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.Random;

import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.TextField;
import org.apache.lucene.search.CollectionStatistics;
import org.apache.lucene.search.TermStatistics;
import org.apache.lucene.search.similarities.DefaultSimilarity;
import org.apache.lucene.search.similarities.PerFieldSimilarityWrapper;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.LineFileDocs;
import org.apache.lucene.util.LuceneTestCase.Slow;
import org.apache.lucene.util.LuceneTestCase.SuppressCodecs;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.util._TestUtil;

/**
 * Test that norms info is preserved during index life - including
 * separate norms, addDocument, addIndexes, forceMerge.
 */
@SuppressCodecs({ "Memory", "Direct", "SimpleText" })
@Slow
public class TestNorms extends LuceneTestCase {
  final String byteTestField = "normsTestByte";

  class CustomNormEncodingSimilarity extends DefaultSimilarity {
    @Override
    public byte encodeNormValue(float f) {
      return (byte) f;
    }
    
    @Override
    public float decodeNormValue(byte b) {
      return (float) b;
    }

    @Override
    public float lengthNorm(FieldInvertState state) {
      return state.getLength();
    }
  }
  
  // LUCENE-1260
  public void testCustomEncoder() throws Exception {
    Directory dir = newDirectory();
    IndexWriterConfig config = newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random()));
    config.setSimilarity(new CustomNormEncodingSimilarity());
    RandomIndexWriter writer = new RandomIndexWriter(random(), dir, config);
    Document doc = new Document();
    Field foo = newTextField("foo", "", Field.Store.NO);
    Field bar = newTextField("bar", "", Field.Store.NO);
    doc.add(foo);
    doc.add(bar);
    
    for (int i = 0; i < 100; i++) {
      bar.setStringValue("singleton");
      writer.addDocument(doc);
    }
    
    IndexReader reader = writer.getReader();
    writer.close();
    
    NumericDocValues fooNorms = MultiDocValues.getNormValues(reader, "foo");
    for (int i = 0; i < reader.maxDoc(); i++) {
      assertEquals(0, fooNorms.get(i));
    }
    
    NumericDocValues barNorms = MultiDocValues.getNormValues(reader, "bar");
    for (int i = 0; i < reader.maxDoc(); i++) {
      assertEquals(1, barNorms.get(i));
    }
    
    reader.close();
    dir.close();
  }
  
  public void testMaxByteNorms() throws IOException {
    Directory dir = newFSDirectory(_TestUtil.getTempDir("TestNorms.testMaxByteNorms"));
    buildIndex(dir);
    AtomicReader open = SlowCompositeReaderWrapper.wrap(DirectoryReader.open(dir));
    NumericDocValues normValues = open.getNormValues(byteTestField);
    assertNotNull(normValues);
    for (int i = 0; i < open.maxDoc(); i++) {
      StoredDocument document = open.document(i);
      int expected = Integer.parseInt(document.get(byteTestField));
      assertEquals(expected, normValues.get(i));
    }
    open.close();
    dir.close();
  }
  
  // TODO: create a testNormsNotPresent ourselves by adding/deleting/merging docs

  public void buildIndex(Directory dir) throws IOException {
    Random random = random();
    IndexWriterConfig config = newIndexWriterConfig(TEST_VERSION_CURRENT,
        new MockAnalyzer(random()));
    Similarity provider = new MySimProvider();
    config.setSimilarity(provider);
    RandomIndexWriter writer = new RandomIndexWriter(random, dir, config);
    final LineFileDocs docs = new LineFileDocs(random, true);
    int num = atLeast(100);
    for (int i = 0; i < num; i++) {
      Document doc = docs.nextDoc();
      int boost = random().nextInt(255);
      Field f = new TextField(byteTestField, "" + boost, Field.Store.YES);
      f.setBoost(boost);
      doc.add(f);
      writer.addDocument(doc);
      doc.removeField(byteTestField);
      if (rarely()) {
        writer.commit();
      }
    }
    writer.commit();
    writer.close();
    docs.close();
  }


  public class MySimProvider extends PerFieldSimilarityWrapper {
    Similarity delegate = new DefaultSimilarity();

    @Override
    public float queryNorm(float sumOfSquaredWeights) {

      return delegate.queryNorm(sumOfSquaredWeights);
    }

    @Override
    public Similarity get(String field) {
      if (byteTestField.equals(field)) {
        return new ByteEncodingBoostSimilarity();
      } else {
        return delegate;
      }
    }

    @Override
    public float coord(int overlap, int maxOverlap) {
      return delegate.coord(overlap, maxOverlap);
    }
  }

  
  public static class ByteEncodingBoostSimilarity extends Similarity {

    @Override
    public long computeNorm(FieldInvertState state) {
      int boost = (int) state.getBoost();
      return (0xFF & boost);
    }

    @Override
    public SimWeight computeWeight(float queryBoost, CollectionStatistics collectionStats, TermStatistics... termStats) {
      throw new UnsupportedOperationException();
    }

    @Override
    public ExactSimScorer exactSimScorer(SimWeight weight, AtomicReaderContext context) throws IOException {
      throw new UnsupportedOperationException();
    }

    @Override
    public SloppySimScorer sloppySimScorer(SimWeight weight, AtomicReaderContext context) throws IOException {
      throw new UnsupportedOperationException();
    }
  } 
}