content: /*
   * 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.camel.dataformat.bindy;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.List;
  
  import com.ibm.icu.text.BreakIterator;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This class replicates the essential parts of the String class in order to aid proper work for Unicode chars in the
   * presense of UTF-16. So for all operations please see {@link String} with the same signature. This class is equally
   * immutable.
   */
  public class UnicodeHelper implements Serializable {
      /**
       * Defines how length if a string is defined, i.e how chars are counted.
       */
      public enum Method {
          /**
           * One "char" is one Unicode codepoint, which is the standard case.
           */
          CODEPOINTS,
  
          /**
           * One "char" is one graphem.
           */
          GRAPHEME;
      }
  
      private static final Logger LOG = LoggerFactory.getLogger(UnicodeHelper.class);
  
      private String input;
  
      private List<Integer> splitted;
  
      private Method method;
  
      /**
       * Create instance.
       *
       * @param input  String, that is to be wrapped.
       * @param method Method, that is used to determin "chars" of string.
       */
      public UnicodeHelper(final String input, final Method method) {
          this.input = input;
          this.method = method;
          this.splitted = null;
      }
  
      /**
       * For Serialization only!
       */
      protected UnicodeHelper() {
          // Empty
      }
  
      /**
       * @return Returns the method used to determining the string length.
       */
      public Method getMethod() {
          return method;
      }
  
      /**
       * @see String#substring(int)
       */
      public String substring(final int beginIndex) {
          split();
  
          final int beginChar = splitted.get(beginIndex);
          return input.substring(beginChar);
      }
  
      /**
       * @see String#substring(int, int)
       */
      public String substring(final int beginIndex, final int endIndex) {
          split();
  
          final int beginChar = splitted.get(beginIndex);
          final int endChar = splitted.get(endIndex);
          return input.substring(beginChar, endChar);
      }
  
      /**
       * @see String#length()
       */
      public int length() {
          split();
  
          return splitted.size() - 1;
      }
  
      /**
       * @see String#indexOf(String)
       */
      public int indexOf(final String str) {
          return indexOf(str, 0);
      }
  
      /**
       * @see String#indexOf(String, int)
       */
      public int indexOf(final String str, final int fromIndex) {
          split();
  
          final int len = new UnicodeHelper(str, method).length();
  
          for (int index = fromIndex; index + len < length(); index++) {
              if (str.equals(input.substring(splitted.get(index), splitted.get(index + len)))) {
                  return index;
              }
          }
  
          return -1;
      }
  
      private void split() {
          if (this.splitted != null) {
              return;
          }
  
          if (method.equals(Method.CODEPOINTS)) {
              splitCodepoints();
  
          } else /* (method.equals(Method.GRAPHEME)) */ {
              splitGrapheme();
          }
  
          LOG.debug("\"{}\" is splitted into {} ({} {}).", input, splitted, splitted.size() - 1, method);
          if (LOG.isTraceEnabled()) {
              for (int i = 0; i < splitted.size() - 2; i++) {
                  LOG.trace("segment [{},{}[=\"{}\".", splitted.get(i), splitted.get(i + 1),
                          input.substring(splitted.get(i), splitted.get(i + 1)));
              }
          }
      }
  
      private void splitCodepoints() {
          final List<Integer> result = new ArrayList<>();
  
          int i = 0;
          final int len = input.length();
          while (i < len) {
              result.add(i);
              i += (Character.codePointAt(input, i) > 0xffff) ? 2 : 1;
          }
          result.add(len);
  
          this.splitted = result;
      }
  
      private void splitGrapheme() {
          final List<Integer> result = new ArrayList<>();
  
          //
          // Caution: The BreakIterator of ICU lib (com.ibm.icu.text.BreakIterator; siehe Dependencies) ist used here,
          //          since the Java builtin one cannot handle modern unicode (Emojis with sex, skin colour, etc.) correctly.
          //
          final BreakIterator bit = BreakIterator.getCharacterInstance();
          bit.setText(input);
  
          result.add(bit.first());
          for (int end = bit.next(); end != BreakIterator.DONE; end = bit.next()) {
              result.add(end);
          }
          this.splitted = result;
      }
  
      @Override
      public String toString() {
          return "StringHelper [input=" + input + ", splitted=" + splitted + ", method=" + method + "]";
      }
  }
  