/*
 * 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.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Set;

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

/**
 * Factory for {@link CapitalizationFilter}.
 * <p>
 * The factory takes parameters:
 * <ul>
 * <li> "onlyFirstWord" - should each word be capitalized or all of the words?
 * <li> "keep" - a keep word list.  Each word that should be kept separated by whitespace.
 * <li> "keepIgnoreCase - true or false.  If true, the keep list will be considered case-insensitive.
 * <li> "forceFirstLetter" - Force the first letter to be capitalized even if it is in the keep list
 * <li> "okPrefix" - do not change word capitalization if a word begins with something in this list.
 * for example if "McK" is on the okPrefix list, the word "McKinley" should not be changed to
 * "Mckinley"
 * <li> "minWordLength" - how long the word needs to be to get capitalization applied.  If the
 * minWordLength is 3, "and" > "And" but "or" stays "or"
 * <li>"maxWordCount" - if the token contains more then maxWordCount words, the capitalization is
 * assumed to be correct.
 * </ul>
 *
 * <pre class="prettyprint">
 * <fieldType name="text_cptlztn" class="solr.TextField" positionIncrementGap="100">
 *   <analyzer>
 *     <tokenizer class="solr.WhitespaceTokenizerFactory"/>
 *     <filter class="solr.CapitalizationFilterFactory" onlyFirstWord="true"
 *           keep="java solr lucene" keepIgnoreCase="false"
 *           okPrefix="McK McD McA"/>   
 *   </analyzer>
 * </fieldType></pre>
 *
 * @since solr 1.3
 */
public class CapitalizationFilterFactory extends TokenFilterFactory {
  public static final String KEEP = "keep";
  public static final String KEEP_IGNORE_CASE = "keepIgnoreCase";
  public static final String OK_PREFIX = "okPrefix";
  public static final String MIN_WORD_LENGTH = "minWordLength";
  public static final String MAX_WORD_COUNT = "maxWordCount";
  public static final String MAX_TOKEN_LENGTH = "maxTokenLength";
  public static final String ONLY_FIRST_WORD = "onlyFirstWord";
  public static final String FORCE_FIRST_LETTER = "forceFirstLetter";

  CharArraySet keep;

  Collection<char[]> okPrefix = Collections.emptyList(); // for Example: McK

  final int minWordLength;  // don't modify capitalization for words shorter then this
  final int maxWordCount;
  final int maxTokenLength;
  final boolean onlyFirstWord;
  final boolean forceFirstLetter; // make sure the first letter is capital even if it is in the keep list

  /** Creates a new CapitalizationFilterFactory */
  public CapitalizationFilterFactory(Map<String, String> args) {
    super(args);
    boolean ignoreCase = getBoolean(args, KEEP_IGNORE_CASE, false);
    Set<String> k = getSet(args, KEEP);
    if (k != null) {
      keep = new CharArraySet(10, ignoreCase);
      keep.addAll(k);
    }

    k = getSet(args, OK_PREFIX);
    if (k != null) {
      okPrefix = new ArrayList<>();
      for (String item : k) {
        okPrefix.add(item.toCharArray());
      }
    }

    minWordLength = getInt(args, MIN_WORD_LENGTH, 0);
    maxWordCount = getInt(args, MAX_WORD_COUNT, CapitalizationFilter.DEFAULT_MAX_WORD_COUNT);
    maxTokenLength = getInt(args, MAX_TOKEN_LENGTH, CapitalizationFilter.DEFAULT_MAX_TOKEN_LENGTH);
    onlyFirstWord = getBoolean(args, ONLY_FIRST_WORD, true);
    forceFirstLetter = getBoolean(args, FORCE_FIRST_LETTER, true);
    if (!args.isEmpty()) {
      throw new IllegalArgumentException("Unknown parameters: " + args);
    }
  }

  @Override
  public CapitalizationFilter create(TokenStream input) {
    return new CapitalizationFilter(input, onlyFirstWord, keep, 
      forceFirstLetter, okPrefix, minWordLength, maxWordCount, maxTokenLength);
  }
}