/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.handler.codec.http.multipart;
  
  import java.io.Serializable;
  import java.util.Comparator;
  
  final class CaseIgnoringComparator implements Comparator<CharSequence>, Serializable {
  
      private static final long serialVersionUID = 4582133183775373862L;
  
      static final CaseIgnoringComparator INSTANCE = new CaseIgnoringComparator();
  
      private CaseIgnoringComparator() {
      }
  
      @Override
      public int compare(CharSequence o1, CharSequence o2) {
          int o1Length = o1.length();
          int o2Length = o2.length();
          int min = Math.min(o1Length, o2Length);
          for (int i = 0; i < min; i++) {
              char c1 = o1.charAt(i);
              char c2 = o2.charAt(i);
              if (c1 != c2) {
                  c1 = Character.toUpperCase(c1);
                  c2 = Character.toUpperCase(c2);
                  if (c1 != c2) {
                      c1 = Character.toLowerCase(c1);
                      c2 = Character.toLowerCase(c2);
                      if (c1 != c2) {
                          return c1 - c2;
                      }
                  }
              }
          }
          return o1Length - o2Length;
      }
  
      private Object readResolve() {
          return INSTANCE;
      }
  }