/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hdfs.server.namenode.snapshot;

import org.apache.hadoop.hdfs.server.namenode.INode;
import org.apache.hadoop.hdfs.server.namenode.INode.BlocksMapUpdateInfo;
import org.apache.hadoop.hdfs.server.namenode.INodeFile;
import org.apache.hadoop.hdfs.server.namenode.INodeFileAttributes;
import org.apache.hadoop.hdfs.server.namenode.Quota;

import java.util.List;

/**
 * The difference of an {@link INodeFile} between two snapshots.
 */
public class FileDiff extends
    AbstractINodeDiff<INodeFile, INodeFileAttributes, FileDiff> {

  /** The file size at snapshot creation time. */
  private final long fileSize;

  FileDiff(int snapshotId, INodeFile file) {
    super(snapshotId, null, null);
    fileSize = file.computeFileSize();
  }

  /** Constructor used by FSImage loading */
  FileDiff(int snapshotId, INodeFileAttributes snapshotINode,
      FileDiff posteriorDiff, long fileSize) {
    super(snapshotId, snapshotINode, posteriorDiff);
    this.fileSize = fileSize;
  }

  /** @return the file size in the snapshot. */
  public long getFileSize() {
    return fileSize;
  }
  
  @Override
  Quota.Counts combinePosteriorAndCollectBlocks(INodeFile currentINode,
      FileDiff posterior, BlocksMapUpdateInfo collectedBlocks,
      final List<INode> removedINodes) {
    return currentINode.getFileWithSnapshotFeature()
        .updateQuotaAndCollectBlocks(currentINode, posterior, collectedBlocks,
            removedINodes);
  }
  
  @Override
  public String toString() {
    return super.toString() + " fileSize=" + fileSize + ", rep="
        + (snapshotINode == null? "?": snapshotINode.getFileReplication());
  }

  @Override
  Quota.Counts destroyDiffAndCollectBlocks(INodeFile currentINode,
      BlocksMapUpdateInfo collectedBlocks, final List<INode> removedINodes) {
    return currentINode.getFileWithSnapshotFeature()
        .updateQuotaAndCollectBlocks(currentINode, this, collectedBlocks,
            removedINodes);
  }
}