/**
    *
    * 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.replication;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.hbase.*;
  import org.apache.hadoop.hbase.client.HConnectable;
  import org.apache.hadoop.hbase.client.HConnection;
  import org.apache.hadoop.hbase.client.HConnectionManager;
  import org.apache.hadoop.hbase.client.HTable;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.ResultScanner;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
  import org.apache.hadoop.hbase.mapreduce.TableInputFormat;
  import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
  import org.apache.hadoop.hbase.mapreduce.TableMapper;
  import org.apache.hadoop.hbase.mapreduce.TableSplit;
  import org.apache.hadoop.hbase.replication.ReplicationException;
  import org.apache.hadoop.hbase.replication.ReplicationFactory;
  import org.apache.hadoop.hbase.replication.ReplicationPeerZKImpl;
  import org.apache.hadoop.hbase.replication.ReplicationPeerConfig;
  import org.apache.hadoop.hbase.replication.ReplicationPeers;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
  import org.apache.hadoop.mapreduce.Job;
  import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
  import org.apache.hadoop.util.Tool;
  import org.apache.hadoop.util.ToolRunner;
  
  /**
   * This map-only job compares the data from a local table with a remote one.
   * Every cell is compared and must have exactly the same keys (even timestamp)
   * as well as same value. It is possible to restrict the job by time range and
   * families. The peer id that's provided must match the one given when the
   * replication stream was setup.
   * <p>
   * Two counters are provided, Verifier.Counters.GOODROWS and BADROWS. The reason
   * for a why a row is different is shown in the map's log.
   */
  public class VerifyReplication extends Configured implements Tool {
  
    private static final Log LOG =
        LogFactory.getLog(VerifyReplication.class);
  
    public final static String NAME = "verifyrep";
    static long startTime = 0;
    static long endTime = Long.MAX_VALUE;
    static int versions = -1;
    static String tableName = null;
    static String families = null;
    static String peerId = null;
  
    /**
     * Map-only comparator for 2 tables
     */
    public static class Verifier
        extends TableMapper<ImmutableBytesWritable, Put> {
  
      public static enum Counters {
        GOODROWS, BADROWS, ONLY_IN_SOURCE_TABLE_ROWS, ONLY_IN_PEER_TABLE_ROWS, CONTENT_DIFFERENT_ROWS}
  
      private ResultScanner replicatedScanner;
      private Result currentCompareRowInPeerTable;
      private Table replicatedTable;
  
      /**
       * Map method that compares every scanned row with the equivalent from
       * a distant cluster.
       * @param row  The current table row key.
       * @param value  The columns.
       * @param context  The current context.
       * @throws IOException When something is broken with the data.
       */
     @Override
     public void map(ImmutableBytesWritable row, final Result value,
                     Context context)
         throws IOException {
       if (replicatedScanner == null) {
         Configuration conf = context.getConfiguration();
         final Scan scan = new Scan();
         scan.setCaching(conf.getInt(TableInputFormat.SCAN_CACHEDROWS, 1));
         long startTime = conf.getLong(NAME + ".startTime", 0);
         long endTime = conf.getLong(NAME + ".endTime", Long.MAX_VALUE);
         String families = conf.get(NAME + ".families", null);
         if(families != null) {
           String[] fams = families.split(",");
           for(String fam : fams) {
             scan.addFamily(Bytes.toBytes(fam));
           }
         }
         scan.setTimeRange(startTime, endTime);
         if (versions >= 0) {
           scan.setMaxVersions(versions);
         }
 
         final TableSplit tableSplit = (TableSplit)(context.getInputSplit());
         HConnectionManager.execute(new HConnectable<Void>(conf) {
           @Override
           public Void connect(HConnection conn) throws IOException {
             String zkClusterKey = conf.get(NAME + ".peerQuorumAddress");
             Configuration peerConf = HBaseConfiguration.create(conf);
             ZKUtil.applyClusterKeyToConf(peerConf, zkClusterKey);
 
