001package net.sf.cpsolver.studentsct.constraint;
002
003import java.util.Set;
004
005import net.sf.cpsolver.ifs.model.GlobalConstraint;
006import net.sf.cpsolver.studentsct.model.Config;
007import net.sf.cpsolver.studentsct.model.Enrollment;
008import net.sf.cpsolver.studentsct.model.Request;
009import net.sf.cpsolver.studentsct.reservation.Reservation;
010
011/**
012 * Required reservation constraint. This global constraint ensures that reservations
013 * with {@link Reservation#mustBeUsed()} flags are used. That is, an enrollment
014 * is conflicting when there is a reservation for the student that must be used,
015 * but the given enrollment does not use it. 
016 * 
017 * @version StudentSct 1.2 (Student Sectioning)<br>
018 *          Copyright (C) 2014 Tomáš Müller<br>
019 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
020 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
021 * <br>
022 *          This library is free software; you can redistribute it and/or modify
023 *          it under the terms of the GNU Lesser General Public License as
024 *          published by the Free Software Foundation; either version 3 of the
025 *          License, or (at your option) any later version. <br>
026 * <br>
027 *          This library is distributed in the hope that it will be useful, but
028 *          WITHOUT ANY WARRANTY; without even the implied warranty of
029 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
030 *          Lesser General Public License for more details. <br>
031 * <br>
032 *          You should have received a copy of the GNU Lesser General Public
033 *          License along with this library; if not see
034 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
035 */
036public class RequiredReservation extends GlobalConstraint<Request, Enrollment> {
037    
038    /**
039     * A given enrollment is conflicting, if there is a reservation that
040     * the student must use, but the given enrollment does not use it.
041     * 
042     * @param enrollment {@link Enrollment} that is being considered
043     * @param conflicts all computed conflicting requests are added into this set
044     */
045    @Override
046    public void computeConflicts(Enrollment enrollment, Set<Enrollment> conflicts) {
047        if (inConflict(enrollment))
048            conflicts.add(enrollment);
049    }
050    
051    /**
052     * A given enrollment is conflicting, if there is a reservation that
053     * the student must use, but the given enrollment does not use it.
054     * 
055     * @param enrollment {@link Enrollment} that is being considered
056     * @return true, if the enrollment does not follow a reservation that must be used 
057     */
058    @Override
059    public boolean inConflict(Enrollment enrollment) {
060        // enrollment's config
061        Config config = enrollment.getConfig();
062
063        // exclude free time requests
064        if (config == null) return false;
065        
066        // no reservations
067        if (!config.getOffering().hasReservations())
068            return false;
069        
070        // enrollment's reservation
071        Reservation reservation = enrollment.getReservation();
072        
073        // already has a reservation that must be used
074        if (reservation != null && reservation.mustBeUsed()) return false;
075        
076        // if a reservation is required for the student, fail
077        for (Reservation r: config.getOffering().getReservations())
078            if (r.mustBeUsed() && r.isApplicable(enrollment.getStudent()))
079                return true;
080        
081        return false;
082    }
083    
084    @Override
085    public String toString() {
086        return "RequiredReservation";
087    }
088}