/*
    * Copyright (C) 2017, 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 static java.nio.file.StandardCopyOption.ATOMIC_MOVE;
  import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH;
  import static org.eclipse.jgit.lib.Constants.OBJ_OFS_DELTA;
  import static org.eclipse.jgit.lib.Constants.OBJ_REF_DELTA;
  
  import java.io.BufferedInputStream;
  import java.io.EOFException;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.FilterInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.RandomAccessFile;
  import java.nio.channels.Channels;
  import java.text.MessageFormat;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.zip.CRC32;
  import java.util.zip.DataFormatException;
  import java.util.zip.Deflater;
  import java.util.zip.DeflaterOutputStream;
  import java.util.zip.Inflater;
  import java.util.zip.InflaterInputStream;
  
  import org.eclipse.jgit.errors.CorruptObjectException;
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.LargeObjectException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AbbreviatedObjectId;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.InflaterCache;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdOwnerMap;
  import org.eclipse.jgit.lib.ObjectInserter;
  import org.eclipse.jgit.lib.ObjectLoader;
  import org.eclipse.jgit.lib.ObjectReader;
  import org.eclipse.jgit.lib.ObjectStream;
  import org.eclipse.jgit.transport.PackParser;
  import org.eclipse.jgit.transport.PackedObjectInfo;
  import org.eclipse.jgit.util.BlockList;
  import org.eclipse.jgit.util.FileUtils;
  import org.eclipse.jgit.util.IO;
  import org.eclipse.jgit.util.NB;
  import org.eclipse.jgit.util.io.CountingOutputStream;
  import org.eclipse.jgit.util.sha1.SHA1;
  
  /**
   * Object inserter that inserts one pack per call to {@link #flush()}, and never
  * inserts loose objects.
  */
 public class PackInserter extends ObjectInserter {
 	/** Always produce version 2 indexes, to get CRC data. */
 	private static final int INDEX_VERSION = 2;
 
 	private final ObjectDirectory db;
 
 	private List<PackedObjectInfo> objectList;
 	private ObjectIdOwnerMap<PackedObjectInfo> objectMap;
 	private boolean rollback;
 	private boolean checkExisting = true;
 
 	private int compression = Deflater.BEST_COMPRESSION;
 	private File tmpPack;
 	private PackStream packOut;
 	private Inflater cachedInflater;
 
 	PackInserter(ObjectDirectory db) {
 		this.db = db;
 	}
 
 	/**
 	 * Whether to check if objects exist in the repo
 	 *
 	 * @param check
 	 *            if {@code false}, will write out possibly-duplicate objects
 	 *            without first checking whether they exist in the repo; default
 	 *            is true.
 	 */
 	public void checkExisting(boolean check) {
 		checkExisting = check;
 	}
 
 	/**
 	 * Set compression level for zlib deflater.
 	 *
 	 * @param compression
 	 *            compression level for zlib deflater.
 	 */
 	public void setCompressionLevel(int compression) {
 		this.compression = compression;
 	}
 
 	int getBufferSize() {
 		return buffer().length;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public ObjectId insert(int type, byte[] data, int off, int len)
 			throws IOException {
 		ObjectId id = idFor(type, data, off, len);
 		if (objectMap != null && objectMap.contains(id)) {
 			return id;
 		}
 		// Ignore loose objects, which are potentially unreachable.
 		if (checkExisting && db.hasPackedObject(id)) {
 			return id;
 		}
 
 		long offset = beginObject(type, len);
 		packOut.compress.write(data, off, len);
 		packOut.compress.finish();
 		return endObject(id, offset);
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public ObjectId insert(int type, long len, InputStream in)
 			throws IOException {
 		byte[] buf = buffer();
 		if (len <= buf.length) {
 			IO.readFully(in, buf, 0, (int) len);
 			return insert(type, buf, 0, (int) len);
 		}
 
 		long offset = beginObject(type, len);
 		SHA1 md = digest();
 		md.update(Constants.encodedTypeString(type));
 		md.update((byte) ' ');
 		md.update(Constants.encodeASCII(len));
 		md.update((byte) 0);
 
