/*
    * Copyright (C) 2011, 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,
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   * 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.dfs;
  
  import static org.eclipse.jgit.internal.storage.pack.PackExt.INDEX;
  import static org.eclipse.jgit.internal.storage.pack.PackExt.PACK;
  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.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.security.MessageDigest;
  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.LargeObjectException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.internal.storage.file.PackIndex;
  import org.eclipse.jgit.internal.storage.file.PackIndexWriter;
  import org.eclipse.jgit.internal.storage.pack.PackExt;
  import org.eclipse.jgit.lib.AbbreviatedObjectId;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  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.PackedObjectInfo;
  import org.eclipse.jgit.util.BlockList;
  import org.eclipse.jgit.util.IO;
  import org.eclipse.jgit.util.NB;
  import org.eclipse.jgit.util.TemporaryBuffer;
  import org.eclipse.jgit.util.io.CountingOutputStream;
  
  /** Inserts objects into the DFS. */
  public class DfsInserter extends ObjectInserter {
  	/** Always produce version 2 indexes, to get CRC data. */
  	private static final int INDEX_VERSION = 2;
  
  	private final DfsObjDatabase db;
  	private int compression = Deflater.BEST_COMPRESSION;
 
 	private List<PackedObjectInfo> objectList;
 	private ObjectIdOwnerMap<PackedObjectInfo> objectMap;
 
 	private DfsBlockCache cache;
 	private DfsPackKey packKey;
 	private DfsPackDescription packDsc;
 	private PackStream packOut;
 	private boolean rollback;
 
 	/**
 	 * Initialize a new inserter.
 	 *
 	 * @param db
 	 *            database the inserter writes to.
 	 */
 	protected DfsInserter(DfsObjDatabase db) {
 		this.db = db;
 	}
 
 	void setCompressionLevel(int compression) {
 		this.compression = compression;
 	}
 
 	@Override
 	public DfsPackParser newPackParser(InputStream in) throws IOException {
 		return new DfsPackParser(db, this, in);
 	}
 
 	@Override
 	public ObjectReader newReader() {
 		return new Reader();
 	}
 
 	@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;
 		if (db.has(id))
 			return id;
 
 		long offset = beginObject(type, len);
 		packOut.compress.write(data, off, len);
 		packOut.compress.finish();
 		return endObject(id, offset);
 	}
 
 	@Override
 	public ObjectId insert(int type, long len, InputStream in)
 			throws IOException {
 		byte[] buf = insertBuffer(len);
 		if (len <= buf.length) {
 			IO.readFully(in, buf, 0, (int) len);
 			return insert(type, buf, 0, (int) len);
 		}
 
 		long offset = beginObject(type, len);
 		MessageDigest 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(ObjectId.fromRaw(md.digest()), offset);
 	}
 
 	private byte[] insertBuffer(long len) {
 		byte[] buf = buffer();
 		if (len <= buf.length)
 			return buf;
 		if (len < db.getReaderOptions().getStreamFileThreshold()) {
 			try {
 				return new byte[(int) len];
 			} catch (OutOfMemoryError noMem) {
 				return buf;
 			}
 		}
 		return buf;
 	}
 
 	@Override
 	public void flush() throws IOException {
 		if (packDsc == null)
 			return;
 
 		if (packOut == null)
 			throw new IOException();
 
 		byte[] packHash = packOut.writePackFooter();
 		packDsc.addFileExt(PACK);
 		packDsc.setFileSize(PACK, packOut.getCount());
 		packOut.close();
 		packOut = null;
 
 		sortObjectsById();
 
 		PackIndex index = writePackIndex(packDsc, packHash, objectList);
 		db.commitPack(Collections.singletonList(packDsc), null);
 		rollback = false;
 
 		DfsPackFile p = cache.getOrCreate(packDsc, packKey);
 		if (index != null)
 			p.setPackIndex(index);
 		db.addPack(p);
 		clear();
 	}
 
