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 java.util.ArrayList;
  import java.util.Arrays;
  
  import org.apache.lucene.analysis.MockAnalyzer;
  import org.apache.lucene.document.Document;
  import org.apache.lucene.document.Field;
  import org.apache.lucene.document.FieldType;
  import org.apache.lucene.document.TextField;
  import org.apache.lucene.search.DocIdSetIterator;
  import org.apache.lucene.store.Directory;
  import org.apache.lucene.util.Bits;
  import org.apache.lucene.util.BytesRef;
  import org.apache.lucene.util.LuceneTestCase;
  import org.apache.lucene.util.TestUtil;
  
  public class TestDocsAndPositions extends LuceneTestCase {
    private String fieldName;
  
    @Override
    public void setUp() throws Exception {
      super.setUp();
      fieldName = "field" + random().nextInt();
    }
  
    /**
     * Simple testcase for {@link PostingsEnum}
     */
    public void testPositionsSimple() throws IOException {
      Directory directory = newDirectory();
      RandomIndexWriter writer = new RandomIndexWriter(random(), directory,
          newIndexWriterConfig(new MockAnalyzer(random())));
      for (int i = 0; i < 39; i++) {
        Document doc = new Document();
        FieldType customType = new FieldType(TextField.TYPE_NOT_STORED);
        customType.setOmitNorms(true);
        doc.add(newField(fieldName, "1 2 3 4 5 6 7 8 9 10 "
            + "1 2 3 4 5 6 7 8 9 10 " + "1 2 3 4 5 6 7 8 9 10 "
            + "1 2 3 4 5 6 7 8 9 10", customType));
        writer.addDocument(doc);
      }
      IndexReader reader = writer.getReader();
      writer.close();
  
      int num = atLeast(13);
      for (int i = 0; i < num; i++) {
        BytesRef bytes = new BytesRef("1");
        IndexReaderContext topReaderContext = reader.getContext();
        for (LeafReaderContext leafReaderContext : topReaderContext.leaves()) {
          PostingsEnum docsAndPosEnum = getDocsAndPositions(
              leafReaderContext.reader(), bytes);
          assertNotNull(docsAndPosEnum);
          if (leafReaderContext.reader().maxDoc() == 0) {
            continue;
          }
          final int advance = docsAndPosEnum.advance(random().nextInt(leafReaderContext.reader().maxDoc()));
          do {
            String msg = "Advanced to: " + advance + " current doc: "
                + docsAndPosEnum.docID(); // TODO: + " usePayloads: " + usePayload;
            assertEquals(msg, 4, docsAndPosEnum.freq());
            assertEquals(msg, 0, docsAndPosEnum.nextPosition());
            assertEquals(msg, 4, docsAndPosEnum.freq());
            assertEquals(msg, 10, docsAndPosEnum.nextPosition());
            assertEquals(msg, 4, docsAndPosEnum.freq());
            assertEquals(msg, 20, docsAndPosEnum.nextPosition());
            assertEquals(msg, 4, docsAndPosEnum.freq());
            assertEquals(msg, 30, docsAndPosEnum.nextPosition());
          } while (docsAndPosEnum.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
        }
      }
      reader.close();
      directory.close();
    }
  
    public PostingsEnum getDocsAndPositions(LeafReader reader,
        BytesRef bytes) throws IOException {
      Terms terms = reader.terms(fieldName);
      if (terms != null) {
        TermsEnum te = terms.iterator();
        if (te.seekExact(bytes)) {
          return te.postings(null, PostingsEnum.ALL);
       }
     }
     return null;
   }
 
   /**
    * this test indexes random numbers within a range into a field and checks
    * their occurrences by searching for a number from that range selected at
    * random. All positions for that number are saved up front and compared to
    * the enums positions.
    */
   public void testRandomPositions() throws IOException {
     Directory dir = newDirectory();
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir,
         newIndexWriterConfig(new MockAnalyzer(random()))
           .setMergePolicy(newLogMergePolicy()));
     int numDocs = atLeast(47);
     int max = 1051;
     int term = random().nextInt(max);
     Integer[][] positionsInDoc = new Integer[numDocs][];
     FieldType customType = new FieldType(TextField.TYPE_NOT_STORED);
     customType.setOmitNorms(true);
     for (int i = 0; i < numDocs; i++) {
       Document doc = new Document();
       ArrayList<Integer> positions = new ArrayList<>();
       StringBuilder builder = new StringBuilder();
       int num = atLeast(131);
       for (int j = 0; j < num; j++) {
         int nextInt = random().nextInt(max);
         builder.append(nextInt).append(" ");
         if (nextInt == term) {
           positions.add(Integer.valueOf(j));
         }
       }
       if (positions.size() == 0) {
         builder.append(term);
         positions.add(num);
       }
       doc.add(newField(fieldName, builder.toString(), customType));
       positionsInDoc[i] = positions.toArray(new Integer[0]);
       writer.addDocument(doc);
     }
 
