package org.kuali.student.lum.program.server;

 import java.util.List;

 import org.kuali.student.common.dto.DtoConstants;

 import org.kuali.student.common.exceptions.DoesNotExistException;

 import org.kuali.student.common.exceptions.InvalidParameterException;

 import org.kuali.student.common.versionmanagement.dto.VersionDisplayInfo;

 import org.kuali.student.core.statement.dto.StatementTreeViewInfo;

 import org.kuali.student.lum.common.server.StatementUtil;

 import org.kuali.student.lum.program.client.ProgramConstants;

 import org.kuali.student.lum.program.dto.MajorDisciplineInfo;

 import org.kuali.student.lum.program.dto.ProgramRequirementInfo;

 import org.kuali.student.lum.program.service.ProgramService;

 import org.kuali.student.lum.program.service.ProgramServiceConstants;

 import org.springframework.transaction.annotation.Transactional;

 /**

  * This class is called whenever the state of a major discipline changes.

  * <p>

  * We have a separate class because the operations need to be marked with the @Transactional annotation.

  * <p>

  * THIS CLASS IS DUPLICATED FOR MAJOR DISCIPLINE, CORE, AND CREDENTIAL PROGRAMS SINCE THERE ARE DIFFERENT

  * SERVICE METHODS FOR EACH OF THESE TYPES (THOUGH THEY ARE SIMILAR)

  * <P>

  * @author Kuali Rice Team (kuali-rice@googlegroups.com)

  */

 @Transactional(noRollbackFor = {DoesNotExistException.class}, rollbackFor = {Throwable.class})

 public class ProgramStateChangeServiceImpl {

     /**

      * The program service - injected by spring.

      */

     private ProgramService programService;

     /**

      * This method is called by workflow when the state changes.

      * 

      * @param majorDisciplineId

      * @param state

      * @return

      * @throws Exception

      */

     public void changeState( String majorDisciplineId, String newState) throws Exception {

         // This method will be called from workflow.

         // Since we cannot activate a program from the workflow we do not need to add endEntryTerm and endEnrollTerm

         changeState(null, null, null, majorDisciplineId, newState);

     }

     /**

      * This method is called from the UI (servlet) when state changes.

      * 

      * @param endEntryTerm

      * @param endEnrollTerm

      * @param programType

      * @param majorDisciplineId

      * @param newState

      * @return

      * @throws Exception

      */

     public void changeState(String endEntryTerm, String endEnrollTerm, String endInstAdmitTerm,  String majorDisciplineId, String newState) throws Exception {

         // New state must not be null

         if (newState == null)

             throw new InvalidParameterException("new state cannot be null");

         // The version selected in the UI

         MajorDisciplineInfo selectedVersion = programService.getMajorDiscipline(majorDisciplineId);

         // If we are activating this version we need to mark the previous version superseded,

         // update the previous version end terms, and make the selected version current.

         if (newState.equals(DtoConstants.STATE_ACTIVE)) {

             // Find the previous version

             MajorDisciplineInfo previousVersion = findPreviousVersion(selectedVersion);

             if (previousVersion != null) {

                 // Set end terms on previous version

                 setEndTerms(previousVersion, endEntryTerm, endEnrollTerm, endInstAdmitTerm);

                 // Mark previous version as superseded and update state on all associated objects

                 updateMajorDisciplineInfoState(previousVersion, DtoConstants.STATE_SUPERSEDED);

             }

             // Update state of all associated objects for current version

             // NOTE: we must update state BEFORE making the version current

             updateMajorDisciplineInfoState(selectedVersion, newState);

             // Make this the current version

             makeCurrent(selectedVersion);

         } else {

             // Update state of all associated objects for current version

             updateMajorDisciplineInfoState(selectedVersion, newState);

         }

     }

     /**

      * This method updates the end terms for the major discipline passed into it.

      * <p>

      * You must still call updateState() to save the object using the web service.

      * 

      * @param majorDisciplineInfo

      * @param endEntryTerm

      * @param endEnrollTerm

      * @param endInstAdmitTerm 

      */

     private void setEndTerms(MajorDisciplineInfo majorDisciplineInfo, String endEntryTerm, String endEnrollTerm, String endInstAdmitTerm) {

         majorDisciplineInfo.setEndProgramEntryTerm(endEntryTerm);

         majorDisciplineInfo.setEndTerm(endEnrollTerm);

         majorDisciplineInfo.getAttributes().put(ProgramConstants.END_INSTITUTIONAL_ADMIT_TERM, endInstAdmitTerm);

     }

     /**

      * This method will update the state of this object and all associated objects.