 		while (0 < len) {
 			int n = in.read(buf, 0, (int) Math.min(buf.length, len));
 			if (n <= 0) {
 				throw new EOFException();
 			}
 			md.update(buf, 0, n);
 			packOut.compress.write(buf, 0, n);
 			len -= n;
 		}
 		packOut.compress.finish();
 		return endObject(md.toObjectId(), offset);
 	}
 
 	private long beginObject(int type, long len) throws IOException {
 		if (packOut == null) {
 			beginPack();
 		}
 		long offset = packOut.getOffset();
 		packOut.beginObject(type, len);
 		return offset;
 	}
 
 	private ObjectId endObject(ObjectId id, long offset) {
 		PackedObjectInfo obj = new PackedObjectInfo(id);
 		obj.setOffset(offset);
 		obj.setCRC((int) packOut.crc32.getValue());
 		objectList.add(obj);
 		objectMap.addIfAbsent(obj);
 		return id;
 	}
 
 	private static File idxFor(File packFile) {
 		String p = packFile.getName();
 		return new File(
 				packFile.getParentFile(),
 				p.substring(0, p.lastIndexOf('.')) + ".idx"); //$NON-NLS-1$
 	}
 
 	private void beginPack() throws IOException {
 		objectList = new BlockList<>();
 		objectMap = new ObjectIdOwnerMap<>();
 
 		rollback = true;
 		tmpPack = File.createTempFile("insert_", ".pack", db.getDirectory()); //$NON-NLS-1$ //$NON-NLS-2$
 		packOut = new PackStream(tmpPack);
 
 		// Write the header as though it were a single object pack.
 		packOut.write(packOut.hdrBuf, 0, writePackHeader(packOut.hdrBuf, 1));
 	}
 
 	private static int writePackHeader(byte[] buf, int objectCount) {
 		System.arraycopy(Constants.PACK_SIGNATURE, 0, buf, 0, 4);
 		NB.encodeInt32(buf, 4, 2); // Always use pack version 2.
 		NB.encodeInt32(buf, 8, objectCount);
 		return 12;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public PackParser newPackParser(InputStream in) {
 		throw new UnsupportedOperationException();
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public ObjectReader newReader() {
 		return new Reader();
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void flush() throws IOException {
 		if (tmpPack == null) {
 			return;
 		}
 
 		if (packOut == null) {
 			throw new IOException();
 		}
 
 		byte[] packHash;
 		try {
 			packHash = packOut.finishPack();
 		} finally {
 			packOut = null;
 		}
 
 		Collections.sort(objectList);
 		File tmpIdx = idxFor(tmpPack);
 		writePackIndex(tmpIdx, packHash, objectList);
 
 		File realPack = new File(db.getPackDirectory(),
 				"pack-" + computeName(objectList).name() + ".pack"); //$NON-NLS-1$ //$NON-NLS-2$
 		db.closeAllPackHandles(realPack);
 		tmpPack.setReadOnly();
 		FileUtils.rename(tmpPack, realPack, ATOMIC_MOVE);
 
 		File realIdx = idxFor(realPack);
 		tmpIdx.setReadOnly();
 		try {
 			FileUtils.rename(tmpIdx, realIdx, ATOMIC_MOVE);
 		} catch (IOException e) {
 			File newIdx = new File(
 					realIdx.getParentFile(), realIdx.getName() + ".new"); //$NON-NLS-1$
 			try {
 				FileUtils.rename(tmpIdx, newIdx, ATOMIC_MOVE);
 			} catch (IOException e2) {
 				newIdx = tmpIdx;
 				e = e2;
 			}
 			throw new IOException(MessageFormat.format(
 					JGitText.get().panicCantRenameIndexFile, newIdx,
 					realIdx), e);
 		}
 
 		db.openPack(realPack);
 		rollback = false;
 		clear();
 	}
 
 	private static void writePackIndex(File idx, byte[] packHash,
 			List<PackedObjectInfo> list) throws IOException {
 		try (OutputStream os = new FileOutputStream(idx)) {
 			PackIndexWriter w = PackIndexWriter.createVersion(os, INDEX_VERSION);
 			w.write(list, packHash);
 		}
 	}
 
