/*
 * 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.search.spell;

import java.util.Arrays;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.StringField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.store.ByteBuffersDirectory;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.util.LuceneTestCase;

public class TestSpellCheckerFrequencyComparator extends LuceneTestCase {

  public void testMostFrequentWordRanksFirst() throws Exception {
    try (Directory userDir = new ByteBuffersDirectory();
        Directory spellDir = new ByteBuffersDirectory()) {
      try (IndexWriter w = new IndexWriter(userDir, new IndexWriterConfig())) {
        for (int i = 0; i < 51; i++) {
          Document doc = new Document();
          doc.add(new StringField("body", i < 50 ? "receive" : "relieve", Field.Store.NO));
          w.addDocument(doc);
        }
      }
      try (DirectoryReader reader = DirectoryReader.open(userDir);
          SpellChecker checker =
              new SpellChecker(
                  spellDir, new LevenshteinDistance(), new SuggestWordFrequencyComparator())) {
        checker.indexDictionary(
            new LuceneDictionary(reader, "body"), new IndexWriterConfig(), false);
        String[] top =
            checker.suggestSimilar(
                "recieve", 1, reader, "body", SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX);
        // expected "receive" (50 docs) first under "frequency first", actual "relieve" (1 doc)
        assertEquals("[receive]", Arrays.toString(top));
      }
    }
  }
}