package org.kuali.student.lum.program.server;
   
   import java.util.List;
   
   import org.kuali.student.lum.common.server.StatementUtil;
   import org.kuali.student.r2.core.versionmanagement.dto.VersionDisplayInfo;
   import org.kuali.student.r1.core.statement.dto.StatementTreeViewInfo;
   import org.kuali.student.r2.common.dto.DtoConstants;
   import org.kuali.student.r2.common.exceptions.DoesNotExistException;
  import org.kuali.student.r2.common.exceptions.InvalidParameterException;
  import org.kuali.student.r2.common.util.ContextUtils;
  import org.kuali.student.r2.common.util.constants.ProgramServiceConstants;
  import org.kuali.student.r2.lum.program.dto.CredentialProgramInfo;
  import org.kuali.student.r2.lum.program.dto.ProgramRequirementInfo;
  import org.kuali.student.r2.lum.program.service.ProgramService;
  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 CredentialProgramStateChangeServiceImpl implements StateChangeService {
  
      /**
       * 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 credentialProgramId, 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, credentialProgramId, 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 credentialProgramId, 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
          CredentialProgramInfo selectedVersion = programService.getCredentialProgram(credentialProgramId,ContextUtils.getContextInfo());
  
          // 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)) {
  
              // Update previous versions to superseded and set end terms on previous current version.
          	updatePreviousVersions(selectedVersion, endEntryTerm, endEnrollTerm, endInstAdmitTerm);
          	
              // Update state of all associated objects for current version
              // NOTE: we must update state BEFORE making the version current
              updateCredentialProgramInfoState(selectedVersion, newState);
  
              // Make this the current version
              makeCurrent(selectedVersion);
          } else {
  
              // Update state of all associated objects for current version
              updateCredentialProgramInfoState(selectedVersion, newState);
          }
  
      }
  
      /**
       * This method finds all previous versions of program and sets all previous ACTIVE,APPROVED,DRAFT versions to SUPERSEDED and
       * sets new end terms for previous current version.
   
       * @param selectedVersion The version of credential  program being activated
       * @param endEntryTerm The new end entry term to set on previous active version
       * @param endEnrollTerm The new end enroll term to set on previous active version
       * @throws Exception
      */
     private void updatePreviousVersions (CredentialProgramInfo selectedVersion, String endEntryTerm, String endEnrollTerm, String endInstAdmitTerm) throws Exception {
     	// Get the current version of major discipline given the selected version
     	CredentialProgramInfo currentVersion = getCurrentVersion(selectedVersion);
     	
     	boolean isSelectedVersionCurrent = selectedVersion.getId().equals(currentVersion.getId());
     	
     	//Set the end terms on the current version of major discipline and update it's state to superseded
     	setEndTerms(currentVersion, endEntryTerm, endEnrollTerm);
     	updateCredentialProgramInfoState(currentVersion, DtoConstants.STATE_SUPERSEDED);
 
 		// Loop through all previous active or approved programs and set the state to superseded.
 		// We should only need to evaluated versions with sequence number
 		// higher than previous active program
 
 		List<VersionDisplayInfo> versions = programService.getVersions(ProgramServiceConstants.PROGRAM_NAMESPACE_MAJOR_DISCIPLINE_URI,
 		selectedVersion.getVersionInfo(ContextUtils.getContextInfo()).getVersionIndId(),ContextUtils.getContextInfo());
 		Long startSeq = new Long(1);
 
 		if (!isSelectedVersionCurrent) {
 			startSeq = currentVersion.getVersionInfo(ContextUtils.getContextInfo()).getSequenceNumber() + 1;
 		}
 
 		for (VersionDisplayInfo versionInfo : versions) {
 			boolean isVersionNewerThanCurrentVersion = versionInfo.getSequenceNumber() >= startSeq;
 			boolean isVersionSelectedVersion = versionInfo.getSequenceNumber().equals(selectedVersion.getVersionInfo(ContextUtils.getContextInfo()).getSequenceNumber());  
 			boolean updateState = isVersionNewerThanCurrentVersion && !isVersionSelectedVersion;
 			if (updateState) {
 				CredentialProgramInfo otherProgram = programService.getCredentialProgram(versionInfo.getId(),ContextUtils.getContextInfo());
 				if (otherProgram.getStateKey().equals(DtoConstants.STATE_APPROVED) ||
 					otherProgram.getStateKey().equals(DtoConstants.STATE_ACTIVE)){
 			        updateCredentialProgramInfoState(otherProgram, DtoConstants.STATE_SUPERSEDED);
 				}		
 			}
 		}    	
 
