content: /**
   * 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.solr.spelling;
  
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.List;
  
  import org.apache.lucene.index.*;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.lucene.document.Document;
  import org.apache.lucene.document.Field;
  import org.apache.lucene.search.spell.PlainTextDictionary;
  import org.apache.lucene.search.spell.HighFrequencyDictionary;
  import org.apache.lucene.store.RAMDirectory;
  import org.apache.solr.common.util.NamedList;
  import org.apache.solr.core.SolrCore;
  import org.apache.solr.schema.FieldType;
  
  import org.apache.solr.search.SolrIndexSearcher;
  
  /**
   * <p>
   * A spell checker implementation that loads words from a text file (one word per line).
   * </p>
   *
   * @since solr 1.3
   **/
  public class FileBasedSpellChecker extends AbstractLuceneSpellChecker {
  
    private static final Logger log = LoggerFactory.getLogger(FileBasedSpellChecker.class);
  
    public static final String SOURCE_FILE_CHAR_ENCODING = "characterEncoding";
  
    private String characterEncoding;
    public static final String WORD_FIELD_NAME = "word";
  
    @Override
    public String init(NamedList config, SolrCore core) {
      super.init(config, core);
      characterEncoding = (String) config.get(SOURCE_FILE_CHAR_ENCODING);
      return name;
    }
  
    @Override
    public void build(SolrCore core, SolrIndexSearcher searcher) {
      try {
        loadExternalFileDictionary(core);
        spellChecker.clearIndex();
        spellChecker.indexDictionary(dictionary, new IndexWriterConfig(core.getSolrConfig().luceneMatchVersion, null), false);
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  
    /**
     * Override to return null, since there is no reader associated with a file based index
     */
    @Override
    protected IndexReader determineReader(IndexReader reader) {
      return null;
    }
  
    @SuppressWarnings("unchecked")
    private void loadExternalFileDictionary(SolrCore core) {
      try {
  
        // Get the field's analyzer
        if (fieldTypeName != null && core.getSchema().getFieldTypeNoEx(fieldTypeName) != null) {
          FieldType fieldType = core.getSchema().getFieldTypes().get(fieldTypeName);
          // Do index-time analysis using the given fieldType's analyzer
          RAMDirectory ramDir = new RAMDirectory();
  
          LogMergePolicy mp = new LogByteSizeMergePolicy();
          mp.setMergeFactor(300);
  
          IndexWriter writer = new IndexWriter(
              ramDir,
              new IndexWriterConfig(core.getSolrConfig().luceneMatchVersion, fieldType.getAnalyzer()).
                  setMaxBufferedDocs(150).
                  setMergePolicy(mp).
                  setOpenMode(IndexWriterConfig.OpenMode.CREATE)
          );
  
          List<String> lines = core.getResourceLoader().getLines(sourceLocation, characterEncoding);
  
          for (String s : lines) {
            Document d = new Document();
            d.add(new Field(WORD_FIELD_NAME, s, Field.Store.NO, Field.Index.ANALYZED));
            writer.addDocument(d);
          }
          writer.forceMerge(1);
          writer.close();
  
          dictionary = new HighFrequencyDictionary(IndexReader.open(ramDir),
                  WORD_FIELD_NAME, 0.0f);
        } else {
          // check if character encoding is defined
          if (characterEncoding == null) {
            dictionary = new PlainTextDictionary(core.getResourceLoader().openResource(sourceLocation));
          } else {
            dictionary = new PlainTextDictionary(new InputStreamReader(core.getResourceLoader().openResource(sourceLocation), characterEncoding));
          }
        }
  
  
      } catch (IOException e) {
        log.error( "Unable to load spellings", e);
      }
    }
  
    public String getCharacterEncoding() {
      return characterEncoding;
    }
  }
  