package org.apache.lucene.search;

/*
 * 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 org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.util.LuceneTestCase;

import java.io.IOException;

public class TestCachingCollector extends LuceneTestCase {

  private static final double ONE_BYTE = 1.0 / (1024 * 1024); // 1 byte out of MB
  
  private static class MockScorer extends Scorer {
    
    private MockScorer() {
      super((Weight) null);
    }
    
    @Override
    public float score() throws IOException { return 0; }
    
    @Override
    public int freq() throws IOException { return 0; }

    @Override
    public int docID() { return 0; }

    @Override
    public int nextDoc() throws IOException { return 0; }

    @Override
    public int advance(int target) throws IOException { return 0; }
    
    @Override
    public long cost() {
      return 1;
    } 
  }
  
  private static class NoOpCollector extends Collector {

    private final boolean acceptDocsOutOfOrder;
    
    public NoOpCollector(boolean acceptDocsOutOfOrder) {
      this.acceptDocsOutOfOrder = acceptDocsOutOfOrder;
    }
    
    @Override
    public void setScorer(Scorer scorer) throws IOException {}

    @Override
    public void collect(int doc) throws IOException {}

    @Override
    public void setNextReader(AtomicReaderContext context) throws IOException {}

    @Override
    public boolean acceptsDocsOutOfOrder() {
      return acceptDocsOutOfOrder;
    }
    
  }

  public void testBasic() throws Exception {
    for (boolean cacheScores : new boolean[] { false, true }) {
      CachingCollector cc = CachingCollector.create(new NoOpCollector(false), cacheScores, 1.0);
      cc.setScorer(new MockScorer());

      // collect 1000 docs
      for (int i = 0; i < 1000; i++) {
        cc.collect(i);
      }

      // now replay them
      cc.replay(new Collector() {
        int prevDocID = -1;

        @Override
        public void setScorer(Scorer scorer) {}

        @Override
        public void setNextReader(AtomicReaderContext context) {}

        @Override
        public void collect(int doc) {
          assertEquals(prevDocID + 1, doc);
          prevDocID = doc;
        }

        @Override
        public boolean acceptsDocsOutOfOrder() {
          return false;
        }
      });
    }
  }
  
  public void testIllegalStateOnReplay() throws Exception {
    CachingCollector cc = CachingCollector.create(new NoOpCollector(false), true, 50 * ONE_BYTE);
    cc.setScorer(new MockScorer());
    
    // collect 130 docs, this should be enough for triggering cache abort.
    for (int i = 0; i < 130; i++) {
      cc.collect(i);
    }
    
    assertFalse("CachingCollector should not be cached due to low memory limit", cc.isCached());
    
    try {
      cc.replay(new NoOpCollector(false));
      fail("replay should fail if CachingCollector is not cached");
    } catch (IllegalStateException e) {
      // expected
    }
  }
  
  public void testIllegalCollectorOnReplay() throws Exception {
    // tests that the Collector passed to replay() has an out-of-order mode that
    // is valid with the Collector passed to the ctor
    
    // 'src' Collector does not support out-of-order
    CachingCollector cc = CachingCollector.create(new NoOpCollector(false), true, 50 * ONE_BYTE);
    cc.setScorer(new MockScorer());
    for (int i = 0; i < 10; i++) cc.collect(i);
    cc.replay(new NoOpCollector(true)); // this call should not fail
    cc.replay(new NoOpCollector(false)); // this call should not fail

    // 'src' Collector supports out-of-order
    cc = CachingCollector.create(new NoOpCollector(true), true, 50 * ONE_BYTE);
    cc.setScorer(new MockScorer());
    for (int i = 0; i < 10; i++) cc.collect(i);
    cc.replay(new NoOpCollector(true)); // this call should not fail
    try {
      cc.replay(new NoOpCollector(false)); // this call should fail
      fail("should have failed if an in-order Collector was given to replay(), " +
           "while CachingCollector was initialized with out-of-order collection");
    } catch (IllegalArgumentException e) {
      // ok
    }
  }
  
  public void testCachedArraysAllocation() throws Exception {
    // tests the cached arrays allocation -- if the 'nextLength' was too high,
    // caching would terminate even if a smaller length would suffice.
    
    // set RAM limit enough for 150 docs + random(10000)
    int numDocs = random().nextInt(10000) + 150;
    for (boolean cacheScores : new boolean[] { false, true }) {
      int bytesPerDoc = cacheScores ? 8 : 4;
      CachingCollector cc = CachingCollector.create(new NoOpCollector(false),
          cacheScores, bytesPerDoc * ONE_BYTE * numDocs);
      cc.setScorer(new MockScorer());
      for (int i = 0; i < numDocs; i++) cc.collect(i);
      assertTrue(cc.isCached());

      // The 151's document should terminate caching
      cc.collect(numDocs);
      assertFalse(cc.isCached());
    }
  }

  public void testNoWrappedCollector() throws Exception {
    for (boolean cacheScores : new boolean[] { false, true }) {
      // create w/ null wrapped collector, and test that the methods work
      CachingCollector cc = CachingCollector.create(true, cacheScores, 50 * ONE_BYTE);
      cc.setNextReader(null);
      cc.setScorer(new MockScorer());
      cc.collect(0);
      
      assertTrue(cc.isCached());
      cc.replay(new NoOpCollector(true));
    }
  }
  
}