/**
 * IK 中文分词  版本 5.0
 * IK Analyzer release 5.0
 * 
 * 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.
 *
 * 源代码由林良益(linliangyi2005@gmail.com)提供
 * 版权声明 2012，乌龙茶工作室
 * provided by Linliangyi and copyright 2012 by Oolong studio
 * 
 * 字符集识别工具类
 */
package com.xywy.lucene.core;

/**
 *
 * 字符集识别工具类
 */
class CharacterUtil {

  public static final int CHAR_USELESS = 0;

  public static final int CHAR_ARABIC = 0X00000001;

  public static final int CHAR_ENGLISH = 0X00000002;

  public static final int CHAR_CHINESE = 0X00000004;

  public static final int CHAR_OTHER_CJK = 0X00000008;

  /**
   * 识别字符类型
   * @param input
   * @return int CharacterUtil定义的字符类型常量
   */
  static int identifyCharType(char input) {
    if (input >= '0' && input <= '9') {
      return CHAR_ARABIC;

    } else if ((input >= 'a' && input <= 'z') || (input >= 'A' && input <= 'Z')) {
      return CHAR_ENGLISH;

    } else {
      Character.UnicodeBlock ub = Character.UnicodeBlock.of(input);

      if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
          || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
          || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A) {
        // 目前已知的中文字符UTF-8集合
        return CHAR_CHINESE;

      } else if (ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS // 全角数字字符和日韩字符
          // 韩文字符集
          || ub == Character.UnicodeBlock.HANGUL_SYLLABLES
          || ub == Character.UnicodeBlock.HANGUL_JAMO
          || ub == Character.UnicodeBlock.HANGUL_COMPATIBILITY_JAMO
          // 日文字符集
          || ub == Character.UnicodeBlock.HIRAGANA // 平假名
          || ub == Character.UnicodeBlock.KATAKANA // 片假名
          || ub == Character.UnicodeBlock.KATAKANA_PHONETIC_EXTENSIONS) {
        return CHAR_OTHER_CJK;

      }
    }
    // 其他的不做处理的字符
    return CHAR_USELESS;
  }

  /**
   * 进行字符规格化（全角转半角，大写转小写处理）
   * @param input
   * @return char
   */
  static char regularize(char input) {
    if (input == 12288) {
      input = (char) 32;

    } else if (input > 65280 && input < 65375) {
      input = (char) (input - 65248);

    } else if (input >= 'A' && input <= 'Z') {
      input += 32;
    }

    return input;
  }
}