/**
    * 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.filter;
  
  import com.google.common.base.Preconditions;
  import com.google.protobuf.InvalidProtocolBufferException;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.TreeSet;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.KeyValueUtil;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.exceptions.DeserializationException;
  import org.apache.hadoop.hbase.protobuf.generated.FilterProtos;
  
  /**
   * Filter that returns only cells whose timestamp (version) is
   * in the specified list of timestamps (versions).
   * <p>
   * Note: Use of this filter overrides any time range/time stamp
   * options specified using {@link org.apache.hadoop.hbase.client.Get#setTimeRange(long, long)},
   * {@link org.apache.hadoop.hbase.client.Scan#setTimeRange(long, long)}, {@link org.apache.hadoop.hbase.client.Get#setTimeStamp(long)},
   * or {@link org.apache.hadoop.hbase.client.Scan#setTimeStamp(long)}.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class TimestampsFilter extends FilterBase {
  
    private final boolean canHint;
    TreeSet<Long> timestamps;
    private static final int MAX_LOG_TIMESTAMPS = 5;
  
    // Used during scans to hint the scan to stop early
    // once the timestamps fall below the minTimeStamp.
    long minTimeStamp = Long.MAX_VALUE;
  
    /**
     * Constructor for filter that retains only the specified timestamps in the list.
     * @param timestamps
     */
    public TimestampsFilter(List<Long> timestamps) {
      this(timestamps, false);
    }
  
    /**
     * Constructor for filter that retains only those
     * cells whose timestamp (version) is in the specified
     * list of timestamps.
     *
     * @param timestamps list of timestamps that are wanted.
     * @param canHint should the filter provide a seek hint? This can skip
     *                past delete tombstones, so it should only be used when that
     *                is not an issue ( no deletes, or don't care if data
     *                becomes visible)
     */
    public TimestampsFilter(List<Long> timestamps, boolean canHint) {
      for (Long timestamp : timestamps) {
        Preconditions.checkArgument(timestamp >= 0, "must be positive %s", timestamp);
      }
      this.canHint = canHint;
      this.timestamps = new TreeSet<Long>(timestamps);
      init();
    }
  
    /**
     * @return the list of timestamps
     */
    public List<Long> getTimestamps() {
      List<Long> list = new ArrayList<Long>(timestamps.size());
      list.addAll(timestamps);
      return list;
    }
  
    private void init() {
      if (this.timestamps.size() > 0) {
        minTimeStamp = this.timestamps.first();
      }
    }
  
    /**
     * Gets the minimum timestamp requested by filter.
    * @return  minimum timestamp requested by filter.
    */
   public long getMin() {
     return minTimeStamp;
   }
 
   @Override
   public ReturnCode filterKeyValue(Cell v) {
     if (this.timestamps.contains(v.getTimestamp())) {
       return ReturnCode.INCLUDE;
     } else if (v.getTimestamp() < minTimeStamp) {
       // The remaining versions of this column are guaranteed
       // to be lesser than all of the other values.
       return ReturnCode.NEXT_COL;
     }
     return canHint ? ReturnCode.SEEK_NEXT_USING_HINT : ReturnCode.SKIP;
   }
 
 
   /**
    * Pick the next cell that the scanner should seek to. Since this can skip any number of cells
    * any of which can be a delete this can resurect old data.
    *
    * The method will only be used if canHint was set to true while creating the filter.
    *
    * @throws IOException This will never happen.
    */
   @Override
   public Cell getNextCellHint(Cell currentCell) throws IOException {
     if (!canHint) {
       return null;
     }
 
     Long nextTimestampObject = timestamps.lower(currentCell.getTimestamp());
 
     if (nextTimestampObject == null) {
       // This should only happen if the current column's
       // timestamp is below the last one in the list.
       //
       // It should never happen as the filterKeyValue should return NEXT_COL
       // but it's always better to be extra safe and protect against future
       // behavioral changes.
 
       return KeyValueUtil.createLastOnRowCol(currentCell);
     }
 
     // Since we know the nextTimestampObject isn't null here there must still be
     // timestamps that can be included. Cast the Long to a long and return the
     // a cell with the current row/cf/col and the next found timestamp.
     long nextTimestamp = nextTimestampObject;
     return KeyValueUtil.createFirstOnRowColTS(currentCell, nextTimestamp);
   }
 
   // Override here explicitly as the method in super class FilterBase might do a KeyValue recreate.
   // See HBASE-12068
   @Override
   public Cell transformCell(Cell v) {
     return v;
   }
 
   public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
     ArrayList<Long> timestamps = new ArrayList<Long>();
     for (int i = 0; i<filterArguments.size(); i++) {
       long timestamp = ParseFilter.convertByteArrayToLong(filterArguments.get(i));
       timestamps.add(timestamp);
     }
     return new TimestampsFilter(timestamps);
   }
 
   /**
    * @return The filter serialized using pb
    */
   @Override
   public byte[] toByteArray() {
     FilterProtos.TimestampsFilter.Builder builder =
         FilterProtos.TimestampsFilter.newBuilder();
     builder.addAllTimestamps(this.timestamps);
     builder.setCanHint(canHint);
     return builder.build().toByteArray();
   }
 
   /**
    * @param pbBytes A pb serialized {@link TimestampsFilter} instance
    *
    * @return An instance of {@link TimestampsFilter} made from <code>bytes</code>
    * @see #toByteArray
    */
   public static TimestampsFilter parseFrom(final byte[] pbBytes)
       throws DeserializationException {
     FilterProtos.TimestampsFilter proto;
     try {
       proto = FilterProtos.TimestampsFilter.parseFrom(pbBytes);
     } catch (InvalidProtocolBufferException e) {
       throw new DeserializationException(e);
     }
     return new TimestampsFilter(proto.getTimestampsList(),
         proto.hasCanHint() && proto.getCanHint());
   }
 
   /**
    * @param other
    * @return true if and only if the fields of the filter that are serialized
    * are equal to the corresponding fields in other.  Used for testing.
    */
   @Override
   boolean areSerializedFieldsEqual(Filter o) {
     if (o == this) return true;
     if (!(o instanceof TimestampsFilter)) return false;
 
     TimestampsFilter other = (TimestampsFilter)o;
     return this.getTimestamps().equals(other.getTimestamps());
   }
 
   @Override
   public String toString() {
     return toString(MAX_LOG_TIMESTAMPS);
   }
 
   protected String toString(int maxTimestamps) {
     StringBuilder tsList = new StringBuilder();
 
     int count = 0;
     for (Long ts : this.timestamps) {
       if (count >= maxTimestamps) {
         break;
       }
       ++count;
       tsList.append(ts.toString());
       if (count < this.timestamps.size() && count < maxTimestamps) {
         tsList.append(", ");
       }
     }
 
     return String.format("%s (%d/%d): [%s] canHint: [%b]", this.getClass().getSimpleName(),
         count, this.timestamps.size(), tsList.toString(), canHint);
   }
 }