     IndexReader reader = writer.getReader();
     writer.close();
 
     int num = atLeast(13);
     for (int i = 0; i < num; i++) {
       BytesRef bytes = new BytesRef("" + term);
       IndexReaderContext topReaderContext = reader.getContext();
       for (LeafReaderContext leafReaderContext : topReaderContext.leaves()) {
         PostingsEnum docsAndPosEnum = getDocsAndPositions(
             leafReaderContext.reader(), bytes);
         assertNotNull(docsAndPosEnum);
         int initDoc = 0;
         int maxDoc = leafReaderContext.reader().maxDoc();
         // initially advance or do next doc
         if (random().nextBoolean()) {
           initDoc = docsAndPosEnum.nextDoc();
         } else {
           initDoc = docsAndPosEnum.advance(random().nextInt(maxDoc));
         }
         // now run through the scorer and check if all positions are there...
         do {
           int docID = docsAndPosEnum.docID();
           if (docID == DocIdSetIterator.NO_MORE_DOCS) {
             break;
           }
           Integer[] pos = positionsInDoc[leafReaderContext.docBase + docID];
           assertEquals(pos.length, docsAndPosEnum.freq());
           // number of positions read should be random - don't read all of them
           // allways
           final int howMany = random().nextInt(20) == 0 ? pos.length
               - random().nextInt(pos.length) : pos.length;
           for (int j = 0; j < howMany; j++) {
             assertEquals("iteration: " + i + " initDoc: " + initDoc + " doc: "
                 + docID + " base: " + leafReaderContext.docBase
                 + " positions: " + Arrays.toString(pos) /* TODO: + " usePayloads: "
                 + usePayload*/, pos[j].intValue(), docsAndPosEnum.nextPosition());
           }
 
           if (random().nextInt(10) == 0) { // once is a while advance
             if (docsAndPosEnum.advance(docID + 1 + random().nextInt((maxDoc - docID))) == DocIdSetIterator.NO_MORE_DOCS) {
               break;
             }
           }
 
         } while (docsAndPosEnum.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
       }
 
     }
     reader.close();
     dir.close();
   }
 
   public void testRandomDocs() throws IOException {
     Directory dir = newDirectory();
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir,
                                                      newIndexWriterConfig(new MockAnalyzer(random()))
                                                        .setMergePolicy(newLogMergePolicy()));
     int numDocs = atLeast(49);
     int max = 15678;
     int term = random().nextInt(max);
     int[] freqInDoc = new int[numDocs];
     FieldType customType = new FieldType(TextField.TYPE_NOT_STORED);
     customType.setOmitNorms(true);
     for (int i = 0; i < numDocs; i++) {
       Document doc = new Document();
       StringBuilder builder = new StringBuilder();
       for (int j = 0; j < 199; j++) {
         int nextInt = random().nextInt(max);
         builder.append(nextInt).append(' ');
         if (nextInt == term) {
           freqInDoc[i]++;
         }
       }
       doc.add(newField(fieldName, builder.toString(), customType));
       writer.addDocument(doc);
     }
 
     IndexReader reader = writer.getReader();
     writer.close();
 
     int num = atLeast(13);
     for (int i = 0; i < num; i++) {
       BytesRef bytes = new BytesRef("" + term);
       IndexReaderContext topReaderContext = reader.getContext();
       for (LeafReaderContext context : topReaderContext.leaves()) {
         int maxDoc = context.reader().maxDoc();
         PostingsEnum postingsEnum = TestUtil.docs(random(), context.reader(), fieldName, bytes, null, PostingsEnum.FREQS);
         if (findNext(freqInDoc, context.docBase, context.docBase + maxDoc) == Integer.MAX_VALUE) {
           assertNull(postingsEnum);
           continue;
         }
         assertNotNull(postingsEnum);
         postingsEnum.nextDoc();
         for (int j = 0; j < maxDoc; j++) {
           if (freqInDoc[context.docBase + j] != 0) {
             assertEquals(j, postingsEnum.docID());
             assertEquals(postingsEnum.freq(), freqInDoc[context.docBase +j]);
             if (i % 2 == 0 && random().nextInt(10) == 0) {
               int next = findNext(freqInDoc, context.docBase+j+1, context.docBase + maxDoc) - context.docBase;
               int advancedTo = postingsEnum.advance(next);
               if (next >= maxDoc) {
                 assertEquals(DocIdSetIterator.NO_MORE_DOCS, advancedTo);
               } else {
                 assertTrue("advanced to: " +advancedTo + " but should be <= " + next, next >= advancedTo);  
               }
             } else {
               postingsEnum.nextDoc();
             }
           } 
         }
         assertEquals("docBase: " + context.docBase + " maxDoc: " + maxDoc + " " + postingsEnum.getClass(), DocIdSetIterator.NO_MORE_DOCS, postingsEnum.docID());
       }
       
