/*
    * 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.file;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  class PackInputStream extends InputStream {
  	private final WindowCursor wc;
  
  	private final PackFile pack;
  
  	private long pos;
  
  	PackInputStream(PackFile pack, long pos, WindowCursor wc)
  			throws IOException {
  		this.pack = pack;
  		this.pos = pos;
  		this.wc = wc;
  
  		// Pin the first window, to ensure the pack is open and valid.
  		//
  		wc.pin(pack, pos);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public int read(byte[] b, int off, int len) throws IOException {
  		int n = wc.copy(pack, pos, b, off, len);
  		pos += n;
  		return n;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public int read() throws IOException {
  		byte[] buf = new byte[1];
  		int n = read(buf, 0, 1);
  		return n == 1 ? buf[0] & 0xff : -1;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void close() {
  		wc.close();
  	}
  }