      * <p>

      * It is needed because we need to make separate web service calls to update the state of these objects.

      * 

      * @param majorDisciplineInfo

      * @param newState

      */

     private void updateMajorDisciplineInfoState(MajorDisciplineInfo majorDisciplineInfo, String newState) throws Exception {

         // Update the statement tree

         updateRequirementsState(majorDisciplineInfo, newState);

         // Update major discipline

         majorDisciplineInfo.setState(newState);

         programService.updateMajorDiscipline(majorDisciplineInfo);

     }

     /**

      * This method will make this version of the major discipline the current one.

      * 

      * @param majorDisciplineInfo

      */

     private void makeCurrent(MajorDisciplineInfo majorDisciplineInfo) throws Exception {

         // Check if this is the current version before trying to make it current

         // (the web service will error if you try to make a version current that is already current)

         VersionDisplayInfo currentVersion = programService.getCurrentVersion(ProgramServiceConstants.PROGRAM_NAMESPACE_MAJOR_DISCIPLINE_URI, majorDisciplineInfo.getVersionInfo().getVersionIndId());

         // If this is not the current version, then make it current

         if (!currentVersion.getSequenceNumber().equals(majorDisciplineInfo.getVersionInfo().getSequenceNumber())) {

             programService.setCurrentMajorDisciplineVersion(majorDisciplineInfo.getId(), null);

         }

     }

     /**

      * This method finds the previous version (the version right before this one).

      * <p>

      * e.g. v1 = ACTIVE v2 = APPROVED

      * <p>

      * If you passed v2 into this method, it would return v1.

      * <p>

      * If there is only one major discipline this method will return null.

      * 

      * @param majorDisciplineInfo

      * @return

      */

     private MajorDisciplineInfo findPreviousVersion(MajorDisciplineInfo majorDisciplineInfo) throws Exception {

         // Find all previous versions using the version independent indicator

         List<VersionDisplayInfo> versions = programService.getVersions(ProgramServiceConstants.PROGRAM_NAMESPACE_MAJOR_DISCIPLINE_URI, majorDisciplineInfo.getVersionInfo().getVersionIndId());

         // Take the sequence number for this version

         Long sequenceNumber = majorDisciplineInfo.getVersionInfo().getSequenceNumber();

         // And subtract 1 from the sequence number to get the previous version

         sequenceNumber -= 1;

         // Loop over all versions and find the previous version based on the sequence number

         /*

          * NOTE: Dan suggested we loop over all versions and change any version with state=active to

          *       state=superseded.  However, we decided not to go that route because we would need

          *       to pull back all data for each version to determine if a version is active, since

          *       versioninfo does not have a getState() method

          */

         MajorDisciplineInfo previousVersion = null;

         for (VersionDisplayInfo versionInfo : versions) {

             if (versionInfo.getSequenceNumber().equals(sequenceNumber)) {

                 previousVersion = programService.getMajorDiscipline(versionInfo.getId());

                 break;

             }

         }

         return previousVersion;

     }

     /**

      * This method will update the requirement state.

      * <p>

      * Note that it uses StatementUtil to update the statement tree.

      * 

      * @param majorDisciplineInfo

      * @param newState

      * @throws Exception

      */

     public void updateRequirementsState(MajorDisciplineInfo majorDisciplineInfo, String newState) throws Exception {

         // Loop over list of requirement ids returned in the major discipline object

         List<String> programRequirementIds = majorDisciplineInfo.getProgramRequirements();

         for (String programRequirementId : programRequirementIds) {

             // Get program requirement from the program service

             ProgramRequirementInfo programRequirementInfo = programService.getProgramRequirement(programRequirementId, null, null);

             // Look in the requirement for the statement tree

             StatementTreeViewInfo statementTree = programRequirementInfo.getStatement();

             // And recursively update the entire tree with the new state

             StatementUtil.updateStatementTreeViewInfoState(newState, statementTree);

             // Update the state of the requirement object

             programRequirementInfo.setState(newState);

             // The write the requirement back to the program service

             programService.updateProgramRequirement(programRequirementInfo);

         }

     }

     /**

      * This method is used by Spring to inject the program service into this bean.

      * 

      * @param programService

      */

     public void setProgramService(ProgramService programService) {

         this.programService = programService;

     }

 }