/*
    * 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:
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   * - 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.
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   * - 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
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   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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  package org.eclipse.jgit.internal.storage.dfs;
  
  import java.io.IOException;
  
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.RefUpdate;
  import org.eclipse.jgit.lib.SymbolicRef;
  import org.eclipse.jgit.lib.Ref.Storage;
  import org.eclipse.jgit.revwalk.RevObject;
  import org.eclipse.jgit.revwalk.RevTag;
  import org.eclipse.jgit.revwalk.RevWalk;
  
  final class DfsRefUpdate extends RefUpdate {
  	private final DfsRefDatabase refdb;
  
  	private Ref dstRef;
  
  	private RevWalk rw;
  
  	DfsRefUpdate(DfsRefDatabase refdb, Ref ref) {
  		super(ref);
  		this.refdb = refdb;
  	}
  
  	@Override
  	protected DfsRefDatabase getRefDatabase() {
  		return refdb;
  	}
  
  	@Override
  	protected DfsRepository getRepository() {
  		return refdb.getRepository();
  	}
  
  	@Override
  	protected boolean tryLock(boolean deref) throws IOException {
  		dstRef = getRef();
  		if (deref)
  			dstRef = dstRef.getLeaf();
  
  		if (dstRef.isSymbolic())
  			setOldObjectId(null);
  		else
  			setOldObjectId(dstRef.getObjectId());
  
  		return true;
  	}
  
  	@Override
  	protected void unlock() {
  		// No state is held while "locked".
  	}
  
  	@Override
  	public Result update(RevWalk walk) throws IOException {
 		try {
 			rw = walk;
 			return super.update(walk);
 		} finally {
 			rw = null;
 		}
 	}
 
 	@Override
 	protected Result doUpdate(Result desiredResult) throws IOException {
 		ObjectIdRef newRef;
 		RevObject obj = rw.parseAny(getNewObjectId());
 		if (obj instanceof RevTag) {
 			newRef = new ObjectIdRef.PeeledTag(
 					Storage.PACKED,
 					dstRef.getName(),
 					getNewObjectId(),
 					rw.peel(obj).copy());
 		} else {
 			newRef = new ObjectIdRef.PeeledNonTag(
 					Storage.PACKED,
 					dstRef.getName(),
 					getNewObjectId());
 		}
 
 		if (getRefDatabase().compareAndPut(dstRef, newRef)) {
 			getRefDatabase().stored(newRef);
 			return desiredResult;
 		}
 		return Result.LOCK_FAILURE;
 	}
 
 	@Override
 	protected Result doDelete(Result desiredResult) throws IOException {
 		if (getRefDatabase().compareAndRemove(dstRef)) {
 			getRefDatabase().removed(dstRef.getName());
 			return desiredResult;
 		}
 		return Result.LOCK_FAILURE;
 	}
 
 	@Override
 	protected Result doLink(String target) throws IOException {
 		final SymbolicRef newRef = new SymbolicRef(
 				dstRef.getName(),
 				new ObjectIdRef.Unpeeled(
 						Storage.NEW,
 						target,
 						null));
 		if (getRefDatabase().compareAndPut(dstRef, newRef)) {
 			getRefDatabase().stored(newRef);
 			if (dstRef.getStorage() == Ref.Storage.NEW)
 				return Result.NEW;
 			return Result.FORCED;
 		}
 		return Result.LOCK_FAILURE;
 	}
 }