package org.apache.lucene.index;

/**
 * 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 java.io.IOException;

import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.store.Directory;

import org.apache.lucene.util.LuceneTestCase;

public class TestIndexWriterMergePolicy extends LuceneTestCase {
  
  // Test the normal case
  public void testNormalCase() throws IOException {
    Directory dir = newDirectory();

    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setMaxBufferedDocs(10).setMergePolicy(new LogDocMergePolicy()));

    for (int i = 0; i < 100; i++) {
      addDoc(writer);
      checkInvariants(writer);
    }

    writer.close();
    dir.close();
  }

  // Test to see if there is over merge
  public void testNoOverMerge() throws IOException {
    Directory dir = newDirectory();

    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setMaxBufferedDocs(10).setMergePolicy(new LogDocMergePolicy()));

    boolean noOverMerge = false;
    for (int i = 0; i < 100; i++) {
      addDoc(writer);
      checkInvariants(writer);
      if (writer.getNumBufferedDocuments() + writer.getSegmentCount() >= 18) {
        noOverMerge = true;
      }
    }
    assertTrue(noOverMerge);

    writer.close();
    dir.close();
  }

  // Test the case where flush is forced after every addDoc
  public void testForceFlush() throws IOException {
    Directory dir = newDirectory();

    LogDocMergePolicy mp = new LogDocMergePolicy();
    mp.setMinMergeDocs(100);
    mp.setMergeFactor(10);
    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setMaxBufferedDocs(10).setMergePolicy(mp));

    for (int i = 0; i < 100; i++) {
      addDoc(writer);
      writer.close();

      mp = new LogDocMergePolicy();
      mp.setMergeFactor(10);
      writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT,
          new MockAnalyzer(random)).setOpenMode(
          OpenMode.APPEND).setMaxBufferedDocs(10).setMergePolicy(mp));
      mp.setMinMergeDocs(100);
      checkInvariants(writer);
    }

    writer.close();
    dir.close();
  }

  // Test the case where mergeFactor changes
  public void testMergeFactorChange() throws IOException {
    Directory dir = newDirectory();

    IndexWriter writer = new IndexWriter(
        dir,
        newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random)).
            setMaxBufferedDocs(10).
            setMergePolicy(newLogMergePolicy()).
            setMergeScheduler(new SerialMergeScheduler())
    );

    writer.setInfoStream(VERBOSE ? System.out : null);

    for (int i = 0; i < 250; i++) {
      addDoc(writer);
      checkInvariants(writer);
    }

    ((LogMergePolicy) writer.getConfig().getMergePolicy()).setMergeFactor(5);

    // merge policy only fixes segments on levels where merges
    // have been triggered, so check invariants after all adds
    for (int i = 0; i < 10; i++) {
      addDoc(writer);
    }
    checkInvariants(writer);

    writer.close();
    dir.close();
  }

  // Test the case where both mergeFactor and maxBufferedDocs change
  public void testMaxBufferedDocsChange() throws IOException {
    Directory dir = newDirectory();

    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setMaxBufferedDocs(101).setMergePolicy(new LogDocMergePolicy())
        .setMergeScheduler(new SerialMergeScheduler()));

    // leftmost* segment has 1 doc
    // rightmost* segment has 100 docs
    for (int i = 1; i <= 100; i++) {
      for (int j = 0; j < i; j++) {
        addDoc(writer);
        checkInvariants(writer);
      }
      writer.close();

      writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT,
          new MockAnalyzer(random)).setOpenMode(
          OpenMode.APPEND).setMaxBufferedDocs(101).setMergePolicy(new LogDocMergePolicy())
                          .setMergeScheduler(new SerialMergeScheduler()));
    }

    writer.close();
    LogDocMergePolicy ldmp = new LogDocMergePolicy();
    ldmp.setMergeFactor(10);
    writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT,
        new MockAnalyzer(random)).setOpenMode(
        OpenMode.APPEND).setMaxBufferedDocs(10).setMergePolicy(ldmp).setMergeScheduler(new SerialMergeScheduler()));

