/*
    * 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
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   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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  package org.eclipse.jgit.internal.storage.dfs;
  
  import static org.eclipse.jgit.internal.storage.pack.PackExt.REFTABLE;
  import static org.eclipse.jgit.lib.Ref.Storage.NEW;
  import static org.eclipse.jgit.lib.Ref.Storage.PACKED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.LOCK_FAILURE;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.OK;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_MISSING_OBJECT;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_NONFASTFORWARD;
  import static org.eclipse.jgit.transport.ReceiveCommand.Type.UPDATE_NONFASTFORWARD;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource;
  import org.eclipse.jgit.internal.storage.io.BlockSource;
  import org.eclipse.jgit.internal.storage.pack.PackExt;
  import org.eclipse.jgit.internal.storage.reftable.Reftable;
  import org.eclipse.jgit.internal.storage.reftable.ReftableCompactor;
  import org.eclipse.jgit.internal.storage.reftable.ReftableConfig;
  import org.eclipse.jgit.internal.storage.reftable.ReftableReader;
  import org.eclipse.jgit.internal.storage.reftable.ReftableWriter;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.BatchRefUpdate;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.PersonIdent;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.ReflogEntry;
  import org.eclipse.jgit.lib.SymbolicRef;
  import org.eclipse.jgit.revwalk.RevObject;
  import org.eclipse.jgit.revwalk.RevTag;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.transport.ReceiveCommand;
  
  /**
   * {@link org.eclipse.jgit.lib.BatchRefUpdate} for
   * {@link org.eclipse.jgit.internal.storage.dfs.DfsReftableDatabase}.
   */
  public class ReftableBatchRefUpdate extends BatchRefUpdate {
  	private static final int AVG_BYTES = 36;
  
  	private final DfsReftableDatabase refdb;
 
 	private final DfsObjDatabase odb;
 
 	private final ReentrantLock lock;
 
 	private final ReftableConfig reftableConfig;
 
 	/**
 	 * Initialize batch update.
 	 *
 	 * @param refdb
 	 *            database the update will modify.
 	 * @param odb
 	 *            object database to store the reftable.
 	 */
 	protected ReftableBatchRefUpdate(DfsReftableDatabase refdb,
 			DfsObjDatabase odb) {
 		super(refdb);
 		this.refdb = refdb;
 		this.odb = odb;
 		lock = refdb.getLock();
 		reftableConfig = refdb.getReftableConfig();
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void execute(RevWalk rw, ProgressMonitor pm, List<String> options) {
 		List<ReceiveCommand> pending = getPending();
 		if (pending.isEmpty()) {
 			return;
 		}
 		if (options != null) {
 			setPushOptions(options);
 		}
 		try {
 			if (!checkObjectExistence(rw, pending)) {
 				return;
 			}
 			if (!checkNonFastForwards(rw, pending)) {
 				return;
 			}
 
 			lock.lock();
 			try {
 				Reftable table = refdb.reader();
 				if (!checkExpected(table, pending)) {
 					return;
 				}
 				if (!checkConflicting(pending)) {
 					return;
 				}
 				if (!blockUntilTimestamps(MAX_WAIT)) {
 					return;
 				}
 				applyUpdates(rw, pending);
 				for (ReceiveCommand cmd : pending) {
 					cmd.setResult(OK);
 				}
 			} finally {
 				lock.unlock();
 			}
 		} catch (IOException e) {
 			pending.get(0).setResult(LOCK_FAILURE, "io error"); //$NON-NLS-1$
 			ReceiveCommand.abort(pending);
 		}
 	}
 
 	private List<ReceiveCommand> getPending() {
 		return ReceiveCommand.filter(getCommands(), NOT_ATTEMPTED);
 	}
 
 	private boolean checkObjectExistence(RevWalk rw,
 			List<ReceiveCommand> pending) throws IOException {
 		for (ReceiveCommand cmd : pending) {
 			try {
 				if (!cmd.getNewId().equals(ObjectId.zeroId())) {
 					rw.parseAny(cmd.getNewId());
 				}
 			} catch (MissingObjectException e) {
 				// ReceiveCommand#setResult(Result) converts REJECTED to
 				// REJECTED_NONFASTFORWARD, even though that result is also
 				// used for a missing object. Eagerly handle this case so we
 				// can set the right result.
 				cmd.setResult(REJECTED_MISSING_OBJECT);
 				ReceiveCommand.abort(pending);
 				return false;
 			}
 		}
 		return true;
 	}
 
 	private boolean checkNonFastForwards(RevWalk rw,
 			List<ReceiveCommand> pending) throws IOException {
 		if (isAllowNonFastForwards()) {
 			return true;
 		}
 		for (ReceiveCommand cmd : pending) {
 			cmd.updateType(rw);
 			if (cmd.getType() == UPDATE_NONFASTFORWARD) {
 				cmd.setResult(REJECTED_NONFASTFORWARD);
 				ReceiveCommand.abort(pending);
 				return false;
 			}
 		}
 		return true;
 	}
 