 	@Override
 	public void close() {
 		if (packOut != null) {
 			try {
 				packOut.close();
 			} catch (IOException err) {
 				// Ignore a close failure, the pack should be removed.
 			} finally {
 				packOut = null;
 			}
 		}
 		if (rollback && packDsc != null) {
 			try {
 				db.rollbackPack(Collections.singletonList(packDsc));
 			} finally {
 				packDsc = null;
 				rollback = false;
 			}
 		}
 		clear();
 	}
 
 	private void clear() {
 		objectList = null;
 		objectMap = null;
 		packKey = null;
 		packDsc = null;
 	}
 
 	private long beginObject(int type, long len) throws IOException {
 		if (packOut == null)
 			beginPack();
 		long offset = packOut.getCount();
 		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 void beginPack() throws IOException {
 		objectList = new BlockList<PackedObjectInfo>();
 		objectMap = new ObjectIdOwnerMap<PackedObjectInfo>();
 		cache = DfsBlockCache.getInstance();
 
 		rollback = true;
 		packDsc = db.newPack(DfsObjDatabase.PackSource.INSERT);
 		packOut = new PackStream(db.writeFile(packDsc, PACK));
 		packKey = new DfsPackKey();
 
 		// Write the header as though it were a single object pack.
 		byte[] buf = packOut.hdrBuf;
 		System.arraycopy(Constants.PACK_SIGNATURE, 0, buf, 0, 4);
 		NB.encodeInt32(buf, 4, 2); // Always use pack version 2.
 		NB.encodeInt32(buf, 8, 1); // Always assume 1 object.
 		packOut.write(buf, 0, 12);
 	}
 
 	private void sortObjectsById() {
 		Collections.sort(objectList);
 	}
 
 	PackIndex writePackIndex(DfsPackDescription pack, byte[] packHash,
 			List<PackedObjectInfo> list) throws IOException {
 		pack.setIndexVersion(INDEX_VERSION);
 		pack.setObjectCount(list.size());
 
 		// If there are less than 58,000 objects, the entire index fits in under
 		// 2 MiB. Callers will probably need the index immediately, so buffer
 		// the index in process and load from the buffer.
 		TemporaryBuffer.Heap buf = null;
 		PackIndex packIndex = null;
 		if (list.size() <= 58000) {
 			buf = new TemporaryBuffer.Heap(2 << 20);
 			index(buf, packHash, list);
 			packIndex = PackIndex.read(buf.openInputStream());
 		}
 
 		DfsOutputStream os = db.writeFile(pack, INDEX);
 		try {
 			CountingOutputStream cnt = new CountingOutputStream(os);
 			if (buf != null)
 				buf.writeTo(cnt, null);
 			else
 				index(cnt, packHash, list);
 			pack.addFileExt(INDEX);
 			pack.setFileSize(INDEX, cnt.getCount());
 		} finally {
 			os.close();
 		}
 		return packIndex;
 	}
 
 	private static void index(OutputStream out, byte[] packHash,
 			List<PackedObjectInfo> list) throws IOException {
 		PackIndexWriter.createVersion(out, INDEX_VERSION).write(list, packHash);
 	}
 
 	private class PackStream extends OutputStream {
 		private final DfsOutputStream out;
 		private final MessageDigest md;
 		private final byte[] hdrBuf;
 		private final Deflater deflater;
 		private final int blockSize;
 
 		private long currPos; // Position of currBuf[0] in the output stream.
 		private int currPtr; // Number of bytes in currBuf.
 		private byte[] currBuf;
 
 		final CRC32 crc32;
 		final DeflaterOutputStream compress;
 
 		PackStream(DfsOutputStream out) {
 			this.out = out;
 
 			hdrBuf = new byte[32];
 			md = Constants.newMessageDigest();
 			crc32 = new CRC32();
 			deflater = new Deflater(compression);
 			compress = new DeflaterOutputStream(this, deflater, 8192);
 
 			int size = out.blockSize();
 			if (size <= 0)
 				size = cache.getBlockSize();
 			else if (size < cache.getBlockSize())
 				size = (cache.getBlockSize() / size) * size;
 			blockSize = size;
 			currBuf = new byte[blockSize];
 		}
 
 		long getCount() {
 			return currPos + currPtr;
 		}
 
 		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(final 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);
 			md.update(data, off, len);
 			writeNoHash(data, off, len);
 		}
 
 		private void writeNoHash(byte[] data, int off, int len)
 				throws IOException {
 			while (0 < len) {
 				int n = Math.min(len, currBuf.length - currPtr);
 				if (n == 0) {
 					flushBlock();
 					currBuf = new byte[blockSize];
 					continue;
 				}
 
