/*
    * Copyright 2009 Red Hat, Inc.
    *
    * Red Hat 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.jboss.netty.handler.codec.http2;
  
  import java.nio.charset.Charset;
  import java.util.List;
  
  import org.jboss.netty.util.CharsetUtil;
  
  /**
   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
   * @author Andy Taylor (andy.taylor@jboss.org)
   * @version $Rev: 619 $, $Date: 2010-11-11 20:30:06 +0100 (jeu., 11 nov. 2010) $
   */
  class HttpCodecUtil {
      //space ' '
      static final byte SP = 32;
  
      //tab ' '
      static final byte HT = 9;
  
      /**
       * Carriage return
       */
      static final byte CR = 13;
  
      /**
       * Equals '='
       */
      static final byte EQUALS = 61;
  
      /**
       * Line feed character
       */
      static final byte LF = 10;
  
      /**
       * carriage return line feed
       */
      static final byte[] CRLF = new byte[] { CR, LF };
  
      /**
      * Colon ':'
      */
      static final byte COLON = 58;
  
      /**
      * Semicolon ';'
      */
      static final byte SEMICOLON = 59;
  
       /**
      * comma ','
      */
      static final byte COMMA = 44;
  
      static final byte DOUBLE_QUOTE = '"';
  
      static final Charset DEFAULT_CHARSET = CharsetUtil.UTF_8;
  
      private HttpCodecUtil() {
          super();
      }
  
      static void validateHeaderName(String name) {
          if (name == null) {
              throw new NullPointerException("name");
          }
          for (int i = 0; i < name.length(); i ++) {
              char c = name.charAt(i);
              if (c > 127) {
                  throw new IllegalArgumentException(
                          "name contains non-ascii character: " + name);
              }
  
              // Check prohibited characters.
              switch (c) {
              case '\t': case '\n': case 0x0b: case '\f': case '\r':
              case ' ':  case ',':  case ':':  case ';':  case '=':
                  throw new IllegalArgumentException(
                          "name contains one of the following prohibited characters: " +
                          "=,;: \\t\\r\\n\\v\\f: " + name);
              }
          }
      }
  
     static void validateHeaderValue(String value) {
         if (value == null) {
             throw new NullPointerException("value");
         }
 
         // 0 - the previous character was neither CR nor LF
         // 1 - the previous character was CR
         // 2 - the previous character was LF
         int state = 0;
 
         for (int i = 0; i < value.length(); i ++) {
             char c = value.charAt(i);
 
             // Check the absolutely prohibited characters.
             switch (c) {
             case 0x0b: // Vertical tab
                 throw new IllegalArgumentException(
                         "value contains a prohibited character '\\v': " + value);
             case '\f':
                 throw new IllegalArgumentException(
                         "value contains a prohibited character '\\f': " + value);
             }
 
             // Check the CRLF (HT | SP) pattern
             switch (state) {
             case 0:
                 switch (c) {
                 case '\r':
                     state = 1;
                     break;
                 case '\n':
                     state = 2;
                     break;
                 }
                 break;
             case 1:
                 switch (c) {
                 case '\n':
                     state = 2;
                     break;
                 default:
                     throw new IllegalArgumentException(
                             "Only '\\n' is allowed after '\\r': " + value);
                 }
                 break;
             case 2:
                 switch (c) {
                 case '\t': case ' ':
                     state = 0;
                     break;
                 default:
                     throw new IllegalArgumentException(
                             "Only ' ' and '\\t' are allowed after '\\n': " + value);
                 }
             }
         }
 
         if (state != 0) {
             throw new IllegalArgumentException(
                     "value must not end with '\\r' or '\\n':" + value);
         }
     }
 
     static boolean isTransferEncodingChunked(HttpMessage m) {
         List<String> chunked = m.getHeaders(HttpHeaders.Names.TRANSFER_ENCODING);
         if (chunked.isEmpty()) {
             return false;
         }
 
         for (String v: chunked) {
             if (v.equalsIgnoreCase(HttpHeaders.Values.CHUNKED)) {
                 return true;
             }
         }
         return false;
     }
 }