 	private boolean checkConflicting(List<ReceiveCommand> pending)
 			throws IOException {
 		Set<String> names = new HashSet<>();
 		for (ReceiveCommand cmd : pending) {
 			names.add(cmd.getRefName());
 		}
 
 		boolean ok = true;
 		for (ReceiveCommand cmd : pending) {
 			String name = cmd.getRefName();
 			if (refdb.isNameConflicting(name)) {
 				cmd.setResult(LOCK_FAILURE);
 				ok = false;
 			} else {
 				int s = name.lastIndexOf('/');
 				while (0 < s) {
 					if (names.contains(name.substring(0, s))) {
 						cmd.setResult(LOCK_FAILURE);
 						ok = false;
 						break;
 					}
 					s = name.lastIndexOf('/', s - 1);
 				}
 			}
 		}
 		if (!ok && isAtomic()) {
 			ReceiveCommand.abort(pending);
 			return false;
 		}
 		return ok;
 	}
 
 	private boolean checkExpected(Reftable table, List<ReceiveCommand> pending)
 			throws IOException {
 		for (ReceiveCommand cmd : pending) {
 			if (!matchOld(cmd, table.exactRef(cmd.getRefName()))) {
 				cmd.setResult(LOCK_FAILURE);
 				if (isAtomic()) {
 					ReceiveCommand.abort(pending);
 					return false;
 				}
 			}
 		}
 		return true;
 	}
 
 	private static boolean matchOld(ReceiveCommand cmd, @Nullable Ref ref) {
 		if (ref == null) {
 			return AnyObjectId.equals(ObjectId.zeroId(), cmd.getOldId())
 					&& cmd.getOldSymref() == null;
 		} else if (ref.isSymbolic()) {
 			return ref.getTarget().getName().equals(cmd.getOldSymref());
 		}
 		ObjectId id = ref.getObjectId();
 		if (id == null) {
 			id = ObjectId.zeroId();
 		}
 		return cmd.getOldId().equals(id);
 	}
 
 	private void applyUpdates(RevWalk rw, List<ReceiveCommand> pending)
 			throws IOException {
 		List<Ref> newRefs = toNewRefs(rw, pending);
 		long updateIndex = nextUpdateIndex();
 		Set<DfsPackDescription> prune = Collections.emptySet();
 		DfsPackDescription pack = odb.newPack(PackSource.INSERT);
 		try (DfsOutputStream out = odb.writeFile(pack, REFTABLE)) {
 			ReftableConfig cfg = DfsPackCompactor
 					.configureReftable(reftableConfig, out);
 
 			ReftableWriter.Stats stats;
 			if (refdb.compactDuringCommit()
 					&& newRefs.size() * AVG_BYTES <= cfg.getRefBlockSize()
 					&& canCompactTopOfStack(cfg)) {
 				ByteArrayOutputStream tmp = new ByteArrayOutputStream();
 				write(tmp, cfg, updateIndex, newRefs, pending);
 				stats = compactTopOfStack(out, cfg, tmp.toByteArray());
 				prune = toPruneTopOfStack();
 			} else {
 				stats = write(out, cfg, updateIndex, newRefs, pending);
 			}
 			pack.addFileExt(REFTABLE);
 			pack.setReftableStats(stats);
 		}
 
 		odb.commitPack(Collections.singleton(pack), prune);
 		odb.addReftable(pack, prune);
 		refdb.clearCache();
 	}
 
 	private ReftableWriter.Stats write(OutputStream os, ReftableConfig cfg,
 			long updateIndex, List<Ref> newRefs, List<ReceiveCommand> pending)
 			throws IOException {
 		ReftableWriter writer = new ReftableWriter(cfg)
 				.setMinUpdateIndex(updateIndex).setMaxUpdateIndex(updateIndex)
 				.begin(os).sortAndWriteRefs(newRefs);
 		if (!isRefLogDisabled()) {
 			writeLog(writer, updateIndex, pending);
 		}
 		writer.finish();
 		return writer.getStats();
 	}
 
 	private void writeLog(ReftableWriter writer, long updateIndex,
 			List<ReceiveCommand> pending) throws IOException {
 		Map<String, ReceiveCommand> cmds = new HashMap<>();
 		List<String> byName = new ArrayList<>(pending.size());
 		for (ReceiveCommand cmd : pending) {
 			cmds.put(cmd.getRefName(), cmd);
 			byName.add(cmd.getRefName());
 		}
 		Collections.sort(byName);
 
