package com.atlassian.activeobjects.internal;
   
   import static com.atlassian.activeobjects.ao.ConverterUtils.toLowerCase;
   import static com.google.common.base.Preconditions.checkNotNull;
   
   public final class SimplePrefix implements Prefix {
       private static final String DEFAULT_SEPARATOR = "_";
       private final String prefix;
       private final String separator;
  
      public SimplePrefix(String prefix) {
          this(prefix, DEFAULT_SEPARATOR);
      }
  
      public SimplePrefix(String prefix, String separator) {
          this.prefix = checkNotNull(prefix);
          this.separator = checkNotNull(separator);
      }
  
      public String prepend(String string) {
          return new StringBuilder().append(prefix).append(separator).append(string).toString();
      }
  
      /**
       * Checks whether the string parameter starts with the prefix. This method is {@code null} safe and will return
       * {@code false} if the {@code string} parameter is {@code null}.
       * When checking case insensitively, the default locale will be used to lower case both the prefix and the
       * {@code string} parameter before comparing.
       *
       * @param string        checks whether {@code this} starts the String
       * @param caseSensitive whether or not we're case sensitive
       * @return {@code true} of {@code string} starts with the prefix
       */
      public boolean isStarting(String string, boolean caseSensitive) {
          return string != null &&
                  transform(string, caseSensitive).startsWith(transform(prefix + separator, caseSensitive));
      }
  
      private String transform(String s, boolean caseSensitive) {
          return caseSensitive ? s : toLowerCase(s);
      }
  }