     }
 
     reader.close();
     dir.close();
   }
   
   private static int findNext(int[] docs, int pos, int max) {
     for (int i = pos; i < max; i++) {
       if( docs[i] != 0) {
         return i;
       }
     }
     return Integer.MAX_VALUE;
   }
 
   /**
    * tests retrieval of positions for terms that have a large number of
    * occurrences to force test of buffer refill during positions iteration.
    */
   public void testLargeNumberOfPositions() throws IOException {
     Directory dir = newDirectory();
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir,
         newIndexWriterConfig(new MockAnalyzer(random())));
     int howMany = 1000;
     FieldType customType = new FieldType(TextField.TYPE_NOT_STORED);
     customType.setOmitNorms(true);
     for (int i = 0; i < 39; i++) {
       Document doc = new Document();
       StringBuilder builder = new StringBuilder();
       for (int j = 0; j < howMany; j++) {
         if (j % 2 == 0) {
           builder.append("even ");
         } else {
           builder.append("odd ");
         }
       }
       doc.add(newField(fieldName, builder.toString(), customType));
       writer.addDocument(doc);
     }
 
     // now do searches
     IndexReader reader = writer.getReader();
     writer.close();
 
     int num = atLeast(13);
     for (int i = 0; i < num; i++) {
       BytesRef bytes = new BytesRef("even");
 
       IndexReaderContext topReaderContext = reader.getContext();
       for (LeafReaderContext leafReaderContext : topReaderContext.leaves()) {
         PostingsEnum docsAndPosEnum = getDocsAndPositions(
             leafReaderContext.reader(), bytes);
         assertNotNull(docsAndPosEnum);
 
         int initDoc = 0;
         int maxDoc = leafReaderContext.reader().maxDoc();
         // initially advance or do next doc
         if (random().nextBoolean()) {
           initDoc = docsAndPosEnum.nextDoc();
         } else {
           initDoc = docsAndPosEnum.advance(random().nextInt(maxDoc));
         }
         String msg = "Iteration: " + i + " initDoc: " + initDoc; // TODO: + " payloads: " + usePayload;
         assertEquals(howMany / 2, docsAndPosEnum.freq());
         for (int j = 0; j < howMany; j += 2) {
           assertEquals("position missmatch index: " + j + " with freq: "
               + docsAndPosEnum.freq() + " -- " + msg, j,
               docsAndPosEnum.nextPosition());
         }
       }
     }
     reader.close();
     dir.close();
   }
   
   public void testDocsEnumStart() throws Exception {
     Directory dir = newDirectory();
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir);
     Document doc = new Document();
     doc.add(newStringField("foo", "bar", Field.Store.NO));
     writer.addDocument(doc);
     DirectoryReader reader = writer.getReader();
     LeafReader r = getOnlySegmentReader(reader);
     PostingsEnum disi = TestUtil.docs(random(), r, "foo", new BytesRef("bar"), null, PostingsEnum.NONE);
     int docid = disi.docID();
     assertEquals(-1, docid);
     assertTrue(disi.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
     
     // now reuse and check again
     TermsEnum te = r.terms("foo").iterator();
     assertTrue(te.seekExact(new BytesRef("bar")));
     disi = TestUtil.docs(random(), te, disi, PostingsEnum.NONE);
     docid = disi.docID();
     assertEquals(-1, docid);
     assertTrue(disi.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
     writer.close();
     r.close();
     dir.close();
   }
   
   public void testDocsAndPositionsEnumStart() throws Exception {
     Directory dir = newDirectory();
     RandomIndexWriter writer = new RandomIndexWriter(random(), dir);
     Document doc = new Document();
     doc.add(newTextField("foo", "bar", Field.Store.NO));
     writer.addDocument(doc);
     DirectoryReader reader = writer.getReader();
     LeafReader r = getOnlySegmentReader(reader);
     PostingsEnum disi = r.postings(new Term("foo", "bar"), PostingsEnum.ALL);
     int docid = disi.docID();
     assertEquals(-1, docid);
     assertTrue(disi.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
     
     // now reuse and check again
     TermsEnum te = r.terms("foo").iterator();
     assertTrue(te.seekExact(new BytesRef("bar")));
     disi = te.postings(disi, PostingsEnum.ALL);
     docid = disi.docID();
     assertEquals(-1, docid);
     assertTrue(disi.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
     writer.close();
     r.close();
     dir.close();
   }
 }