             TableName tableName = TableName.valueOf(conf.get(NAME + ".tableName"));
             replicatedTable = new HTable(peerConf, tableName);
             scan.setStartRow(value.getRow());
             scan.setStopRow(tableSplit.getEndRow());
             replicatedScanner = replicatedTable.getScanner(scan);
             return null;
           }
         });
         currentCompareRowInPeerTable = replicatedScanner.next();
       }
       while (true) {
         if (currentCompareRowInPeerTable == null) {
           // reach the region end of peer table, row only in source table
           logFailRowAndIncreaseCounter(context, Counters.ONLY_IN_SOURCE_TABLE_ROWS, value);
           break;
         }
         int rowCmpRet = Bytes.compareTo(value.getRow(), currentCompareRowInPeerTable.getRow());
         if (rowCmpRet == 0) {
           // rowkey is same, need to compare the content of the row
           try {
             Result.compareResults(value, currentCompareRowInPeerTable);
             context.getCounter(Counters.GOODROWS).increment(1);
           } catch (Exception e) {
             logFailRowAndIncreaseCounter(context, Counters.CONTENT_DIFFERENT_ROWS, value);
             LOG.error("Exception while comparing row : " + e);
           }
           currentCompareRowInPeerTable = replicatedScanner.next();
           break;
         } else if (rowCmpRet < 0) {
           // row only exists in source table
           logFailRowAndIncreaseCounter(context, Counters.ONLY_IN_SOURCE_TABLE_ROWS, value);
           break;
         } else {
           // row only exists in peer table
           logFailRowAndIncreaseCounter(context, Counters.ONLY_IN_PEER_TABLE_ROWS,
             currentCompareRowInPeerTable);
           currentCompareRowInPeerTable = replicatedScanner.next();
         }
       }
     }
 
     private void logFailRowAndIncreaseCounter(Context context, Counters counter, Result row) {
       context.getCounter(counter).increment(1);
       context.getCounter(Counters.BADROWS).increment(1);
       LOG.error(counter.toString() + ", rowkey=" + Bytes.toString(row.getRow()));
     }
 
     @Override
     protected void cleanup(Context context) {
       if (replicatedScanner != null) {
         try {
           while (currentCompareRowInPeerTable != null) {
             logFailRowAndIncreaseCounter(context, Counters.ONLY_IN_PEER_TABLE_ROWS,
               currentCompareRowInPeerTable);
             currentCompareRowInPeerTable = replicatedScanner.next();
           }
         } catch (Exception e) {
           LOG.error("fail to scan peer table in cleanup", e);
         } finally {
           replicatedScanner.close();
           replicatedScanner = null;
         }
       }
       if (replicatedTable != null) {
         TableName tableName = replicatedTable.getName();
         try {
           replicatedTable.close();
         } catch (IOException ioe) {
           LOG.warn("Exception closing " + tableName, ioe);
         }
       }
     }
   }
 
   private static String getPeerQuorumAddress(final Configuration conf) throws IOException {
     ZooKeeperWatcher localZKW = null;
     ReplicationPeerZKImpl peer = null;
     try {
       localZKW = new ZooKeeperWatcher(conf, "VerifyReplication",
           new Abortable() {
             @Override public void abort(String why, Throwable e) {}
             @Override public boolean isAborted() {return false;}
           });
 
       ReplicationPeers rp = ReplicationFactory.getReplicationPeers(localZKW, conf, localZKW);
       rp.init();
 
       Pair<ReplicationPeerConfig, Configuration> pair = rp.getPeerConf(peerId);
       if (pair == null) {
         throw new IOException("Couldn't get peer conf!");
       }
       Configuration peerConf = rp.getPeerConf(peerId).getSecond();
       return ZKUtil.getZooKeeperClusterKey(peerConf);
     } catch (ReplicationException e) {
       throw new IOException(
           "An error occured while trying to connect to the remove peer cluster", e);
     } finally {
       if (peer != null) {
         peer.close();
       }
       if (localZKW != null) {
         localZKW.close();
       }
     }
   }
 
   /**
    * Sets up the actual job.
    *
    * @param conf  The current configuration.
    * @param args  The command line parameters.
    * @return The newly created job.
    * @throws java.io.IOException When setting up the job fails.
    */
   public static Job createSubmittableJob(Configuration conf, String[] args)
   throws IOException {
     if (!doCommandLine(args)) {
       return null;
     }
     if (!conf.getBoolean(HConstants.REPLICATION_ENABLE_KEY,
         HConstants.REPLICATION_ENABLE_DEFAULT)) {
       throw new IOException("Replication needs to be enabled to verify it.");
     }
     conf.set(NAME+".peerId", peerId);
     conf.set(NAME+".tableName", tableName);
     conf.setLong(NAME+".startTime", startTime);
     conf.setLong(NAME+".endTime", endTime);
     if (families != null) {
       conf.set(NAME+".families", families);
     }
 
