/*
    * 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:
    *
    *   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 java.text.ParseException;
  import java.util.Calendar;
  import java.util.Collections;
  import java.util.Date;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Set;
  
  import static io.netty.handler.codec.http.HttpConstants.*;
  
  /**
   * Provides the constants for the standard HTTP header names and values and
   * commonly used utility methods that accesses an {@link HttpMessage}.
   */
  public abstract class HttpHeaders implements Iterable<Map.Entry<String, String>> {
  
      private static final byte[] HEADER_SEPERATOR = { COLON, SP };
      private static final byte[] CRLF = { CR, LF };
      private static final CharSequence CONTENT_LENGTH_ENTITY = newEntity(Names.CONTENT_LENGTH);
      private static final CharSequence CONNECTION_ENTITY = newEntity(Names.CONNECTION);
      private static final CharSequence CLOSE_ENTITY = newEntity(Values.CLOSE);
      private static final CharSequence KEEP_ALIVE_ENTITY = newEntity(Values.KEEP_ALIVE);
      private static final CharSequence HOST_ENTITY = newEntity(Names.HOST);
      private static final CharSequence DATE_ENTITY = newEntity(Names.DATE);
      private static final CharSequence EXPECT_ENTITY = newEntity(Names.EXPECT);
      private static final CharSequence CONTINUE_ENTITY = newEntity(Values.CONTINUE);
      private static final CharSequence TRANSFER_ENCODING_ENTITY = newEntity(Names.TRANSFER_ENCODING);
      private static final CharSequence CHUNKED_ENTITY = newEntity(Values.CHUNKED);
      private static final CharSequence SEC_WEBSOCKET_KEY1_ENTITY = newEntity(Names.SEC_WEBSOCKET_KEY1);
      private static final CharSequence SEC_WEBSOCKET_KEY2_ENTITY = newEntity(Names.SEC_WEBSOCKET_KEY2);
      private static final CharSequence SEC_WEBSOCKET_ORIGIN_ENTITY = newEntity(Names.SEC_WEBSOCKET_ORIGIN);
      private static final CharSequence SEC_WEBSOCKET_LOCATION_ENTITY = newEntity(Names.SEC_WEBSOCKET_LOCATION);
  
      public static final HttpHeaders EMPTY_HEADERS = new HttpHeaders() {
          @Override
          public String get(String name) {
              return null;
          }
  
          @Override
          public List<String> getAll(String name) {
              return Collections.emptyList();
          }
  
          @Override
          public List<Entry<String, String>> entries() {
              return Collections.emptyList();
          }
  
          @Override
          public boolean contains(String name) {
              return false;
          }
  
          @Override
          public boolean isEmpty() {
              return true;
          }
  
          @Override
          public Set<String> names() {
              return Collections.emptySet();
          }
  
          @Override
          public HttpHeaders add(String name, Object value) {
              throw new UnsupportedOperationException("read only");
          }
  
          @Override
          public HttpHeaders add(String name, Iterable<?> values) {
              throw new UnsupportedOperationException("read only");
          }
  
          @Override
          public HttpHeaders set(String name, Object value) {
              throw new UnsupportedOperationException("read only");
          }
 
         @Override
         public HttpHeaders set(String name, Iterable<?> values) {
             throw new UnsupportedOperationException("read only");
         }
 
         @Override
         public HttpHeaders remove(String name) {
             throw new UnsupportedOperationException("read only");
         }
 
         @Override
         public HttpHeaders clear() {
             throw new UnsupportedOperationException("read only");
         }
 
         @Override
         public Iterator<Entry<String, String>> iterator() {
             return entries().iterator();
         }
     };
 
