/*
 * 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.search;

import java.io.IOException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.index.RandomIndexWriter;
import org.apache.lucene.tests.util.LuceneTestCase;

public class TestScoreCachingWrappingScorer extends LuceneTestCase {

  private static final class SimpleScorer extends Scorer {
    private int idx = 0;
    private int doc = -1;

    public SimpleScorer(Weight weight) {
      super(weight);
    }

    @Override
    public float score() {
      // advance idx on purpose, so that consecutive calls to score will get
      // different results. This is to emulate computation of a score. If
      // ScoreCachingWrappingScorer is used, this should not be called more than
      // once per document.
      return idx == scores.length ? Float.NaN : scores[idx++];
    }

    @Override
    public float getMaxScore(int upTo) throws IOException {
      return Float.POSITIVE_INFINITY;
    }

    @Override
    public int docID() {
      return doc;
    }

    @Override
    public DocIdSetIterator iterator() {
      return new DocIdSetIterator() {
        @Override
        public int docID() {
          return doc;
        }

        @Override
        public int nextDoc() {
          return ++doc < scores.length ? doc : NO_MORE_DOCS;
        }

        @Override
        public int advance(int target) {
          doc = target;
          return doc < scores.length ? doc : NO_MORE_DOCS;
        }

        @Override
        public long cost() {
          return scores.length;
        }
      };
    }
  }

  private static final class ScoreCachingCollector extends SimpleCollector {

    private int idx = 0;
    private Scorable scorer;
    float[] mscores;

    public ScoreCachingCollector(int numToCollect) {
      mscores = new float[numToCollect];
    }

    @Override
    public void collect(int doc) throws IOException {
      // just a sanity check to avoid IOOB.
      if (idx == mscores.length) {
        return;
      }

      // just call score() a couple of times and record the score.
      mscores[idx] = scorer.score();
      mscores[idx] = scorer.score();
      mscores[idx] = scorer.score();
      ++idx;
    }

    @Override
    public void setScorer(Scorable scorer) {
      this.scorer = ScoreCachingWrappingScorer.wrap(scorer);
    }

    @Override
    public ScoreMode scoreMode() {
      return ScoreMode.COMPLETE;
    }
  }

  private static final float[] scores =
      new float[] {
        0.7767749f,
        1.7839992f,
        8.9925785f,
        7.9608946f,
        0.07948637f,
        2.6356435f,
        7.4950366f,
        7.1490803f,
        8.108544f,
        4.961808f,
        2.2423935f,
        7.285586f,
        4.6699767f
      };

  public void testGetScores() throws Exception {
    Directory directory = newDirectory();
    RandomIndexWriter writer = new RandomIndexWriter(random(), directory);
    writer.commit();
    IndexReader ir = writer.getReader();
    writer.close();
    IndexSearcher searcher = newSearcher(ir);
    Weight fake =
        new TermQuery(new Term("fake", "weight")).createWeight(searcher, ScoreMode.COMPLETE, 1f);
    Scorer s = new SimpleScorer(fake);
    ScoreCachingCollector scc = new ScoreCachingCollector(scores.length);
    scc.setScorer(s);

    // We need to iterate on the scorer so that its doc() advances.
    int doc;
    while ((doc = s.iterator().nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
      scc.collect(doc);
    }

    for (int i = 0; i < scores.length; i++) {
      assertEquals(scores[i], scc.mscores[i], 0f);
    }
    ir.close();
    directory.close();
  }

  public void testNoUnnecessaryWrap() throws Exception {
    Scorable base =
        new Scorable() {
          @Override
          public float score() throws IOException {
            return -1;
          }

          @Override
          public int docID() {
            return -1;
          }
        };

    // Wrapping the first time should produce a different instance:
    Scorable wrapped = ScoreCachingWrappingScorer.wrap(base);
    assertNotEquals(base, wrapped);

    // But if we try to wrap an instance of ScoreCachingWrappingScorer, it shouldn't unnecessarily
    // wrap again:
    Scorable doubleWrapped = ScoreCachingWrappingScorer.wrap(wrapped);
    assertSame(wrapped, doubleWrapped);
  }
}
