/*
 * 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;
  }
}
