/*
 * 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.index;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.analysis.MockAnalyzer;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.apache.lucene.tests.util.TestUtil;

public class TestStressDeletes extends LuceneTestCase {

  /**
   * Make sure that order of adds/deletes across threads is respected as long as each ID is only
   * changed by one thread at a time.
   */
  public void test() throws Exception {
    final int numIDs = atLeast(100);
    final Object[] locks = new Object[numIDs];
    for (int i = 0; i < locks.length; i++) {
      locks[i] = new Object();
    }

    Directory dir = newDirectory();
    IndexWriterConfig iwc = new IndexWriterConfig(new MockAnalyzer(random()));
    final IndexWriter w = new IndexWriter(dir, iwc);
    final int iters = atLeast(2000);
    final Map<Integer, Boolean> exists = new ConcurrentHashMap<>();
    Thread[] threads = new Thread[TestUtil.nextInt(random(), 2, 6)];
    final CountDownLatch startingGun = new CountDownLatch(1);
    final int deleteMode = random().nextInt(3);
    for (int i = 0; i < threads.length; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {
              try {
                startingGun.await();
                for (int iter = 0; iter < iters; iter++) {
                  int id = random().nextInt(numIDs);
                  synchronized (locks[id]) {
                    Boolean v = exists.get(id);
                    if (v == null || v.booleanValue() == false) {
                      Document doc = new Document();
                      doc.add(newStringField("id", "" + id, Field.Store.NO));
                      w.addDocument(doc);
                      exists.put(id, true);
                    } else {
                      if (deleteMode == 0) {
                        // Always delete by term
                        w.deleteDocuments(new Term("id", "" + id));
                      } else if (deleteMode == 1) {
                        // Always delete by query
                        w.deleteDocuments(new TermQuery(new Term("id", "" + id)));
                      } else {
                        // Mixed
                        if (random().nextBoolean()) {
                          w.deleteDocuments(new Term("id", "" + id));
                        } else {
                          w.deleteDocuments(new TermQuery(new Term("id", "" + id)));
                        }
                      }
                      exists.put(id, false);
                    }
                  }
                  if (random().nextInt(500) == 2) {
                    DirectoryReader.open(w, random().nextBoolean(), false).close();
                  }
                  if (random().nextInt(500) == 2) {
                    w.commit();
                  }
                }
              } catch (Exception e) {
                throw new RuntimeException(e);
              }
            }
          };
      threads[i].start();
    }

    startingGun.countDown();
    for (Thread thread : threads) {
      thread.join();
    }

    IndexReader r = DirectoryReader.open(w);
    IndexSearcher s = newSearcher(r);
    for (Map.Entry<Integer, Boolean> ent : exists.entrySet()) {
      int id = ent.getKey();
      TopDocs hits = s.search(new TermQuery(new Term("id", "" + id)), 1);
      if (ent.getValue()) {
        assertEquals(1, hits.totalHits.value());
      } else {
        assertEquals(0, hits.totalHits.value());
      }
    }
    r.close();
    w.close();
    dir.close();
  }
}
