/*
 * Copyright (C) 2008-2011, Google Inc.
 * Copyright (C) 2007-2008, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
 * 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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.nio.file.StandardCopyOption;
import java.security.MessageDigest;
import java.text.MessageFormat;
import java.util.Arrays;
import java.util.List;
import java.util.zip.CRC32;
import java.util.zip.Deflater;

import org.eclipse.jgit.errors.LockFailedException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.CoreConfig;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.storage.pack.PackConfig;
import org.eclipse.jgit.transport.PackParser;
import org.eclipse.jgit.transport.PackedObjectInfo;
import org.eclipse.jgit.util.FileUtils;
import org.eclipse.jgit.util.NB;

Consumes a pack stream and stores as a pack file in ObjectDirectory. 
 To obtain an instance of a parser, applications should use ObjectInserter.newPackParser(InputStream). /**
 * Consumes a pack stream and stores as a pack file in
 * {@link org.eclipse.jgit.internal.storage.file.ObjectDirectory}.
 * <p>
 * To obtain an instance of a parser, applications should use
 * {@link org.eclipse.jgit.lib.ObjectInserter#newPackParser(InputStream)}.
 */
public class ObjectDirectoryPackParser extends PackParser {
	private final FileObjectDatabase db;

	
CRC-32 computation for objects that are appended onto the pack. /** CRC-32 computation for objects that are appended onto the pack. */
	private final CRC32 crc;

	
Running SHA-1 of any base objects appended after origEnd. /** Running SHA-1 of any base objects appended after {@link #origEnd}. */
	private final MessageDigest tailDigest;

	
Preferred format version of the pack-*.idx file to generate. /** Preferred format version of the pack-*.idx file to generate. */
	private int indexVersion;

	
If true, pack with 0 objects will be stored. Usually these are deleted. /** If true, pack with 0 objects will be stored. Usually these are deleted. */
	private boolean keepEmpty;

	
Path of the temporary file holding the pack data. /** Path of the temporary file holding the pack data. */
	private File tmpPack;

	
Path of the index created for the pack, to find objects quickly at read
time.
/**
	 * Path of the index created for the pack, to find objects quickly at read
	 * time.
	 */
	private File tmpIdx;

	
Read/write handle to tmpPack while it is being parsed. /** Read/write handle to {@link #tmpPack} while it is being parsed. */
	private RandomAccessFile out;

	
Length of the original pack stream, before missing bases were appended. /** Length of the original pack stream, before missing bases were appended. */
	private long origEnd;

	
The original checksum of data up to origEnd. /** The original checksum of data up to {@link #origEnd}. */
	private byte[] origHash;

	
Current end of the pack file. /** Current end of the pack file. */
	private long packEnd;

	
Checksum of the entire pack file. /** Checksum of the entire pack file. */
	private byte[] packHash;

	
Compresses delta bases when completing a thin pack. /** Compresses delta bases when completing a thin pack. */
	private Deflater def;

	
The pack that was created, if parsing was successful. /** The pack that was created, if parsing was successful. */
	private PackFile newPack;

	private PackConfig pconfig;

	ObjectDirectoryPackParser(FileObjectDatabase odb, InputStream src) {
		super(odb, src);
		this.db = odb;
		this.pconfig = new PackConfig(odb.getConfig());
		this.crc = new CRC32();
		this.tailDigest = Constants.newMessageDigest();

		indexVersion = db.getConfig().get(CoreConfig.KEY).getPackIndexVersion();
	}

	
Set the pack index file format version this instance will create.
Params:
version – 
           the version to write. The special version 0 designates the
           oldest (most compatible) format available for the objects.
See Also:
PackIndexWriter/**
	 * Set the pack index file format version this instance will create.
	 *
	 * @param version
	 *            the version to write. The special version 0 designates the
	 *            oldest (most compatible) format available for the objects.
	 * @see PackIndexWriter
	 */
	public void setIndexVersion(int version) {
		indexVersion = version;
	}

	
Configure this index pack instance to keep an empty pack.

