content: package org.apache.lucene.search.function;
  
  /**
   * 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 java.io.IOException;
  import java.util.Set;
  import java.util.Arrays;
  
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.index.Term;
  import org.apache.lucene.search.ComplexExplanation;
  import org.apache.lucene.search.Explanation;
  import org.apache.lucene.search.Query;
  import org.apache.lucene.search.Weight;
  import org.apache.lucene.search.Scorer;
  import org.apache.lucene.search.Searcher;
  import org.apache.lucene.search.Similarity;
  import org.apache.lucene.util.ToStringUtils;
  
  /**
   * Query that sets document score as a programmatic function of several (sub) scores:
   * <ol>
   *    <li>the score of its subQuery (any query)</li>
   *    <li>(optional) the score of its ValueSourceQuery (or queries).
   *        For most simple/convenient use cases this query is likely to be a 
   *        {@link org.apache.lucene.search.function.FieldScoreQuery FieldScoreQuery}</li>
   * </ol>
   * Subclasses can modify the computation by overriding {@link #getCustomScoreProvider}.
   * 
   * @lucene.experimental
   */
  public class CustomScoreQuery extends Query {
  
    private Query subQuery;
    private ValueSourceQuery[] valSrcQueries; // never null (empty array if there are no valSrcQueries).
    private boolean strict = false; // if true, valueSource part of query does not take part in weights normalization.  
    
    /**
     * Create a CustomScoreQuery over input subQuery.
     * @param subQuery the sub query whose scored is being customized. Must not be null. 
     */
    public CustomScoreQuery(Query subQuery) {
      this(subQuery, new ValueSourceQuery[0]);
    }
  
    /**
     * Create a CustomScoreQuery over input subQuery and a {@link ValueSourceQuery}.
     * @param subQuery the sub query whose score is being customized. Must not be null.
     * @param valSrcQuery a value source query whose scores are used in the custom score
     * computation. For most simple/convenient use case this would be a 
     * {@link org.apache.lucene.search.function.FieldScoreQuery FieldScoreQuery}.
     * This parameter is optional - it can be null.
     */
    public CustomScoreQuery(Query subQuery, ValueSourceQuery valSrcQuery) {
  	  this(subQuery, valSrcQuery!=null ? // don't want an array that contains a single null.. 
          new ValueSourceQuery[] {valSrcQuery} : new ValueSourceQuery[0]);
    }
  
    /**
     * Create a CustomScoreQuery over input subQuery and a {@link ValueSourceQuery}.
     * @param subQuery the sub query whose score is being customized. Must not be null.
     * @param valSrcQueries value source queries whose scores are used in the custom score
     * computation. For most simple/convenient use case these would be 
     * {@link org.apache.lucene.search.function.FieldScoreQuery FieldScoreQueries}.
     * This parameter is optional - it can be null or even an empty array.
     */
    public CustomScoreQuery(Query subQuery, ValueSourceQuery... valSrcQueries) {
      this.subQuery = subQuery;
      this.valSrcQueries = valSrcQueries!=null?
          valSrcQueries : new ValueSourceQuery[0];
      if (subQuery == null) throw new IllegalArgumentException("<subquery> must not be null!");
    }
  
    /*(non-Javadoc) @see org.apache.lucene.search.Query#rewrite(org.apache.lucene.index.IndexReader) */
    @Override
    public Query rewrite(IndexReader reader) throws IOException {
      CustomScoreQuery clone = null;
      
      final Query sq = subQuery.rewrite(reader);
      if (sq != subQuery) {
        clone = (CustomScoreQuery) clone();
        clone.subQuery = sq;
      }
  
      for(int i = 0; i < valSrcQueries.length; i++) {
        final ValueSourceQuery v = (ValueSourceQuery) valSrcQueries[i].rewrite(reader);
        if (v != valSrcQueries[i]) {
          if (clone == null) clone = (CustomScoreQuery) clone();
          clone.valSrcQueries[i] = v;
        }
      }
      
      return (clone == null) ? this : clone;
    }
  
    /*(non-Javadoc) @see org.apache.lucene.search.Query#extractTerms(java.util.Set) */
    @Override
    public void extractTerms(Set<Term> terms) {
      subQuery.extractTerms(terms);
      for(int i = 0; i < valSrcQueries.length; i++) {
        valSrcQueries[i].extractTerms(terms);
      }
    }
  