     /**
      * Standard HTTP header names.
      */
     public static final class Names {
         /**
          * {@code "Accept"}
          */
         public static final String ACCEPT = "Accept";
         /**
          * {@code "Accept-Charset"}
          */
         public static final String ACCEPT_CHARSET = "Accept-Charset";
         /**
          * {@code "Accept-Encoding"}
          */
         public static final String ACCEPT_ENCODING = "Accept-Encoding";
         /**
          * {@code "Accept-Language"}
          */
         public static final String ACCEPT_LANGUAGE = "Accept-Language";
         /**
          * {@code "Accept-Ranges"}
          */
         public static final String ACCEPT_RANGES = "Accept-Ranges";
         /**
          * {@code "Accept-Patch"}
          */
         public static final String ACCEPT_PATCH = "Accept-Patch";
         /**
          * {@code "Access-Control-Allow-Credentials"}
          */
         public static final String ACCESS_CONTROL_ALLOW_CREDENTIALS = "Access-Control-Allow-Credentials";
         /**
          * {@code "Access-Control-Allow-Headers"}
          */
         public static final String ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers";
         /**
          * {@code "Access-Control-Allow-Methods"}
          */
         public static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";
         /**
          * {@code "Access-Control-Allow-Origin"}
          */
         public static final String ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin";
         /**
          * {@code "Access-Control-Expose-Headers"}
          */
         public static final String ACCESS_CONTROL_EXPOSE_HEADERS = "Access-Control-Expose-Headers";
         /**
          * {@code "Access-Control-Max-Age"}
          */
         public static final String ACCESS_CONTROL_MAX_AGE = "Access-Control-Max-Age";
         /**
          * {@code "Access-Control-Request-Headers"}
          */
         public static final String ACCESS_CONTROL_REQUEST_HEADERS = "Access-Control-Request-Headers";
         /**
          * {@code "Access-Control-Request-Method"}
          */
         public static final String ACCESS_CONTROL_REQUEST_METHOD = "Access-Control-Request-Method";
         /**
          * {@code "Age"}
          */
         public static final String AGE = "Age";
         /**
          * {@code "Allow"}
          */
         public static final String ALLOW = "Allow";
         /**
          * {@code "Authorization"}
          */
         public static final String AUTHORIZATION = "Authorization";
         /**
          * {@code "Cache-Control"}
          */
         public static final String CACHE_CONTROL = "Cache-Control";
         /**
          * {@code "Connection"}
          */
         public static final String CONNECTION = "Connection";
         /**
          * {@code "Content-Base"}
          */
         public static final String CONTENT_BASE = "Content-Base";
         /**
          * {@code "Content-Encoding"}
          */
         public static final String CONTENT_ENCODING = "Content-Encoding";
         /**
          * {@code "Content-Language"}
          */
         public static final String CONTENT_LANGUAGE = "Content-Language";
         /**
          * {@code "Content-Length"}
          */
         public static final String CONTENT_LENGTH = "Content-Length";
         /**
          * {@code "Content-Location"}
          */
         public static final String CONTENT_LOCATION = "Content-Location";
         /**
          * {@code "Content-Transfer-Encoding"}
          */
         public static final String CONTENT_TRANSFER_ENCODING = "Content-Transfer-Encoding";
         /**
          * {@code "Content-MD5"}
          */
         public static final String CONTENT_MD5 = "Content-MD5";
         /**
          * {@code "Content-Range"}
          */
         public static final String CONTENT_RANGE = "Content-Range";
         /**
          * {@code "Content-Type"}
          */
         public static final String CONTENT_TYPE = "Content-Type";
         /**
          * {@code "Cookie"}
          */
         public static final String COOKIE = "Cookie";
         /**
          * {@code "Date"}
          */
         public static final String DATE = "Date";
         /**
          * {@code "ETag"}
          */
         public static final String ETAG = "ETag";
         /**
          * {@code "Expect"}
          */
         public static final String EXPECT = "Expect";
         /**
          * {@code "Expires"}
          */
         public static final String EXPIRES = "Expires";
         /**
          * {@code "From"}
          */
         public static final String FROM = "From";
         /**
          * {@code "Host"}
          */
         public static final String HOST = "Host";
         /**
          * {@code "If-Match"}
          */
         public static final String IF_MATCH = "If-Match";
         /**
          * {@code "If-Modified-Since"}
          */
         public static final String IF_MODIFIED_SINCE = "If-Modified-Since";
         /**
          * {@code "If-None-Match"}
          */
         public static final String IF_NONE_MATCH = "If-None-Match";
         /**
          * {@code "If-Range"}
          */
         public static final String IF_RANGE = "If-Range";
         /**
          * {@code "If-Unmodified-Since"}
          */
         public static final String IF_UNMODIFIED_SINCE = "If-Unmodified-Since";
         /**
          * {@code "Last-Modified"}
          */
         public static final String LAST_MODIFIED = "Last-Modified";
         /**
          * {@code "Location"}
          */
         public static final String LOCATION = "Location";
         /**
          * {@code "Max-Forwards"}
          */
         public static final String MAX_FORWARDS = "Max-Forwards";
         /**
          * {@code "Origin"}
          */
         public static final String ORIGIN = "Origin";
         /**
          * {@code "Pragma"}
          */
         public static final String PRAGMA = "Pragma";
         /**
          * {@code "Proxy-Authenticate"}
          */
         public static final String PROXY_AUTHENTICATE = "Proxy-Authenticate";
         /**
          * {@code "Proxy-Authorization"}
          */
         public static final String PROXY_AUTHORIZATION = "Proxy-Authorization";
         /**
          * {@code "Range"}
          */
         public static final String RANGE = "Range";
         /**
          * {@code "Referer"}
          */
         public static final String REFERER = "Referer";
         /**
          * {@code "Retry-After"}
          */
         public static final String RETRY_AFTER = "Retry-After";
         /**
          * {@code "Sec-WebSocket-Key1"}
          */
         public static final String SEC_WEBSOCKET_KEY1 = "Sec-WebSocket-Key1";
         /**
          * {@code "Sec-WebSocket-Key2"}
          */
         public static final String SEC_WEBSOCKET_KEY2 = "Sec-WebSocket-Key2";
         /**
          * {@code "Sec-WebSocket-Location"}
          */
         public static final String SEC_WEBSOCKET_LOCATION = "Sec-WebSocket-Location";
         /**
          * {@code "Sec-WebSocket-Origin"}
          */
         public static final String SEC_WEBSOCKET_ORIGIN = "Sec-WebSocket-Origin";
         /**
          * {@code "Sec-WebSocket-Protocol"}
          */
         public static final String SEC_WEBSOCKET_PROTOCOL = "Sec-WebSocket-Protocol";
         /**
          * {@code "Sec-WebSocket-Version"}
          */
         public static final String SEC_WEBSOCKET_VERSION = "Sec-WebSocket-Version";
         /**
          * {@code "Sec-WebSocket-Key"}
          */
         public static final String SEC_WEBSOCKET_KEY = "Sec-WebSocket-Key";
         /**
          * {@code "Sec-WebSocket-Accept"}
          */
         public static final String SEC_WEBSOCKET_ACCEPT = "Sec-WebSocket-Accept";
         /**
          * {@code "Server"}
          */
         public static final String SERVER = "Server";
         /**
          * {@code "Set-Cookie"}
          */
         public static final String SET_COOKIE = "Set-Cookie";
         /**
          * {@code "Set-Cookie2"}
          */
         public static final String SET_COOKIE2 = "Set-Cookie2";
         /**
          * {@code "TE"}
          */
         public static final String TE = "TE";
         /**
          * {@code "Trailer"}
          */
         public static final String TRAILER = "Trailer";
         /**
          * {@code "Transfer-Encoding"}
          */
         public static final String TRANSFER_ENCODING = "Transfer-Encoding";
         /**
          * {@code "Upgrade"}
          */
         public static final String UPGRADE = "Upgrade";
         /**
          * {@code "User-Agent"}
          */
         public static final String USER_AGENT = "User-Agent";
         /**
          * {@code "Vary"}
          */
         public static final String VARY = "Vary";
         /**
          * {@code "Via"}
          */
         public static final String VIA = "Via";
         /**
          * {@code "Warning"}
          */
         public static final String WARNING = "Warning";
         /**
          * {@code "WebSocket-Location"}
          */
         public static final String WEBSOCKET_LOCATION = "WebSocket-Location";
         /**
          * {@code "WebSocket-Origin"}
          */
         public static final String WEBSOCKET_ORIGIN = "WebSocket-Origin";
         /**
          * {@code "WebSocket-Protocol"}
          */
         public static final String WEBSOCKET_PROTOCOL = "WebSocket-Protocol";
         /**
          * {@code "WWW-Authenticate"}
          */
         public static final String WWW_AUTHENTICATE = "WWW-Authenticate";
 