 	private ObjectId computeName(List<PackedObjectInfo> list) {
 		SHA1 md = digest().reset();
 		byte[] buf = buffer();
 		for (PackedObjectInfo otp : list) {
 			otp.copyRawTo(buf, 0);
 			md.update(buf, 0, OBJECT_ID_LENGTH);
 		}
 		return ObjectId.fromRaw(md.digest());
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void close() {
 		try {
 			if (packOut != null) {
 				try {
 					packOut.close();
 				} catch (IOException err) {
 					// Ignore a close failure, the pack should be removed.
 				}
 			}
 			if (rollback && tmpPack != null) {
 				try {
 					FileUtils.delete(tmpPack);
 				} catch (IOException e) {
 					// Still delete idx.
 				}
 				try {
 					FileUtils.delete(idxFor(tmpPack));
 				} catch (IOException e) {
 					// Ignore error deleting temp idx.
 				}
 				rollback = false;
 			}
 		} finally {
 			clear();
 			try {
 				InflaterCache.release(cachedInflater);
 			} finally {
 				cachedInflater = null;
 			}
 		}
 	}
 
 	private void clear() {
 		objectList = null;
 		objectMap = null;
 		tmpPack = null;
 		packOut = null;
 	}
 
 	private Inflater inflater() {
 		if (cachedInflater == null) {
 			cachedInflater = InflaterCache.get();
 		} else {
 			cachedInflater.reset();
 		}
 		return cachedInflater;
 	}
 
 	/**
 	 * Stream that writes to a pack file.
 	 * <p>
 	 * Backed by two views of the same open file descriptor: a random-access file,
 	 * and an output stream. Seeking in the file causes subsequent writes to the
 	 * output stream to occur wherever the file pointer is pointing, so we need to
 	 * take care to always seek to the end of the file before writing a new
 	 * object.
 	 * <p>
 	 * Callers should always use {@link #seek(long)} to seek, rather than reaching
 	 * into the file member. As long as this contract is followed, calls to {@link
 	 * #write(byte[], int, int)} are guaranteed to write at the end of the file,
 	 * even if there have been intermediate seeks.
 	 */
 	private class PackStream extends OutputStream {
 		final byte[] hdrBuf;
 		final CRC32 crc32;
 		final DeflaterOutputStream compress;
 
 		private final RandomAccessFile file;
 		private final CountingOutputStream out;
 		private final Deflater deflater;
 
 		private boolean atEnd;
 
 		PackStream(File pack) throws IOException {
 			file = new RandomAccessFile(pack, "rw"); //$NON-NLS-1$
 			out = new CountingOutputStream(new FileOutputStream(file.getFD()));
 			deflater = new Deflater(compression);
 			compress = new DeflaterOutputStream(this, deflater, 8192);
 			hdrBuf = new byte[32];
 			crc32 = new CRC32();
 			atEnd = true;
 		}
 
 		long getOffset() {
 			// This value is accurate as long as we only ever write to the end of the
 			// file, and don't seek back to overwrite any previous segments. Although
 			// this is subtle, storing the stream counter this way is still preferable
 			// to returning file.length() here, as it avoids a syscall and possible
 			// IOException.
 			return out.getCount();
 		}
 
 		void seek(long offset) throws IOException {
 			file.seek(offset);
 			atEnd = false;
 		}
 
 		void beginObject(int objectType, long length) throws IOException {
 			crc32.reset();
 			deflater.reset();
 			write(hdrBuf, 0, encodeTypeSize(objectType, length));
 		}
 
 		private int encodeTypeSize(int type, long rawLength) {
 			long nextLength = rawLength >>> 4;
 			hdrBuf[0] = (byte) ((nextLength > 0 ? 0x80 : 0x00) | (type << 4) | (rawLength & 0x0F));
 			rawLength = nextLength;
 			int n = 1;
 			while (rawLength > 0) {
 				nextLength >>>= 7;
 				hdrBuf[n++] = (byte) ((nextLength > 0 ? 0x80 : 0x00) | (rawLength & 0x7F));
 				rawLength = nextLength;
 			}
 			return n;
 		}
 
