content: package org.apache.lucene.search.payloads;
  
  /**
   * 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.index.Term;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.TermPositions;
  import org.apache.lucene.search.Searcher;
  import org.apache.lucene.search.Scorer;
  import org.apache.lucene.search.Weight;
  import org.apache.lucene.search.Similarity;
  import org.apache.lucene.search.Explanation;
  import org.apache.lucene.search.ComplexExplanation;
  import org.apache.lucene.search.spans.TermSpans;
  import org.apache.lucene.search.spans.SpanTermQuery;
  import org.apache.lucene.search.spans.SpanWeight;
  import org.apache.lucene.search.spans.SpanScorer;
  
  import java.io.IOException;
  
  /**
   * This class is very similar to
   * {@link org.apache.lucene.search.spans.SpanTermQuery} except that it factors
   * in the value of the payload located at each of the positions where the
   * {@link org.apache.lucene.index.Term} occurs.
   * <p>
   * In order to take advantage of this, you must override
   * {@link org.apache.lucene.search.Similarity#scorePayload(int, String, int, int, byte[],int,int)}
   * which returns 1 by default.
   * <p>
   * Payload scores are aggregated using a pluggable {@link PayloadFunction}.
   **/
  public class PayloadTermQuery extends SpanTermQuery {
    protected PayloadFunction function;
    private boolean includeSpanScore;
  
    public PayloadTermQuery(Term term, PayloadFunction function) {
      this(term, function, true);
    }
  
    public PayloadTermQuery(Term term, PayloadFunction function,
        boolean includeSpanScore) {
      super(term);
      this.function = function;
      this.includeSpanScore = includeSpanScore;
    }
  
    @Override
    public Weight createWeight(Searcher searcher) throws IOException {
      return new PayloadTermWeight(this, searcher);
    }
  
    protected class PayloadTermWeight extends SpanWeight {
  
      public PayloadTermWeight(PayloadTermQuery query, Searcher searcher)
          throws IOException {
        super(query, searcher);
      }
  
      @Override
      public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder,
          boolean topScorer) throws IOException {
        return new PayloadTermSpanScorer((TermSpans) query.getSpans(reader),
            this, similarity, reader.norms(query.getField()));
      }
      
      @Override
      public Explanation explain(IndexReader reader, int doc) throws IOException {
        if (includeSpanScore) {
          return super.explain(reader, doc);
        } else {
          // if we don't include the span score, we need to return our scorer's explanation only
          PayloadTermSpanScorer scorer = (PayloadTermSpanScorer) scorer(reader, true, false);
          return scorer.explain(doc);
        }
      }
  
      protected class PayloadTermSpanScorer extends SpanScorer {
        // TODO: is this the best way to allocate this?
        protected byte[] payload = new byte[256];
        protected TermPositions positions;
        protected float payloadScore;
        protected int payloadsSeen;
  
        public PayloadTermSpanScorer(TermSpans spans, Weight weight,
            Similarity similarity, byte[] norms) throws IOException {
          super(spans, weight, similarity, norms);
          positions = spans.getPositions();
        }
  
        @Override
        protected boolean setFreqCurrentDoc() throws IOException {
          if (!more) {
            return false;
          }
          doc = spans.doc();
          freq = 0.0f;
          payloadScore = 0;
          payloadsSeen = 0;
          Similarity similarity1 = getSimilarity();
          while (more && doc == spans.doc()) {
            int matchLength = spans.end() - spans.start();
  
            freq += similarity1.sloppyFreq(matchLength);
            processPayload(similarity1);
  
            more = spans.next();// this moves positions to the next match in this
                                // document
          }
          return more || (freq != 0);
        }
  
        protected void processPayload(Similarity similarity) throws IOException {
          if (positions.isPayloadAvailable()) {
            payload = positions.getPayload(payload, 0);
            payloadScore = function.currentScore(doc, term.field(),
                spans.start(), spans.end(), payloadsSeen, payloadScore,
                similarity.scorePayload(doc, term.field(), spans.start(), spans
                    .end(), payload, 0, positions.getPayloadLength()));
            payloadsSeen++;
  
          } else {
            // zero out the payload?
          }
        }
  
        /**
         * 
         * @return {@link #getSpanScore()} * {@link #getPayloadScore()}
         * @throws IOException
         */
        @Override
        public float score() throws IOException {
  
          return includeSpanScore ? getSpanScore() * getPayloadScore()
              : getPayloadScore();
        }
  
        /**
         * Returns the SpanScorer score only.
         * <p/>
         * Should not be overridden without good cause!
         * 
         * @return the score for just the Span part w/o the payload
         * @throws IOException
         * 
         * @see #score()
         */
        protected float getSpanScore() throws IOException {
          return super.score();
        }
  
        /**
         * The score for the payload
         * 
         * @return The score, as calculated by
         *         {@link PayloadFunction#docScore(int, String, int, float)}
         */
        protected float getPayloadScore() {
          return function.docScore(doc, term.field(), payloadsSeen, payloadScore);
        }
  
        @Override
        protected Explanation explain(final int doc) throws IOException {
          Explanation nonPayloadExpl = super.explain(doc);
          
          // QUESTION: Is there a way to avoid this skipTo call? We need to know
          // whether to load the payload or not
          Explanation payloadBoost = new Explanation();
  
          float payloadScore = getPayloadScore();
          payloadBoost.setValue(payloadScore);
          // GSI: I suppose we could toString the payload, but I don't think that
          // would be a good idea
          payloadBoost.setDescription("scorePayload(...)");
          
          ComplexExplanation result = new ComplexExplanation();
          if (includeSpanScore) {
            result.addDetail(nonPayloadExpl);
            result.addDetail(payloadBoost);
            result.setValue(nonPayloadExpl.getValue() * payloadScore);
            result.setDescription("btq, product of:");
          } else {
            result.addDetail(payloadBoost);
            result.setValue(payloadScore);
            result.setDescription("btq(includeSpanScore=false), result of:");
          }
          result.setMatch(nonPayloadExpl.getValue() == 0 ? Boolean.FALSE
              : Boolean.TRUE); // LUCENE-1303
          return result;
        }
  
      }
    }
  
    @Override
    public int hashCode() {
      final int prime = 31;
      int result = super.hashCode();
      result = prime * result + ((function == null) ? 0 : function.hashCode());
      result = prime * result + (includeSpanScore ? 1231 : 1237);
      return result;
    }
  
    @Override
    public boolean equals(Object obj) {
      if (this == obj)
        return true;
      if (!super.equals(obj))
        return false;
      if (getClass() != obj.getClass())
        return false;
      PayloadTermQuery other = (PayloadTermQuery) obj;
      if (function == null) {
        if (other.function != null)
          return false;
      } else if (!function.equals(other.function))
        return false;
      if (includeSpanScore != other.includeSpanScore)
        return false;
      return true;
    }
  
  }
  