/**
    *
    * 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.regionserver.wal;
  
  import java.io.DataInput;
  import java.io.DataOutput;
  import java.io.EOFException;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.NavigableMap;
  import java.util.TreeMap;
  import java.util.UUID;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  import org.apache.hadoop.hbase.protobuf.generated.WALProtos.FamilyScope;
  import org.apache.hadoop.hbase.protobuf.generated.WALProtos.ScopeType;
  import org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.io.WritableComparable;
  import org.apache.hadoop.io.WritableUtils;
  
  import com.google.protobuf.ByteString;
  
  /**
   * A Key for an entry in the change log.
   *
   * The log intermingles edits to many tables and rows, so each log entry
   * identifies the appropriate table and row.  Within a table and row, they're
   * also sorted.
   *
   * <p>Some Transactional edits (START, COMMIT, ABORT) will not have an
   * associated row.
   */
  // TODO: Key and WALEdit are never used separately, or in one-to-many relation, for practical
  //       purposes. They need to be merged into HLogEntry.
  @InterfaceAudience.Private
  public class HLogKey implements WritableComparable<HLogKey> {
    public static final Log LOG = LogFactory.getLog(HLogKey.class);
  
    // should be < 0 (@see #readFields(DataInput))
    // version 2 supports HLog compression
    enum Version {
      UNVERSIONED(0),
      // Initial number we put on HLogKey when we introduced versioning.
      INITIAL(-1),
      // Version -2 introduced a dictionary compression facility.  Only this
      // dictionary-based compression is available in version -2.
      COMPRESSED(-2);
  
      final int code;
      static final Version[] byCode;
      static {
        byCode = Version.values();
        for (int i = 0; i < byCode.length; i++) {
          if (byCode[i].code != -1 * i) {
            throw new AssertionError("Values in this enum should be descending by one");
          }
        }
      }
  
      Version(int code) {
        this.code = code;
      }
  
      boolean atLeast(Version other) {
        return code <= other.code;
      }
  
      static Version fromCode(int code) {
        return byCode[code * -1];
      }
    }
  
    private static final Version VERSION = Version.COMPRESSED;
  
    //  The encoded region name.
    private byte [] encodedRegionName;
   private byte [] tablename;
   private long logSeqNum;
   // Time at which this edit was written.
   private long writeTime;
 
   private UUID clusterId;
 
   private NavigableMap<byte[], Integer> scopes;
 
   private CompressionContext compressionContext;
 
   public HLogKey() {
     this(null, null, 0L, HConstants.LATEST_TIMESTAMP,
         HConstants.DEFAULT_CLUSTER_ID);
   }
 
   /**
    * Create the log key for writing to somewhere.
    * We maintain the tablename mainly for debugging purposes.
    * A regionName is always a sub-table object.
    *
    * @param encodedRegionName Encoded name of the region as returned by
    * <code>HRegionInfo#getEncodedNameAsBytes()</code>.
    * @param tablename   - name of table
    * @param logSeqNum   - log sequence number
    * @param now Time at which this edit was written.
    * @param clusterId of the cluster (used in Replication)
    */
   public HLogKey(final byte [] encodedRegionName, final byte [] tablename,
       long logSeqNum, final long now, UUID clusterId) {
     this.logSeqNum = logSeqNum;
     this.writeTime = now;
     this.clusterId = clusterId;
     this.encodedRegionName = encodedRegionName;
     this.tablename = tablename;
   }
 
   /**
    * Create HLogKey wrapper around protobuf WAL key; takes care of compression.
    * @throws IOException Never, as the compression is not enabled.
    */
   public HLogKey(WALKey walKey) throws IOException {
     readFieldsFromPb(walKey, null);
   }
 
   /**
    * @param compressionContext Compression context to use
    */
   public void setCompressionContext(CompressionContext compressionContext) {
     this.compressionContext = compressionContext;
   }
 
   /** @return encoded region name */
   public byte [] getEncodedRegionName() {
     return encodedRegionName;
   }
 
   /** @return table name */
   public byte [] getTablename() {
     return tablename;
   }
 
   /** @return log sequence number */
   public long getLogSeqNum() {
     return this.logSeqNum;
   }
 
   /**
    * @return the write time
    */
   public long getWriteTime() {
     return this.writeTime;
   }
 
   /**
    * Get the id of the original cluster
    * @return Cluster id.
    */
   public UUID getClusterId() {
     return clusterId;
   }
 
   public NavigableMap<byte[], Integer> getScopes() {
     return scopes;
   }
 
   public void setScopes(NavigableMap<byte[], Integer> scopes) {
     this.scopes = scopes;
   }
 