 		@Override
 		public void write(int b) throws IOException {
 			hdrBuf[0] = (byte) b;
 			write(hdrBuf, 0, 1);
 		}
 
 		@Override
 		public void write(byte[] data, int off, int len) throws IOException {
 			crc32.update(data, off, len);
 			if (!atEnd) {
 				file.seek(file.length());
 				atEnd = true;
 			}
 			out.write(data, off, len);
 		}
 
 		byte[] finishPack() throws IOException {
 			// Overwrite placeholder header with actual object count, then hash. This
 			// method intentionally uses direct seek/write calls rather than the
 			// wrappers which keep track of atEnd. This leaves atEnd, the file
 			// pointer, and out's counter in an inconsistent state; that's ok, since
 			// this method closes the file anyway.
 			try {
 				file.seek(0);
 				out.write(hdrBuf, 0, writePackHeader(hdrBuf, objectList.size()));
 
 				byte[] buf = buffer();
 				SHA1 md = digest().reset();
 				file.seek(0);
 				while (true) {
 					int r = file.read(buf);
 					if (r < 0) {
 						break;
 					}
 					md.update(buf, 0, r);
 				}
 				byte[] packHash = md.digest();
 				out.write(packHash, 0, packHash.length);
 				return packHash;
 			} finally {
 				close();
 			}
 		}
 
 		@Override
 		public void close() throws IOException {
 			deflater.end();
 			try {
 				out.close();
 			} finally {
 				file.close();
 			}
 		}
 
 		byte[] inflate(long filePos, int len) throws IOException, DataFormatException {
 			byte[] dstbuf;
 			try {
 				dstbuf = new byte[len];
 			} catch (OutOfMemoryError noMemory) {
 				return null; // Caller will switch to large object streaming.
 			}
 
 			byte[] srcbuf = buffer();
 			Inflater inf = inflater();
 			filePos += setInput(filePos, inf, srcbuf);
 			for (int dstoff = 0;;) {
 				int n = inf.inflate(dstbuf, dstoff, dstbuf.length - dstoff);
 				dstoff += n;
 				if (inf.finished()) {
 					return dstbuf;
 				}
 				if (inf.needsInput()) {
 					filePos += setInput(filePos, inf, srcbuf);
 				} else if (n == 0) {
 					throw new DataFormatException();
 				}
 			}
 		}
 
 		private int setInput(long filePos, Inflater inf, byte[] buf)
 				throws IOException {
 			if (file.getFilePointer() != filePos) {
 				seek(filePos);
 			}
 			int n = file.read(buf);
 			if (n < 0) {
 				throw new EOFException(JGitText.get().unexpectedEofInPack);
 			}
 			inf.setInput(buf, 0, n);
 			return n;
 		}
 	}
 
 	private class Reader extends ObjectReader {
 		private final ObjectReader ctx;
 
 		private Reader() {
 			ctx = db.newReader();
 			setStreamFileThreshold(ctx.getStreamFileThreshold());
 		}
 
 		@Override
 		public ObjectReader newReader() {
 			return db.newReader();
 		}
 
 		@Override
 		public ObjectInserter getCreatedFromInserter() {
 			return PackInserter.this;
 		}
 
 		@Override
 		public Collection<ObjectId> resolve(AbbreviatedObjectId id)
 				throws IOException {
 			Collection<ObjectId> stored = ctx.resolve(id);
 			if (objectList == null) {
 				return stored;
 			}
 
 			Set<ObjectId> r = new HashSet<>(stored.size() + 2);
 			r.addAll(stored);
 			for (PackedObjectInfo obj : objectList) {
 				if (id.prefixCompare(obj) == 0) {
 					r.add(obj.copy());
 				}
 			}
 			return r;
 		}
 
 		@Override
 		public ObjectLoader open(AnyObjectId objectId, int typeHint)
 				throws MissingObjectException, IncorrectObjectTypeException,
 				IOException {
 			if (objectMap == null) {
 				return ctx.open(objectId, typeHint);
 			}
 