         private Names() {
         }
     }
 
     /**
      * Standard HTTP header values.
      */
     public static final class Values {
         /**
          * {@code "application/json"}
          */
         public static final String APPLICATION_JSON = "application/json";
         /**
          * {@code "application/x-www-form-urlencoded"}
          */
          public static final String APPLICATION_X_WWW_FORM_URLENCODED =
              "application/x-www-form-urlencoded";
         /**
          * {@code "base64"}
          */
         public static final String BASE64 = "base64";
         /**
          * {@code "binary"}
          */
         public static final String BINARY = "binary";
         /**
          * {@code "boundary"}
          */
         public static final String BOUNDARY = "boundary";
         /**
          * {@code "bytes"}
          */
         public static final String BYTES = "bytes";
         /**
          * {@code "charset"}
          */
         public static final String CHARSET = "charset";
         /**
          * {@code "chunked"}
          */
         public static final String CHUNKED = "chunked";
         /**
          * {@code "close"}
          */
         public static final String CLOSE = "close";
         /**
          * {@code "compress"}
          */
         public static final String COMPRESS = "compress";
         /**
          * {@code "100-continue"}
          */
         public static final String CONTINUE =  "100-continue";
         /**
          * {@code "deflate"}
          */
         public static final String DEFLATE = "deflate";
         /**
          * {@code "gzip"}
          */
         public static final String GZIP = "gzip";
         /**
          * {@code "gzip,deflate"}
          */
         public static final String GZIP_DEFLATE = "gzip,deflate";
         /**
          * {@code "identity"}
          */
         public static final String IDENTITY = "identity";
         /**
          * {@code "keep-alive"}
          */
         public static final String KEEP_ALIVE = "keep-alive";
         /**
          * {@code "max-age"}
          */
         public static final String MAX_AGE = "max-age";
         /**
          * {@code "max-stale"}
          */
         public static final String MAX_STALE = "max-stale";
         /**
          * {@code "min-fresh"}
          */
         public static final String MIN_FRESH = "min-fresh";
         /**
          * {@code "multipart/form-data"}
          */
         public static final String MULTIPART_FORM_DATA = "multipart/form-data";
         /**
          * {@code "must-revalidate"}
          */
         public static final String MUST_REVALIDATE = "must-revalidate";
         /**
          * {@code "no-cache"}
          */
         public static final String NO_CACHE = "no-cache";
         /**
          * {@code "no-store"}
          */
         public static final String NO_STORE = "no-store";
         /**
          * {@code "no-transform"}
          */
         public static final String NO_TRANSFORM = "no-transform";
         /**
          * {@code "none"}
          */
         public static final String NONE = "none";
         /**
          * {@code "only-if-cached"}
          */
         public static final String ONLY_IF_CACHED = "only-if-cached";
         /**
          * {@code "private"}
          */
         public static final String PRIVATE = "private";
         /**
          * {@code "proxy-revalidate"}
          */
         public static final String PROXY_REVALIDATE = "proxy-revalidate";
         /**
          * {@code "public"}
          */
         public static final String PUBLIC = "public";
         /**
          * {@code "quoted-printable"}
          */
         public static final String QUOTED_PRINTABLE = "quoted-printable";
         /**
          * {@code "s-maxage"}
          */
         public static final String S_MAXAGE = "s-maxage";
         /**
          * {@code "trailers"}
          */
         public static final String TRAILERS = "trailers";
         /**
          * {@code "Upgrade"}
          */
         public static final String UPGRADE = "Upgrade";
         /**
          * {@code "WebSocket"}
          */
         public static final String WEBSOCKET = "WebSocket";
 
         private Values() {
         }
     }
 
     /**
      * Returns {@code true} if and only if the connection can remain open and
      * thus 'kept alive'.  This methods respects the value of the
      * {@code "Connection"} header first and then the return value of
      * {@link HttpVersion#isKeepAliveDefault()}.
      */
     public static boolean isKeepAlive(HttpMessage message) {
         String connection = message.headers().get(CONNECTION_ENTITY);
         if (connection != null && equalsIgnoreCase(CLOSE_ENTITY, connection)) {
             return false;
         }
 
         if (message.getProtocolVersion().isKeepAliveDefault()) {
             return !equalsIgnoreCase(CLOSE_ENTITY, connection);
         } else {
             return equalsIgnoreCase(KEEP_ALIVE_ENTITY, connection);
         }
     }
 
     /**
      * Sets the value of the {@code "Connection"} header depending on the
      * protocol version of the specified message.  This getMethod sets or removes
      * the {@code "Connection"} header depending on what the default keep alive
      * mode of the message's protocol version is, as specified by
      * {@link HttpVersion#isKeepAliveDefault()}.
      * <ul>
      * <li>If the connection is kept alive by default:
      *     <ul>
      *     <li>set to {@code "close"} if {@code keepAlive} is {@code false}.</li>
      *     <li>remove otherwise.</li>
      *     </ul></li>
      * <li>If the connection is closed by default:
      *     <ul>
      *     <li>set to {@code "keep-alive"} if {@code keepAlive} is {@code true}.</li>
      *     <li>remove otherwise.</li>
      *     </ul></li>
      * </ul>
      */
     public static void setKeepAlive(HttpMessage message, boolean keepAlive) {
         HttpHeaders h = message.headers();
         if (message.getProtocolVersion().isKeepAliveDefault()) {
             if (keepAlive) {
                 h.remove(CONNECTION_ENTITY);
             } else {
                 h.set(CONNECTION_ENTITY, CLOSE_ENTITY);
             }
         } else {
             if (keepAlive) {
                 h.set(CONNECTION_ENTITY, KEEP_ALIVE_ENTITY);
             } else {
                 h.remove(CONNECTION_ENTITY);
             }
         }
     }
 
     /**
      * @see {@link #getHeader(HttpMessage, CharSequence)}
      */
     public static String getHeader(HttpMessage message, String name) {
         return message.headers().get(name);
     }
 
     /**
      * Returns the header value with the specified header name.  If there are
      * more than one header value for the specified header name, the first
      * value is returned.
      *
      * @return the header value or {@code null} if there is no such header
      */
     public static String getHeader(HttpMessage message, CharSequence name) {
         return message.headers().get(name);
     }
 
     /**
      * @see #getHeader(HttpMessage, CharSequence, String)
      */
     public static String getHeader(HttpMessage message, String name, String defaultValue) {
         return getHeader(message, (CharSequence) name, defaultValue);
     }
 
