/*
    * 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 java.io.IOException;
  import java.util.ArrayList;
  import java.util.Comparator;
  import java.util.TreeSet;
  
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellUtil;
  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;
  import org.apache.hadoop.hbase.util.ByteStringer;
  import org.apache.hadoop.hbase.util.Bytes;
  
  import com.google.protobuf.InvalidProtocolBufferException;
  
  /**
   * This filter is used for selecting only those keys with columns that matches
   * a particular prefix. For example, if prefix is 'an', it will pass keys will
   * columns like 'and', 'anti' but not keys with columns like 'ball', 'act'.
   */
  @InterfaceAudience.Public
  @InterfaceStability.Stable
  public class MultipleColumnPrefixFilter extends FilterBase {
    protected byte [] hint = null;
    protected TreeSet<byte []> sortedPrefixes = createTreeSet();
    private final static int MAX_LOG_PREFIXES = 5;
  
    public MultipleColumnPrefixFilter(final byte [][] prefixes) {
      if (prefixes != null) {
        for (int i = 0; i < prefixes.length; i++) {
          if (!sortedPrefixes.add(prefixes[i]))
            throw new IllegalArgumentException ("prefixes must be distinct");
        }
      }
    }
  
    public byte [][] getPrefix() {
      int count = 0;
      byte [][] temp = new byte [sortedPrefixes.size()][];
      for (byte [] prefixes : sortedPrefixes) {
        temp [count++] = prefixes;
      }
      return temp;
    }
  
    @Override
    public boolean filterRowKey(Cell cell) throws IOException {
      // Impl in FilterBase might do unnecessary copy for Off heap backed Cells.
      return false;
    }
  
    @Override
    public ReturnCode filterKeyValue(Cell kv) {
      if (sortedPrefixes.size() == 0) {
        return ReturnCode.INCLUDE;
      } else {
        return filterColumn(kv);
      }
    }
  
    public ReturnCode filterColumn(Cell cell) {
      byte [] qualifier = CellUtil.cloneQualifier(cell);
      TreeSet<byte []> lesserOrEqualPrefixes =
        (TreeSet<byte []>) sortedPrefixes.headSet(qualifier, true);
  
      if (lesserOrEqualPrefixes.size() != 0) {
        byte [] largestPrefixSmallerThanQualifier = lesserOrEqualPrefixes.last();
        
        if (Bytes.startsWith(qualifier, largestPrefixSmallerThanQualifier)) {
          return ReturnCode.INCLUDE;
        }
        
        if (lesserOrEqualPrefixes.size() == sortedPrefixes.size()) {
          return ReturnCode.NEXT_ROW;
        } else {
          hint = sortedPrefixes.higher(largestPrefixSmallerThanQualifier);
          return ReturnCode.SEEK_NEXT_USING_HINT;
        }
      } else {
       hint = sortedPrefixes.first();
       return ReturnCode.SEEK_NEXT_USING_HINT;
     }
   }
 
   public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
     byte [][] prefixes = new byte [filterArguments.size()][];
     for (int i = 0 ; i < filterArguments.size(); i++) {
       byte [] columnPrefix = ParseFilter.removeQuotesFromByteArray(filterArguments.get(i));
       prefixes[i] = columnPrefix;
     }
     return new MultipleColumnPrefixFilter(prefixes);
   }
 
   /**
    * @return The filter serialized using pb
    */
   public byte [] toByteArray() {
     FilterProtos.MultipleColumnPrefixFilter.Builder builder =
       FilterProtos.MultipleColumnPrefixFilter.newBuilder();
     for (byte [] element : sortedPrefixes) {
       if (element != null) builder.addSortedPrefixes(ByteStringer.wrap(element));
     }
     return builder.build().toByteArray();
   }
 
   /**
    * @param pbBytes A pb serialized {@link MultipleColumnPrefixFilter} instance
    * @return An instance of {@link MultipleColumnPrefixFilter} made from <code>bytes</code>
    * @throws DeserializationException
    * @see #toByteArray
    */
   public static MultipleColumnPrefixFilter parseFrom(final byte [] pbBytes)
   throws DeserializationException {
     FilterProtos.MultipleColumnPrefixFilter proto;
     try {
       proto = FilterProtos.MultipleColumnPrefixFilter.parseFrom(pbBytes);
     } catch (InvalidProtocolBufferException e) {
       throw new DeserializationException(e);
     }
     int numPrefixes = proto.getSortedPrefixesCount();
     byte [][] prefixes = new byte[numPrefixes][];
     for (int i = 0; i < numPrefixes; ++i) {
       prefixes[i] = proto.getSortedPrefixes(i).toByteArray();
     }
 
     return new MultipleColumnPrefixFilter(prefixes);
   }
 
   /**
    * @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.
    */
   boolean areSerializedFieldsEqual(Filter o) {
     if (o == this) return true;
     if (!(o instanceof MultipleColumnPrefixFilter)) return false;
 
     MultipleColumnPrefixFilter other = (MultipleColumnPrefixFilter)o;
     return this.sortedPrefixes.equals(other.sortedPrefixes);
   }
 
   @Override
   public Cell getNextCellHint(Cell cell) {
     return CellUtil.createFirstOnRowCol(cell, hint, 0, hint.length);
   }
 
   public TreeSet<byte []> createTreeSet() {
     return new TreeSet<byte []>(new Comparator<Object>() {
         @Override
           public int compare (Object o1, Object o2) {
           if (o1 == null || o2 == null)
             throw new IllegalArgumentException ("prefixes can't be null");
 
           byte [] b1 = (byte []) o1;
           byte [] b2 = (byte []) o2;
           return Bytes.compareTo (b1, 0, b1.length, b2, 0, b2.length);
         }
       });
   }
 
   @Override
   public String toString() {
     return toString(MAX_LOG_PREFIXES);
   }
 
   protected String toString(int maxPrefixes) {
     StringBuilder prefixes = new StringBuilder();
 
     int count = 0;
     for (byte[] ba : this.sortedPrefixes) {
       if (count >= maxPrefixes) {
         break;
       }
       ++count;
       prefixes.append(Bytes.toStringBinary(ba));
       if (count < this.sortedPrefixes.size() && count < maxPrefixes) {
         prefixes.append(", ");
       }
     }
 
     return String.format("%s (%d/%d): [%s]", this.getClass().getSimpleName(),
         count, this.sortedPrefixes.size(), prefixes.toString());
   }
 }