/**
 * 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.tez.mapreduce.common;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.FileSystem.Statistics;
import org.apache.hadoop.mapred.Counters.Counter;
import org.apache.tez.common.counters.TezCounter;
import org.apache.tez.mapreduce.hadoop.mapred.MRCounters;

import com.google.common.base.Preconditions;

@Private
public class Utils {

  /**
   * Gets a handle to the Statistics instance based on the scheme associated
   * with path.
   *
   * @param path the path.
   * @param conf the configuration to extract the scheme from if not part of
   *   the path.
   * @return a Statistics instance, or null if none is found for the scheme.
   */
  @Private
  public static List<Statistics> getFsStatistics(Path path, Configuration conf) throws IOException {
    List<Statistics> matchedStats = new ArrayList<FileSystem.Statistics>();
    path = path.getFileSystem(conf).makeQualified(path);
    String scheme = path.toUri().getScheme();
    for (Statistics stats : FileSystem.getAllStatistics()) {
      if (stats.getScheme().equals(scheme)) {
        matchedStats.add(stats);
      }
    }
    return matchedStats;
  }

  public static Counter getMRCounter(TezCounter tezCounter) {
    Preconditions.checkNotNull(tezCounter);
    return new MRCounters.MRCounter(tezCounter);
  }
  
}