/*
 * 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.analysis;


import java.io.IOException;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.MultiTerms;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.RandomIndexWriter;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.BytesRef;

public class TestCachingTokenFilter extends BaseTokenStreamTestCase {
  private String[] tokens = new String[] {"term1", "term2", "term3", "term2"};
  
  public void testCaching() throws IOException {
    Directory dir = newDirectory();
    RandomIndexWriter writer = new RandomIndexWriter(random(), dir);
    Document doc = new Document();
    AtomicInteger resetCount = new AtomicInteger(0);
    TokenStream stream = new TokenStream() {
      private int index = 0;
      private CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
      private OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);

      @Override
      public void reset() throws IOException {
        super.reset();
        resetCount.incrementAndGet();
      }

      @Override
      public boolean incrementToken() {
        if (index == tokens.length) {
          return false;
        } else {
          clearAttributes();
          termAtt.append(tokens[index++]);
          offsetAtt.setOffset(0,0);
          return true;
        }        
      }
      
    };

    stream = new CachingTokenFilter(stream);

    doc.add(new TextField("preanalyzed", stream));

    // 1) we consume all tokens twice before we add the doc to the index
    assertFalse(((CachingTokenFilter)stream).isCached());
    stream.reset();
    assertFalse(((CachingTokenFilter) stream).isCached());
    checkTokens(stream);
    stream.reset();  
    checkTokens(stream);
    assertTrue(((CachingTokenFilter)stream).isCached());

    // 2) now add the document to the index and verify if all tokens are indexed
    //    don't reset the stream here, the DocumentWriter should do that implicitly
    writer.addDocument(doc);
    
    IndexReader reader = writer.getReader();
    PostingsEnum termPositions = MultiTerms.getTermPostingsEnum(reader,
                                                                          "preanalyzed",
                                                                          new BytesRef("term1"));
    assertTrue(termPositions.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
    assertEquals(1, termPositions.freq());
    assertEquals(0, termPositions.nextPosition());

    termPositions = MultiTerms.getTermPostingsEnum(reader,
                                                     "preanalyzed",
                                                     new BytesRef("term2"));
    assertTrue(termPositions.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
    assertEquals(2, termPositions.freq());
    assertEquals(1, termPositions.nextPosition());
    assertEquals(3, termPositions.nextPosition());
    
    termPositions = MultiTerms.getTermPostingsEnum(reader,
                                                     "preanalyzed",
                                                     new BytesRef("term3"));
    assertTrue(termPositions.nextDoc() != DocIdSetIterator.NO_MORE_DOCS);
    assertEquals(1, termPositions.freq());
    assertEquals(2, termPositions.nextPosition());
    reader.close();
    writer.close();
    // 3) reset stream and consume tokens again
    stream.reset();
    checkTokens(stream);

    assertEquals(1, resetCount.get());

    dir.close();
  }

  public void testDoubleResetFails() throws IOException {
    Analyzer analyzer = new MockAnalyzer(random());
    final TokenStream input = analyzer.tokenStream("field", "abc");
    CachingTokenFilter buffer = new CachingTokenFilter(input);
    buffer.reset();//ok
    IllegalStateException e = expectThrows(IllegalStateException.class, () -> {
      buffer.reset();//bad (this used to work which we don't want)
    });
    assertEquals("double reset()", e.getMessage());
  }
  
  private void checkTokens(TokenStream stream) throws IOException {
    int count = 0;
    
    CharTermAttribute termAtt = stream.getAttribute(CharTermAttribute.class);
    while (stream.incrementToken()) {
      assertTrue(count < tokens.length);
      assertEquals(tokens[count], termAtt.toString());
      count++;
    }
    
    assertEquals(tokens.length, count);
  }
}