     }
     
 	/**
 	 * Get the current version of program given the selected version of program
 	 * 
 	 * @param verIndId
 	 */
 	protected CredentialProgramInfo getCurrentVersion(CredentialProgramInfo credentialProgramInfo)
 			throws Exception {
 		// Get version independent id of program
 		String verIndId = credentialProgramInfo.getVersionInfo(ContextUtils.getContextInfo()).getVersionIndId();
 
 		// Get id of current version of program given the version independent id
 		VersionDisplayInfo curVerDisplayInfo = programService.getCurrentVersion( ProgramServiceConstants.PROGRAM_NAMESPACE_MAJOR_DISCIPLINE_URI, verIndId,ContextUtils.getContextInfo());
 		String curVerId = curVerDisplayInfo.getId();
 
 		// Return the current version of the course
 		CredentialProgramInfo currentVersion = programService.getCredentialProgram(curVerId,ContextUtils.getContextInfo());
 
 		return currentVersion;
 	}
     
     /**
      * 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 credentialProgramInfo
      * @param endEntryTerm
      * @param endEnrollTerm
      */
     private void setEndTerms(CredentialProgramInfo credentialProgramInfo, String endEntryTerm, String endEnrollTerm) {
         credentialProgramInfo.setEndProgramEntryTerm(endEntryTerm);
         credentialProgramInfo.setEndTerm(endEnrollTerm);
     }
 
     /**
      * 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 credentialProgramInfo
      * @param newState
      */
     private void updateCredentialProgramInfoState(CredentialProgramInfo credentialProgramInfo, String newState) throws Exception {
         // Update the statement tree
         List<String> programRequirementIds = credentialProgramInfo.getProgramRequirements();
         updateRequirementsState(programRequirementIds, newState);
  
         // Credential and core programs do not have variations
         
         // Update program
         credentialProgramInfo.setStateKey(newState);
         programService.updateCredentialProgram(credentialProgramInfo.getId(), credentialProgramInfo, ContextUtils.getContextInfo());
     }
 
     /**
      * This method will make this version of the major discipline the current one.
      * 
      * @param credentialProgramInfo
      */
     private void makeCurrent(CredentialProgramInfo credentialProgramInfo) 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, credentialProgramInfo.getVersionInfo(ContextUtils.getContextInfo()).getVersionIndId(),ContextUtils.getContextInfo());
 
         // If this is not the current version, then make it current
         if (!currentVersion.getSequenceNumber().equals(credentialProgramInfo.getVersionInfo(ContextUtils.getContextInfo()).getSequenceNumber())) {
             programService.setCurrentCredentialProgramVersion(credentialProgramInfo.getId(), null,ContextUtils.getContextInfo());
         }
     }
 
     /**
      * This method will update the requirement state.
      * <p>
      * Note that it uses StatementUtil to update the statement tree.
      * 
      * @param credentialProgramInfo
      * @param newState
      * @throws Exception
      */
     public void updateRequirementsState(List<String> programRequirementIds, String newState) throws Exception {
         
         for (String programRequirementId : programRequirementIds) {
 
             // Get program requirement from the program service
             ProgramRequirementInfo programRequirementInfo = null;
             programRequirementInfo = programService.getProgramRequirement(programRequirementId, ContextUtils.getContextInfo());
 
             // 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.setStateKey(newState);
 
             // The write the requirement back to the program service
             programService.updateProgramRequirement(programRequirementInfo.getId(), programRequirementInfo.getTypeKey(), programRequirementInfo, ContextUtils.getContextInfo());
 
         }
     }
 
     /**
      * This method is used by Spring to inject the program service into this bean.
      * 
      * @param programService
      */
     public void setProgramService(ProgramService programService) {
         this.programService = programService;
     }
 
 }