 				System.arraycopy(data, off, currBuf, currPtr, n);
 				off += n;
 				len -= n;
 				currPtr += n;
 			}
 		}
 
 		private void flushBlock() throws IOException {
 			out.write(currBuf, 0, currPtr);
 
 			byte[] buf;
 			if (currPtr == currBuf.length)
 				buf = currBuf;
 			else
 				buf = copyOf(currBuf, 0, currPtr);
 			cache.put(new DfsBlock(packKey, currPos, buf));
 
 			currPos += currPtr;
 			currPtr = 0;
 			currBuf = null;
 		}
 
 		private byte[] copyOf(byte[] src, int ptr, int cnt) {
 			byte[] dst = new byte[cnt];
 			System.arraycopy(src, ptr, dst, 0, cnt);
 			return dst;
 		}
 
 		byte[] writePackFooter() throws IOException {
 			byte[] packHash = md.digest();
 			writeNoHash(packHash, 0, packHash.length);
 			if (currPtr != 0)
 				flushBlock();
 			return packHash;
 		}
 
 		int read(long pos, byte[] dst, int ptr, int cnt) throws IOException {
 			int r = 0;
 			while (pos < currPos && r < cnt) {
 				DfsBlock b = getOrLoadBlock(pos);
 				int n = b.copy(pos, dst, ptr + r, cnt - r);
 				pos += n;
 				r += n;
 			}
 			if (currPos <= pos && r < cnt) {
 				int s = (int) (pos - currPos);
 				int n = Math.min(currPtr - s, cnt - r);
 				System.arraycopy(currBuf, s, dst, ptr + r, n);
 				r += n;
 			}
 			return r;
 		}
 
 		byte[] inflate(DfsReader ctx, long pos, int len) throws IOException,
 				DataFormatException {
 			byte[] dstbuf;
 			try {
 				dstbuf = new byte[len];
 			} catch (OutOfMemoryError noMemory) {
 				return null; // Caller will switch to large object streaming.
 			}
 
 			Inflater inf = ctx.inflater();
 			pos += setInput(pos, inf);
 			for (int dstoff = 0;;) {
 				int n = inf.inflate(dstbuf, dstoff, dstbuf.length - dstoff);
 				dstoff += n;
 				if (inf.finished())
 					return dstbuf;
 				if (inf.needsInput())
 					pos += setInput(pos, inf);
 				else if (n == 0)
 					throw new DataFormatException();
 			}
 		}
 
 		private int setInput(long pos, Inflater inf) throws IOException {
 			if (pos < currPos)
 				return getOrLoadBlock(pos).setInput(pos, inf);
 			if (pos < currPos + currPtr) {
 				int s = (int) (pos - currPos);
 				int n = currPtr - s;
 				inf.setInput(currBuf, s, n);
 				return n;
 			}
 			throw new EOFException(DfsText.get().unexpectedEofInPack);
 		}
 
 		private DfsBlock getOrLoadBlock(long pos) throws IOException {
 			long s = toBlockStart(pos);
 			DfsBlock b = cache.get(packKey, s);
 			if (b != null)
 				return b;
 
 			byte[] d = new byte[blockSize];
 			for (int p = 0; p < blockSize;) {
 				int n = out.read(s + p, ByteBuffer.wrap(d, p, blockSize - p));
 				if (n <= 0)
 					throw new EOFException(DfsText.get().unexpectedEofInPack);
 				p += n;
 			}
 			b = new DfsBlock(packKey, s, d);
 			cache.put(b);
 			return b;
 		}
 
 		private long toBlockStart(long pos) {
 			return (pos / blockSize) * blockSize;
 		}
 
 		@Override
 		public void close() throws IOException {
 			deflater.end();
 			out.close();
 		}
 	}
 
 	private class Reader extends ObjectReader {
 		private final DfsReader ctx = new DfsReader(db);
 