   /**
    * Set the cluster id of this key.
    * @param clusterId
    */
   public void setClusterId(UUID clusterId) {
     this.clusterId = clusterId;
   }
 
   @Override
   public String toString() {
     return Bytes.toString(tablename) + "/" + Bytes.toString(encodedRegionName) + "/" +
       logSeqNum;
   }
 
   /**
    * Produces a string map for this key. Useful for programmatic use and
    * manipulation of the data stored in an HLogKey, for example, printing 
    * as JSON.
    * 
    * @return a Map containing data from this key
    */
   public Map<String, Object> toStringMap() {
     Map<String, Object> stringMap = new HashMap<String, Object>();
     stringMap.put("table", Bytes.toStringBinary(tablename));
     stringMap.put("region", Bytes.toStringBinary(encodedRegionName));
     stringMap.put("sequence", logSeqNum);
     return stringMap;
   }
 
   @Override
   public boolean equals(Object obj) {
     if (this == obj) {
       return true;
     }
     if (obj == null || getClass() != obj.getClass()) {
       return false;
     }
     return compareTo((HLogKey)obj) == 0;
   }
 
   @Override
   public int hashCode() {
     int result = Bytes.hashCode(this.encodedRegionName);
     result ^= this.logSeqNum;
     result ^= this.writeTime;
     result ^= this.clusterId.hashCode();
     return result;
   }
 
   public int compareTo(HLogKey o) {
     int result = Bytes.compareTo(this.encodedRegionName, o.encodedRegionName);
     if (result == 0) {
       if (this.logSeqNum < o.logSeqNum) {
         result = -1;
       } else if (this.logSeqNum  > o.logSeqNum ) {
         result = 1;
       }
       if (result == 0) {
         if (this.writeTime < o.writeTime) {
           result = -1;
         } else if (this.writeTime > o.writeTime) {
           return 1;
         }
       }
     }
     // why isn't cluster id accounted for?
     return result;
   }
 
   /**
    * Drop this instance's tablename byte array and instead
    * hold a reference to the provided tablename. This is not
    * meant to be a general purpose setter - it's only used
    * to collapse references to conserve memory.
    */
   void internTableName(byte []tablename) {
     // We should not use this as a setter - only to swap
     // in a new reference to the same table name.
     assert Bytes.equals(tablename, this.tablename);
     this.tablename = tablename;
   }
 
   /**
    * Drop this instance's region name byte array and instead
    * hold a reference to the provided region name. This is not
    * meant to be a general purpose setter - it's only used
    * to collapse references to conserve memory.
    */
   void internEncodedRegionName(byte []encodedRegionName) {
     // We should not use this as a setter - only to swap
     // in a new reference to the same table name.
     assert Bytes.equals(this.encodedRegionName, encodedRegionName);
     this.encodedRegionName = encodedRegionName;
   }
 
   @Override
   @Deprecated
   public void write(DataOutput out) throws IOException {
     LOG.warn("HLogKey is being serialized to writable - only expected in test code");
     WritableUtils.writeVInt(out, VERSION.code);
     if (compressionContext == null) {
       Bytes.writeByteArray(out, this.encodedRegionName);
       Bytes.writeByteArray(out, this.tablename);
     } else {
       Compressor.writeCompressed(this.encodedRegionName, 0,
           this.encodedRegionName.length, out,
           compressionContext.regionDict);
       Compressor.writeCompressed(this.tablename, 0, this.tablename.length, out,
           compressionContext.tableDict);
     }
     out.writeLong(this.logSeqNum);
     out.writeLong(this.writeTime);
     // avoid storing 16 bytes when replication is not enabled
     if (this.clusterId == HConstants.DEFAULT_CLUSTER_ID) {
       out.writeBoolean(false);
     } else {
       out.writeBoolean(true);
       out.writeLong(this.clusterId.getMostSignificantBits());
       out.writeLong(this.clusterId.getLeastSignificantBits());
     }
   }
 
