/*
 * 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 java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.SortedDocValuesField;
import org.apache.lucene.document.StringField;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.MultiReader;
import org.apache.lucene.index.RandomIndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause.Occur;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.IOUtils;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.util.NamedThreadFactory;
import org.apache.lucene.util.TestUtil;
import org.junit.Test;

public class TestIndexSearcher extends LuceneTestCase {
  Directory dir;
  IndexReader reader;

  @Override
  public void setUp() throws Exception {
    super.setUp();
    dir = newDirectory();
    RandomIndexWriter iw = new RandomIndexWriter(random(), dir);
    for (int i = 0; i < 100; i++) {
      Document doc = new Document();
      doc.add(newStringField("field", Integer.toString(i), Field.Store.NO));
      doc.add(newStringField("field2", Boolean.toString(i % 2 == 0), Field.Store.NO));
      doc.add(new SortedDocValuesField("field2", new BytesRef(Boolean.toString(i % 2 == 0))));
      iw.addDocument(doc);
    }
    reader = iw.getReader();
    iw.close();
  }

  @Override
  public void tearDown() throws Exception {
    super.tearDown();
    reader.close();
    dir.close();
  }

  // should not throw exception
  public void testHugeN() throws Exception {
    ExecutorService service = new ThreadPoolExecutor(4, 4, 0L, TimeUnit.MILLISECONDS,
                                   new LinkedBlockingQueue<Runnable>(),
                                   new NamedThreadFactory("TestIndexSearcher"));

    IndexSearcher searchers[] = new IndexSearcher[] {
        new IndexSearcher(reader),
        new IndexSearcher(reader, service)
    };
    Query queries[] = new Query[] {
        new MatchAllDocsQuery(),
        new TermQuery(new Term("field", "1"))
    };
    Sort sorts[] = new Sort[] {
        null,
        new Sort(new SortField("field2", SortField.Type.STRING))
    };
    ScoreDoc afters[] = new ScoreDoc[] {
        null,
        new FieldDoc(0, 0f, new Object[] { new BytesRef("boo!") })
    };

    for (IndexSearcher searcher : searchers) {
      for (ScoreDoc after : afters) {
        for (Query query : queries) {
          for (Sort sort : sorts) {
            searcher.search(query, Integer.MAX_VALUE);
            searcher.searchAfter(after, query, Integer.MAX_VALUE);
            if (sort != null) {
              searcher.search(query, Integer.MAX_VALUE, sort);
              searcher.search(query, Integer.MAX_VALUE, sort, true);
              searcher.search(query, Integer.MAX_VALUE, sort, false);
              searcher.searchAfter(after, query, Integer.MAX_VALUE, sort);
              searcher.searchAfter(after, query, Integer.MAX_VALUE, sort, true);
              searcher.searchAfter(after, query, Integer.MAX_VALUE, sort, false);
            }
          }
        }
      }
    }

    TestUtil.shutdownExecutorService(service);
  }

  @Test
  public void testSearchAfterPassedMaxDoc() throws Exception {
    // LUCENE-5128: ensure we get a meaningful message if searchAfter exceeds maxDoc
    Directory dir = newDirectory();
    RandomIndexWriter w = new RandomIndexWriter(random(), dir);
    w.addDocument(new Document());
    IndexReader r = w.getReader();
    w.close();

    IndexSearcher s = new IndexSearcher(r);
    expectThrows(IllegalArgumentException.class, () -> {
      s.searchAfter(new ScoreDoc(r.maxDoc(), 0.54f), new MatchAllDocsQuery(), 10);
    });

    IOUtils.close(r, dir);
  }

  public void testCount() throws IOException {
    Directory dir = newDirectory();
    RandomIndexWriter w = new RandomIndexWriter(random(), dir);
    final int numDocs = atLeast(100);
    for (int i = 0; i < numDocs; ++i) {
      Document doc = new Document();
      if (random().nextBoolean()) {
        doc.add(new StringField("foo", "bar", Store.NO));
      }
      if (random().nextBoolean()) {
        doc.add(new StringField("foo", "baz", Store.NO));
      }
      if (rarely()) {
        doc.add(new StringField("delete", "yes", Store.NO));
      }
      w.addDocument(doc);
    }
    for (boolean delete : new boolean[] {false, true}) {
      if (delete) {
        w.deleteDocuments(new Term("delete", "yes"));
      }
      final IndexReader reader = w.getReader();
      final IndexSearcher searcher = newSearcher(reader);
      // Test multiple queries, some of them are optimized by IndexSearcher.count()
      for (Query query : Arrays.asList(
          new MatchAllDocsQuery(),
          new MatchNoDocsQuery(),
          new TermQuery(new Term("foo", "bar")),
          new ConstantScoreQuery(new TermQuery(new Term("foo", "baz"))),
          new BooleanQuery.Builder()
            .add(new TermQuery(new Term("foo", "bar")), Occur.SHOULD)
            .add(new TermQuery(new Term("foo", "baz")), Occur.SHOULD)
            .build()
          )) {
        assertEquals(searcher.count(query), searcher.search(query, 1).totalHits.value);
      }
      reader.close();
    }
    w.close();
    dir.close();
  }

