// Licensed under Apache License version 2.0
   package javax.jmdns.impl.tasks;
   
   import java.io.IOException;
   import java.util.Timer;
   import java.util.TimerTask;
   
   import javax.jmdns.impl.DNSIncoming;
   import javax.jmdns.impl.DNSOutgoing;
  import javax.jmdns.impl.DNSQuestion;
  import javax.jmdns.impl.DNSRecord;
  import javax.jmdns.impl.JmDNSImpl;
  import javax.jmdns.impl.constants.DNSConstants;
  
  /**
   * This is the root class for all task scheduled by the timer in JmDNS.
   * 
   * @author Pierre Frisch
   */
  public abstract class DNSTask extends TimerTask {
  
      /**
       *
       */
      private final JmDNSImpl _jmDNSImpl;
  
      /**
       * @param jmDNSImpl
       */
      protected DNSTask(JmDNSImpl jmDNSImpl) {
          super();
          this._jmDNSImpl = jmDNSImpl;
      }
  
      /**
       * Return the DNS associated with this task.
       * 
       * @return associated DNS
       */
      public JmDNSImpl getDns() {
          return _jmDNSImpl;
      }
  
      /**
       * Start this task.
       * 
       * @param timer
       *            task timer.
       */
      public abstract void start(Timer timer);
  
      /**
       * Return this task name.
       * 
       * @return task name
       */
      public abstract String getName();
  
      /*
       * (non-Javadoc)
       * @see java.lang.Object#toString()
       */
      @Override
      public String toString() {
          return this.getName();
      }
  
      /**
       * Add a question to the message.
       * 
       * @param out
       *            outgoing message
       * @param rec
       *            DNS question
       * @return outgoing message for the next question
       * @exception IOException
       */
      public DNSOutgoing addQuestion(DNSOutgoing out, DNSQuestion rec) throws IOException {
          DNSOutgoing newOut = out;
          try {
              newOut.addQuestion(rec);
          } catch (final IOException e) {
              int flags = newOut.getFlags();
              boolean multicast = newOut.isMulticast();
              int maxUDPPayload = newOut.getMaxUDPPayload();
              int id = newOut.getId();
  
              newOut.setFlags(flags | DNSConstants.FLAGS_TC);
              newOut.setId(id);
              this._jmDNSImpl.send(newOut);
  
              newOut = new DNSOutgoing(flags, multicast, maxUDPPayload);
              newOut.addQuestion(rec);
          }
          return newOut;
      }
  
      /**
       * Add an answer if it is not suppressed.
      * 
      * @param out
      *            outgoing message
      * @param in
      *            incoming request
      * @param rec
      *            DNS record answer
      * @return outgoing message for the next answer
      * @exception IOException
      */
     public DNSOutgoing addAnswer(DNSOutgoing out, DNSIncoming in, DNSRecord rec) throws IOException {
         DNSOutgoing newOut = out;
         try {
             newOut.addAnswer(in, rec);
         } catch (final IOException e) {
             int flags = newOut.getFlags();
             boolean multicast = newOut.isMulticast();
             int maxUDPPayload = newOut.getMaxUDPPayload();
             int id = newOut.getId();
 
             newOut.setFlags(flags | DNSConstants.FLAGS_TC);
             newOut.setId(id);
             this._jmDNSImpl.send(newOut);
 
             newOut = new DNSOutgoing(flags, multicast, maxUDPPayload);
             newOut.addAnswer(in, rec);
         }
         return newOut;
     }
 
     /**
      * Add an answer to the message.
      * 
      * @param out
      *            outgoing message
      * @param rec
      *            DNS record answer
      * @param now
      * @return outgoing message for the next answer
      * @exception IOException
      */
     public DNSOutgoing addAnswer(DNSOutgoing out, DNSRecord rec, long now) throws IOException {
         DNSOutgoing newOut = out;
         try {
             newOut.addAnswer(rec, now);
         } catch (final IOException e) {
             int flags = newOut.getFlags();
             boolean multicast = newOut.isMulticast();
             int maxUDPPayload = newOut.getMaxUDPPayload();
             int id = newOut.getId();
 
             newOut.setFlags(flags | DNSConstants.FLAGS_TC);
             newOut.setId(id);
             this._jmDNSImpl.send(newOut);
 
             newOut = new DNSOutgoing(flags, multicast, maxUDPPayload);
             newOut.addAnswer(rec, now);
         }
         return newOut;
     }
 
     /**
      * Add an authoritative answer to the message.
      * 
      * @param out
      *            outgoing message
      * @param rec
      *            DNS record answer
      * @return outgoing message for the next answer
      * @exception IOException
      */
     public DNSOutgoing addAuthoritativeAnswer(DNSOutgoing out, DNSRecord rec) throws IOException {
         DNSOutgoing newOut = out;
         try {
             newOut.addAuthorativeAnswer(rec);
         } catch (final IOException e) {
             int flags = newOut.getFlags();
             boolean multicast = newOut.isMulticast();
             int maxUDPPayload = newOut.getMaxUDPPayload();
             int id = newOut.getId();
 
             newOut.setFlags(flags | DNSConstants.FLAGS_TC);
             newOut.setId(id);
             this._jmDNSImpl.send(newOut);
 
             newOut = new DNSOutgoing(flags, multicast, maxUDPPayload);
             newOut.addAuthorativeAnswer(rec);
         }
         return newOut;
     }
 
     /**
      * Add an additional answer to the record. Omit if there is no room.
      * 
      * @param out
      *            outgoing message
      * @param in
      *            incoming request
      * @param rec
      *            DNS record answer
      * @return outgoing message for the next answer
      * @exception IOException
      */
     public DNSOutgoing addAdditionalAnswer(DNSOutgoing out, DNSIncoming in, DNSRecord rec) throws IOException {
         DNSOutgoing newOut = out;
         try {
             newOut.addAdditionalAnswer(in, rec);
         } catch (final IOException e) {
             int flags = newOut.getFlags();
             boolean multicast = newOut.isMulticast();
             int maxUDPPayload = newOut.getMaxUDPPayload();
             int id = newOut.getId();
 
             newOut.setFlags(flags | DNSConstants.FLAGS_TC);
             newOut.setId(id);
             this._jmDNSImpl.send(newOut);
 
             newOut = new DNSOutgoing(flags, multicast, maxUDPPayload);
             newOut.addAdditionalAnswer(in, rec);
         }
         return newOut;
     }
 
 }