content: /*
   * Created on 25-Jan-2006
   */
  package org.apache.lucene.search.similar;
  
  /**
   * 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 org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.search.BooleanClause;
  import org.apache.lucene.search.BooleanQuery;
  import org.apache.lucene.search.Query;
  import org.apache.lucene.search.similar.MoreLikeThis;
  
  import java.io.StringReader;
  
  /**
   * A simple wrapper for MoreLikeThis for use in scenarios where a Query object
   * is required eg in custom QueryParser extensions. At query.rewrite() time the
   * reader is used to construct the actual MoreLikeThis object and obtain the
   * real Query object.
   */
  public class MoreLikeThisQuery extends Query {
    
    private String likeText;
    private String[] moreLikeFields;
    private Analyzer analyzer;
    private String fieldName;
    private float percentTermsToMatch = 0.3f;
    private int minTermFrequency = 1;
    private int maxQueryTerms = 5;
    private Set<?> stopWords = null;
    private int minDocFreq = -1;
  
    /** @deprecated use {@link #MoreLikeThisQuery(String, String[], Analyzer, String)} instead. */
    @Deprecated
    public MoreLikeThisQuery(String likeText, String[] moreLikeFields, Analyzer analyzer) {
      this(likeText, moreLikeFields, analyzer, moreLikeFields[0]);
    }
  
    /**
     * @param moreLikeFields
     */
    public MoreLikeThisQuery(String likeText, String[] moreLikeFields, Analyzer analyzer, String fieldName) {
      this.likeText = likeText;
      this.moreLikeFields = moreLikeFields;
      this.analyzer = analyzer;
      this.fieldName = fieldName;
    }
    
    @Override
    public Query rewrite(IndexReader reader) throws IOException {
      MoreLikeThis mlt = new MoreLikeThis(reader);
      
      mlt.setFieldNames(moreLikeFields);
      mlt.setAnalyzer(analyzer);
      mlt.setMinTermFreq(minTermFrequency);
      if (minDocFreq >= 0) {
        mlt.setMinDocFreq(minDocFreq);
      }
      mlt.setMaxQueryTerms(maxQueryTerms);
      mlt.setStopWords(stopWords);
      BooleanQuery bq = (BooleanQuery) mlt.like(new StringReader(likeText), fieldName);
      BooleanClause[] clauses = bq.getClauses();
      // make at least half the terms match
      bq.setMinimumNumberShouldMatch((int) (clauses.length * percentTermsToMatch));
      return bq;
    }
    
    /*
     * (non-Javadoc)
     * 
     * @see org.apache.lucene.search.Query#toString(java.lang.String)
     */
    @Override
    public String toString(String field) {
      return "like:" + likeText;
    }
    
    public float getPercentTermsToMatch() {
      return percentTermsToMatch;
    }
    
    public void setPercentTermsToMatch(float percentTermsToMatch) {
      this.percentTermsToMatch = percentTermsToMatch;
    }
    
    public Analyzer getAnalyzer() {
      return analyzer;
    }
    
    public void setAnalyzer(Analyzer analyzer) {
      this.analyzer = analyzer;
    }
    
    public String getLikeText() {
      return likeText;
    }
    
    public void setLikeText(String likeText) {
      this.likeText = likeText;
    }
    
    public int getMaxQueryTerms() {
      return maxQueryTerms;
    }
    
    public void setMaxQueryTerms(int maxQueryTerms) {
      this.maxQueryTerms = maxQueryTerms;
    }
    
    public int getMinTermFrequency() {
      return minTermFrequency;
    }
    
    public void setMinTermFrequency(int minTermFrequency) {
      this.minTermFrequency = minTermFrequency;
    }
    
    public String[] getMoreLikeFields() {
      return moreLikeFields;
    }
    
    public void setMoreLikeFields(String[] moreLikeFields) {
      this.moreLikeFields = moreLikeFields;
    }
    
    public Set<?> getStopWords() {
      return stopWords;
    }
    
    public void setStopWords(Set<?> stopWords) {
      this.stopWords = stopWords;
    }
    
    public int getMinDocFreq() {
      return minDocFreq;
    }
    
    public void setMinDocFreq(int minDocFreq) {
      this.minDocFreq = minDocFreq;
    }
  }
  