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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.Facilitator;
import ee.tlu.htk.dippler.entities.Organization;
import ee.tlu.htk.dippler.entities.User;
import ee.tlu.htk.dippler.managers.UserManagerLocal;
import ee.tlu.htk.dippler.utils.XMLHandler;
import ee.tlu.htk.dippler.utils.permissionChecker;
import java.io.StringReader;
import java.util.List;
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.PersistenceContext;
import javax.persistence.Query;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

/**
 *
 * @author metz
 */

enum FacilitatorActions {
    ADD, DELETE, LOAD, SEARCH
}

@Stateless
public class FacilitatorManager implements FacilitatorManagerLocal {
    
    @PersistenceContext
    private EntityManager em;
    @EJB private UserManagerLocal userManager;
    @EJB private CourseManagerLocal courseManager;
    @EJB private ActivityManagerLocal activityManager;

    public static final Integer FACILITATOR_ADD = 50;
    public static final Integer FACILITATOR_DELETE = 50;
    public static final Integer FACILITATOR_ACTIVATE = 50;
    public static final Integer FACILITATOR_LOAD = 1;
    public static final Integer FACILITATOR_ENROLL = 10;
    public static final Integer FACILITATOR_SEARCH = 50;
    
    private Unmarshaller unmarshaller = null;
    
    public FacilitatorManager() {
        try {
            final JAXBContext context = JAXBContext.newInstance(Facilitator.class);
            unmarshaller = context.createUnmarshaller();
        } catch (JAXBException ex) {
            Logger.getLogger(FacilitatorManager.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    @Override
    public String manageFacilitator(String action, String data, User user, Organization org) {
        switch (FacilitatorActions.valueOf(action)) {
            case ADD:
                if (userManager.hasPermission(user, FACILITATOR_ADD)) {
                    return this.addFacilitator(data, user);
                } else {
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for add facilitator");
                }
            case DELETE:
                if (userManager.hasPermission(user, FACILITATOR_DELETE)) {
                    return this.removeFacilitator(data, user);
                } else {
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for delete facilitator");
                }
            case LOAD:
                if (userManager.hasPermission(user, FACILITATOR_LOAD)) {
                    return this.loadFacilitator(data);
                } else {
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for load facilitator");
                }
            case SEARCH:
                if (userManager.hasPermission(user, FACILITATOR_SEARCH)) {
                    return this.searchFacilitators(data, user, org);
                } else {
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "No rights for search facilitator");
                }
            default:
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "");
        }
    }

    public String addFacilitator(String data, User actor) {
        Facilitator facilitator = unMarshal(data);
        if ( facilitator != null ) {
            Course course = courseManager.findById(facilitator.getCourseId());
            if (!permissionChecker.isFacilitator(actor, course)) {
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner, facilitator or admin");
            }
            User user = userManager.findById(facilitator.getUserId());
            if ( user != null && course != null) {
                course.addFacilitator(user);
                activityManager.addActivity("CREATE", course, actor, user.getId(), user.getFullname(), "Facilitator");
                return StatusCodes.respond(StatusCodes.SUCCESS, "");
            }
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Add facilitator failed");
    }

    public String editFacilitator(String data, User user) {
        Facilitator facilitator = findByData(data);
        if ( facilitator != null ) {
            Facilitator l = unMarshal(data);
            if (!permissionChecker.isFacilitator(user, facilitator.getCourse())) {
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner, facilitator or admin");
            }
            facilitator.setStatus(l.getStatus());
            return StatusCodes.respondWithData(StatusCodes.SUCCESS, "", marshal(facilitator));
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Edit facilitator failed");
    }

    public String removeFacilitator(String data, User actor) {
        Facilitator facilitator = findByData(data);
        if ( facilitator != null ) {
            Course course = facilitator.getCourse();
            if (!permissionChecker.isFacilitator(actor, course)) {
                return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner, facilitator or admin");
            }
            User user = facilitator.getUser();
            activityManager.addActivity("DELETE", course, actor, user.getId(), user.getFullname(), "Facilitator");
            //Finish remove
            course.remove(facilitator);
            user.remove(facilitator);
            return StatusCodes.respond(StatusCodes.SUCCESS, "");
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Remove facilitator failed");
    }

    public String loadFacilitator(String data) {
        Facilitator facilitator = findByData(data);
        if ( facilitator != null ) {
            return StatusCodes.respondWithData(StatusCodes.SUCCESS, "", marshal(facilitator));
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "Not loaded");
    }
    
    /**
     * Responds with XML string containing user data. Respects same organization
     * policy, only possible facilitators from same Organization are returned.
     * Filters out users that are already facilitators of the same course.
     * 
     * @param data XML string containing search term and Course identifier.
     * @param user User making the request.
     * @param org  Organization session Client belongs to.
     * @return     A string with response XML.
     */
    public String searchFacilitators(String data, User user, Organization org) {
        XMLHandler doc = new XMLHandler(data);
        if ( doc.parseSuccess() ) {
            String term = doc.getNodeValue("term");
            Course course = courseManager.findById(doc.getNodeValueLong("course"));
            if ( course != null ) {
                if (!permissionChecker.isFacilitator(user, course)) {
                    return StatusCodes.respond(StatusCodes.OPERATION_NOT_ALLOWED, "Not owner, facilitator or admin");
                }
                Query query = em.createNamedQuery("User.findAvailableFacilitators");
                query.setParameter("term", "%"+term+"%");
                query.setParameter("course", course);
                query.setParameter("organization", org);
                
                List<User> users = (List<User>) query.getResultList();
                StringBuilder xml = new StringBuilder("<users>");
                for(User single : users ) {
                    xml.append("<user>")
                            .append("<id>").append(single.getId().toString()).append("</id>")
                            .append("<name><![CDATA[").append(single.getFullname()).append("]]></name>")
                            .append("<email><![CDATA[").append(single.getEmail()).append("]]></email>")
                            .append("</user>");
                }
                xml.append("</users>");
                return StatusCodes.respondWithData(StatusCodes.SUCCESS, "", xml.toString());
            }
        }
        return StatusCodes.respond(StatusCodes.COURSE_ERROR, "");
    }

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

    @Override
    public String marshal(Facilitator facilitator) {
        User fu = facilitator.getUser();
        StringBuilder xml = new StringBuilder("<facilitator>");
        xml.append("<id>").append(facilitator.getId()).append("</id>");
        xml.append("<email><![CDATA[").append(fu.getEmail()).append("]]></email>");
        xml.append("<firstname><![CDATA[").append(fu.getFirstname()).append("]]></firstname>");
        xml.append("<lastname><![CDATA[").append(fu.getLastname()).append("]]></lastname>");
        xml.append("<user_id>").append(fu.getId().toString()).append("</user_id>");
        xml.append("<status>").append(facilitator.getStatus().toString()).append("</status>");
        xml.append("<course>").append(facilitator.getCourse().getId()).append("</course>");
        xml.append("</facilitator>");
        return xml.toString();
    }

    @Override
    public Facilitator findById(Long id) {
        if ( id > 0 ) {
            return em.find(Facilitator.class, id);
        }
        return null;
    }
    
    public Facilitator findByData(String data) {
        Facilitator fakeFacilitator = unMarshal(data);
        if ( fakeFacilitator != null ) {
            return findById(fakeFacilitator.getId());
        }
        return null;
    }
 
}