*/
	public class MemoryCacheImageOutputStream extends ImageOutputStreamImpl {

	private OutputStream stream;

	private MemoryCache cache = new MemoryCache();

	/**
	* Constructs a <code>MemoryCacheImageOutputStream</code> that will write
	* to a given <code>OutputStream</code>.
	*
	* @param stream an <code>OutputStream</code> to write to.
	*
	* @exception IllegalArgumentException if <code>stream</code> is
	* <code>null</code>.
	*/
	public MemoryCacheImageOutputStream(OutputStream stream) {
	if (stream == null) {
	throw new IllegalArgumentException("stream == null!");
	}
	this.stream = stream;
	}

	public int read() throws IOException {
	checkClosed();

	bitOffset = 0;

	int val = cache.read(streamPos);
	if (val != -1) {
	++streamPos;
	}
	return val;
	}

	public int read(byte[] b, int off, int len) throws IOException {
	checkClosed();

	if (b == null) {
	throw new NullPointerException("b == null!");
	}
	// Fix 4467608: read([B,I,I) works incorrectly if len<=0
	if (off < 0 \|\| len < 0 \|\| off + len > b.length \|\| off + len < 0) {
	throw new IndexOutOfBoundsException
	("off < 0 \|\| len < 0 \|\| off+len > b.length \|\| off+len < 0!");
	}

	bitOffset = 0;

	if (len == 0) {
	return 0;
	}

	// check if we're already at/past EOF i.e.
	// no more bytes left to read from cache
	long bytesLeftInCache = cache.getLength() - streamPos;
	if (bytesLeftInCache <= 0) {
	return -1; // EOF
	}

	// guaranteed by now that bytesLeftInCache > 0 && len > 0
	// and so the rest of the error checking is done by cache.read()
	// NOTE that alot of error checking is duplicated
	len = (int)Math.min(bytesLeftInCache, (long)len);
	cache.read(b, off, len, streamPos);
	streamPos += len;
	return len;
	}

	public void write(int b) throws IOException {
	flushBits(); // this will call checkClosed() for us
	cache.write(b, streamPos);
	++streamPos;
	}

	public void write(byte[] b, int off, int len) throws IOException {
	flushBits(); // this will call checkClosed() for us
	cache.write(b, off, len, streamPos);
	streamPos += len;
	}

	public long length() {
	try {
	checkClosed();
	return cache.getLength();
	} catch (IOException e) {
	return -1L;
	}
	}

	/**
	* Returns <code>true</code> since this
	* <code>ImageOutputStream</code> caches data in order to allow
	* seeking backwards.
	*
	* @return <code>true</code>.
	*
	* @see #isCachedMemory
	* @see #isCachedFile
	*/
	public boolean isCached() {
	return true;
	}

	/**
	* Returns <code>false</code> since this
	* <code>ImageOutputStream</code> does not maintain a file cache.
	*
	* @return <code>false</code>.
	*
	* @see #isCached
	* @see #isCachedMemory
	*/
	public boolean isCachedFile() {
	return false;
	}

	/**
	* Returns <code>true</code> since this
	* <code>ImageOutputStream</code> maintains a main memory cache.
	*
	* @return <code>true</code>.
	*
	* @see #isCached
	* @see #isCachedFile
	*/
	public boolean isCachedMemory() {
	return true;
	}

	/**
	* Closes this <code>MemoryCacheImageOutputStream</code>. All
	* pending data is flushed to the output, and the cache
	* is released. The destination <code>OutputStream</code>
	* is not closed.
	*/
	public void close() throws IOException {
	long length = cache.getLength();
	seek(length);
	flushBefore(length);
	super.close();
	cache.reset();
	cache = null;
	stream = null;
	}

	public void flushBefore(long pos) throws IOException {
	long oFlushedPos = flushedPos;
	super.flushBefore(pos); // this will call checkClosed() for us

	long flushBytes = flushedPos - oFlushedPos;
	cache.writeToStream(stream, oFlushedPos, flushBytes);
	cache.disposeBefore(flushedPos);
	stream.flush();
	}
	}

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