By default an empty pack (a pack with no objects) is not kept, as doi so
is completely pointless. With no objects in the pack there is no d stored
by it, so the pack is unnecessary.
Params:
empty – 
           true to enable keeping an empty pack./**
	 * Configure this index pack instance to keep an empty pack.
	 * <p>
	 * By default an empty pack (a pack with no objects) is not kept, as doi so
	 * is completely pointless. With no objects in the pack there is no d stored
	 * by it, so the pack is unnecessary.
	 *
	 * @param empty
	 *            true to enable keeping an empty pack.
	 */
	public void setKeepEmpty(boolean empty) {
		keepEmpty = empty;
	}

	
Get the imported PackFile. 

This method is supplied only to support testing; applications shouldn't
be using it directly to access the imported data.
Returns:
the imported PackFile, if parsing was successful./**
	 * Get the imported {@link org.eclipse.jgit.internal.storage.file.PackFile}.
	 * <p>
	 * This method is supplied only to support testing; applications shouldn't
	 * be using it directly to access the imported data.
	 *
	 * @return the imported PackFile, if parsing was successful.
	 */
	public PackFile getPackFile() {
		return newPack;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public long getPackSize() {
		if (newPack == null)
			return super.getPackSize();

		File pack = newPack.getPackFile();
		long size = pack.length();
		String p = pack.getAbsolutePath();
		String i = p.substring(0, p.length() - ".pack".length()) + ".idx"; //$NON-NLS-1$ //$NON-NLS-2$
		File idx = new File(i);
		if (idx.exists() && idx.isFile())
			size += idx.length();
		return size;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public PackLock parse(ProgressMonitor receiving, ProgressMonitor resolving)
			throws IOException {
		tmpPack = File.createTempFile("incoming_", ".pack", db.getDirectory()); //$NON-NLS-1$ //$NON-NLS-2$
		tmpIdx = new File(db.getDirectory(), baseName(tmpPack) + ".idx"); //$NON-NLS-1$
		try {
			out = new RandomAccessFile(tmpPack, "rw"); //$NON-NLS-1$

			super.parse(receiving, resolving);

			out.seek(packEnd);
			out.write(packHash);
			out.getChannel().force(true);
			out.close();

			writeIdx();

			tmpPack.setReadOnly();
			tmpIdx.setReadOnly();

			return renameAndOpenPack(getLockMessage());
		} finally {
			if (def != null)
				def.end();
			try {
				if (out != null && out.getChannel().isOpen())
					out.close();
			} catch (IOException closeError) {
				// Ignored. We want to delete the file.
			}
			cleanupTemporaryFiles();
		}
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onPackHeader(long objectCount) throws IOException {
		// Ignored, the count is not required.
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onBeginWholeObject(long streamPosition, int type,
			long inflatedSize) throws IOException {
		crc.reset();
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onEndWholeObject(PackedObjectInfo info) throws IOException {
		info.setCRC((int) crc.getValue());
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onBeginOfsDelta(long streamPosition,
			long baseStreamPosition, long inflatedSize) throws IOException {
		crc.reset();
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onBeginRefDelta(long streamPosition, AnyObjectId baseId,
			long inflatedSize) throws IOException {
		crc.reset();
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected UnresolvedDelta onEndDelta() throws IOException {
		UnresolvedDelta delta = new UnresolvedDelta();
		delta.setCRC((int) crc.getValue());
		return delta;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onInflatedObjectData(PackedObjectInfo obj, int typeCode,
			byte[] data) throws IOException {
		// ObjectDirectory ignores this event.
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onObjectHeader(Source src, byte[] raw, int pos, int len)
			throws IOException {
		crc.update(raw, pos, len);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onObjectData(Source src, byte[] raw, int pos, int len)
			throws IOException {
		crc.update(raw, pos, len);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onStoreStream(byte[] raw, int pos, int len)
			throws IOException {
		out.write(raw, pos, len);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onPackFooter(byte[] hash) throws IOException {
		packEnd = out.getFilePointer();
		origEnd = packEnd;
		origHash = hash;
		packHash = hash;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected ObjectTypeAndSize seekDatabase(UnresolvedDelta delta,
			ObjectTypeAndSize info) throws IOException {
		out.seek(delta.getOffset());
		crc.reset();
		return readObjectHeader(info);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected ObjectTypeAndSize seekDatabase(PackedObjectInfo obj,
			ObjectTypeAndSize info) throws IOException {
		out.seek(obj.getOffset());
		crc.reset();
		return readObjectHeader(info);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected int readDatabase(byte[] dst, int pos, int cnt) throws IOException {
		return out.read(dst, pos, cnt);
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected boolean checkCRC(int oldCRC) {
		return oldCRC == (int) crc.getValue();
	}

