/*
 * 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.analysis.miscellaneous;


import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.Map;

import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.util.TokenFilterFactory;

/**
 * Factory for {@link DateRecognizerFilter}.
 * 
 * <pre class="prettyprint">
 * <fieldType name="text_filter_none_date" class="solr.TextField" positionIncrementGap="100">
 *   <analyzer>
 *     <tokenizer class="solr.WhitespaceTokenizerFactory"/>
 *     <filter class="solr.DateRecognizerFilterFactory" datePattern="yyyy/mm/dd" locale="en-US" />
 *   </analyzer>
 * </fieldType>
 * </pre>
 * 
 * <p>
 * The {@code datePattern} is optional. If omitted, {@link DateRecognizerFilter} will be created with the default date
 * format of the system. The {@code locale} is optional and if omitted the filter will be created with
 * {@link Locale#ENGLISH}.
 */
public class DateRecognizerFilterFactory extends TokenFilterFactory {

  public static final String DATE_PATTERN = "datePattern";
  public static final String LOCALE = "locale";

  private final DateFormat dateFormat;
  private final Locale locale;

  /** Creates a new FingerprintFilterFactory */
  public DateRecognizerFilterFactory(Map<String,String> args) {
    super(args);
    this.locale = getLocale(get(args, LOCALE));
    this.dateFormat = getDataFormat(get(args, DATE_PATTERN));
    if (!args.isEmpty()) {
      throw new IllegalArgumentException("Unknown parameters: " + args);
    }
  }

  @Override
  public TokenStream create(TokenStream input) {
    return new DateRecognizerFilter(input, dateFormat);
  }

  private Locale getLocale(String localeStr) {
    if (localeStr == null) {
      return Locale.ENGLISH;
    } else {
      return new Locale.Builder().setLanguageTag(localeStr).build();
    }
  }
  
  public DateFormat getDataFormat(String datePattern) {
    if (datePattern != null) {
      return new SimpleDateFormat(datePattern, locale);
    } else {
      return DateFormat.getDateInstance(DateFormat.DEFAULT, locale);
    }
  }
  
}