/*
    * Copyright 2013 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:
    *
    *   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 io.netty.handler.codec.http;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.util.CharsetUtil;
  
  final class HttpHeaderEntity implements CharSequence {
  
      private final String name;
      private final int hash;
      private final byte[] bytes;
      private final int separatorLen;
  
      public HttpHeaderEntity(String name) {
          this(name, null);
      }
  
      public HttpHeaderEntity(String name, byte[] separator) {
          this.name = name;
          hash = HttpHeaders.hash(name);
          byte[] nameBytes = name.getBytes(CharsetUtil.US_ASCII);
          if (separator == null) {
              bytes = nameBytes;
              separatorLen = 0;
          } else {
              separatorLen = separator.length;
              bytes = new byte[nameBytes.length + separator.length];
              System.arraycopy(nameBytes, 0, bytes, 0, nameBytes.length);
              System.arraycopy(separator, 0, bytes, nameBytes.length, separator.length);
          }
      }
  
      int hash() {
          return hash;
      }
  
      @Override
      public int length() {
          return bytes.length - separatorLen;
      }
  
      @Override
      public char charAt(int index) {
          if ((bytes.length - separatorLen) <= index) {
              throw new IndexOutOfBoundsException();
          }
          return (char) bytes[index];
      }
  
      @Override
      public CharSequence subSequence(int start, int end) {
          return new HttpHeaderEntity(name.substring(start, end));
      }
  
      @Override
      public String toString() {
          return name;
      }
  
      boolean encode(ByteBuf buf) {
          buf.writeBytes(bytes);
          return separatorLen > 0;
      }
  }