package org.jscsi.target.connection.stage.login;

 import java.io.IOException;

 import java.nio.ByteBuffer;

 import java.security.DigestException;

 import org.jscsi.exception.InternetSCSIException;

 import org.jscsi.parser.BasicHeaderSegment;

 import org.jscsi.parser.OperationCode;

 import org.jscsi.parser.ProtocolDataUnit;

 import org.jscsi.parser.login.LoginRequestParser;

 import org.jscsi.parser.login.LoginStage;

 import org.jscsi.parser.login.LoginStatus;

 import org.jscsi.target.connection.TargetPduFactory;

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

 import org.jscsi.target.connection.stage.TargetStage;

 import org.jscsi.target.settings.ConnectionSettingsNegotiator;

 import org.jscsi.target.settings.SettingsException;

 import org.jscsi.target.util.ReadWrite;

 /**

  * This class is an abstract super-class for stages of the {@link TargetLoginPhase} (see <code>Connection</code> for a

  * description of the relationship between sessions, connections, phases and sessions), namely the

  * {@link LoginOperationalParameterNegotiationStage} and the {@link SecurityNegotiationStage}.

  * <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.

  * <p>

  * Of equal importance is the {@link #getNextStageNumber()} method, which must be used to find out which stage or phase

  * will follow this one.

  * 

  * @author Andreas Ergenzinger

  */

 public abstract class TargetLoginStage extends TargetStage {

     /**

      * Manages the text parameter negotiation.

      */

     protected final ConnectionSettingsNegotiator negotiator;

     /**

      * The stage number used for describing this stage in Login Request PDUs.

      * 

      * @see LoginRequestParser#getCurrentStageNumber()

      * @see LoginRequestParser#getNextStageNumber()

      */

     protected final LoginStage stageNumber;

     /**

      * An identifier used by the initiator to identify the login task. Sent with the first Login Request PDU.

      */

     protected int initiatorTaskTag;

     /**

      * A stage number describing which stage the initiator wants to transition to. This value will be updated with every

      * received PDU.

      * 

      * @see #stageNumber

      */

     protected LoginStage requestedNextStageNumber;

     /**

      * A stage number describing which stage must follow this stage.

      * <p>

      * This value is initialized with <code>null</code>, and will be changed in {@link #execute(ProtocolDataUnit)}, if

      * the stage was finished successfully.

      * 

      * @see #stageNumber

      */

     protected LoginStage nextStageNumber;

     /**

      * The abstract constructor.

      * 

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

      * @param stageNumber the stage number used for describing this stage in Login Request PDUs

      */

     public TargetLoginStage (final TargetLoginPhase targetLoginPhase, final LoginStage stageNumber) {

         super(targetLoginPhase);

         this.stageNumber = stageNumber;

         negotiator = connection.getConnectionSettingsNegotiator();

     }

     /**

      * Returns <code>true</code>, if and only if the specified PDU is a Login Request PDU and the CSN and

      * InitiatorTaskTag fields check out.

      * 

      * @param pdu the PDU to check

      * @return <code>true</code> if the PDU checks out

      */

     protected boolean checkPdu (ProtocolDataUnit pdu) {

         final BasicHeaderSegment bhs = pdu.getBasicHeaderSegment();

         final LoginRequestParser parser = (LoginRequestParser) bhs.getParser();

         if (bhs.getOpCode() == OperationCode.LOGIN_REQUEST && parser.getCurrentStageNumber() == stageNumber && bhs.getInitiatorTaskTag() == initiatorTaskTag) return true;

         return false;

     }

     /**

      * Receives a sequence of Login Request PDUs (as indicated by the {@link LoginRequestParser#isContinueFlag()} and

      * returns the concatenated content of the text data segments.

      * 

      * @return the concatenated content of the text data segments

      * @throws DigestException

      * @throws InternetSCSIException

      * @throws IOException

      * @throws SettingsException

      * @throws InterruptedException

      */

     protected final String receivePduSequence () throws DigestException , InternetSCSIException , IOException , SettingsException , InterruptedException {

         final ProtocolDataUnit pdu = connection.receivePdu();

         return receivePduSequence(pdu);

     }

     /**

      * Receives a sequence of Login Request PDUs (as indicated by the {@link LoginRequestParser#isContinueFlag()} and

      * returns the concatenated content of the text data segments.

      * 

      * @param pdu the first PDU of the sequence

      * @return the concatenated content of the text data segments

      * @throws InternetSCSIException

      * @throws InterruptedException

      * @throws IOException

      * @throws DigestException

      * @throws SettingsException

      */

     protected final String receivePduSequence (ProtocolDataUnit pdu) throws InternetSCSIException , InterruptedException , IOException , DigestException , SettingsException {

         // StringBuilder for the key-value pairs received during this sequence

         final StringBuilder stringBuilder = new StringBuilder();

         // for accessing the fields of the last received PDU

         BasicHeaderSegment bhs;

         LoginRequestParser parser;

         // begin sequence

         int sequenceLength = 1;

         while (sequenceLength <= session.getTargetServer().getConfig().getInMaxRecvTextPduSequenceLength()) {

             bhs = pdu.getBasicHeaderSegment();

             parser = (LoginRequestParser) bhs.getParser();

