/**
    *
    * 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 org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.exceptions.DeserializationException;
  import org.apache.hadoop.hbase.protobuf.generated.FilterProtos;
  
  import java.io.IOException;
  import java.util.ArrayList;
  
  /**
   * Implementation of Filter interface that limits results to a specific page
   * size. It terminates scanning once the number of filter-passed rows is >
   * the given page size.
   * <p>
   * Note that this filter cannot guarantee that the number of results returned
   * to a client are &lt;= page size. This is because the filter is applied
   * separately on different region servers. It does however optimize the scan of
   * individual HRegions by making sure that the page size is never exceeded
   * locally.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class PageFilter extends FilterBase {
    private long pageSize = Long.MAX_VALUE;
    private int rowsAccepted = 0;
  
    /**
     * Constructor that takes a maximum page size.
     *
     * @param pageSize Maximum result size.
     */
    public PageFilter(final long pageSize) {
      Preconditions.checkArgument(pageSize >= 0, "must be positive %s", pageSize);
      this.pageSize = pageSize;
    }
  
    public long getPageSize() {
      return pageSize;
    }
  
    @Override
    public ReturnCode filterKeyValue(Cell ignored) throws IOException {
      return ReturnCode.INCLUDE;
    }
  
    // 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;
    }
  
    @Override
    public boolean filterAllRemaining() {
      return this.rowsAccepted >= this.pageSize;
    }
  
    @Override
    public boolean filterRow() {
      this.rowsAccepted++;
      return this.rowsAccepted > this.pageSize;
    }
    
    @Override
    public boolean hasFilterRow() {
      return true;
    }
  
    public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
      Preconditions.checkArgument(filterArguments.size() == 1,
                                  "Expected 1 but got: %s", filterArguments.size());
      long pageSize = ParseFilter.convertByteArrayToLong(filterArguments.get(0));
      return new PageFilter(pageSize);
    }
  
    /**
     * @return The filter serialized using pb
    */
   @Override
   public byte [] toByteArray() {
     FilterProtos.PageFilter.Builder builder =
       FilterProtos.PageFilter.newBuilder();
     builder.setPageSize(this.pageSize);
     return builder.build().toByteArray();
   }
 
   /**
    * @param pbBytes A pb serialized {@link PageFilter} instance
    * @return An instance of {@link PageFilter} made from <code>bytes</code>
    * @throws DeserializationException
    * @see #toByteArray
    */
   public static PageFilter parseFrom(final byte [] pbBytes)
   throws DeserializationException {
     FilterProtos.PageFilter proto;
     try {
       proto = FilterProtos.PageFilter.parseFrom(pbBytes);
     } catch (InvalidProtocolBufferException e) {
       throw new DeserializationException(e);
     }
     return new PageFilter(proto.getPageSize());
   }
 
   /**
    * @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 PageFilter)) return false;
 
     PageFilter other = (PageFilter)o;
     return this.getPageSize() == other.getPageSize();
   }
 
   @Override
   public String toString() {
     return this.getClass().getSimpleName() + " " + this.pageSize;
   }
 }