/**
    *
    * 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.hbase.util;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.fs.PathFilter;
  
  /**
   * Utility methods for interacting with the hbase.root file system.
   */
  @InterfaceAudience.Private
  public final class FSVisitor {
    private static final Log LOG = LogFactory.getLog(FSVisitor.class);
  
    public interface StoreFileVisitor {
      void storeFile(final String region, final String family, final String hfileName)
         throws IOException;
    }
  
    private FSVisitor() {
      // private constructor for utility class
    }
  
    /**
     * Iterate over the table store files
     *
     * @param fs {@link FileSystem}
     * @param tableDir {@link Path} to the table directory
     * @param visitor callback object to get the store files
     * @throws IOException if an error occurred while scanning the directory
     */
    public static void visitTableStoreFiles(final FileSystem fs, final Path tableDir,
        final StoreFileVisitor visitor) throws IOException {
      FileStatus[] regions = FSUtils.listStatus(fs, tableDir, new FSUtils.RegionDirFilter(fs));
      if (regions == null) {
        if (LOG.isTraceEnabled()) {
          LOG.trace("No regions under directory:" + tableDir);
        }
        return;
      }
  
      for (FileStatus region: regions) {
        visitRegionStoreFiles(fs, region.getPath(), visitor);
      }
    }
  
    /**
     * Iterate over the region store files
     *
     * @param fs {@link FileSystem}
     * @param regionDir {@link Path} to the region directory
     * @param visitor callback object to get the store files
     * @throws IOException if an error occurred while scanning the directory
     */
    public static void visitRegionStoreFiles(final FileSystem fs, final Path regionDir,
        final StoreFileVisitor visitor) throws IOException {
      FileStatus[] families = FSUtils.listStatus(fs, regionDir, new FSUtils.FamilyDirFilter(fs));
      if (families == null) {
        if (LOG.isTraceEnabled()) {
          LOG.trace("No families under region directory:" + regionDir);
        }
        return;
      }
  
      PathFilter fileFilter = new FSUtils.FileFilter(fs);
      for (FileStatus family: families) {
        Path familyDir = family.getPath();
        String familyName = familyDir.getName();
  
        // get all the storeFiles in the family
        FileStatus[] storeFiles = FSUtils.listStatus(fs, familyDir, fileFilter);
        if (storeFiles == null) {
          if (LOG.isTraceEnabled()) {
            LOG.trace("No hfiles found for family: " + familyDir + ", skipping.");
          }
          continue;
       }
 
       for (FileStatus hfile: storeFiles) {
         Path hfilePath = hfile.getPath();
         visitor.storeFile(regionDir.getName(), familyName, hfilePath.getName());
       }
     }
   }
 }