/**
    * 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.mapreduce;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.EOFException;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
  import org.apache.hadoop.hbase.wal.WALFactory;
  import org.apache.hadoop.hbase.wal.WALKey;
  import org.apache.hadoop.hbase.wal.WAL.Entry;
  import org.apache.hadoop.hbase.wal.WAL.Reader;
  import org.apache.hadoop.io.Writable;
  import org.apache.hadoop.mapreduce.InputFormat;
  import org.apache.hadoop.mapreduce.InputSplit;
  import org.apache.hadoop.mapreduce.JobContext;
  import org.apache.hadoop.mapreduce.RecordReader;
  import org.apache.hadoop.mapreduce.TaskAttemptContext;
  
  /**
   * Simple {@link InputFormat} for {@link org.apache.hadoop.hbase.wal.WAL} files.
   */
  @InterfaceAudience.Public
  public class WALInputFormat extends InputFormat<WALKey, WALEdit> {
    private static final Log LOG = LogFactory.getLog(WALInputFormat.class);
  
    public static final String START_TIME_KEY = "wal.start.time";
    public static final String END_TIME_KEY = "wal.end.time";
  
    /**
     * {@link InputSplit} for {@link WAL} files. Each split represent
     * exactly one log file.
     */
    static class WALSplit extends InputSplit implements Writable {
      private String logFileName;
      private long fileSize;
      private long startTime;
      private long endTime;
  
      /** for serialization */
      public WALSplit() {}
  
      /**
       * Represent an WALSplit, i.e. a single WAL file.
       * Start- and EndTime are managed by the split, so that WAL files can be
       * filtered before WALEdits are passed to the mapper(s).
       * @param logFileName
       * @param fileSize
       * @param startTime
       * @param endTime
       */
      public WALSplit(String logFileName, long fileSize, long startTime, long endTime) {
        this.logFileName = logFileName;
        this.fileSize = fileSize;
        this.startTime = startTime;
        this.endTime = endTime;
      }
  
      @Override
      public long getLength() throws IOException, InterruptedException {
        return fileSize;
      }
  
      @Override
      public String[] getLocations() throws IOException, InterruptedException {
        // TODO: Find the data node with the most blocks for this WAL?
        return new String[] {};
      }
  
      public String getLogFileName() {
        return logFileName;
      }
 
     public long getStartTime() {
       return startTime;
     }
 
     public long getEndTime() {
       return endTime;
     }
 
     @Override
     public void readFields(DataInput in) throws IOException {
       logFileName = in.readUTF();
       fileSize = in.readLong();
       startTime = in.readLong();
       endTime = in.readLong();
     }
 
     @Override
     public void write(DataOutput out) throws IOException {
       out.writeUTF(logFileName);
       out.writeLong(fileSize);
       out.writeLong(startTime);
       out.writeLong(endTime);
     }
 
     @Override
     public String toString() {
       return logFileName + " (" + startTime + ":" + endTime + ") length:" + fileSize;
     }
   }
 
   /**
    * {@link RecordReader} for an {@link WAL} file.
    * Implementation shared with deprecated HLogInputFormat.
    */
   static abstract class WALRecordReader<K extends WALKey> extends RecordReader<K, WALEdit> {
     private Reader reader = null;
     // visible until we can remove the deprecated HLogInputFormat
     Entry currentEntry = new Entry();
     private long startTime;
     private long endTime;
 
     @Override
     public void initialize(InputSplit split, TaskAttemptContext context)
         throws IOException, InterruptedException {
       WALSplit hsplit = (WALSplit)split;
       Path logFile = new Path(hsplit.getLogFileName());
       Configuration conf = context.getConfiguration();
       LOG.info("Opening reader for "+split);
       try {
         this.reader = WALFactory.createReader(logFile.getFileSystem(conf), logFile, conf);
       } catch (EOFException x) {
         LOG.info("Ignoring corrupted WAL file: " + logFile
             + " (This is normal when a RegionServer crashed.)");
         this.reader = null;
       }
       this.startTime = hsplit.getStartTime();
       this.endTime = hsplit.getEndTime();
     }
 
     @Override
     public boolean nextKeyValue() throws IOException, InterruptedException {
       if (reader == null) return false;
 