    /*(non-Javadoc) @see org.apache.lucene.search.Query#clone() */
    @Override
    public Object clone() {
      CustomScoreQuery clone = (CustomScoreQuery)super.clone();
      clone.subQuery = (Query) subQuery.clone();
      clone.valSrcQueries = new ValueSourceQuery[valSrcQueries.length];
      for(int i = 0; i < valSrcQueries.length; i++) {
        clone.valSrcQueries[i] = (ValueSourceQuery) valSrcQueries[i].clone();
      }
      return clone;
    }
  
    /* (non-Javadoc) @see org.apache.lucene.search.Query#toString(java.lang.String) */
    @Override
    public String toString(String field) {
      StringBuilder sb = new StringBuilder(name()).append("(");
      sb.append(subQuery.toString(field));
      for(int i = 0; i < valSrcQueries.length; i++) {
        sb.append(", ").append(valSrcQueries[i].toString(field));
      }
      sb.append(")");
      sb.append(strict?" STRICT" : "");
      return sb.toString() + ToStringUtils.boost(getBoost());
    }
  
    /** Returns true if <code>o</code> is equal to this. */
    @Override
    public boolean equals(Object o) {
      if (this == o)
        return true;
      if (!super.equals(o))
        return false;
      if (getClass() != o.getClass()) {
        return false;
      }
      CustomScoreQuery other = (CustomScoreQuery)o;
      if (this.getBoost() != other.getBoost() ||
          !this.subQuery.equals(other.subQuery) ||
          this.strict != other.strict ||
          this.valSrcQueries.length != other.valSrcQueries.length) {
        return false;
      }
      return Arrays.equals(valSrcQueries, other.valSrcQueries);
    }
  
    /** Returns a hash code value for this object. */
    @Override
    public int hashCode() {
      return (getClass().hashCode() + subQuery.hashCode() + Arrays.hashCode(valSrcQueries))
        ^ Float.floatToIntBits(getBoost()) ^ (strict ? 1234 : 4321);
    }
    
    /**
     * Returns a {@link CustomScoreProvider} that calculates the custom scores
     * for the given {@link IndexReader}. The default implementation returns a default
     * implementation as specified in the docs of {@link CustomScoreProvider}.
     * @since 2.9.2
     */
    protected CustomScoreProvider getCustomScoreProvider(IndexReader reader) throws IOException {
      return new CustomScoreProvider(reader);
    }
  
    //=========================== W E I G H T ============================
    
    private class CustomWeight extends Weight {
      Similarity similarity;
      Weight subQueryWeight;
      Weight[] valSrcWeights;
      boolean qStrict;
  
      public CustomWeight(Searcher searcher) throws IOException {
        this.similarity = getSimilarity(searcher);
        this.subQueryWeight = subQuery.createWeight(searcher);
        this.valSrcWeights = new Weight[valSrcQueries.length];
        for(int i = 0; i < valSrcQueries.length; i++) {
          this.valSrcWeights[i] = valSrcQueries[i].createWeight(searcher);
        }
        this.qStrict = strict;
      }
  
      /*(non-Javadoc) @see org.apache.lucene.search.Weight#getQuery() */
      @Override
      public Query getQuery() {
        return CustomScoreQuery.this;
      }
  
      /*(non-Javadoc) @see org.apache.lucene.search.Weight#getValue() */
      @Override
      public float getValue() {
        return getBoost();
      }
  
      /*(non-Javadoc) @see org.apache.lucene.search.Weight#sumOfSquaredWeights() */
      @Override
      public float sumOfSquaredWeights() throws IOException {
        float sum = subQueryWeight.sumOfSquaredWeights();
        for(int i = 0; i < valSrcWeights.length; i++) {
          if (qStrict) {
            valSrcWeights[i].sumOfSquaredWeights(); // do not include ValueSource part in the query normalization
          } else {
            sum += valSrcWeights[i].sumOfSquaredWeights();
          }
        }
        sum *= getBoost() * getBoost(); // boost each sub-weight
        return sum ;
      }
  
      /*(non-Javadoc) @see org.apache.lucene.search.Weight#normalize(float) */
      @Override
      public void normalize(float norm) {
        norm *= getBoost(); // incorporate boost
        subQueryWeight.normalize(norm);
        for(int i = 0; i < valSrcWeights.length; i++) {
          if (qStrict) {
            valSrcWeights[i].normalize(1); // do not normalize the ValueSource part
          } else {
            valSrcWeights[i].normalize(norm);
          }
        }
      }
  
