/*
    * Copyright (C) 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.io.OutputStream;
  
  import org.eclipse.jgit.transport.PackedObjectInfo;
  import org.eclipse.jgit.util.NB;
  
  /**
   * Creates the version 2 pack table of contents files.
   *
   * @see PackIndexWriter
   * @see PackIndexV2
   */
  class PackIndexWriterV2 extends PackIndexWriter {
  	private static final int MAX_OFFSET_32 = 0x7fffffff;
  	private static final int IS_OFFSET_64 = 0x80000000;
  
  	PackIndexWriterV2(final OutputStream dst) {
  		super(dst);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	protected void writeImpl() throws IOException {
  		writeTOC(2);
  		writeFanOutTable();
  		writeObjectNames();
  		writeCRCs();
  		writeOffset32();
  		writeOffset64();
  		writeChecksumFooter();
  	}
  
  	private void writeObjectNames() throws IOException {
  		for (PackedObjectInfo oe : entries)
  			oe.copyRawTo(out);
  	}
  
  	private void writeCRCs() throws IOException {
  		for (PackedObjectInfo oe : entries) {
  			NB.encodeInt32(tmp, 0, oe.getCRC());
  			out.write(tmp, 0, 4);
  		}
  	}
  
  	private void writeOffset32() throws IOException {
  		int o64 = 0;
  		for (PackedObjectInfo oe : entries) {
  			final long o = oe.getOffset();
  			if (o <= MAX_OFFSET_32)
  				NB.encodeInt32(tmp, 0, (int) o);
  			else
  				NB.encodeInt32(tmp, 0, IS_OFFSET_64 | o64++);
  			out.write(tmp, 0, 4);
  		}
  	}
  
  	private void writeOffset64() throws IOException {
  		for (PackedObjectInfo oe : entries) {
  			final long o = oe.getOffset();
  			if (MAX_OFFSET_32 < o) {
  				NB.encodeInt64(tmp, 0, o);
  				out.write(tmp, 0, 8);
  			}
  		}
  	}
  }