content: package org.apache.solr.search.function.distance;
  /**
   * 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.
   */
  
  
  import org.apache.lucene.spatial.DistanceUtils;
  import org.apache.solr.search.function.ValueSource;
  import org.apache.solr.search.function.DocValues;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.search.Searcher;
  import org.apache.lucene.spatial.geohash.GeoHashUtils;
  
  import java.util.Map;
  import java.io.IOException;
  
  
  /**
   *  Calculate the Haversine distance between two geo hash codes.
   *
   * <p/>
   * Ex: ghhsin(ValueSource, ValueSource, radius)
   * <p/>
   *
   * @see org.apache.solr.search.function.distance.HaversineFunction for more details on the implementation
   *
   **/
  public class GeohashHaversineFunction extends ValueSource {
  
    private ValueSource geoHash1, geoHash2;
    private double radius;
  
    public GeohashHaversineFunction(ValueSource geoHash1, ValueSource geoHash2, double radius) {
      this.geoHash1 = geoHash1;
      this.geoHash2 = geoHash2;
      this.radius = radius;
    }
  
    protected String name() {
      return "ghhsin";
    }
  
    @Override
    public DocValues getValues(Map context, IndexReader reader) throws IOException {
      final DocValues gh1DV = geoHash1.getValues(context, reader);
      final DocValues gh2DV = geoHash2.getValues(context, reader);
  
      return new DocValues() {
        @Override
        public float floatVal(int doc) {
          return (float) doubleVal(doc);
        }
  
        @Override
        public int intVal(int doc) {
          return (int) doubleVal(doc);
        }
  
        @Override
        public long longVal(int doc) {
          return (long) doubleVal(doc);
        }
  
        @Override
        public double doubleVal(int doc) {
          return distance(doc, gh1DV, gh2DV);
        }
  
        @Override
        public String strVal(int doc) {
          return Double.toString(doubleVal(doc));
        }
  
        @Override
        public String toString(int doc) {
          StringBuilder sb = new StringBuilder();
          sb.append(name()).append('(');
          sb.append(gh1DV.toString(doc)).append(',').append(gh2DV.toString(doc));
          sb.append(')');
          return sb.toString();
        }
      };
    }
  
    protected double distance(int doc, DocValues gh1DV, DocValues gh2DV) {
      double result = 0;
      String h1 = gh1DV.strVal(doc);
      String h2 = gh2DV.strVal(doc);
      if (h1 != null && h2 != null && h1.equals(h2) == false){
        //TODO: If one of the hashes is a literal value source, seems like we could cache it
        //and avoid decoding every time
        double[] h1Pair = GeoHashUtils.decode(h1);
        double[] h2Pair = GeoHashUtils.decode(h2);
        result = DistanceUtils.haversine(Math.toRadians(h1Pair[0]), Math.toRadians(h1Pair[1]),
                Math.toRadians(h2Pair[0]), Math.toRadians(h2Pair[1]), radius);
      } else if (h1 == null || h2 == null){
        result = Double.MAX_VALUE;
      }
      return result;
    }
  
    @Override
    public void createWeight(Map context, Searcher searcher) throws IOException {
      geoHash1.createWeight(context, searcher);
      geoHash2.createWeight(context, searcher);
    }
  
    @Override
    public boolean equals(Object o) {
      if (this.getClass() != o.getClass()) return false;
      GeohashHaversineFunction other = (GeohashHaversineFunction) o;
      return this.name().equals(other.name())
              && geoHash1.equals(other.geoHash1) &&
              geoHash2.equals(other.geoHash2) &&
              radius == other.radius;
    }
  
    @Override
    public int hashCode() {
      int result;
      result = geoHash1.hashCode();
      result = 31 * result + geoHash2.hashCode();
      result = 31 * result + name().hashCode();
      long temp =Double.doubleToRawLongBits(radius);
      result = 31 * result + (int) (temp ^ (temp >>> 32));
      return result;
    }
  
    @Override
    public String description() {
      StringBuilder sb = new StringBuilder();
      sb.append(name()).append('(');
      sb.append(geoHash1).append(',').append(geoHash2);
      sb.append(')');
      return sb.toString();
    }
  }
  