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package ee.tlu.htk.dippler.course;

import ee.tlu.htk.dippler.backoffice.StatusCodes;
import ee.tlu.htk.dippler.entities.Course;
import ee.tlu.htk.dippler.entities.Coursegroup;
import ee.tlu.htk.dippler.entities.Learner;
import ee.tlu.htk.dippler.entities.User;
import ee.tlu.htk.dippler.managers.UserManagerLocal;
import ee.tlu.htk.dippler.utils.permissionChecker;
import java.io.StringReader;
import java.util.Collection;
import java.util.LinkedList;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.ejb.EJB;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.NonUniqueResultException;
import javax.persistence.PersistenceContext;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

/**
 *
 * @author metz
 */

enum GroupActions {
    ADD, EDIT, DELETE, LOAD
}

@Stateless
public class GroupManager implements GroupManagerLocal {
    @PersistenceContext
    private EntityManager em;
    @EJB private UserManagerLocal userManager;
    @EJB private LearnerManagerLocal learnerManager;
    @EJB private ActivityManagerLocal activityManager;

    public static final Integer GROUP_VIEW = 10;
    public static final Integer GROUP_EDIT = 10;
    
    private Unmarshaller unmarshaller = null;
    
    public GroupManager() {
        try {
            final JAXBContext context = JAXBContext.newInstance(Coursegroup.class);
            unmarshaller = context.createUnmarshaller();
        } catch (JAXBException ex) {
            Logger.getLogger(GroupManager.class.getName()).log(Level.SEVERE, null, ex);
        }
    }


    @Override
    public String manageGroup(String action, String data, User user) {
        Coursegroup group = unMarshal(data);
        if ( group != null ) {
            switch (GroupActions.valueOf(action)) {
                case EDIT:
                    if (userManager.hasPermission(user, GROUP_EDIT)) {
                        return this.editGroup(group, user);
                    } else {
                        return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for edit group");
                    }
                case DELETE:
                    if (userManager.hasPermission(user, GROUP_EDIT)) {
                        return this.deleteGroup(group, user);
                    } else {
                        return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for delete group");
                    }
                case LOAD:
                    if (userManager.hasPermission(user, GROUP_VIEW)) {
                        return this.loadGroup(group);
                    } else {
                        return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for load group");
                    }
                default:
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "");
            }
        }
        return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "");
    }

    public String loadGroup(Coursegroup g) {
        Coursegroup group = findById(g.getId());
        if ( group != null ) {
            return StatusCodes.respondWithData(StatusCodes.SUCCESS, "", marshal(group));
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Not loaded");
    }

    public String editGroup(Coursegroup g, User user) {
        Coursegroup group = findById(g.getId());
        if ( group != null ) {
            if (!permissionChecker.isFacilitator(user, group.getCourse())) {
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner, admin or facilitator");
            }
            group.setTitle(g.getTitle());
            group.setDescription(g.getDescription());
            group.setWorkspace(g.getWorkspace());
           // Collection<Learner> members = group.getMembers();
            // TODO Needs to become a standalone method if add/remove members is allowed not only to owner or admin
            group.setMembers(editMembers(g));
            activityManager.addActivity("EDIT", group.getCourse(), user, group.getId(), group.getTitle(), "Coursegroup");
            return StatusCodes.respondWithData(StatusCodes.SUCCESS, "", marshal(group));
        }
        return StatusCodes.respond(StatusCodes.BLOG_ERROR, "Edit failed");
    }

    public String deleteGroup(Coursegroup g, User user) {
        Coursegroup group = findById(g.getId());
        if ( group != null ) {
            if (!permissionChecker.isFacilitator(user, group.getCourse())) {
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner or admin");
            }
            activityManager.addActivity("DELETE", group.getCourse(), user, group.getId(), group.getTitle(), "Coursegroup");
            Course course = group.getCourse();
            course.remove(group);
            em.remove(group);
            return StatusCodes.respond(StatusCodes.SUCCESS, "");
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Delete failed");
    }
    
    @Override
    public Collection<Learner> editMembers(Coursegroup g) {
        Collection<Learner> members = new LinkedList<Learner>();
        Collection<Long> ids = g.memberIds;
        for(Long id : ids ) {
            members.add(learnerManager.findById(id));
        }
        return members;
    }

    public static String getMemberIds(Coursegroup group) {
        StringBuilder xml = new StringBuilder();
        Collection<Learner> members = group.getMembers();
        for(Learner member : members ){
            xml.append("<member-id>").append(member.getId()).append("</member-id>");
        }
        return xml.toString();
    }

    @Override
    public Coursegroup unMarshal(String data) {
        if ( unmarshaller != null ) {
            try {
                final Coursegroup coursegroupUNM = (Coursegroup) unmarshaller.unmarshal(new StringReader(data));
                return coursegroupUNM;
            } catch(JAXBException e) {
                //something went wrong
            }
        }
        return null;
    }

    @Override
    public String marshal(Coursegroup group) {
        StringBuilder xml = new StringBuilder("<coursegroup>");
        xml.append("<id>").append(group.getId()).append("</id>");
        xml.append("<title><![CDATA[").append(group.getTitle()).append("]]></title>");
        xml.append("<description><![CDATA[").append(group.getDescription()).append("]]></description>");
        xml.append("<workspace><![CDATA[").append(group.getWorkspace()).append("]]></workspace>");
        xml.append("<created>").append(group.getCreated()).append("</created>");
        xml.append("<creator>").append(group.getCreator().getId().toString()).append("</creator>");
        xml.append("<course>").append(group.getCourse().getId().toString()).append("</course>");
        xml.append("<member-ids>").append(getMemberIds(group)).append("</member-ids>");
        xml.append("</coursegroup>");
        return xml.toString();
    }

    @Override
    public Coursegroup findById(Long id) throws NoResultException, NonUniqueResultException {
        if ( id > 0 ) {
            return em.find(Coursegroup.class, id);
        }
        return null;
    }
}