             // check PDU

             if (!checkPdu(pdu)) {

                 // send login reject and leave stage

                 sendRejectPdu(LoginStatus.INVALID_DURING_LOGIN);

                 throw new InternetSCSIException("Wrong PDU in TargetLoginStage");

             }

             // PDU is okay, so append text data segment to stringBuilder

             ReadWrite.appendTextDataSegmentToStringBuffer(pdu.getDataSegment(), stringBuilder);

             // remember what stage the initiator wants to transition to

             requestedNextStageNumber = parser.getNextStageNumber();

             // continue?

             if (parser.isContinueFlag()) {

                 // send reception confirmation

                 pdu = TargetPduFactory.createLoginResponsePdu(false,// transitFlag

                         false,// continueFlag

                         stageNumber,// currentStage

                         stageNumber,// nextStage

                         session.getInitiatorSessionID(),// initiatorSessionID

                         session.getTargetSessionIdentifyingHandle(),// targetSessionIdentifyingHandle

                         initiatorTaskTag, LoginStatus.SUCCESS,// status

                         ByteBuffer.allocate(0));// dataSegment

                 connection.sendPdu(pdu);

                 // receive the next pdu

                 pdu = connection.receivePdu();

             } else

                 // sequence is over

                 return stringBuilder.toString();

         }

         // initiator's text PDU sequence was too long

         // send login reject and leave stage

         sendRejectPdu(LoginStatus.OUT_OF_RESOURCES);

         throw new InternetSCSIException("Wrong PDU in TargetLoginStage");

     }

     /**

      * Sends a Login Response PDU sequence containing the specified <i>key-value</i> pairs.

      * 

      * @param keyValuePairs contains <i>key-value</i> pairs to send

      * @param nextStage indicates if the target is willing to transition to a different stage

      * @throws SettingsException

      * @throws InterruptedException

      * @throws IOException

      * @throws InternetSCSIException

      * @throws DigestException

      */

     protected final void sendPduSequence (final String keyValuePairs, final LoginStage nextStage) throws SettingsException , InterruptedException , IOException , InternetSCSIException , DigestException {

         // some variables

         ProtocolDataUnit pdu;

         BasicHeaderSegment bhs;

         LoginRequestParser parser;

         boolean continueFlag = true;

         boolean transitFlag = false;

         // split input string into text data segments

         final ByteBuffer[] dataSegments = ReadWrite.stringToTextDataSegments(keyValuePairs,// string

                 settings.getMaxRecvDataSegmentLength());// bufferSize

         // send all data segments (and receive confirmations)

         for (int i = 0; i < dataSegments.length; ++i) {

             // adjust flags

             if (i == dataSegments.length - 1) {

                 continueFlag = false;

                 if (stageNumber != nextStage) transitFlag = true;

             }

             // create and send PDU

             pdu = TargetPduFactory.createLoginResponsePdu(transitFlag,// transitFlag

                     continueFlag,// continueFlag

                     stageNumber,// currentStage

                     nextStage,// nextStage

                     session.getInitiatorSessionID(),// initiatorSessionID

                     session.getTargetSessionIdentifyingHandle(),// targetSessionIdentifyingHandle

                     initiatorTaskTag, LoginStatus.SUCCESS,// status

                     dataSegments[i]);// dataSegment

             connection.sendPdu(pdu);

             // receive confirmation

             if (continueFlag) {

                 // receive and check

                 pdu = connection.receivePdu();

                 bhs = pdu.getBasicHeaderSegment();

                 parser = (LoginRequestParser) bhs.getParser();

                 if (!checkPdu(pdu) || parser.isContinueFlag()) {

                     // send login reject and leave stage

                     sendRejectPdu(LoginStatus.INITIATOR_ERROR);

                     throw new InternetSCSIException();

                 }

             }

         }

     }

     /**

      * Sends a Login Response PDU informing the initiator that an error has occurred and that the connection must be

      * closed.

      * 

      * @param errorStatus hints to the cause of the error

      * @throws InterruptedException

      * @throws IOException

      * @throws InternetSCSIException

      */

     protected final void sendRejectPdu (final LoginStatus errorStatus) throws InterruptedException , IOException , InternetSCSIException {

         final ProtocolDataUnit rejectPDU = TargetPduFactory.createLoginResponsePdu(false,// transit flag

                 false,// continueFlag

                 stageNumber,// currentStage

                 stageNumber,// nextStage

                 session.getInitiatorSessionID(),// initiatorSessionID

                 session.getTargetSessionIdentifyingHandle(),// targetSessionIdentifyingHandle

                 initiatorTaskTag,// initiatorTaskTag

                 errorStatus,// status

                 ByteBuffer.allocate(0));// dataSegment

         connection.sendPdu(rejectPDU);

     }

     /**

      * Returns a stage number describing which stage of phase must follow this stage, or <code>null</code> if the

      * initiator is not allowed to transition any further.

      * 

      * @return an identifier of the next stage/phase or <code>null</code>

      */

     public final LoginStage getNextStageNumber () {

         return nextStageNumber;

     }

 }