 		PersonIdent ident = getRefLogIdent();
 		if (ident == null) {
 			ident = new PersonIdent(refdb.getRepository());
 		}
 		for (String name : byName) {
 			ReceiveCommand cmd = cmds.get(name);
 			if (isRefLogDisabled(cmd)) {
 				continue;
 			}
 			String msg = getRefLogMessage(cmd);
 			if (isRefLogIncludingResult(cmd)) {
 				String strResult = toResultString(cmd);
 				if (strResult != null) {
 					msg = msg.isEmpty() ? strResult : msg + ": " + strResult; //$NON-NLS-1$
 				}
 			}
 			writer.writeLog(name, updateIndex, ident, cmd.getOldId(),
 					cmd.getNewId(), msg);
 		}
 	}
 
 	private String toResultString(ReceiveCommand cmd) {
 		switch (cmd.getType()) {
 		case CREATE:
 			return ReflogEntry.PREFIX_CREATED;
 		case UPDATE:
 			// Match the behavior of a single RefUpdate. In that case, setting
 			// the force bit completely bypasses the potentially expensive
 			// isMergedInto check, by design, so the reflog message may be
 			// inaccurate.
 			//
 			// Similarly, this class bypasses the isMergedInto checks when the
 			// force bit is set, meaning we can't actually distinguish between
 			// UPDATE and UPDATE_NONFASTFORWARD when isAllowNonFastForwards()
 			// returns true.
 			return isAllowNonFastForwards() ? ReflogEntry.PREFIX_FORCED_UPDATE
 					: ReflogEntry.PREFIX_FAST_FORWARD;
 		case UPDATE_NONFASTFORWARD:
 			return ReflogEntry.PREFIX_FORCED_UPDATE;
 		default:
 			return null;
 		}
 	}
 
 	private static List<Ref> toNewRefs(RevWalk rw, List<ReceiveCommand> pending)
 			throws IOException {
 		List<Ref> refs = new ArrayList<>(pending.size());
 		for (ReceiveCommand cmd : pending) {
 			String name = cmd.getRefName();
 			ObjectId newId = cmd.getNewId();
 			String newSymref = cmd.getNewSymref();
 			if (AnyObjectId.equals(ObjectId.zeroId(), newId)
 					&& newSymref == null) {
 				refs.add(new ObjectIdRef.Unpeeled(NEW, name, null));
 				continue;
 			} else if (newSymref != null) {
 				refs.add(new SymbolicRef(name,
 						new ObjectIdRef.Unpeeled(NEW, newSymref, null)));
 				continue;
 			}
 
 			RevObject obj = rw.parseAny(newId);
 			RevObject peel = null;
 			if (obj instanceof RevTag) {
 				peel = rw.peel(obj);
 			}
 			if (peel != null) {
 				refs.add(new ObjectIdRef.PeeledTag(PACKED, name, newId,
 						peel.copy()));
 			} else {
 				refs.add(new ObjectIdRef.PeeledNonTag(PACKED, name, newId));
 			}
 		}
 		return refs;
 	}
 
 	private long nextUpdateIndex() throws IOException {
 		long updateIndex = 0;
 		for (Reftable r : refdb.stack().readers()) {
 			if (r instanceof ReftableReader) {
 				updateIndex = Math.max(updateIndex,
 						((ReftableReader) r).maxUpdateIndex());
 			}
 		}
 		return updateIndex + 1;
 	}
 
 	private boolean canCompactTopOfStack(ReftableConfig cfg)
 			throws IOException {
 		ReftableStack stack = refdb.stack();
 		List<Reftable> readers = stack.readers();
 		if (readers.isEmpty()) {
 			return false;
 		}
 
 		int lastIdx = readers.size() - 1;
 		DfsReftable last = stack.files().get(lastIdx);
 		DfsPackDescription desc = last.getPackDescription();
 		if (desc.getPackSource() != PackSource.INSERT
 				|| !packOnlyContainsReftable(desc)) {
 			return false;
 		}
 
 		Reftable table = readers.get(lastIdx);
 		int bs = cfg.getRefBlockSize();
 		return table instanceof ReftableReader
 				&& ((ReftableReader) table).size() <= 3 * bs;
 	}
 
 	private ReftableWriter.Stats compactTopOfStack(OutputStream out,
 			ReftableConfig cfg, byte[] newTable) throws IOException {
 		List<Reftable> stack = refdb.stack().readers();
 		Reftable last = stack.get(stack.size() - 1);
 
 		List<Reftable> tables = new ArrayList<>(2);
 		tables.add(last);
 		tables.add(new ReftableReader(BlockSource.from(newTable)));
 
 		ReftableCompactor compactor = new ReftableCompactor();
 		compactor.setConfig(cfg);
 		compactor.setIncludeDeletes(true);
 		compactor.addAll(tables);
 		compactor.compact(out);
 		return compactor.getStats();
 	}
 
 	private Set<DfsPackDescription> toPruneTopOfStack() throws IOException {
 		List<DfsReftable> stack = refdb.stack().files();
 		DfsReftable last = stack.get(stack.size() - 1);
 		return Collections.singleton(last.getPackDescription());
 	}
 
 	private boolean packOnlyContainsReftable(DfsPackDescription desc) {
 		for (PackExt ext : PackExt.values()) {
 			if (ext != REFTABLE && desc.hasFileExt(ext)) {
 				return false;
 			}
 		}
 		return true;
 	}
 }