001package org.cpsolver.studentsct.constraint;
002
003import java.util.Set;
004
005import org.cpsolver.ifs.assignment.Assignment;
006import org.cpsolver.ifs.model.GlobalConstraint;
007import org.cpsolver.studentsct.model.Config;
008import org.cpsolver.studentsct.model.Enrollment;
009import org.cpsolver.studentsct.model.Request;
010import org.cpsolver.studentsct.reservation.Reservation;
011
012
013/**
014 * Required reservation constraint. This global constraint ensures that reservations
015 * with {@link Reservation#mustBeUsed()} flags are used. That is, an enrollment
016 * is conflicting when there is a reservation for the student that must be used,
017 * but the given enrollment does not use it. 
018 * 
019 * @version StudentSct 1.3 (Student Sectioning)<br>
020 *          Copyright (C) 2014 Tomáš Müller<br>
021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
023 * <br>
024 *          This library is free software; you can redistribute it and/or modify
025 *          it under the terms of the GNU Lesser General Public License as
026 *          published by the Free Software Foundation; either version 3 of the
027 *          License, or (at your option) any later version. <br>
028 * <br>
029 *          This library is distributed in the hope that it will be useful, but
030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
032 *          Lesser General Public License for more details. <br>
033 * <br>
034 *          You should have received a copy of the GNU Lesser General Public
035 *          License along with this library; if not see
036 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
037 */
038public class RequiredReservation extends GlobalConstraint<Request, Enrollment> {
039    
040    /**
041     * A given enrollment is conflicting, if there is a reservation that
042     * the student must use, but the given enrollment does not use it.
043     * 
044     * @param enrollment {@link Enrollment} that is being considered
045     * @param conflicts all computed conflicting requests are added into this set
046     */
047    @Override
048    public void computeConflicts(Assignment<Request, Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) {
049        if (inConflict(assignment, enrollment))
050            conflicts.add(enrollment);
051    }
052    
053    /**
054     * A given enrollment is conflicting, if there is a reservation that
055     * the student must use, but the given enrollment does not use it.
056     * 
057     * @param enrollment {@link Enrollment} that is being considered
058     * @return true, if the enrollment does not follow a reservation that must be used 
059     */
060    @Override
061    public boolean inConflict(Assignment<Request, Enrollment> assignment, Enrollment enrollment) {
062        // enrollment's config
063        Config config = enrollment.getConfig();
064
065        // exclude free time requests
066        if (config == null) return false;
067        
068        // no reservations
069        if (!config.getOffering().hasReservations())
070            return false;
071        
072        // enrollment's reservation
073        Reservation reservation = enrollment.getReservation();
074        
075        // already has a reservation that must be used
076        if (reservation != null && reservation.mustBeUsed()) return false;
077        
078        // if a reservation is required for the student, fail
079        for (Reservation r: config.getOffering().getReservations())
080            if (r.mustBeUsed() && r.isApplicable(enrollment.getStudent()))
081                return true;
082        
083        return false;
084    }
085    
086    @Override
087    public String toString() {
088        return "RequiredReservation";
089    }
090}