/*
    * Copyright 2015 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.dns;
  
  import io.netty.channel.AddressedEnvelope;
  import io.netty.util.internal.StringUtil;
  
  import java.net.SocketAddress;
  
  /**
   * Provides some utility methods for DNS message implementations.
   */
  final class DnsMessageUtil {
  
      static StringBuilder appendQuery(StringBuilder buf, DnsQuery query) {
          appendQueryHeader(buf, query);
          appendAllRecords(buf, query);
          return buf;
      }
  
      static StringBuilder appendResponse(StringBuilder buf, DnsResponse response) {
          appendResponseHeader(buf, response);
          appendAllRecords(buf, response);
          return buf;
      }
  
      static StringBuilder appendRecordClass(StringBuilder buf, int dnsClass) {
          final String name;
          switch (dnsClass &= 0xFFFF) {
          case DnsRecord.CLASS_IN:
              name = "IN";
              break;
          case DnsRecord.CLASS_CSNET:
              name = "CSNET";
              break;
          case DnsRecord.CLASS_CHAOS:
              name = "CHAOS";
              break;
          case DnsRecord.CLASS_HESIOD:
              name = "HESIOD";
              break;
          case DnsRecord.CLASS_NONE:
              name = "NONE";
              break;
          case DnsRecord.CLASS_ANY:
              name = "ANY";
              break;
          default:
              name = null;
              break;
          }
  
          if (name != null) {
              buf.append(name);
          } else {
              buf.append("UNKNOWN(").append(dnsClass).append(')');
          }
  
          return buf;
      }
  
      private static void appendQueryHeader(StringBuilder buf, DnsQuery msg) {
          buf.append(StringUtil.simpleClassName(msg))
             .append('(');
  
          appendAddresses(buf, msg)
             .append(msg.id())
             .append(", ")
             .append(msg.opCode());
  
          if (msg.isRecursionDesired()) {
              buf.append(", RD");
          }
          if (msg.z() != 0) {
              buf.append(", Z: ")
                 .append(msg.z());
          }
          buf.append(')');
      }
  
      private static void appendResponseHeader(StringBuilder buf, DnsResponse msg) {
          buf.append(StringUtil.simpleClassName(msg))
             .append('(');
  
          appendAddresses(buf, msg)
             .append(msg.id())
            .append(", ")
            .append(msg.opCode())
            .append(", ")
            .append(msg.code())
            .append(',');
 
         boolean hasComma = true;
         if (msg.isRecursionDesired()) {
             hasComma = false;
             buf.append(" RD");
         }
         if (msg.isAuthoritativeAnswer()) {
             hasComma = false;
             buf.append(" AA");
         }
         if (msg.isTruncated()) {
             hasComma = false;
             buf.append(" TC");
         }
         if (msg.isRecursionAvailable()) {
             hasComma = false;
             buf.append(" RA");
         }
         if (msg.z() != 0) {
             if (!hasComma) {
                 buf.append(',');
             }
             buf.append(" Z: ")
                .append(msg.z());
         }
 
         if (hasComma) {
             buf.setCharAt(buf.length() - 1, ')');
         } else {
             buf.append(')');
         }
     }
 
     private static StringBuilder appendAddresses(StringBuilder buf, DnsMessage msg) {
 
         if (!(msg instanceof AddressedEnvelope)) {
             return buf;
         }
 
         @SuppressWarnings("unchecked")
         AddressedEnvelope<?, SocketAddress> envelope = (AddressedEnvelope<?, SocketAddress>) msg;
 
         SocketAddress addr = envelope.sender();
         if (addr != null) {
             buf.append("from: ")
                .append(addr)
                .append(", ");
         }
 
         addr = envelope.recipient();
         if (addr != null) {
             buf.append("to: ")
                .append(addr)
                .append(", ");
         }
 
         return buf;
     }
 
     private static void appendAllRecords(StringBuilder buf, DnsMessage msg) {
         appendRecords(buf, msg, DnsSection.QUESTION);
         appendRecords(buf, msg, DnsSection.ANSWER);
         appendRecords(buf, msg, DnsSection.AUTHORITY);
         appendRecords(buf, msg, DnsSection.ADDITIONAL);
     }
 
     private static void appendRecords(StringBuilder buf, DnsMessage message, DnsSection section) {
         final int count = message.count(section);
         for (int i = 0; i < count; i ++) {
             buf.append(StringUtil.NEWLINE)
                .append(StringUtil.TAB)
                .append(message.<DnsRecord>recordAt(section, i));
         }
     }
 
     private DnsMessageUtil() { }
 }