     /**
      * Returns the header value with the specified header name.  If there are
      * more than one header value for the specified header name, the first
      * value is returned.
      *
      * @return the header value or the {@code defaultValue} if there is no such
      *         header
      */
     public static String getHeader(HttpMessage message, CharSequence name, String defaultValue) {
         String value = message.headers().get(name);
         if (value == null) {
             return defaultValue;
         }
         return value;
     }
 
     /**
      * @see #setHeader(HttpMessage, CharSequence, Object)
      */
     public static void setHeader(HttpMessage message, String name, Object value) {
         message.headers().set(name, value);
     }
 
     /**
      * Sets a new header with the specified name and value.  If there is an
      * existing header with the same name, the existing header is removed.
      * If the specified value is not a {@link String}, it is converted into a
      * {@link String} by {@link Object#toString()}, except for {@link Date}
      * and {@link Calendar} which are formatted to the date format defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>.
      */
     public static void setHeader(HttpMessage message, CharSequence name, Object value) {
         message.headers().set(name, value);
     }
 
     /**
      *
      * @see #setHeader(HttpMessage, CharSequence, Iterable)
      */
     public static void setHeader(HttpMessage message, String name, Iterable<?> values) {
         message.headers().set(name, values);
     }
 
     /**
      * Sets a new header with the specified name and values.  If there is an
      * existing header with the same name, the existing header is removed.
      * This getMethod can be represented approximately as the following code:
      * <pre>
      * removeHeader(message, name);
      * for (Object v: values) {
      *     if (v == null) {
      *         break;
      *     }
      *     addHeader(message, name, v);
      * }
      * </pre>
      */
     public static void setHeader(HttpMessage message, CharSequence name, Iterable<?> values) {
         message.headers().set(name, values);
     }
 
     /**
      * @see #addHeader(HttpMessage, CharSequence, Object)
      */
     public static void addHeader(HttpMessage message, String name, Object value) {
         message.headers().add(name, value);
     }
 
     /**
      * Adds a new header with the specified name and value.
      * If the specified value is not a {@link String}, it is converted into a
      * {@link String} by {@link Object#toString()}, except for {@link Date}
      * and {@link Calendar} which are formatted to the date format defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>.
      */
     public static void addHeader(HttpMessage message, CharSequence name, Object value) {
         message.headers().add(name, value);
     }
 
     /**
      * @see #removeHeader(HttpMessage, CharSequence)
      */
     public static void removeHeader(HttpMessage message, String name) {
         message.headers().remove(name);
     }
 
     /**
      * Removes the header with the specified name.
      */
     public static void removeHeader(HttpMessage message, CharSequence name) {
         message.headers().remove(name);
     }
 
     /**
      * Removes all headers from the specified message.
      */
     public static void clearHeaders(HttpMessage message) {
         message.headers().clear();
     }
 
     /**
      * @see #getIntHeader(HttpMessage, CharSequence)
      */
     public static int getIntHeader(HttpMessage message, String name) {
         return getIntHeader(message, (CharSequence) name);
     }
 
     /**
      * Returns the integer header value with the specified header name.  If
      * there are more than one header value for the specified header name, the
      * first value is returned.
      *
      * @return the header value
      * @throws NumberFormatException
      *         if there is no such header or the header value is not a number
      */
     public static int getIntHeader(HttpMessage message, CharSequence name) {
         String value = getHeader(message, name);
         if (value == null) {
             throw new NumberFormatException("header not found: " + name);
         }
         return Integer.parseInt(value);
     }
 
     /**
      * @see #getIntHeader(HttpMessage, CharSequence, int)
      */
     public static int getIntHeader(HttpMessage message, String name, int defaultValue) {
         return getIntHeader(message, (CharSequence) name, defaultValue);
     }
 
     /**
      * Returns the integer header value with the specified header name.  If
      * there are more than one header value for the specified header name, the
      * first value is returned.
      *
      * @return the header value or the {@code defaultValue} if there is no such
      *         header or the header value is not a number
      */
     public static int getIntHeader(HttpMessage message, CharSequence name, int defaultValue) {
         String value = getHeader(message, name);
         if (value == null) {
             return defaultValue;
         }
 
         try {
             return Integer.parseInt(value);
         } catch (NumberFormatException ignored) {
             return defaultValue;
         }
     }
 
     /**
      * @see #setIntHeader(HttpMessage, CharSequence, int)
      */
     public static void setIntHeader(HttpMessage message, String name, int value) {
         message.headers().set(name, value);
     }
 
     /**
      * Sets a new integer header with the specified name and value.  If there
      * is an existing header with the same name, the existing header is removed.
      */
     public static void setIntHeader(HttpMessage message, CharSequence name, int value) {
         message.headers().set(name, value);
     }
 
     /**
      * @see #setIntHeader(HttpMessage, CharSequence, Iterable)
      */
     public static void setIntHeader(HttpMessage message, String name, Iterable<Integer> values) {
         message.headers().set(name, values);
     }
 
     /**
      * Sets a new integer header with the specified name and values.  If there
      * is an existing header with the same name, the existing header is removed.
      */
     public static void setIntHeader(HttpMessage message, CharSequence name, Iterable<Integer> values) {
         message.headers().set(name, values);
     }
 
     /**
      *
      * @see #addIntHeader(HttpMessage, CharSequence, int)
      */
     public static void addIntHeader(HttpMessage message, String name, int value) {
         message.headers().add(name, value);
     }
 
     /**
      * Adds a new integer header with the specified name and value.
      */
     public static void addIntHeader(HttpMessage message, CharSequence name, int value) {
         message.headers().add(name, value);
     }
 
     /**
      * @see #getDateHeader(HttpMessage, CharSequence)
      */
     public static Date getDateHeader(HttpMessage message, String name) throws ParseException {
         return getDateHeader(message, (CharSequence) name);
     }
 
     /**
      * Returns the date header value with the specified header name.  If
      * there are more than one header value for the specified header name, the
      * first value is returned.
      *
      * @return the header value
      * @throws ParseException
      *         if there is no such header or the header value is not a formatted date
      */
     public static Date getDateHeader(HttpMessage message, CharSequence name) throws ParseException {
         String value = getHeader(message, name);
         if (value == null) {
             throw new ParseException("header not found: " + name, 0);
         }
         return HttpHeaderDateFormat.get().parse(value);
     }
 
