/*
 * 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.mahout.utils.vectors.lucene;


import java.io.IOException;

import com.google.common.io.Closeables;

import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.document.StringField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexOptions;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.store.RAMDirectory;
import org.apache.mahout.common.MahoutTestCase;
import org.junit.Before;
import org.junit.Test;

public class CachedTermInfoTest extends MahoutTestCase {
  private RAMDirectory directory;
  private static final String[] DOCS = {
          "a a b b c c",
          "a b a b a b a b",
          "a b a",
          "a",
          "b",
          "a",
          "a"
  };

  private static final String[] DOCS2 = {
          "d d d d",
          "e e e e",
          "d e d e",
          "d",
          "e",
          "d",
          "e"
  };

  @Before
  public void before() throws IOException {
    directory = new RAMDirectory();

    FieldType fieldType = new FieldType();
    fieldType.setStored(false);
    fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
    fieldType.setTokenized(true);
    fieldType.setStoreTermVectors(false);
    fieldType.setStoreTermVectorPositions(false);
    fieldType.setStoreTermVectorOffsets(false);
    fieldType.freeze();

    directory = createTestIndex(fieldType, directory, 0);
  }

  @Test
  public void test() throws Exception {
    IndexReader reader = DirectoryReader.open(directory);
    CachedTermInfo cti = new CachedTermInfo(reader, "content", 0, 100);
    assertEquals(3, cti.totalTerms("content"));
    assertNotNull(cti.getTermEntry("content", "a"));
    assertNull(cti.getTermEntry("content", "e"));
    //minDf
    cti = new CachedTermInfo(reader, "content", 3, 100);
    assertEquals(2, cti.totalTerms("content"));
    assertNotNull(cti.getTermEntry("content", "a"));
    assertNull(cti.getTermEntry("content", "c"));
    //maxDFPercent, a is in 6 of 7 docs: numDocs * maxDfPercent / 100 < 6 to exclude, 85% should suffice to exclude a
    cti = new CachedTermInfo(reader, "content", 0, 85);
    assertEquals(2, cti.totalTerms("content"));
    assertNotNull(cti.getTermEntry("content", "b"));
    assertNotNull(cti.getTermEntry("content", "c"));
    assertNull(cti.getTermEntry("content", "a"));


  }

  static RAMDirectory createTestIndex(FieldType fieldType,
                                      RAMDirectory directory,
                                      int startingId) throws IOException {
    IndexWriter writer = new IndexWriter(directory, new IndexWriterConfig(new WhitespaceAnalyzer()));

    try {
      for (int i = 0; i < DOCS.length; i++) {
        Document doc = new Document();
        Field id = new StringField("id", "doc_" + (i + startingId), Field.Store.YES);
        doc.add(id);
        Field text = new Field("content", DOCS[i], fieldType);
        doc.add(text);
        Field text2 = new Field("content2", DOCS2[i], fieldType);
        doc.add(text2);
        writer.addDocument(doc);
      }
    } finally {
      Closeables.close(writer, false);
    }
    return directory;
  }
}
