/*

  * 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.giraph.utils;

 import org.apache.commons.io.FilenameUtils;

 import org.apache.hadoop.conf.Configuration;

 import org.apache.hadoop.filecache.DistributedCache;

 import org.apache.hadoop.fs.FileSystem;

 import org.apache.hadoop.fs.Path;

 import org.apache.log4j.Logger;

 import com.google.common.base.Optional;

 import java.io.IOException;

 import static org.apache.commons.io.FilenameUtils.getBaseName;

 /**

  * Helpers for dealing with {@link org.apache.hadoop.filecache.DistributedCache}

  */

 public class DistributedCacheUtils {

   /** Logger */

   private static final Logger LOG = Logger.getLogger(

       DistributedCacheUtils.class);

   /** Don't construct */

   private DistributedCacheUtils() { }

   /**

    * Get local path to file from a DistributedCache.

    *

    * @param conf Configuration

    * @param pathToMatch Path that was used to insert into DistributedCache

    * @return Path matched, or Optional.absent()

    */

   public static Optional<Path>

   getLocalCacheFile(Configuration conf, String pathToMatch) {

     String nameToPath = FilenameUtils.getName(pathToMatch);

     Path[] paths;

     try {

       paths = DistributedCache.getLocalCacheFiles(conf);

     } catch (IOException e) {

       return Optional.absent();

     }

     for (Path path : paths) {

       if (FilenameUtils.getName(path.toString()).equals(nameToPath)) {

         return Optional.of(path);

       }

     }

     return Optional.absent();

   }

   /**

    * Copy a file to HDFS if it is local. If the path is already in HDFS, this

    * call does nothing.

    *

    * @param path path to file

    * @param conf Configuration

    * @return path to file on HDFS.

    */

   public static Path copyToHdfs(Path path, Configuration conf) {

     if (path.toString().startsWith("hdfs://")) {

       // Already on HDFS

       return path;

     }

     FileSystem fs = null;

     try {

       fs = FileSystem.get(conf);

     } catch (IOException e) {

       throw new IllegalArgumentException("Failed to get HDFS FileSystem", e);

     }

     String name = getBaseName(path.toString()) + "-" + System.nanoTime();

     Path remotePath = new Path("/tmp/giraph", name);

     LOG.info("copyToHdfsIfNecessary: Copying " + path + " to " +

         remotePath + " on hdfs " + fs.getUri());

     try {

       fs.copyFromLocalFile(false, true, path, remotePath);

     } catch (IOException e) {

       throw new IllegalArgumentException(

           "Failed to copy jython script from local path " + path +

           " to hdfs path " + remotePath + " on hdfs " + fs.getUri(), e);

     }

     return remotePath;

   }

   /**

    * Copy a file to HDFS if it is local, and adds it to the distributed cache.

    *

    * @param path path to file

    * @param conf Configuration

    * @return remote path to file

    */

   public static Path copyAndAdd(Path path, Configuration conf) {

     Path remotePath = copyToHdfs(path, conf);

     DistributedCache.addCacheFile(remotePath.toUri(), conf);

     return remotePath;

   }

 }