     /**
      * @see #getDateHeader(HttpMessage, CharSequence, Date)
      */
     public static Date getDateHeader(HttpMessage message, String name, Date defaultValue) {
         return getDateHeader(message, (CharSequence) name, defaultValue);
     }
 
     /**
      * Returns the date header value with the specified header name.  If
      * there are more than one header value for the specified header name, the
      * first value is returned.
      *
      * @return the header value or the {@code defaultValue} if there is no such
      *         header or the header value is not a formatted date
      */
     public static Date getDateHeader(HttpMessage message, CharSequence name, Date defaultValue) {
         final String value = getHeader(message, name);
         if (value == null) {
             return defaultValue;
         }
 
         try {
             return HttpHeaderDateFormat.get().parse(value);
         } catch (ParseException ignored) {
             return defaultValue;
         }
     }
 
     /**
      * @see #setDateHeader(HttpMessage, CharSequence, Date)
      */
     public static void setDateHeader(HttpMessage message, String name, Date value) {
         setDateHeader(message, (CharSequence) name, value);
     }
 
     /**
      * Sets a new date header with the specified name and value.  If there
      * is an existing header with the same name, the existing header is removed.
      * The specified value is formatted as defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>
      */
     public static void setDateHeader(HttpMessage message, CharSequence name, Date value) {
         if (value != null) {
             message.headers().set(name, HttpHeaderDateFormat.get().format(value));
         } else {
             message.headers().set(name, null);
         }
     }
 
     /**
      * @see #setDateHeader(HttpMessage, CharSequence, Iterable)
      */
     public static void setDateHeader(HttpMessage message, String name, Iterable<Date> values) {
         message.headers().set(name, values);
     }
 
     /**
      * Sets a new date header with the specified name and values.  If there
      * is an existing header with the same name, the existing header is removed.
      * The specified values are formatted as defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>
      */
     public static void setDateHeader(HttpMessage message, CharSequence name, Iterable<Date> values) {
         message.headers().set(name, values);
     }
 
     /**
      * @see #addDateHeader(HttpMessage, CharSequence, Date)
      */
     public static void addDateHeader(HttpMessage message, String name, Date value) {
         message.headers().add(name, value);
     }
 
     /**
      * Adds a new date header with the specified name and value.  The specified
      * value is formatted as defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>
      */
     public static void addDateHeader(HttpMessage message, CharSequence name, Date value) {
         message.headers().add(name, value);
     }
 
     /**
      * Returns the length of the content.  Please note that this value is
      * not retrieved from {@link HttpContent#content()} but from the
      * {@code "Content-Length"} header, and thus they are independent from each
      * other.
      *
      * @return the content length
      *
      * @throws NumberFormatException
      *         if the message does not have the {@code "Content-Length"} header
      *         or its value is not a number
      */
     public static long getContentLength(HttpMessage message) {
         String value = getHeader(message, CONTENT_LENGTH_ENTITY);
         if (value != null) {
             return Long.parseLong(value);
         }
 
         // We know the content length if it's a Web Socket message even if
         // Content-Length header is missing.
         long webSocketContentLength = getWebSocketContentLength(message);
         if (webSocketContentLength >= 0) {
             return webSocketContentLength;
         }
 
         // Otherwise we don't.
         throw new NumberFormatException("header not found: " + Names.CONTENT_LENGTH);
     }
 
     /**
      * Returns the length of the content.  Please note that this value is
      * not retrieved from {@link HttpContent#content()} but from the
      * {@code "Content-Length"} header, and thus they are independent from each
      * other.
      *
      * @return the content length or {@code defaultValue} if this message does
      *         not have the {@code "Content-Length"} header or its value is not
      *         a number
      */
     public static long getContentLength(HttpMessage message, long defaultValue) {
         String contentLength = message.headers().get(CONTENT_LENGTH_ENTITY);
         if (contentLength != null) {
             try {
                 return Long.parseLong(contentLength);
             } catch (NumberFormatException ignored) {
                 return defaultValue;
             }
         }
 
         // We know the content length if it's a Web Socket message even if
         // Content-Length header is missing.
         long webSocketContentLength = getWebSocketContentLength(message);
         if (webSocketContentLength >= 0) {
             return webSocketContentLength;
         }
 
         // Otherwise we don't.
         return defaultValue;
     }
 
     /**
      * Returns the content length of the specified web socket message.  If the
      * specified message is not a web socket message, {@code -1} is returned.
      */
     private static int getWebSocketContentLength(HttpMessage message) {
         // WebSockset messages have constant content-lengths.
         HttpHeaders h = message.headers();
         if (message instanceof HttpRequest) {
             HttpRequest req = (HttpRequest) message;
             if (HttpMethod.GET.equals(req.getMethod()) &&
                 h.contains(SEC_WEBSOCKET_KEY1_ENTITY) &&
                 h.contains(SEC_WEBSOCKET_KEY2_ENTITY)) {
                 return 8;
             }
         } else if (message instanceof HttpResponse) {
             HttpResponse res = (HttpResponse) message;
             if (res.getStatus().code() == 101 &&
                 h.contains(SEC_WEBSOCKET_ORIGIN_ENTITY) &&
                 h.contains(SEC_WEBSOCKET_LOCATION_ENTITY)) {
                 return 16;
             }
         }
 
         // Not a web socket message
         return -1;
     }
 
     /**
      * Sets the {@code "Content-Length"} header.
      */
     public static void setContentLength(HttpMessage message, long length) {
         message.headers().set(CONTENT_LENGTH_ENTITY, length);
     }
 
     /**
      * Returns the value of the {@code "Host"} header.
      */
     public static String getHost(HttpMessage message) {
         return message.headers().get(HOST_ENTITY);
     }
 
     /**
      * Returns the value of the {@code "Host"} header.  If there is no such
      * header, the {@code defaultValue} is returned.
      */
     public static String getHost(HttpMessage message, String defaultValue) {
         return getHeader(message, HOST_ENTITY, defaultValue);
     }
 
     /**
      * @see #setHost(HttpMessage, CharSequence)
      */
     public static void setHost(HttpMessage message, String value) {
         message.headers().set(HOST_ENTITY, value);
     }
 