    // merge policy only fixes segments on levels where merges
    // have been triggered, so check invariants after all adds
    for (int i = 0; i < 100; i++) {
      addDoc(writer);
    }
    checkInvariants(writer);

    for (int i = 100; i < 1000; i++) {
      addDoc(writer);
    }
    writer.commit();
    writer.waitForMerges();
    writer.commit();
    checkInvariants(writer);

    writer.close();
    dir.close();
  }

  // Test the case where a merge results in no doc at all
  public void testMergeDocCount0() throws IOException {
    Directory dir = newDirectory();

    LogDocMergePolicy ldmp = new LogDocMergePolicy();
    ldmp.setMergeFactor(100);
    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setMaxBufferedDocs(10).setMergePolicy(ldmp));

    for (int i = 0; i < 250; i++) {
      addDoc(writer);
      checkInvariants(writer);
    }
    writer.close();

    IndexReader reader = IndexReader.open(dir, false);
    reader.deleteDocuments(new Term("content", "aaa"));
    reader.close();

    ldmp = new LogDocMergePolicy();
    ldmp.setMergeFactor(5);
    writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT,
        new MockAnalyzer(random)).setOpenMode(
        OpenMode.APPEND).setMaxBufferedDocs(10).setMergePolicy(ldmp).setMergeScheduler(new ConcurrentMergeScheduler()));

    // merge factor is changed, so check invariants after all adds
    for (int i = 0; i < 10; i++) {
      addDoc(writer);
    }
    writer.commit();
    writer.waitForMerges();
    writer.commit();
    checkInvariants(writer);
    assertEquals(10, writer.maxDoc());

    writer.close();
    dir.close();
  }

  private void addDoc(IndexWriter writer) throws IOException {
    Document doc = new Document();
    doc.add(newField("content", "aaa", Field.Store.NO, Field.Index.ANALYZED));
    writer.addDocument(doc);
  }

  private void checkInvariants(IndexWriter writer) throws IOException {
    writer.waitForMerges();
    int maxBufferedDocs = writer.getConfig().getMaxBufferedDocs();
    int mergeFactor = ((LogMergePolicy) writer.getConfig().getMergePolicy()).getMergeFactor();
    int maxMergeDocs = ((LogMergePolicy) writer.getConfig().getMergePolicy()).getMaxMergeDocs();

    int ramSegmentCount = writer.getNumBufferedDocuments();
    assertTrue(ramSegmentCount < maxBufferedDocs);

    int lowerBound = -1;
    int upperBound = maxBufferedDocs;
    int numSegments = 0;

    int segmentCount = writer.getSegmentCount();
    for (int i = segmentCount - 1; i >= 0; i--) {
      int docCount = writer.getDocCount(i);
      assertTrue("docCount=" + docCount + " lowerBound=" + lowerBound + " upperBound=" + upperBound + " i=" + i + " segmentCount=" + segmentCount + " index=" + writer.segString() + " config=" + writer.getConfig(), docCount > lowerBound);

      if (docCount <= upperBound) {
        numSegments++;
      } else {
        if (upperBound * mergeFactor <= maxMergeDocs) {
          assertTrue("maxMergeDocs=" + maxMergeDocs + "; numSegments=" + numSegments + "; upperBound=" + upperBound + "; mergeFactor=" + mergeFactor + "; segs=" + writer.segString() + " config=" + writer.getConfig(), numSegments < mergeFactor);
        }

        do {
          lowerBound = upperBound;
          upperBound *= mergeFactor;
        } while (docCount > upperBound);
        numSegments = 1;
      }
    }
    if (upperBound * mergeFactor <= maxMergeDocs) {
      assertTrue(numSegments < mergeFactor);
    }
  }
}