     String peerQuorumAddress = getPeerQuorumAddress(conf);
     conf.set(NAME + ".peerQuorumAddress", peerQuorumAddress);
     LOG.info("Peer Quorum Address: " + peerQuorumAddress);
 
     Job job = new Job(conf, NAME + "_" + tableName);
     job.setJarByClass(VerifyReplication.class);
 
     Scan scan = new Scan();
     scan.setTimeRange(startTime, endTime);
     if (versions >= 0) {
       scan.setMaxVersions(versions);
     }
     if(families != null) {
       String[] fams = families.split(",");
       for(String fam : fams) {
         scan.addFamily(Bytes.toBytes(fam));
       }
     }
     TableMapReduceUtil.initTableMapperJob(tableName, scan,
         Verifier.class, null, null, job);
 
     // Obtain the auth token from peer cluster
     TableMapReduceUtil.initCredentialsForCluster(job, peerQuorumAddress);
 
     job.setOutputFormatClass(NullOutputFormat.class);
     job.setNumReduceTasks(0);
     return job;
   }
 
   private static boolean doCommandLine(final String[] args) {
     if (args.length < 2) {
       printUsage(null);
       return false;
     }
     try {
       for (int i = 0; i < args.length; i++) {
         String cmd = args[i];
         if (cmd.equals("-h") || cmd.startsWith("--h")) {
           printUsage(null);
           return false;
         }
 
         final String startTimeArgKey = "--starttime=";
         if (cmd.startsWith(startTimeArgKey)) {
           startTime = Long.parseLong(cmd.substring(startTimeArgKey.length()));
           continue;
         }
 
         final String endTimeArgKey = "--endtime=";
         if (cmd.startsWith(endTimeArgKey)) {
           endTime = Long.parseLong(cmd.substring(endTimeArgKey.length()));
           continue;
         }
 
         final String versionsArgKey = "--versions=";
         if (cmd.startsWith(versionsArgKey)) {
           versions = Integer.parseInt(cmd.substring(versionsArgKey.length()));
           continue;
         }
 
         final String familiesArgKey = "--families=";
         if (cmd.startsWith(familiesArgKey)) {
           families = cmd.substring(familiesArgKey.length());
           continue;
         }
 
         if (i == args.length-2) {
           peerId = cmd;
         }
 
         if (i == args.length-1) {
           tableName = cmd;
         }
       }
     } catch (Exception e) {
       e.printStackTrace();
       printUsage("Can't start because " + e.getMessage());
       return false;
     }
     return true;
   }
 
   /*
    * @param errorMsg Error message.  Can be null.
    */
   private static void printUsage(final String errorMsg) {
     if (errorMsg != null && errorMsg.length() > 0) {
       System.err.println("ERROR: " + errorMsg);
     }
     System.err.println("Usage: verifyrep [--starttime=X]" +
         " [--stoptime=Y] [--families=A] <peerid> <tablename>");
     System.err.println();
     System.err.println("Options:");
     System.err.println(" starttime    beginning of the time range");
     System.err.println("              without endtime means from starttime to forever");
     System.err.println(" endtime      end of the time range");
     System.err.println(" versions     number of cell versions to verify");
     System.err.println(" families     comma-separated list of families to copy");
     System.err.println();
     System.err.println("Args:");
     System.err.println(" peerid       Id of the peer used for verification, must match the one given for replication");
     System.err.println(" tablename    Name of the table to verify");
     System.err.println();
     System.err.println("Examples:");
     System.err.println(" To verify the data replicated from TestTable for a 1 hour window with peer #5 ");
     System.err.println(" $ bin/hbase " +
         "org.apache.hadoop.hbase.mapreduce.replication.VerifyReplication" +
         " --starttime=1265875194289 --endtime=1265878794289 5 TestTable ");
   }
 
   @Override
   public int run(String[] args) throws Exception {
     Configuration conf = this.getConf();
     Job job = createSubmittableJob(conf, args);
     if (job != null) {
       return job.waitForCompletion(true) ? 0 : 1;
     } 
     return 1;
   }
 
   /**
    * Main entry point.
    *
    * @param args  The command line parameters.
    * @throws Exception When running the job fails.
    */
   public static void main(String[] args) throws Exception {
     int res = ToolRunner.run(HBaseConfiguration.create(), new VerifyReplication(), args);
     System.exit(res);
   }
 }