     /**
      * Sets the {@code "Host"} header.
      */
     public static void setHost(HttpMessage message, CharSequence value) {
         message.headers().set(HOST_ENTITY, value);
     }
 
     /**
      * Returns the value of the {@code "Date"} header.
      *
      * @throws ParseException
      *         if there is no such header or the header value is not a formatted date
      */
     public static Date getDate(HttpMessage message) throws ParseException {
         return getDateHeader(message, DATE_ENTITY);
     }
 
     /**
      * Returns the value of the {@code "Date"} header. If there is no such
      * header or the header is not a formatted date, the {@code defaultValue}
      * is returned.
      */
     public static Date getDate(HttpMessage message, Date defaultValue) {
         return getDateHeader(message, DATE_ENTITY, defaultValue);
     }
 
     /**
      * Sets the {@code "Date"} header.
      */
     public static void setDate(HttpMessage message, Date value) {
         if (value != null) {
             message.headers().set(DATE_ENTITY, HttpHeaderDateFormat.get().format(value));
         } else {
             message.headers().set(DATE_ENTITY, null);
         }
     }
 
     /**
      * Returns {@code true} if and only if the specified message contains the
      * {@code "Expect: 100-continue"} header.
      */
     public static boolean is100ContinueExpected(HttpMessage message) {
         // Expect: 100-continue is for requests only.
         if (!(message instanceof HttpRequest)) {
             return false;
         }
 
         // It works only on HTTP/1.1 or later.
         if (message.getProtocolVersion().compareTo(HttpVersion.HTTP_1_1) < 0) {
             return false;
         }
 
         // In most cases, there will be one or zero 'Expect' header.
         String value = message.headers().get(EXPECT_ENTITY);
         if (value == null) {
             return false;
         }
         if (equalsIgnoreCase(CONTINUE_ENTITY, value)) {
             return true;
         }
 
         // Multiple 'Expect' headers.  Search through them.
         return message.headers().contains(EXPECT_ENTITY, CONTINUE_ENTITY, true);
     }
 
     /**
      * Sets the {@code "Expect: 100-continue"} header to the specified message.
      * If there is any existing {@code "Expect"} header, they are replaced with
      * the new one.
      */
     public static void set100ContinueExpected(HttpMessage message) {
         set100ContinueExpected(message, true);
     }
 
     /**
      * Sets or removes the {@code "Expect: 100-continue"} header to / from the
      * specified message.  If {@code set} is {@code true},
      * the {@code "Expect: 100-continue"} header is set and all other previous
      * {@code "Expect"} headers are removed.  Otherwise, all {@code "Expect"}
      * headers are removed completely.
      */
     public static void set100ContinueExpected(HttpMessage message, boolean set) {
         if (set) {
             message.headers().set(EXPECT_ENTITY, CONTINUE_ENTITY);
         } else {
             message.headers().remove(EXPECT_ENTITY);
         }
     }
 
     /**
      * Validates the name of a header
      *
      * @param headerName The header name being validated
      */
     static void validateHeaderName(CharSequence headerName) {
         //Check to see if the name is null
         if (headerName == null) {
             throw new NullPointerException("Header names cannot be null");
         }
         //Go through each of the characters in the name
         for (int index = 0; index < headerName.length(); index ++) {
             //Actually get the character
             char character = headerName.charAt(index);
 
             //Check to see if the character is not an ASCII character
             if (character > 127) {
                 throw new IllegalArgumentException(
                         "Header name cannot contain non-ASCII characters: " + headerName);
             }
 
             //Check for prohibited characters.
             switch (character) {
                 case '\t': case '\n': case 0x0b: case '\f': case '\r':
                 case ' ':  case ',':  case ':':  case ';':  case '=':
                     throw new IllegalArgumentException(
                             "Header name cannot contain the following prohibited characters: " +
                                     "=,;: \\t\\r\\n\\v\\f: " + headerName);
             }
         }
     }
 
     /**
      * Validates the specified header value
      *
      * @param headerValue The value being validated
      */
     static void validateHeaderValue(CharSequence headerValue) {
         //Check to see if the value is null
         if (headerValue == null) {
             throw new NullPointerException("Header values cannot be null");
         }
 
         /*
          * Set up the state of the validation
          *
          * States are as follows:
          *
          * 0: Previous character was neither CR nor LF
          * 1: The previous character was CR
          * 2: The previous character was LF
          */
         int state = 0;
 
         //Start looping through each of the character
 
         for (int index = 0; index < headerValue.length(); index ++) {
             char character = headerValue.charAt(index);
 
             //Check the absolutely prohibited characters.
             switch (character) {
                 case 0x0b: // Vertical tab
                     throw new IllegalArgumentException(
                             "Header value contains a prohibited character '\\v': " + headerValue);
                 case '\f':
                     throw new IllegalArgumentException(
                             "Header value contains a prohibited character '\\f': " + headerValue);
             }
 
             // Check the CRLF (HT | SP) pattern
             switch (state) {
                 case 0:
                     switch (character) {
                         case '\r':
                             state = 1;
                             break;
                         case '\n':
                             state = 2;
                             break;
                     }
                     break;
                 case 1:
                     switch (character) {
                         case '\n':
                             state = 2;
                             break;
                         default:
                             throw new IllegalArgumentException(
                                     "Only '\\n' is allowed after '\\r': " + headerValue);
                     }
                     break;
                 case 2:
                     switch (character) {
                         case '\t': case ' ':
                             state = 0;
                             break;
                         default:
                             throw new IllegalArgumentException(
                                     "Only ' ' and '\\t' are allowed after '\\n': " + headerValue);
                     }
             }
         }
 
         if (state != 0) {
             throw new IllegalArgumentException(
                     "Header value must not end with '\\r' or '\\n':" + headerValue);
         }
     }
 
