/*
    * Copyright (C) 2008-2009, Google Inc.
    * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
    * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
   * SPDX-License-Identifier: BSD-3-Clause
   */
  
  package org.eclipse.jgit.internal.storage.file;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.zip.DataFormatException;
  import java.util.zip.Inflater;
  
  import org.eclipse.jgit.internal.storage.pack.PackOutputStream;
  
  /**
   * A window for accessing git packs using a {@link ByteBuffer} for storage.
   *
   * @see ByteWindow
   */
  final class ByteBufferWindow extends ByteWindow {
  	private final ByteBuffer buffer;
  
  	ByteBufferWindow(PackFile pack, long o, ByteBuffer b) {
  		super(pack, o, b.capacity());
  		buffer = b;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	protected int copy(int p, byte[] b, int o, int n) {
  		final ByteBuffer s = buffer.slice();
  		s.position(p);
  		n = Math.min(s.remaining(), n);
  		s.get(b, o, n);
  		return n;
  	}
  
  	@Override
  	void write(PackOutputStream out, long pos, int cnt)
  			throws IOException {
  		final ByteBuffer s = buffer.slice();
  		s.position((int) (pos - start));
  
  		while (0 < cnt) {
  			byte[] buf = out.getCopyBuffer();
  			int n = Math.min(cnt, buf.length);
  			s.get(buf, 0, n);
  			out.write(buf, 0, n);
  			cnt -= n;
  		}
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	protected int setInput(int pos, Inflater inf)
  			throws DataFormatException {
  		final ByteBuffer s = buffer.slice();
  		s.position(pos);
  		final byte[] tmp = new byte[Math.min(s.remaining(), 512)];
  		s.get(tmp, 0, tmp.length);
  		inf.setInput(tmp, 0, tmp.length);
  		return tmp.length;
  	}
  }