/*
    * Copyright (C) 2012, 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.
   *
   * - 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,
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  package org.eclipse.jgit.internal.storage.pack;
  
  import java.io.IOException;
  import java.util.Set;
  
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.lib.BitmapIndex;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
  import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.revwalk.ObjectWalk;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevFlag;
  import org.eclipse.jgit.revwalk.RevObject;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.revwalk.filter.RevFilter;
  
  /** Helper class for PackWriter to do ObjectWalks with pack index bitmaps. */
  final class PackWriterBitmapWalker {
  
  	private final ObjectWalk walker;
  
  	private final BitmapIndex bitmapIndex;
  
  	private final ProgressMonitor pm;
  
  	private long countOfBitmapIndexMisses;
  
  	PackWriterBitmapWalker(
  			ObjectWalk walker, BitmapIndex bitmapIndex, ProgressMonitor pm) {
  		this.walker = walker;
  		this.bitmapIndex = bitmapIndex;
  		this.pm = (pm == null) ? NullProgressMonitor.INSTANCE : pm;
  	}
  
  	long getCountOfBitmapIndexMisses() {
  		return countOfBitmapIndexMisses;
  	}
  
  	BitmapBuilder findObjects(Set<? extends ObjectId> start, BitmapBuilder seen, boolean ignoreMissingStart)
  			throws MissingObjectException, IncorrectObjectTypeException,
  			IOException {
  		final BitmapBuilder bitmapResult = bitmapIndex.newBitmapBuilder();
  
  		for (ObjectId obj : start) {
  			Bitmap bitmap = bitmapIndex.getBitmap(obj);
  			if (bitmap != null)
  				bitmapResult.or(bitmap);
  		}
  
  		boolean marked = false;
  		for (ObjectId obj : start) {
 			try {
 				if (!bitmapResult.contains(obj)) {
 					walker.markStart(walker.parseAny(obj));
 					marked = true;
 				}
 			} catch (MissingObjectException e) {
 				if (ignoreMissingStart)
 					continue;
 				throw e;
 			}
 		}
 
 		if (marked) {
 			BitmapRevFilter filter = newRevFilter(seen, bitmapResult);
 			walker.setRevFilter(filter);
 
 			while (walker.next() != null) {
 				// Iterate through all of the commits. The BitmapRevFilter does
 				// the work.
 				pm.update(1);
 			}
 
 			RevObject ro;
 			while ((ro = walker.nextObject()) != null) {
 				bitmapResult.add(ro, ro.getType());
 				pm.update(1);
 			}
 			countOfBitmapIndexMisses += filter.getCountOfLoadedCommits();
 		}
 
 		return bitmapResult;
 	}
 
 	void reset() {
 		walker.reset();
 	}
 
 	static BitmapRevFilter newRevFilter(
 			final BitmapBuilder seen, final BitmapBuilder bitmapResult) {
 		if (seen != null) {
 			return new BitmapRevFilter() {
 				protected boolean load(RevCommit cmit) {
 					if (seen.contains(cmit))
 						return false;
 					return bitmapResult.add(cmit, Constants.OBJ_COMMIT);
 				}
 			};
 		}
 		return new BitmapRevFilter() {
 			@Override
 			protected boolean load(RevCommit cmit) {
 				return bitmapResult.add(cmit, Constants.OBJ_COMMIT);
 			}
 		};
 	}
 
 	static abstract class BitmapRevFilter extends RevFilter {
 		private long countOfLoadedCommits;
 
 		protected abstract boolean load(RevCommit cmit);
 
 		@Override
 		public final boolean include(RevWalk walker, RevCommit cmit) {
 			if (load(cmit)) {
 				countOfLoadedCommits++;
 				return true;
 			}
 			for (RevCommit p : cmit.getParents())
 				p.add(RevFlag.SEEN);
 			return false;
 		}
 
 		@Override
 		public final RevFilter clone() {
 			return this;
 		}
 
 		@Override
 		public final boolean requiresCommitBody() {
 			return false;
 		}
 
 		long getCountOfLoadedCommits() {
 			return countOfLoadedCommits;
 		}
 	}
 }