  public void testGetQueryCache() throws IOException {
    IndexSearcher searcher = new IndexSearcher(new MultiReader());
    assertEquals(IndexSearcher.getDefaultQueryCache(), searcher.getQueryCache());
    QueryCache dummyCache = new QueryCache() {
      @Override
      public Weight doCache(Weight weight, QueryCachingPolicy policy) {
        return weight;
      }
    };
    searcher.setQueryCache(dummyCache);
    assertEquals(dummyCache, searcher.getQueryCache());

    IndexSearcher.setDefaultQueryCache(dummyCache);
    searcher = new IndexSearcher(new MultiReader());
    assertEquals(dummyCache, searcher.getQueryCache());

    searcher.setQueryCache(null);
    assertNull(searcher.getQueryCache());

    IndexSearcher.setDefaultQueryCache(null);
    searcher = new IndexSearcher(new MultiReader());
    assertNull(searcher.getQueryCache());
  }

  public void testGetQueryCachingPolicy() throws IOException {
    IndexSearcher searcher = new IndexSearcher(new MultiReader());
    assertEquals(IndexSearcher.getDefaultQueryCachingPolicy(), searcher.getQueryCachingPolicy());
    QueryCachingPolicy dummyPolicy = new QueryCachingPolicy() {
      @Override
      public boolean shouldCache(Query query) throws IOException {
        return false;
      }
      @Override
      public void onUse(Query query) {}
    };
    searcher.setQueryCachingPolicy(dummyPolicy);
    assertEquals(dummyPolicy, searcher.getQueryCachingPolicy());

    IndexSearcher.setDefaultQueryCachingPolicy(dummyPolicy);
    searcher = new IndexSearcher(new MultiReader());
    assertEquals(dummyPolicy, searcher.getQueryCachingPolicy());
  }

  public void testGetSlices() throws Exception {
    assertNull(new IndexSearcher(new MultiReader()).getSlices());

    Directory dir = newDirectory();
    RandomIndexWriter w = new RandomIndexWriter(random(), dir);
    w.addDocument(new Document());
    IndexReader r = w.getReader();
    w.close();

    ExecutorService service = new ThreadPoolExecutor(4, 4, 0L, TimeUnit.MILLISECONDS,
                                   new LinkedBlockingQueue<Runnable>(),
                                   new NamedThreadFactory("TestIndexSearcher"));
    IndexSearcher s = new IndexSearcher(r, service);
    IndexSearcher.LeafSlice[] slices = s.getSlices();
    assertNotNull(slices);
    assertEquals(1, slices.length);
    assertEquals(1, slices[0].leaves.length);
    assertTrue(slices[0].leaves[0] == r.leaves().get(0));
    service.shutdown();
    IOUtils.close(r, dir);
  }

  public void testOneSegmentExecutesOnTheCallerThread() throws IOException {
    List<LeafReaderContext> leaves = reader.leaves();
    AtomicInteger numExecutions = new AtomicInteger(0);
    IndexSearcher searcher = new IndexSearcher(reader, task -> {
      numExecutions.incrementAndGet();
      task.run();
    }) {
      @Override
      protected LeafSlice[] slices(List<LeafReaderContext> leaves) {
        ArrayList<LeafSlice> slices = new ArrayList<>();
        for (LeafReaderContext ctx : leaves) {
          slices.add(new LeafSlice(ctx));
        }
        return slices.toArray(new LeafSlice[0]);
      }
    };
    searcher.search(new MatchAllDocsQuery(), 10);
    if (leaves.size() <= 1) {
      assertEquals(0, numExecutions.get());
    } else {
      assertEquals(leaves.size() - 1, numExecutions.get());
    }
  }
}