      @Override
      public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
        // Pass true for "scoresDocsInOrder", because we
        // require in-order scoring, even if caller does not,
        // since we call advance on the valSrcScorers.  Pass
        // false for "topScorer" because we will not invoke
        // score(Collector) on these scorers:
        Scorer subQueryScorer = subQueryWeight.scorer(reader, true, false);
        if (subQueryScorer == null) {
          return null;
        }
        Scorer[] valSrcScorers = new Scorer[valSrcWeights.length];
        for(int i = 0; i < valSrcScorers.length; i++) {
           valSrcScorers[i] = valSrcWeights[i].scorer(reader, true, topScorer);
        }
        return new CustomScorer(similarity, reader, this, subQueryScorer, valSrcScorers);
      }
  
      @Override
      public Explanation explain(IndexReader reader, int doc) throws IOException {
        Explanation explain = doExplain(reader, doc);
        return explain == null ? new Explanation(0.0f, "no matching docs") : explain;
      }
      
      private Explanation doExplain(IndexReader reader, int doc) throws IOException {
        Explanation subQueryExpl = subQueryWeight.explain(reader, doc);
        if (!subQueryExpl.isMatch()) {
          return subQueryExpl;
        }
        // match
        Explanation[] valSrcExpls = new Explanation[valSrcWeights.length];
        for(int i = 0; i < valSrcWeights.length; i++) {
          valSrcExpls[i] = valSrcWeights[i].explain(reader, doc);
        }
        Explanation customExp = CustomScoreQuery.this.getCustomScoreProvider(reader).customExplain(doc,subQueryExpl,valSrcExpls);
        float sc = getValue() * customExp.getValue();
        Explanation res = new ComplexExplanation(
          true, sc, CustomScoreQuery.this.toString() + ", product of:");
        res.addDetail(customExp);
        res.addDetail(new Explanation(getValue(), "queryBoost")); // actually using the q boost as q weight (== weight value)
        return res;
      }
  
      @Override
      public boolean scoresDocsOutOfOrder() {
        return false;
      }
      
    }
  
  
    //=========================== S C O R E R ============================
    
    /**
     * A scorer that applies a (callback) function on scores of the subQuery.
     */
    private class CustomScorer extends Scorer {
      private final float qWeight;
      private Scorer subQueryScorer;
      private Scorer[] valSrcScorers;
      private final CustomScoreProvider provider;
      private float vScores[]; // reused in score() to avoid allocating this array for each doc 
  
      // constructor
      private CustomScorer(Similarity similarity, IndexReader reader, CustomWeight w,
          Scorer subQueryScorer, Scorer[] valSrcScorers) throws IOException {
        super(similarity,w);
        this.qWeight = w.getValue();
        this.subQueryScorer = subQueryScorer;
        this.valSrcScorers = valSrcScorers;
        this.vScores = new float[valSrcScorers.length];
        this.provider = CustomScoreQuery.this.getCustomScoreProvider(reader);
      }
  
      @Override
      public int nextDoc() throws IOException {
        int doc = subQueryScorer.nextDoc();
        if (doc != NO_MORE_DOCS) {
          for (int i = 0; i < valSrcScorers.length; i++) {
            valSrcScorers[i].advance(doc);
          }
        }
        return doc;
      }
  
      @Override
      public int docID() {
        return subQueryScorer.docID();
      }
      
      /*(non-Javadoc) @see org.apache.lucene.search.Scorer#score() */
      @Override
      public float score() throws IOException {
        for (int i = 0; i < valSrcScorers.length; i++) {
          vScores[i] = valSrcScorers[i].score();
        }
        return qWeight * provider.customScore(subQueryScorer.docID(), subQueryScorer.score(), vScores);
      }
  
      @Override
      public int advance(int target) throws IOException {
        int doc = subQueryScorer.advance(target);
        if (doc != NO_MORE_DOCS) {
          for (int i = 0; i < valSrcScorers.length; i++) {
            valSrcScorers[i].advance(doc);
          }
        }
        return doc;
      }
    }
  
    @Override
    public Weight createWeight(Searcher searcher) throws IOException {
      return new CustomWeight(searcher);
    }
  
    /**
     * Checks if this is strict custom scoring.
     * In strict custom scoring, the ValueSource part does not participate in weight normalization.
     * This may be useful when one wants full control over how scores are modified, and does 
     * not care about normalizing by the ValueSource part.
     * One particular case where this is useful if for testing this query.   
     * <P>
     * Note: only has effect when the ValueSource part is not null.
     */
    public boolean isStrict() {
      return strict;
    }
  
    /**
     * Set the strict mode of this query. 
     * @param strict The strict mode to set.
     * @see #isStrict()
     */
    public void setStrict(boolean strict) {
      this.strict = strict;
    }
  
    /**
     * A short name of this query, used in {@link #toString(String)}.
     */
    public String name() {
      return "custom";
    }
  
  }
  