/*
    * 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.util.CharTokenizer;
  import org.apache.maven.index.creator.JarFileContentsIndexCreator;
  
  /**
   * A Nexus specific analyzer. Only difference from Lucene's SimpleAnalyzer is that we use LetterOrDigitTokenizer instead
   * of LowerCaseTokenizer. LetterOrDigitTokenizer does pretty much the same as LowerCaseTokenizer, it normalizes to lower
   * case letter, but it takes letters and numbers too (as opposed to LowerCaseTokenizer) as token chars.
   *
   * @author Eugene Kuleshov
   * @author cstamas
   */
  public final class NexusAnalyzer extends AnalyzerWrapper {
      private static final Analyzer CLASS_NAMES_ANALYZER = new Analyzer() {
          @Override
          protected TokenStreamComponents createComponents(String fieldName) {
              final Tokenizer tokenizer = new DeprecatedClassnamesTokenizer();
              return new TokenStreamComponents(tokenizer, new LowerCaseFilter(tokenizer));
          }
      };
  
      private static final Analyzer LETTER_OR_DIGIT_ANALYZER = new Analyzer() {
          @Override
          protected TokenStreamComponents createComponents(String filedName) {
              final Tokenizer tokenizer = new LetterOrDigitTokenizer();
              return new TokenStreamComponents(tokenizer, new LowerCaseFilter(tokenizer));
          }
      };
  
      public NexusAnalyzer() {
          super(PER_FIELD_REUSE_STRATEGY);
      }
  
      @Override
      protected Analyzer getWrappedAnalyzer(String fieldName) {
          if (JarFileContentsIndexCreator.FLD_CLASSNAMES_KW.getKey().equals(fieldName)) {
              // To keep "backward" compatibility, we have to use old flawed tokenizer.
              return CLASS_NAMES_ANALYZER;
          } else {
              return LETTER_OR_DIGIT_ANALYZER;
          }
      }
  
      // ==
  
      public static class NoopTokenizer extends CharTokenizer {
          public NoopTokenizer() {
              super();
          }
  
          @Override
          protected boolean isTokenChar(int i) {
              return true;
          }
      }
  
      @Deprecated
      public static class DeprecatedClassnamesTokenizer extends CharTokenizer {
          public DeprecatedClassnamesTokenizer() {
              super();
          }
  
          @Override
          protected boolean isTokenChar(int i) {
              return i != '\n';
          }
      }
  
      public static class LetterOrDigitTokenizer extends CharTokenizer {
          public LetterOrDigitTokenizer() {
              super();
          }
  
          @Override
          protected boolean isTokenChar(int c) {
              return Character.isLetterOrDigit(c);
         }
     }
 }