   @Override
   public void readFields(DataInput in) throws IOException {
     Version version = Version.UNVERSIONED;
     // HLogKey was not versioned in the beginning.
     // In order to introduce it now, we make use of the fact
     // that encodedRegionName was written with Bytes.writeByteArray,
     // which encodes the array length as a vint which is >= 0.
     // Hence if the vint is >= 0 we have an old version and the vint
     // encodes the length of encodedRegionName.
     // If < 0 we just read the version and the next vint is the length.
     // @see Bytes#readByteArray(DataInput)
     this.scopes = null; // writable HLogKey does not contain scopes
     int len = WritableUtils.readVInt(in);
     if (len < 0) {
       // what we just read was the version
       version = Version.fromCode(len);
       // We only compress V2 of HLogkey.
       // If compression is on, the length is handled by the dictionary
       if (compressionContext == null || !version.atLeast(Version.COMPRESSED)) {
         len = WritableUtils.readVInt(in);
       }
     }
     if (compressionContext == null || !version.atLeast(Version.COMPRESSED)) {
       this.encodedRegionName = new byte[len];
       in.readFully(this.encodedRegionName);
       this.tablename = Bytes.readByteArray(in);
     } else {
       this.encodedRegionName = Compressor.readCompressed(in, compressionContext.regionDict);
       this.tablename = Compressor.readCompressed(in, compressionContext.tableDict);
     }
 
     this.logSeqNum = in.readLong();
     this.writeTime = in.readLong();
     this.clusterId = HConstants.DEFAULT_CLUSTER_ID;
     if (version.atLeast(Version.INITIAL)) {
       if (in.readBoolean()) {
         this.clusterId = new UUID(in.readLong(), in.readLong());
       }
     } else {
       try {
         // dummy read (former byte cluster id)
         in.readByte();
       } catch(EOFException e) {
         // Means it's a very old key, just continue
       }
     }
   }
 
   public WALKey.Builder getBuilder(
       WALCellCodec.ByteStringCompressor compressor) throws IOException {
     WALKey.Builder builder = WALKey.newBuilder();
     if (compressionContext == null) {
       builder.setEncodedRegionName(ByteString.copyFrom(this.encodedRegionName));
       builder.setTableName(ByteString.copyFrom(this.tablename));
     } else {
       builder.setEncodedRegionName(
           compressor.compress(this.encodedRegionName, compressionContext.regionDict));
       builder.setTableName(compressor.compress(this.tablename, compressionContext.tableDict));
     }
     builder.setLogSequenceNumber(this.logSeqNum);
     builder.setWriteTime(writeTime);
     if (this.clusterId != HConstants.DEFAULT_CLUSTER_ID) {
       builder.setClusterId(HBaseProtos.UUID.newBuilder()
           .setLeastSigBits(this.clusterId.getLeastSignificantBits())
           .setMostSigBits(this.clusterId.getMostSignificantBits()));
     }
     if (scopes != null) {
       for (Map.Entry<byte[], Integer> e : scopes.entrySet()) {
         ByteString family = (compressionContext == null) ? ByteString.copyFrom(e.getKey())
             : compressor.compress(e.getKey(), compressionContext.familyDict);
         builder.addScopes(FamilyScope.newBuilder()
             .setFamily(family).setScopeType(ScopeType.valueOf(e.getValue())));
       }
     }
     return builder;
   }
 
   public void readFieldsFromPb(
       WALKey walKey, WALCellCodec.ByteStringUncompressor uncompressor) throws IOException {
     if (this.compressionContext != null) {
       this.encodedRegionName = uncompressor.uncompress(
           walKey.getEncodedRegionName(), compressionContext.regionDict);
       this.tablename = uncompressor.uncompress(
           walKey.getTableName(), compressionContext.tableDict);
     } else {
       this.encodedRegionName = walKey.getEncodedRegionName().toByteArray();
       this.tablename = walKey.getTableName().toByteArray();
     }
     this.clusterId = HConstants.DEFAULT_CLUSTER_ID;
     if (walKey.hasClusterId()) {
       this.clusterId = new UUID(
           walKey.getClusterId().getMostSigBits(), walKey.getClusterId().getLeastSigBits());
     }
     this.scopes = null;
     if (walKey.getScopesCount() > 0) {
       this.scopes = new TreeMap<byte[], Integer>(Bytes.BYTES_COMPARATOR);
       for (FamilyScope scope : walKey.getScopesList()) {
         byte[] family = (compressionContext == null) ? scope.getFamily().toByteArray() :
           uncompressor.uncompress(scope.getFamily(), compressionContext.familyDict);
         this.scopes.put(family, scope.getScopeType().getNumber());
       }
     }
     this.logSeqNum = walKey.getLogSequenceNumber();
     this.writeTime = walKey.getWriteTime();
   }
 }