/*
 * Copyright (C) 2012, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.internal.storage.file;

import java.io.BufferedOutputStream;
import java.io.DataOutput;
import java.io.IOException;
import java.io.OutputStream;
import java.security.DigestOutputStream;
import java.text.MessageFormat;

import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.internal.storage.file.PackBitmapIndexBuilder.StoredEntry;
import org.eclipse.jgit.lib.Constants;

import com.googlecode.javaewah.EWAHCompressedBitmap;

Creates the version 1 pack bitmap index files.
See Also:
PackBitmapIndexV1/**
 * Creates the version 1 pack bitmap index files.
 *
 * @see PackBitmapIndexV1
 */
public class PackBitmapIndexWriterV1 {
	private final DigestOutputStream out;
	private final DataOutput dataOutput;

	
Creates the version 1 pack bitmap index files.
Params:
dst – 
           the output stream to which the index will be written./**
	 * Creates the version 1 pack bitmap index files.
	 *
	 * @param dst
	 *            the output stream to which the index will be written.
	 */
	public PackBitmapIndexWriterV1(final OutputStream dst) {
		out = new DigestOutputStream(dst instanceof BufferedOutputStream ? dst
				: new BufferedOutputStream(dst),
				Constants.newMessageDigest());
		dataOutput = new SimpleDataOutput(out);
	}

	
Write all object entries to the index stream.

After writing the stream passed to the factory is flushed but remains
open. Callers are always responsible for closing the output stream.
Params:
bitmaps – 
           the index data for the bitmaps
packDataChecksum – 
           checksum signature of the entire pack data content. This is
           traditionally the last 20 bytes of the pack file's own stream.
Throws:
IOException – 
            an error occurred while writing to the output stream, or this
            index format cannot store the object data supplied./**
	 * Write all object entries to the index stream.
	 * <p>
	 * After writing the stream passed to the factory is flushed but remains
	 * open. Callers are always responsible for closing the output stream.
	 *
	 * @param bitmaps
	 *            the index data for the bitmaps
	 * @param packDataChecksum
	 *            checksum signature of the entire pack data content. This is
	 *            traditionally the last 20 bytes of the pack file's own stream.
	 * @throws java.io.IOException
	 *             an error occurred while writing to the output stream, or this
	 *             index format cannot store the object data supplied.
	 */
	public void write(PackBitmapIndexBuilder bitmaps, byte[] packDataChecksum)
			throws IOException {
		if (bitmaps == null || packDataChecksum.length != 20)
			throw new IllegalStateException();

		writeHeader(bitmaps.getOptions(), bitmaps.getBitmapCount(),
				packDataChecksum);
		writeBody(bitmaps);
		writeFooter();

		out.flush();
	}

	private void writeHeader(
			int options, int bitmapCount, byte[] packDataChecksum)
			throws IOException {
		out.write(PackBitmapIndexV1.MAGIC);
		dataOutput.writeShort(1);
		dataOutput.writeShort(options);
		dataOutput.writeInt(bitmapCount);
		out.write(packDataChecksum);
	}

	private void writeBody(PackBitmapIndexBuilder bitmaps) throws IOException {
		writeBitmap(bitmaps.getCommits());
		writeBitmap(bitmaps.getTrees());
		writeBitmap(bitmaps.getBlobs());
		writeBitmap(bitmaps.getTags());
		writeBitmaps(bitmaps);
	}

	private void writeBitmap(EWAHCompressedBitmap bitmap) throws IOException {
		bitmap.serialize(dataOutput);
	}

	private void writeBitmaps(PackBitmapIndexBuilder bitmaps)
			throws IOException {
		int bitmapCount = 0;
		for (StoredEntry entry : bitmaps.getCompressedBitmaps()) {
			writeBitmapEntry(entry);
			bitmapCount++;
		}

		int expectedBitmapCount = bitmaps.getBitmapCount();
		if (expectedBitmapCount != bitmapCount)
			throw new IOException(MessageFormat.format(
					JGitText.get().expectedGot,
					String.valueOf(expectedBitmapCount),
					String.valueOf(bitmapCount)));
	}

	private void writeBitmapEntry(StoredEntry entry) throws IOException {
		// Write object, XOR offset, and bitmap
		dataOutput.writeInt((int) entry.getObjectId());
		out.write(entry.getXorOffset());
		out.write(entry.getFlags());
		writeBitmap(entry.getBitmap());
	}

	private void writeFooter() throws IOException {
		out.on(false);
		out.write(out.getMessageDigest().digest());
	}
}