package org.kuali.student.lum.lu.ui.course.server.gwt;
   
   import java.util.Iterator;
   import java.util.List;
   
   import org.kuali.student.common.dto.DtoConstants;
   import org.kuali.student.common.dto.StatusInfo;
   import org.kuali.student.common.exceptions.CircularReferenceException;
   import org.kuali.student.common.exceptions.DataValidationErrorException;
  import org.kuali.student.common.exceptions.DoesNotExistException;
  import org.kuali.student.common.exceptions.InvalidParameterException;
  import org.kuali.student.common.exceptions.MissingParameterException;
  import org.kuali.student.common.exceptions.OperationFailedException;
  import org.kuali.student.common.exceptions.PermissionDeniedException;
  import org.kuali.student.common.exceptions.VersionMismatchException;
  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.course.dto.CourseInfo;
  import org.kuali.student.lum.course.service.CourseService;
  import org.kuali.student.lum.course.service.CourseServiceConstants;
  import org.springframework.transaction.annotation.Transactional;
  
  @Transactional(noRollbackFor = { DoesNotExistException.class }, rollbackFor = { Throwable.class })
  public class CourseStateChangeServiceImpl {
  	private CourseService courseService;
  
  	/**
  	 * Change the state of a course to a new state
  	 * 
  	 * @param courseId id of course
  	 * @param newState the new state for the course
  	 * @param prevEndTermAtpId the current version end date of course
  	 * @return
  	 * @throws Exception
  	 */
  	public StatusInfo changeState(String courseId, String newState,	String prevEndTermAtpId) throws Exception {
  
  		CourseInfo courseInfo = courseService.getCourse(courseId);
  
  		StatusInfo ret = new StatusInfo();
  		try {
  			if (newState.equals(DtoConstants.STATE_ACTIVE)) {
  				activateCourse(courseInfo, prevEndTermAtpId);
  			} else if (newState.equals(DtoConstants.STATE_RETIRED)) {
  				retireCourse(courseInfo);
  			}
  
  			ret.setSuccess(new Boolean(true));
  		} catch (Exception e) {
  			ret.setSuccess(new Boolean(false));
  			ret.setMessage(e.getMessage());
  		}
  
  		return ret;
  	}
  
  	/**
  	 * Activate a course version. Only course with a state of "Approved" can be activated.
  	 * 
  	 * @param courseToActivate
  	 * @param prevEndTermAtpId the end term we set on the current version
  	 */
  	protected void activateCourse(CourseInfo courseToActivate, String prevEndTermAtpId) throws Exception{
      	CourseInfo currVerCourse = getCurrentVersionOfCourse(courseToActivate);
      	String existingState = courseToActivate.getState();
  		String currVerState = currVerCourse.getState();
  		boolean isCurrVer = (courseToActivate.getId().equals(currVerCourse.getId()));
  		
  		if (existingState.equals(DtoConstants.STATE_DRAFT)) {
  			// since this is approved if isCurrVer we can assume there are no previously active versions to deal with
  			if (isCurrVer) {
  				// setstate for thisVerCourse and setCurrentVersion(courseId)
  				updateCourseVersionStates(courseToActivate, DtoConstants.STATE_ACTIVE, currVerCourse, null, true, prevEndTermAtpId);
  			} else if (currVerState.equals(DtoConstants.STATE_ACTIVE) ||
  					currVerState.equals(DtoConstants.STATE_SUSPENDED)) {
  				updateCourseVersionStates(courseToActivate, DtoConstants.STATE_ACTIVE, currVerCourse, DtoConstants.STATE_SUPERSEDED, true, prevEndTermAtpId);
  			}
  		}
  	}
  	
  	/**
  	 * Retire a course version. Only course with a state of "Active" or "Suspended" can be retired
  	 * 
  	 * @param courseToRetire the course to retire
  	 */
  	protected void retireCourse(CourseInfo courseToRetire) throws Exception{
      	String existingState = courseToRetire.getState();		
  		
      	if (existingState.equals(DtoConstants.STATE_ACTIVE) || existingState.equals(DtoConstants.STATE_SUSPENDED)){
      		courseToRetire.setState(DtoConstants.STATE_RETIRED);
  
      		courseService.updateCourse(courseToRetire);
  			updateStatementTreeViewInfoState(courseToRetire);    		
      	}
  	}
  	
  	/**
  	 * Get the current version of course from another version of course
 	 * 
 	 * @param verIndId
 	 */
 	protected CourseInfo getCurrentVersionOfCourse(CourseInfo course)
 			throws Exception {
 		// Get version independent id of course
 		String verIndId = course.getVersionInfo().getVersionIndId();
 
 		// Get id of current version of course given the versionindependen id
 		VersionDisplayInfo curVerDisplayInfo = courseService.getCurrentVersion(
 				CourseServiceConstants.COURSE_NAMESPACE_URI, verIndId);
 		String curVerId = curVerDisplayInfo.getId();
 
