/*
    * 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.maven.index.context;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.AnalyzerWrapper;
  import org.apache.lucene.analysis.LowerCaseFilter;
  import org.apache.lucene.analysis.Tokenizer;
  import org.apache.lucene.analysis.standard.StandardAnalyzer;
  import org.apache.lucene.analysis.util.CharTokenizer;
  import org.apache.maven.index.ArtifactInfo;
  
  /**
   * A Nexus specific <a
   * href="http://lucene.apache.org/java/2_4_0/api/core/org/apache/lucene/analysis/Analyzer.html">Lucene Analyzer</a> used
   * to produce legacy index transfer format
   *
   * @author Jason van Zyl
   */
  public final class NexusLegacyAnalyzer extends AnalyzerWrapper {
      private static final Analyzer DEFAULT_ANALYZER = new StandardAnalyzer();
  
      private static final Analyzer LETTER_OR_DIGIT_ANALYZER = new Analyzer() {
          @Override
          protected TokenStreamComponents createComponents(final String fieldName) {
              final Tokenizer tokenizer = new CharTokenizer() {
                  @Override
                  protected boolean isTokenChar(int c) {
                      return Character.isLetterOrDigit(c);
                  }
              };
  
              return new TokenStreamComponents(tokenizer, new LowerCaseFilter(tokenizer));
          }
      };
  
      public NexusLegacyAnalyzer() {
          super(PER_FIELD_REUSE_STRATEGY);
      }
  
      @Override
      protected Analyzer getWrappedAnalyzer(String fieldName) {
          if (!isTextField(fieldName)) {
              return LETTER_OR_DIGIT_ANALYZER;
          } else {
              return DEFAULT_ANALYZER;
          }
      }
  
      protected boolean isTextField(String field) {
          return ArtifactInfo.NAME.equals(field)
                  || ArtifactInfo.DESCRIPTION.equals(field)
                  || ArtifactInfo.NAMES.equals(field);
      }
  }