     /**
      * Checks to see if the transfer encoding in a specified {@link HttpMessage} is chunked
      *
      * @param message The message to check
      * @return True if transfer encoding is chunked, otherwise false
      */
     public static boolean isTransferEncodingChunked(HttpMessage message) {
         return message.headers().contains(TRANSFER_ENCODING_ENTITY, CHUNKED_ENTITY, true);
     }
 
     public static void removeTransferEncodingChunked(HttpMessage m) {
         List<String> values = m.headers().getAll(TRANSFER_ENCODING_ENTITY);
         if (values.isEmpty()) {
             return;
         }
         Iterator<String> valuesIt = values.iterator();
         while (valuesIt.hasNext()) {
             String value = valuesIt.next();
             if (equalsIgnoreCase(value, CHUNKED_ENTITY)) {
                 valuesIt.remove();
             }
         }
         if (values.isEmpty()) {
             m.headers().remove(TRANSFER_ENCODING_ENTITY);
         } else {
             m.headers().set(TRANSFER_ENCODING_ENTITY, values);
         }
     }
 
     public static void setTransferEncodingChunked(HttpMessage m) {
         setHeader(m, TRANSFER_ENCODING_ENTITY, CHUNKED_ENTITY);
         removeHeader(m, CONTENT_LENGTH_ENTITY);
     }
 
     public static boolean isContentLengthSet(HttpMessage m) {
         return m.headers().contains(CONTENT_LENGTH_ENTITY);
     }
 
     /**
      * Returns {@code true} if both {@link CharSequence}'s are equals when ignore the case.
      * This only supports US_ASCII.
      */
     public static boolean equalsIgnoreCase(CharSequence name1, CharSequence name2) {
         if (name1 == name2) {
             return true;
         }
 
         if (name1 == null || name2 == null) {
             return false;
         }
 
         int nameLen = name1.length();
         if (nameLen != name2.length()) {
             return false;
         }
 
         for (int i = nameLen - 1; i >= 0; i --) {
             char c1 = name1.charAt(i);
             char c2 = name2.charAt(i);
             if (c1 != c2) {
                 if (c1 >= 'A' && c1 <= 'Z') {
                     c1 += 32;
                 }
                 if (c2 >= 'A' && c2 <= 'Z') {
                     c2 += 32;
                 }
                 if (c1 != c2) {
                     return false;
                 }
             }
         }
         return true;
     }
 
     static int hash(CharSequence name) {
         if (name instanceof HttpHeaderEntity) {
             return ((HttpHeaderEntity) name).hash();
         }
         int h = 0;
         for (int i = name.length() - 1; i >= 0; i --) {
             char c = name.charAt(i);
             if (c >= 'A' && c <= 'Z') {
                 c += 32;
             }
             h = 31 * h + c;
         }
 
         if (h > 0) {
             return h;
         } else if (h == Integer.MIN_VALUE) {
             return Integer.MAX_VALUE;
         } else {
             return -h;
         }
     }
 
     static void encode(HttpHeaders headers, ByteBuf buf) {
         if (headers instanceof DefaultHttpHeaders) {
             ((DefaultHttpHeaders) headers).encode(buf);
         } else {
             for (Entry<String, String> header: headers) {
                 encode(header.getKey(), header.getValue(), buf);
             }
         }
     }
 
     @SuppressWarnings("deprecation")
     static void encode(CharSequence key, CharSequence value, ByteBuf buf) {
         if (!encodeAscii(key, buf)) {
             buf.writeBytes(HEADER_SEPERATOR);
         }
         if (!encodeAscii(value, buf)) {
             buf.writeBytes(CRLF);
         }
     }
 
     public static boolean encodeAscii(CharSequence seq, ByteBuf buf) {
         if (seq instanceof HttpHeaderEntity) {
             return ((HttpHeaderEntity) seq).encode(buf);
         } else {
             encodeAscii0(seq, buf);
             return false;
         }
     }
 
     static void encodeAscii0(CharSequence seq, ByteBuf buf) {
         int length = seq.length();
         for (int i = 0 ; i < length; i++) {
             buf.writeByte(c2b(seq.charAt(i)));
         }
     }
 
     private static byte c2b(char c) {
         if (c > 255) {
             return '?';
         }
         return (byte) c;
     }
 
     /**
      * Create a new {@link CharSequence} which is optimized for reuse as {@link HttpHeaders} name or value.
      * So if you have a Header name or value that you want to reuse you should make use of this.
      */
     public static CharSequence newEntity(String name) {
         if (name == null) {
             throw new NullPointerException("name");
         }
         return new HttpHeaderEntity(name);
     }
 
     /**
      * Create a new {@link CharSequence} which is optimized for reuse as {@link HttpHeaders} name.
      * So if you have a Header name that you want to reuse you should make use of this.
      */
     public static CharSequence newNameEntity(String name) {
         if (name == null) {
             throw new NullPointerException("name");
         }
         return new HttpHeaderEntity(name, HEADER_SEPERATOR);
     }
 
     /**
      * Create a new {@link CharSequence} which is optimized for reuse as {@link HttpHeaders} value.
      * So if you have a Header value that you want to reuse you should make use of this.
      */
     public static CharSequence newValueEntity(String name) {
         if (name == null) {
             throw new NullPointerException("name");
         }
         return new HttpHeaderEntity(name, CRLF);
     }
 
     protected HttpHeaders() { }
 
     /**
      * @see {@link #get(CharSequence)}
      */
     public abstract String get(String name);
 
     /**
      * Returns the value of a header with the specified name.  If there are
      * more than one values for the specified name, the first value is returned.
      *
      * @param name The name of the header to search
      * @return The first header value or {@code null} if there is no such header
      */
     public String get(CharSequence name) {
         return get(name.toString());
     }
 
     /**
      * @see {@link #getAll(CharSequence)}
      */
     public abstract List<String> getAll(String name);
 
     /**
      * Returns the values of headers with the specified name
      *
      * @param name The name of the headers to search
      * @return A {@link List} of header values which will be empty if no values
      *         are found
      */
     public List<String> getAll(CharSequence name) {
         return getAll(name.toString());
     }
 
     /**
      * Returns a new {@link List} that contains all headers in this object.  Note that modifying the
      * returned {@link List} will not affect the state of this object.  If you intend to enumerate over the header
      * entries only, use {@link #iterator()} instead, which has much less overhead.
      */
     public abstract List<Map.Entry<String, String>> entries();
 
     /**
      * @see #contains(CharSequence)
      */
     public abstract boolean contains(String name);
 
     /**
      * Checks to see if there is a header with the specified name
      *
      * @param name The name of the header to search for
      * @return True if at least one header is found
      */
     public boolean contains(CharSequence name) {
         return contains(name.toString());
     }
 
     /**
      * Checks if no header exists.
      */
     public abstract boolean isEmpty();
 
