package org.apache.lucene.analysis.synonym;

/*
 * 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.
 */

import java.io.IOException;
import java.util.Map;

import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.synonym.SynonymFilter;
import org.apache.lucene.util.Version;
import org.apache.lucene.analysis.util.ResourceLoader;
import org.apache.lucene.analysis.util.ResourceLoaderAware;
import org.apache.lucene.analysis.util.TokenFilterFactory;

/**
 * Factory for {@link SynonymFilter}.
 * <pre class="prettyprint" >
 * <fieldType name="text_synonym" class="solr.TextField" positionIncrementGap="100">
 *   <analyzer>
 *     <tokenizer class="solr.WhitespaceTokenizerFactory"/>
 *     <filter class="solr.SynonymFilterFactory" synonyms="synonyms.txt" 
 *             format="solr" ignoreCase="false" expand="true" 
 *             tokenizerFactory="solr.WhitespaceTokenizerFactory"/>
 *   </analyzer>
 * </fieldType></pre>
 */
public class SynonymFilterFactory extends TokenFilterFactory implements ResourceLoaderAware {
  private TokenFilterFactory delegator;

  @Override
  public void init(Map<String,String> args) {
    super.init(args);
    assureMatchVersion();
    if (luceneMatchVersion.onOrAfter(Version.LUCENE_34)) {
      delegator = new FSTSynonymFilterFactory();
    } else {
      // check if you use the new optional arg "format". this makes no sense for the old one, 
      // as its wired to solr's synonyms format only.
      if (args.containsKey("format") && !args.get("format").equals("solr")) {
        throw new IllegalArgumentException("You must specify luceneMatchVersion >= 3.4 to use alternate synonyms formats");
      }
      delegator = new SlowSynonymFilterFactory();
    }
    delegator.init(args);
  }

  @Override
  public TokenStream create(TokenStream input) {
    assert delegator != null : "init() was not called!";
    return delegator.create(input);
  }

  @Override
  public void inform(ResourceLoader loader) throws IOException {
    assert delegator != null : "init() was not called!";
    ((ResourceLoaderAware) delegator).inform(loader);
  }
}