 		@Override
 		public ObjectReader newReader() {
 			return db.newReader();
 		}
 
 		@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<ObjectId>(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 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();
 			int cnt = packOut.read(obj.getOffset(), buf, 0, 20);
 			if (cnt <= 0)
 					throw new EOFException(DfsText.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(
 						DfsText.get().cannotReadBackDelta, Integer.toString(type)));
 
 			long sz = c & 0x0f;
 			int ptr = 1;
 			int shift = 4;
 			while ((c & 0x80) != 0) {
 				if (ptr >= cnt)
 					throw new EOFException(DfsText.get().unexpectedEofInPack);
 				c = buf[ptr++] & 0xff;
 				sz += ((long) (c & 0x7f)) << shift;
 				shift += 7;
 			}
 
 			long zpos = obj.getOffset() + ptr;
 			if (sz < ctx.getStreamFileThreshold()) {
 				byte[] data = inflate(obj, zpos, (int) sz);
 				if (data != null)
 					return new ObjectLoader.SmallObject(type, data);
 			}
 			return new StreamLoader(obj.copy(), type, sz, packKey, zpos);
 		}
 
 		private byte[] inflate(PackedObjectInfo obj, long zpos, int sz)
 				throws IOException, CorruptObjectException {
 			try {
 				return packOut.inflate(ctx, zpos, sz);
 			} catch (DataFormatException dfe) {
 				CorruptObjectException coe = new CorruptObjectException(
 						MessageFormat.format(
 								JGitText.get().objectAtHasBadZlibStream,
 								Long.valueOf(obj.getOffset()),
 								packDsc.getFileName(PackExt.PACK)));
 				coe.initCause(dfe);
 				throw coe;
 			}
 		}
 
 		@Override
 		public Set<ObjectId> getShallowCommits() throws IOException {
 			return ctx.getShallowCommits();
 		}
 
 		@Override
 		public void close() {
 			ctx.close();
 		}
 	}
 
 	private class StreamLoader extends ObjectLoader {
 		private final ObjectId id;
 		private final int type;
 		private final long size;
 
 		private final DfsPackKey srcPack;
 		private final long pos;
 
 		StreamLoader(ObjectId id, int type, long sz,
 				DfsPackKey key, long pos) {
 			this.id = id;
 			this.type = type;
 			this.size = sz;
 			this.srcPack = key;
 			this.pos = pos;
 		}
 
 		@Override
 		public ObjectStream openStream() throws IOException {
 			final DfsReader ctx = new DfsReader(db);
 			if (srcPack != packKey) {
 				try {
 					// Post DfsInserter.flush() use the normal code path.
 					// The newly created pack is registered in the cache.
 					return ctx.open(id, type).openStream();
 				} finally {
 					ctx.close();
 				}
 			}
 
 			int bufsz = 8192;
 			final Inflater inf = ctx.inflater();
 			return new ObjectStream.Filter(type,
 					size, new BufferedInputStream(new InflaterInputStream(
 							new ReadBackStream(pos), inf, bufsz), bufsz)) {
 				@Override
 				public void close() throws IOException {
 					ctx.close();
 					super.close();
 				}
 			};
 		}
 
 		@Override
 		public int getType() {
 			return type;
 		}
 
 		@Override
 		public long getSize() {
 			return size;
 		}
 
 		@Override
 		public boolean isLarge() {
 			return true;
 		}
 
 		@Override
 		public byte[] getCachedBytes() throws LargeObjectException {
 			throw new LargeObjectException.ExceedsLimit(
 					db.getReaderOptions().getStreamFileThreshold(), size);
 		}
 	}
 
 	private final class ReadBackStream extends InputStream {
 		private long pos;
 
 		ReadBackStream(long offset) {
 			pos = offset;
 		}
 
 		@Override
 		public int read() throws IOException {
 			byte[] b = new byte[1];
 			int n = read(b);
 			return n == 1 ? b[0] & 0xff : -1;
 		}
 
 		@Override
 		public int read(byte[] buf, int ptr, int len) throws IOException {
 			int n = packOut.read(pos, buf, ptr, len);
 			if (n > 0) {
 				pos += n;
 			}
 			return n;
 		}
 	}
 }