     /**
      * Returns a new {@link Set} that contains the names of all headers in this object.  Note that modifying the
      * returned {@link Set} will not affect the state of this object.  If you intend to enumerate over the header
      * entries only, use {@link #iterator()} instead, which has much less overhead.
      */
     public abstract Set<String> names();
 
     /**
      * @see {@link #add(CharSequence, Object)}
      */
     public abstract HttpHeaders add(String name, Object value);
 
     /**
      * Adds a new header with the specified name and value.
      *
      * If the specified value is not a {@link String}, it is converted
      * into a {@link String} by {@link Object#toString()}, except in the cases
      * of {@link Date} and {@link Calendar}, which are formatted to the date
      * format defined in <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>.
      *
      * @param name The name of the header being added
      * @param value The value of the header being added
      *
      * @return {@code this}
      */
     public HttpHeaders add(CharSequence name, Object value) {
         return add(name.toString(), value);
     }
 
     /**
      * @see {@link #add(CharSequence, Iterable)}
      */
     public abstract HttpHeaders add(String name, Iterable<?> values);
 
     /**
      * Adds a new header with the specified name and values.
      *
      * This getMethod can be represented approximately as the following code:
      * <pre>
      * for (Object v: values) {
      *     if (v == null) {
      *         break;
      *     }
      *     headers.add(name, v);
      * }
      * </pre>
      *
      * @param name The name of the headers being set
      * @param values The values of the headers being set
      * @return {@code this}
      */
     public HttpHeaders add(CharSequence name, Iterable<?> values) {
         return add(name.toString(), values);
     }
 
     /**
      * Adds all header entries of the specified {@code headers}.
      *
      * @return {@code this}
      */
     public HttpHeaders add(HttpHeaders headers) {
         if (headers == null) {
             throw new NullPointerException("headers");
         }
         for (Map.Entry<String, String> e: headers) {
             add(e.getKey(), e.getValue());
         }
         return this;
     }
 
     /**
      * @see {@link #set(CharSequence, Object)}
      */
     public abstract HttpHeaders set(String name, Object value);
 
     /**
      * Sets a header with the specified name and value.
      *
      * If there is an existing header with the same name, it is removed.
      * If the specified value is not a {@link String}, it is converted into a
      * {@link String} by {@link Object#toString()}, except for {@link Date}
      * and {@link Calendar}, which are formatted to the date format defined in
      * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.3.1">RFC2616</a>.
      *
      * @param name The name of the header being set
      * @param value The value of the header being set
      * @return {@code this}
      */
     public HttpHeaders set(CharSequence name, Object value) {
         return set(name.toString(), value);
     }
 
     /**
      * @see {@link #set(CharSequence, Iterable)}
      */
     public abstract HttpHeaders set(String name, Iterable<?> values);
 
     /**
      * Sets a header with the specified name and values.
      *
      * If there is an existing header with the same name, it is removed.
      * This getMethod can be represented approximately as the following code:
      * <pre>
      * headers.remove(name);
      * for (Object v: values) {
      *     if (v == null) {
      *         break;
      *     }
      *     headers.add(name, v);
      * }
      * </pre>
      *
      * @param name The name of the headers being set
      * @param values The values of the headers being set
      * @return {@code this}
      */
     public HttpHeaders set(CharSequence name, Iterable<?> values) {
         return set(name.toString(), values);
     }
 
     /**
      * Cleans the current header entries and copies all header entries of the specified {@code headers}.
      *
      * @return {@code this}
      */
     public HttpHeaders set(HttpHeaders headers) {
         if (headers == null) {
             throw new NullPointerException("headers");
         }
         if (headers != this) {
             clear();
             for (Map.Entry<String, String> e : headers) {
                 add(e.getKey(), e.getValue());
             }
         }
         return this;
     }
 
     /**
      * @see {@link #remove(CharSequence)}
      */
     public abstract HttpHeaders remove(String name);
 
     /**
      * Removes the header with the specified name.
      *
      * @param name The name of the header to remove
      * @return {@code this}
      */
     public HttpHeaders remove(CharSequence name) {
         return remove(name.toString());
     }
 
     /**
      * Removes all headers from this {@link HttpMessage}.
      *
      * @return {@code this}
      */
     public abstract HttpHeaders clear();
 
     /**
      * @see {@link #contains(CharSequence, CharSequence, boolean)}
      */
     public boolean contains(String name, String value, boolean ignoreCaseValue) {
         List<String> values = getAll(name);
         if (values.isEmpty()) {
             return false;
         }
 
         for (String v: values) {
             if (ignoreCaseValue) {
                 if (equalsIgnoreCase(v, value)) {
                     return true;
                 }
             } else {
                 if (v.equals(value)) {
                     return true;
                 }
             }
         }
         return false;
     }
 
     /**
      * Returns {@code true} if a header with the {@code name} and {@code value} exists, {@code false} otherwise.
      * This also handles multiple values that are seperated with a {@code ,}.
      * <p>
      * If {@code ignoreCase} is {@code true} then a case insensitive compare is done on the value.
      * @param name the name of the header to find
      * @param value the value of the header to find
      * @param ignoreCase {@code true} then a case insensitive compare is run to compare values.
      * otherwise a case sensitive compare is run to compare values.
      */
     public boolean containsValue(CharSequence name, CharSequence value, boolean ignoreCase) {
         List<String> values = getAll(name);
         if (values.isEmpty()) {
             return false;
         }
 
         for (String v: values) {
             if (contains(v, value, ignoreCase)) {
                 return true;
             }
         }
         return false;
     }
 
     private static boolean contains(String value, CharSequence expected, boolean ignoreCase) {
         String[] parts = value.split(",");
         if (ignoreCase) {
             for (String s: parts) {
                 if (equalsIgnoreCase(expected, s.trim())) {
                     return true;
                 }
             }
         } else {
             for (String s: parts) {
                 if (s.trim().contentEquals(expected)) {
                     return true;
                 }
             }
         }
         return false;
     }
 
     /**
      * Returns {@code true} if a header with the name and value exists.
      *
      * @param name              the headername
      * @param value             the value
      * @param ignoreCaseValue   {@code true} if case should be ignored
      * @return contains         {@code true} if it contains it {@code false} otherwise
      */
     public boolean contains(CharSequence name, CharSequence value, boolean ignoreCaseValue) {
         return contains(name.toString(), value.toString(), ignoreCaseValue);
     }
 }