	private static String baseName(File tmpPack) {
		String name = tmpPack.getName();
		return name.substring(0, name.lastIndexOf('.'));
	}

	private void cleanupTemporaryFiles() {
		if (tmpIdx != null && !tmpIdx.delete() && tmpIdx.exists())
			tmpIdx.deleteOnExit();
		if (tmpPack != null && !tmpPack.delete() && tmpPack.exists())
			tmpPack.deleteOnExit();
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected boolean onAppendBase(final int typeCode, final byte[] data,
			final PackedObjectInfo info) throws IOException {
		info.setOffset(packEnd);

		final byte[] buf = buffer();
		int sz = data.length;
		int len = 0;
		buf[len++] = (byte) ((typeCode << 4) | (sz & 15));
		sz >>>= 4;
		while (sz > 0) {
			buf[len - 1] |= (byte) 0x80;
			buf[len++] = (byte) (sz & 0x7f);
			sz >>>= 7;
		}

		tailDigest.update(buf, 0, len);
		crc.reset();
		crc.update(buf, 0, len);
		out.seek(packEnd);
		out.write(buf, 0, len);
		packEnd += len;

		if (def == null)
			def = new Deflater(Deflater.DEFAULT_COMPRESSION, false);
		else
			def.reset();
		def.setInput(data);
		def.finish();

		while (!def.finished()) {
			len = def.deflate(buf);
			tailDigest.update(buf, 0, len);
			crc.update(buf, 0, len);
			out.write(buf, 0, len);
			packEnd += len;
		}

		info.setCRC((int) crc.getValue());
		return true;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	protected void onEndThinPack() throws IOException {
		final byte[] buf = buffer();

		final MessageDigest origDigest = Constants.newMessageDigest();
		final MessageDigest tailDigest2 = Constants.newMessageDigest();
		final MessageDigest packDigest = Constants.newMessageDigest();

		long origRemaining = origEnd;
		out.seek(0);
		out.readFully(buf, 0, 12);
		origDigest.update(buf, 0, 12);
		origRemaining -= 12;

		NB.encodeInt32(buf, 8, getObjectCount());
		out.seek(0);
		out.write(buf, 0, 12);
		packDigest.update(buf, 0, 12);

		for (;;) {
			final int n = out.read(buf);
			if (n < 0)
				break;
			if (origRemaining != 0) {
				final int origCnt = (int) Math.min(n, origRemaining);
				origDigest.update(buf, 0, origCnt);
				origRemaining -= origCnt;
				if (origRemaining == 0)
					tailDigest2.update(buf, origCnt, n - origCnt);
			} else
				tailDigest2.update(buf, 0, n);

			packDigest.update(buf, 0, n);
		}

		if (!Arrays.equals(origDigest.digest(), origHash) || !Arrays
				.equals(tailDigest2.digest(), this.tailDigest.digest()))
			throw new IOException(
					JGitText.get().packCorruptedWhileWritingToFilesystem);

