/*
    * Copyright (C) 2010, Google Inc. 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.dfs;
  
  import java.io.BufferedInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.zip.InflaterInputStream;
  
  import org.eclipse.jgit.errors.LargeObjectException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectLoader;
  import org.eclipse.jgit.lib.ObjectStream;
  
  final class LargePackedWholeObject extends ObjectLoader {
  	private final int type;
  
  	private final long size;
  
  	private final long objectOffset;
  
  	private final int headerLength;
  
  	private final DfsPackFile pack;
  
  	private final DfsObjDatabase db;
  
  	LargePackedWholeObject(int type, long size, long objectOffset,
  			int headerLength, DfsPackFile pack, DfsObjDatabase db) {
  		this.type = type;
  		this.size = size;
  		this.objectOffset = objectOffset;
  		this.headerLength = headerLength;
  		this.pack = pack;
  		this.db = db;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public int getType() {
  		return type;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public long getSize() {
  		return size;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public boolean isLarge() {
  		return true;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public byte[] getCachedBytes() throws LargeObjectException {
  		throw new LargeObjectException();
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public ObjectStream openStream() throws MissingObjectException, IOException {
  		PackInputStream packIn;
  		// ctx is closed by PackInputStream, or explicitly in the finally block
  		@SuppressWarnings("resource")
  		DfsReader ctx = db.newReader();
  		try {
  			try {
  				packIn = new PackInputStream(
  						pack, objectOffset + headerLength, ctx);
  				ctx = null; // owned by packIn
  			} catch (IOException packGone) {
  				// If the pack file cannot be pinned into the cursor, it
  				// probably was repacked recently. Go find the object
  				// again and open the stream from that location instead.
  				ObjectId obj = pack.getReverseIdx(ctx).findObject(objectOffset);
  				return ctx.open(obj, type).openStream();
  			}
  		} finally {
  			if (ctx != null) {
  				ctx.close();
  			}
  		}
  
  		// Align buffer to inflater size, at a larger than default block.
  		// This reduces the number of context switches from the
  		// caller down into the pack stream inflation.
  		int bufsz = 8192;
 		InputStream in = new BufferedInputStream(
 				new InflaterInputStream(packIn, packIn.ctx.inflater(), bufsz),
 				bufsz);
 		return new ObjectStream.Filter(type, size, in);
 	}
 }