 			PackedObjectInfo obj = objectMap.get(objectId);
 			if (obj == null) {
 				return ctx.open(objectId, typeHint);
 			}
 
 			byte[] buf = buffer();
 			packOut.seek(obj.getOffset());
 			int cnt = packOut.file.read(buf, 0, 20);
 			if (cnt <= 0) {
 				throw new EOFException(JGitText.get().unexpectedEofInPack);
 			}
 
 			int c = buf[0] & 0xff;
 			int type = (c >> 4) & 7;
 			if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
 				throw new IOException(MessageFormat.format(
 						JGitText.get().cannotReadBackDelta, Integer.toString(type)));
 			}
 			if (typeHint != OBJ_ANY && type != typeHint) {
 				throw new IncorrectObjectTypeException(objectId.copy(), typeHint);
 			}
 
 			long sz = c & 0x0f;
 			int ptr = 1;
 			int shift = 4;
 			while ((c & 0x80) != 0) {
 				if (ptr >= cnt) {
 					throw new EOFException(JGitText.get().unexpectedEofInPack);
 				}
 				c = buf[ptr++] & 0xff;
 				sz += ((long) (c & 0x7f)) << shift;
 				shift += 7;
 			}
 
 			long zpos = obj.getOffset() + ptr;
 			if (sz < getStreamFileThreshold()) {
 				byte[] data = inflate(obj, zpos, (int) sz);
 				if (data != null) {
 					return new ObjectLoader.SmallObject(type, data);
 				}
 			}
 			return new StreamLoader(type, sz, zpos);
 		}
 
 		private byte[] inflate(PackedObjectInfo obj, long zpos, int sz)
 				throws IOException, CorruptObjectException {
 			try {
 				return packOut.inflate(zpos, sz);
 			} catch (DataFormatException dfe) {
 				throw new CorruptObjectException(
 						MessageFormat.format(
 								JGitText.get().objectAtHasBadZlibStream,
 								Long.valueOf(obj.getOffset()),
 								tmpPack.getAbsolutePath()),
 						dfe);
 			}
 		}
 
 		@Override
 		public Set<ObjectId> getShallowCommits() throws IOException {
 			return ctx.getShallowCommits();
 		}
 
 		@Override
 		public void close() {
 			ctx.close();
 		}
 
 		private class StreamLoader extends ObjectLoader {
 			private final int type;
 			private final long size;
 			private final long pos;
 
 			StreamLoader(int type, long size, long pos) {
 				this.type = type;
 				this.size = size;
 				this.pos = pos;
 			}
 
 			@Override
 			public ObjectStream openStream()
 					throws MissingObjectException, IOException {
 				int bufsz = buffer().length;
 				packOut.seek(pos);
 
 				InputStream fileStream = new FilterInputStream(
 						Channels.newInputStream(packOut.file.getChannel())) {
 							// atEnd was already set to false by the previous seek, but it's
 							// technically possible for a caller to call insert on the
 							// inserter in the middle of reading from this stream. Behavior is
 							// undefined in this case, so it would arguably be ok to ignore,
 							// but it's not hard to at least make an attempt to not corrupt
 							// the data.
 							@Override
 							public int read() throws IOException {
 								packOut.atEnd = false;
 								return super.read();
 							}
 
 							@Override
 							public int read(byte[] b) throws IOException {
 								packOut.atEnd = false;
 								return super.read(b);
 							}
 
 							@Override
 							public int read(byte[] b, int off, int len) throws IOException {
 								packOut.atEnd = false;
 								return super.read(b,off,len);
 							}
 
 							@Override
 							public void close() {
 								// Never close underlying RandomAccessFile, which lasts the
 								// lifetime of the enclosing PackStream.
 							}
 						};
 				return new ObjectStream.Filter(
 						type, size,
 						new BufferedInputStream(
 								new InflaterInputStream(fileStream, inflater(), bufsz), bufsz));
 			}
 
 			@Override
 			public int getType() {
 				return type;
 			}
 
 			@Override
 			public long getSize() {
 				return size;
 			}
 
 			@Override
 			public byte[] getCachedBytes() throws LargeObjectException {
 				throw new LargeObjectException.ExceedsLimit(
 						getStreamFileThreshold(), size);
 			}
 		}
 	}
 }