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   /*
    * 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;
  
  import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
  import static io.netty.util.internal.ObjectUtil.checkNonEmptyAfterTrim;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.util.CharsetUtil;
  import io.netty.util.internal.ObjectUtil;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * The version of HTTP or its derived protocols, such as
   * <a href="https://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
   * <a href="https://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
   */
  public class HttpVersion implements Comparable<HttpVersion> {
  
      private static final Pattern VERSION_PATTERN =
          Pattern.compile("(\\S+)/(\\d+)\\.(\\d+)");
  
      static final String HTTP_1_0_STRING = "HTTP/1.0";
      static final String HTTP_1_1_STRING = "HTTP/1.1";
  
      /**
       * HTTP/1.0
       */
      public static final HttpVersion HTTP_1_0 = new HttpVersion("HTTP", 1, 0, false, true);
  
      /**
       * HTTP/1.1
       */
      public static final HttpVersion HTTP_1_1 = new HttpVersion("HTTP", 1, 1, true, true);
  
      /**
       * Returns an existing or new {@link HttpVersion} instance which matches to
       * the specified protocol version string.  If the specified {@code text} is
       * equal to {@code "HTTP/1.0"}, {@link #HTTP_1_0} will be returned.  If the
       * specified {@code text} is equal to {@code "HTTP/1.1"}, {@link #HTTP_1_1}
       * will be returned.  Otherwise, a new {@link HttpVersion} instance will be
       * returned.
       */
      public static HttpVersion valueOf(String text) {
          ObjectUtil.checkNotNull(text, "text");
  
          // super fast-path
          if (text == HTTP_1_1_STRING) {
              return HTTP_1_1;
          } else if (text == HTTP_1_0_STRING) {
              return HTTP_1_0;
          }
  
          text = text.trim();
  
          if (text.isEmpty()) {
              throw new IllegalArgumentException("text is empty (possibly HTTP/0.9)");
          }
  
          // Try to match without convert to uppercase first as this is what 99% of all clients
          // will send anyway. Also there is a change to the RFC to make it clear that it is
          // expected to be case-sensitive
          //
          // See:
          // * https://trac.tools.ietf.org/wg/httpbis/trac/ticket/1
          // * https://trac.tools.ietf.org/wg/httpbis/trac/wiki
          //
          HttpVersion version = version0(text);
          if (version == null) {
              version = new HttpVersion(text, true);
          }
          return version;
      }
  
      private static HttpVersion version0(String text) {
          if (HTTP_1_1_STRING.equals(text)) {
              return HTTP_1_1;
          }
          if (HTTP_1_0_STRING.equals(text)) {
              return HTTP_1_0;
          }
          return null;
      }
  
     private final String protocolName;
     private final int majorVersion;
     private final int minorVersion;
     private final String text;
     private final boolean keepAliveDefault;
     private final byte[] bytes;
 
     /**
      * Creates a new HTTP version with the specified version string.  You will
      * not need to create a new instance unless you are implementing a protocol
      * derived from HTTP, such as
      * <a href="https://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
      * <a href="https://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
      *
      * @param keepAliveDefault
      *        {@code true} if and only if the connection is kept alive unless
      *        the {@code "Connection"} header is set to {@code "close"} explicitly.
      */
     public HttpVersion(String text, boolean keepAliveDefault) {
         text = checkNonEmptyAfterTrim(text, "text").toUpperCase();
 
         Matcher m = VERSION_PATTERN.matcher(text);
         if (!m.matches()) {
             throw new IllegalArgumentException("invalid version format: " + text);
         }
 
         protocolName = m.group(1);
         majorVersion = Integer.parseInt(m.group(2));
         minorVersion = Integer.parseInt(m.group(3));
         this.text = protocolName + '/' + majorVersion + '.' + minorVersion;
         this.keepAliveDefault = keepAliveDefault;
         bytes = null;
     }
 
     /**
      * Creates a new HTTP version with the specified protocol name and version
      * numbers.  You will not need to create a new instance unless you are
      * implementing a protocol derived from HTTP, such as
      * <a href="https://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
      * <a href="https://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>
      *
      * @param keepAliveDefault
      *        {@code true} if and only if the connection is kept alive unless
      *        the {@code "Connection"} header is set to {@code "close"} explicitly.
      */
     public HttpVersion(
             String protocolName, int majorVersion, int minorVersion,
             boolean keepAliveDefault) {
         this(protocolName, majorVersion, minorVersion, keepAliveDefault, false);
     }
 
     private HttpVersion(
             String protocolName, int majorVersion, int minorVersion,
             boolean keepAliveDefault, boolean bytes) {
         protocolName = checkNonEmptyAfterTrim(protocolName, "protocolName").toUpperCase();
 
         for (int i = 0; i < protocolName.length(); i ++) {
             if (Character.isISOControl(protocolName.charAt(i)) ||
                     Character.isWhitespace(protocolName.charAt(i))) {
                 throw new IllegalArgumentException("invalid character in protocolName");
             }
         }
 
         checkPositiveOrZero(majorVersion, "majorVersion");
         checkPositiveOrZero(minorVersion, "minorVersion");
 
         this.protocolName = protocolName;
         this.majorVersion = majorVersion;
         this.minorVersion = minorVersion;
         text = protocolName + '/' + majorVersion + '.' + minorVersion;
         this.keepAliveDefault = keepAliveDefault;
 
         if (bytes) {
             this.bytes = text.getBytes(CharsetUtil.US_ASCII);
         } else {
             this.bytes = null;
         }
     }
 
     /**
      * Returns the name of the protocol such as {@code "HTTP"} in {@code "HTTP/1.0"}.
      */
     public String protocolName() {
         return protocolName;
     }
 
     /**
      * Returns the name of the protocol such as {@code 1} in {@code "HTTP/1.0"}.
      */
     public int majorVersion() {
         return majorVersion;
     }
 
     /**
      * Returns the name of the protocol such as {@code 0} in {@code "HTTP/1.0"}.
      */
     public int minorVersion() {
         return minorVersion;
     }
 
     /**
      * Returns the full protocol version text such as {@code "HTTP/1.0"}.
      */
     public String text() {
         return text;
     }
 
     /**
      * Returns {@code true} if and only if the connection is kept alive unless
      * the {@code "Connection"} header is set to {@code "close"} explicitly.
      */
     public boolean isKeepAliveDefault() {
         return keepAliveDefault;
     }
 
     /**
      * Returns the full protocol version text such as {@code "HTTP/1.0"}.
      */
     @Override
     public String toString() {
         return text();
     }
 
     @Override
     public int hashCode() {
         return (protocolName().hashCode() * 31 + majorVersion()) * 31 +
                minorVersion();
     }
 
     @Override
     public boolean equals(Object o) {
         if (!(o instanceof HttpVersion)) {
             return false;
         }
 
         HttpVersion that = (HttpVersion) o;
         return minorVersion() == that.minorVersion() &&
                majorVersion() == that.majorVersion() &&
                protocolName().equals(that.protocolName());
     }
 
     @Override
     public int compareTo(HttpVersion o) {
         int v = protocolName().compareTo(o.protocolName());
         if (v != 0) {
             return v;
         }
 
         v = majorVersion() - o.majorVersion();
         if (v != 0) {
             return v;
         }
 
         return minorVersion() - o.minorVersion();
     }
 
     void encode(ByteBuf buf) {
         if (bytes == null) {
             buf.writeCharSequence(text, CharsetUtil.US_ASCII);
         } else {
             buf.writeBytes(bytes);
         }
     }
 }