/*
 * 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.
 */

package org.apache.lucene.queries.function;

import java.io.IOException;

import org.apache.lucene.index.Term;
import org.apache.lucene.search.BaseExplanationTestCase;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.BoostQuery;
import org.apache.lucene.search.DoubleValuesSource;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.similarities.BM25Similarity;
import org.apache.lucene.search.similarities.ClassicSimilarity;

public class TestFunctionScoreExplanations extends BaseExplanationTestCase {

  public void testOneTerm() throws Exception {
    Query q = new TermQuery(new Term(FIELD, "w1"));
    FunctionScoreQuery fsq = new FunctionScoreQuery(q, DoubleValuesSource.constant(5));
    qtest(fsq, new int[] { 0,1,2,3 });
  }

  public void testBoost() throws Exception {
    Query q = new TermQuery(new Term(FIELD, "w1"));
    FunctionScoreQuery csq = new FunctionScoreQuery(q, DoubleValuesSource.constant(5));
    qtest(new BoostQuery(csq, 4), new int[] { 0,1,2,3 });
  }

  public void testTopLevelBoost() throws Exception {
    Query q = new TermQuery(new Term(FIELD, "w1"));
    FunctionScoreQuery csq = new FunctionScoreQuery(q, DoubleValuesSource.constant(5));
    BooleanQuery.Builder bqB = new BooleanQuery.Builder();
    bqB.add(new MatchAllDocsQuery(), BooleanClause.Occur.MUST);
    bqB.add(csq, BooleanClause.Occur.MUST);
    BooleanQuery bq = bqB.build();
    qtest(new BoostQuery(bq, 6), new int[] { 0,1,2,3 });
  }

  public void testExplanationsIncludingScore() throws Exception {

    DoubleValuesSource scores = DoubleValuesSource.function(DoubleValuesSource.SCORES, "v * 2", v -> v * 2);

    Query q = new TermQuery(new Term(FIELD, "w1"));
    FunctionScoreQuery csq = new FunctionScoreQuery(q, scores);

    qtest(csq, new int[] { 0, 1, 2, 3 });

    Explanation e1 = searcher.explain(q, 0);
    Explanation e = searcher.explain(csq, 0);

    assertEquals(e.getDetails().length, 2);

    assertEquals(e1.getValue() * 2, e.getValue(), 0.00001);
  }

  public void testSubExplanations() throws IOException {
    Query query = new FunctionScoreQuery(new MatchAllDocsQuery(), DoubleValuesSource.constant(5));
    IndexSearcher searcher = newSearcher(BaseExplanationTestCase.searcher.getIndexReader());
    searcher.setSimilarity(new BM25Similarity());

    Explanation expl = searcher.explain(query, 0);
    assertEquals("constant(5.0)", expl.getDescription());
    assertEquals(0, expl.getDetails().length);

    query = new BoostQuery(query, 2);
    expl = searcher.explain(query, 0);
    assertEquals(2, expl.getDetails().length);
    // function
    assertEquals(5f, expl.getDetails()[1].getValue(), 0f);
    // boost
    assertEquals("boost", expl.getDetails()[0].getDescription());
    assertEquals(2f, expl.getDetails()[0].getValue(), 0f);

    searcher.setSimilarity(new ClassicSimilarity()); // in order to have a queryNorm != 1
    expl = searcher.explain(query, 0);
    assertEquals(2, expl.getDetails().length);
    // function
    assertEquals(5f, expl.getDetails()[1].getValue(), 0f);
    // boost
    assertEquals("boost", expl.getDetails()[0].getDescription());
    assertEquals(2f, expl.getDetails()[0].getValue(), 0f);
  }

}