 		// Return the current version of the course
 		CourseInfo currVerCourse = courseService.getCourse(curVerId);
 
 		return currVerCourse;
 	}
 
 	/**
 	 * Based on null values, updates states of thisVerCourse and currVerCourse
 	 * and sets thisVerCourse as the current version. Attempts to rollback
 	 * transaction on exception.
 	 * 
 	 * @param thisVerCourse
 	 *            this is the version that the user selected to change the state
 	 * @param thisVerNewState
 	 *            this is state that the user selected to change thisVerCourse
 	 *            to
 	 * @param currVerCourse
 	 *            this is the current version of the course
 	 *            (currentVersionStartDt <= now && currentVersionEndDt > now)
 	 * @param currVerNewState
 	 *            this is the state that we need to set the current version to.
 	 *            Set to null to not update the currVerCourse state.
 	 * @param makeCurrent
 	 *            if true we'll set thisVerCourse as the current version.
 	 * @param prevEndTermAtpId
 	 *            the end term for the previous version to end on
 	 * @throws Exception
 	 */
 	@Transactional(readOnly = false)
 	private void updateCourseVersionStates(CourseInfo thisVerCourse,
 			String thisVerNewState, CourseInfo currVerCourse,
 			String currVerNewState, boolean makeCurrent,
 			String prevEndTermAtpId) throws Exception {
 		String thisVerPrevState = thisVerCourse.getState();
 
 		// if already current, will throw error if you try to make the current
 		// version the current version.
 		boolean isCurrent = thisVerCourse.getId().equals(currVerCourse.getId());
 		if(!makeCurrent || !isCurrent || !thisVerCourse.getVersionInfo().getSequenceNumber().equals(1)){
 			makeCurrent &= !isCurrent;
 		}
 
 		if (thisVerNewState == null) {
 			throw new InvalidParameterException("new state cannot be null");
 		} else {
 			thisVerCourse.setState(thisVerNewState);
 			courseService.updateCourse(thisVerCourse);
 			updateStatementTreeViewInfoState(thisVerCourse);
 		}
 
 		// won't get called if previous exception was thrown
 		if (currVerNewState != null) {
 			currVerCourse.setState(currVerNewState);
 			if(currVerCourse.getEndTerm()==null){
 				currVerCourse.setEndTerm(prevEndTermAtpId);
 			}
 			courseService.updateCourse(currVerCourse);
 			updateStatementTreeViewInfoState(currVerCourse);
 		}
 
 		if (makeCurrent == true) {
 			courseService.setCurrentCourseVersion(thisVerCourse.getId(),
 					null);
 		}
 
 		// for all draft and approved courses set the state to superseded.
 		// we should only need to evaluated versions with sequence number
 		// higher than previous active course. If the course you're
 		// activating is the current course check all versions.
 		if (thisVerPrevState.equals(DtoConstants.STATE_APPROVED)
 				&& thisVerNewState.equals(DtoConstants.STATE_ACTIVE)) {
 
 			List<VersionDisplayInfo> versions = courseService.getVersions(
 					CourseServiceConstants.COURSE_NAMESPACE_URI, thisVerCourse
 							.getVersionInfo().getVersionIndId());
 			Long startSeq = new Long(1);
 
 			if (!isCurrent && (currVerCourse.getId() != thisVerCourse.getId())) {
 				startSeq = currVerCourse.getVersionInfo().getSequenceNumber() + 1;
 			}
 
 			for (VersionDisplayInfo versionInfo : versions) {
 				if (versionInfo.getSequenceNumber() >= startSeq) {
 					CourseInfo otherCourse = courseService
 							.getCourse(versionInfo.getId());
 					if (otherCourse.getState().equals(
 							DtoConstants.STATE_APPROVED)
 							|| otherCourse.getState().equals(
 									DtoConstants.STATE_SUBMITTED)
 							|| otherCourse.getState().equals(
 									DtoConstants.STATE_DRAFT)) {
 						otherCourse.setState(DtoConstants.STATE_SUPERSEDED);
 						courseService.updateCourse(otherCourse);
 						updateStatementTreeViewInfoState(otherCourse);
 					}
 				}
 			}
 		}
 
 	}
 
 	public void setCourseService(CourseService courseService) {
 		this.courseService = courseService;
 	}
 
 	/**
 	 * This method will load all the statements in a course from the course web
 	 * service, recursively update the state of each statement in the statement
 	 * tree, and save the update statements back to the web service.
 	 * 
 	 * 
 	 * @param courseInfo
 	 *            The course to update (call setState() in this object to set
 	 *            the state)
 	 * @throws DoesNotExistException
 	 * @throws InvalidParameterException
 	 * @throws MissingParameterException
 	 * @throws OperationFailedException
 	 * @throws PermissionDeniedException
 	 * @throws DataValidationErrorException
 	 * @throws CircularReferenceException
 	 * @throws VersionMismatchException
 	 */
 	public void updateStatementTreeViewInfoState(CourseInfo courseInfo)
 			throws DoesNotExistException, InvalidParameterException,
 			MissingParameterException, OperationFailedException,
 			PermissionDeniedException, DataValidationErrorException,
 			CircularReferenceException, VersionMismatchException {
 
 		// Call course web service to get all requirements/statements for this
 		// course
 		List<StatementTreeViewInfo> statementTreeViewInfos = courseService
 				.getCourseStatements(courseInfo.getId(), null, null);
 
 		if (statementTreeViewInfos != null){
 			// Recursively update state on all requirements/statements in the tree
 			for (Iterator<StatementTreeViewInfo> it = statementTreeViewInfos
 					.iterator(); it.hasNext();)
 				StatementUtil.updateStatementTreeViewInfoState(courseInfo
 						.getState(), it.next());
 	
 			// Call the course web service and update the requirement/statement tree
 			// with the new state
 			for (Iterator<StatementTreeViewInfo> it = statementTreeViewInfos
 					.iterator(); it.hasNext();)
 				courseService.updateCourseStatement(courseInfo.getId(), it.next());
 		}
 	}
 
 }