		packHash = packDigest.digest();
	}

	private void writeIdx() throws IOException {
		List<PackedObjectInfo> list = getSortedObjectList(null /* by ObjectId */);
		try (FileOutputStream os = new FileOutputStream(tmpIdx)) {
			final PackIndexWriter iw;
			if (indexVersion <= 0)
				iw = PackIndexWriter.createOldestPossible(os, list);
			else
				iw = PackIndexWriter.createVersion(os, indexVersion);
			iw.write(list, packHash);
			os.getChannel().force(true);
		}
	}

	private PackLock renameAndOpenPack(String lockMessage)
			throws IOException {
		if (!keepEmpty && getObjectCount() == 0) {
			cleanupTemporaryFiles();
			return null;
		}

		final MessageDigest d = Constants.newMessageDigest();
		final byte[] oeBytes = new byte[Constants.OBJECT_ID_LENGTH];
		for (int i = 0; i < getObjectCount(); i++) {
			final PackedObjectInfo oe = getObject(i);
			oe.copyRawTo(oeBytes, 0);
			d.update(oeBytes);
		}

		final String name = ObjectId.fromRaw(d.digest()).name();
		final File packDir = new File(db.getDirectory(), "pack"); //$NON-NLS-1$
		final File finalPack = new File(packDir, "pack-" + name + ".pack"); //$NON-NLS-1$ //$NON-NLS-2$
		final File finalIdx = new File(packDir, "pack-" + name + ".idx"); //$NON-NLS-1$ //$NON-NLS-2$
		final PackLock keep = new PackLock(finalPack, db.getFS());

		if (!packDir.exists() && !packDir.mkdir() && !packDir.exists()) {
			// The objects/pack directory isn't present, and we are unable
			// to create it. There is no way to move this pack in.
			//
			cleanupTemporaryFiles();
			throw new IOException(MessageFormat.format(
					JGitText.get().cannotCreateDirectory, packDir
							.getAbsolutePath()));
		}

		if (finalPack.exists()) {
			// If the pack is already present we should never replace it.
			//
			cleanupTemporaryFiles();
			return null;
		}

		if (lockMessage != null) {
			// If we have a reason to create a keep file for this pack, do
			// so, or fail fast and don't put the pack in place.
			//
			try {
				if (!keep.lock(lockMessage))
					throw new LockFailedException(finalPack,
							MessageFormat.format(
									JGitText.get().cannotLockPackIn, finalPack));
			} catch (IOException e) {
				cleanupTemporaryFiles();
				throw e;
			}
		}

		try {
			FileUtils.rename(tmpPack, finalPack,
					StandardCopyOption.ATOMIC_MOVE);
		} catch (IOException e) {
			cleanupTemporaryFiles();
			keep.unlock();
			throw new IOException(MessageFormat.format(
					JGitText.get().cannotMovePackTo, finalPack), e);
		}

		try {
			FileUtils.rename(tmpIdx, finalIdx, StandardCopyOption.ATOMIC_MOVE);
		} catch (IOException e) {
			cleanupTemporaryFiles();
			keep.unlock();
			if (!finalPack.delete())
				finalPack.deleteOnExit();
			throw new IOException(MessageFormat.format(
					JGitText.get().cannotMoveIndexTo, finalIdx), e);
		}

		boolean interrupted = false;
		try {
			FileSnapshot snapshot = FileSnapshot.save(finalPack);
			if (pconfig.doWaitPreventRacyPack(snapshot.size())) {
				snapshot.waitUntilNotRacy();
			}
		} catch (InterruptedException e) {
			interrupted = true;
		}
		try {
			newPack = db.openPack(finalPack);
		} catch (IOException err) {
			keep.unlock();
			if (finalPack.exists())
				FileUtils.delete(finalPack);
			if (finalIdx.exists())
				FileUtils.delete(finalIdx);
			throw err;
		} finally {
			if (interrupted) {
				// Re-set interrupted flag
				Thread.currentThread().interrupt();
			}
		}

		return lockMessage != null ? keep : null;
	}
}