       Entry temp;
       long i = -1;
       do {
         // skip older entries
         try {
           temp = reader.next(currentEntry);
           i++;
         } catch (EOFException x) {
           LOG.info("Corrupted entry detected. Ignoring the rest of the file."
               + " (This is normal when a RegionServer crashed.)");
           return false;
         }
       }
       while(temp != null && temp.getKey().getWriteTime() < startTime);
 
       if (temp == null) {
         if (i > 0) LOG.info("Skipped " + i + " entries.");
         LOG.info("Reached end of file.");
         return false;
       } else if (i > 0) {
         LOG.info("Skipped " + i + " entries, until ts: " + temp.getKey().getWriteTime() + ".");
       }
       boolean res = temp.getKey().getWriteTime() <= endTime;
       if (!res) {
         LOG.info("Reached ts: " + temp.getKey().getWriteTime() + " ignoring the rest of the file.");
       }
       return res;
     }
 
     @Override
     public WALEdit getCurrentValue() throws IOException, InterruptedException {
       return currentEntry.getEdit();
     }
 
     @Override
     public float getProgress() throws IOException, InterruptedException {
       // N/A depends on total number of entries, which is unknown
       return 0;
     }
 
     @Override
     public void close() throws IOException {
       LOG.info("Closing reader");
       if (reader != null) this.reader.close();
     }
   }
 
   /**
    * handler for non-deprecated WALKey version. fold into WALRecordReader once we no longer
    * need to support HLogInputFormat.
    */
   static class WALKeyRecordReader extends WALRecordReader<WALKey> {
     @Override
     public WALKey getCurrentKey() throws IOException, InterruptedException {
       return currentEntry.getKey();
     }
   }
 
   @Override
   public List<InputSplit> getSplits(JobContext context) throws IOException,
       InterruptedException {
     return getSplits(context, START_TIME_KEY, END_TIME_KEY);
   }
 
   /**
    * implementation shared with deprecated HLogInputFormat
    */
   List<InputSplit> getSplits(final JobContext context, final String startKey, final String endKey)
       throws IOException, InterruptedException {
     Configuration conf = context.getConfiguration();
     Path inputDir = new Path(conf.get("mapreduce.input.fileinputformat.inputdir",
       conf.get("mapred.input.dir")));
 
     long startTime = conf.getLong(startKey, Long.MIN_VALUE);
     long endTime = conf.getLong(endKey, Long.MAX_VALUE);
 
     FileSystem fs = inputDir.getFileSystem(conf);
     List<FileStatus> files = getFiles(fs, inputDir, startTime, endTime);
 
     List<InputSplit> splits = new ArrayList<InputSplit>(files.size());
     for (FileStatus file : files) {
       splits.add(new WALSplit(file.getPath().toString(), file.getLen(), startTime, endTime));
     }
     return splits;
   }
 
   private List<FileStatus> getFiles(FileSystem fs, Path dir, long startTime, long endTime)
       throws IOException {
     List<FileStatus> result = new ArrayList<FileStatus>();
     LOG.debug("Scanning " + dir.toString() + " for WAL files");
 
     FileStatus[] files = fs.listStatus(dir);
     if (files == null) return Collections.emptyList();
     for (FileStatus file : files) {
       if (file.isDirectory()) {
         // recurse into sub directories
         result.addAll(getFiles(fs, file.getPath(), startTime, endTime));
       } else {
         String name = file.getPath().toString();
         int idx = name.lastIndexOf('.');
         if (idx > 0) {
           try {
             long fileStartTime = Long.parseLong(name.substring(idx+1));
             if (fileStartTime <= endTime) {
               LOG.info("Found: " + name);
               result.add(file);
             }
           } catch (NumberFormatException x) {
             idx = 0;
           }
         }
         if (idx == 0) {
           LOG.warn("File " + name + " does not appear to be an WAL file. Skipping...");
         }
       }
     }
     return result;
   }
 
   @Override
   public RecordReader<WALKey, WALEdit> createRecordReader(InputSplit split,
       TaskAttemptContext context) throws IOException, InterruptedException {
     return new WALKeyRecordReader();
   }
 }