package org.jscsi.target.connection.stage;

 import java.io.IOException;

 import java.security.DigestException;

 import org.jscsi.exception.InternetSCSIException;

 import org.jscsi.parser.ProtocolDataUnit;

 import org.jscsi.target.connection.Connection;

 import org.jscsi.target.connection.TargetSession;

 import org.jscsi.target.connection.phase.TargetPhase;

 import org.jscsi.target.settings.Settings;

 import org.jscsi.target.settings.SettingsException;

 /**

  * This class is an abstract super-class for stages of the (see {@link Connection} for a description of the relationship

  * between sessions, connections, phases, and sessions).

  * <p>

  * The stage is started by calling the {@link #execute(ProtocolDataUnit)} method with the first {@link ProtocolDataUnit}

  * to be processed as part of the stage.

  * 

  * @author Andreas Ergenzinger

  */

 public abstract class TargetStage {

     /**

      * The phase this stage is a part of.

      */

     protected final TargetPhase targetPhase;

     /**

      * The connection the {@link org.jscsi.target.connection.phase.TargetFullFeaturePhase} is a part of

      */

     protected final Connection connection;

     /**

      * The session the {@link #connection} is a part of.

      */

     protected final TargetSession session;

     /**

      * The current {@link Settings} of {@link #connection}.

      */

     protected final Settings settings;

     /**

      * The abstract constructor.

      * 

      * @param targetPhase the phase this stage is a part of

      */

     public TargetStage (TargetPhase targetPhase) {

         this.targetPhase = targetPhase;

         this.connection = targetPhase.getTargetConnection();

         this.session = connection.getTargetSession();

         this.settings = connection.getSettings();

     }

     /**

      * Starts the stage. This method contains the operational logic required for the receiving, processing and sending

      * of PDUs which is needed to successfully complete the represented iSCSI stage.

      * 

      * @param pdu the first {@link ProtocolDataUnit} to be processed in the stage

      * @throws IOException if the connection was closed unexpectedly

      * @throws InterruptedException

      * @throws InternetSCSIException if a PDU has violated the iSCSI standard

      * @throws DigestException if a digest error was detected

      * @throws SettingsException if the program has attempted to access a value from settings which has not been

      *             negotiated and which does not have a default value

      */

     public abstract void execute (ProtocolDataUnit pdu) throws IOException , InterruptedException , InternetSCSIException , DigestException , SettingsException;

     /**

      * Getting connection of this stage.

      * 

      * @return the related Connection of this stage.

      */

     public Connection getConnection () {

         return connection;

     }

 }