001package net.sf.cpsolver.coursett.constraint;
002
003import java.util.Collection;
004import java.util.Comparator;
005import java.util.List;
006import java.util.Set;
007import java.util.TreeSet;
008
009import net.sf.cpsolver.coursett.model.Lecture;
010import net.sf.cpsolver.coursett.model.Placement;
011import net.sf.cpsolver.ifs.model.Constraint;
012
013/**
014 * Class limit constraint.
015 * 
016 * @version CourseTT 1.2 (University Course Timetabling)<br>
017 *          Copyright (C) 2006 - 2010 Tomáš Müller<br>
018 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
019 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
020 * <br>
021 *          This library is free software; you can redistribute it and/or modify
022 *          it under the terms of the GNU Lesser General Public License as
023 *          published by the Free Software Foundation; either version 3 of the
024 *          License, or (at your option) any later version. <br>
025 * <br>
026 *          This library is distributed in the hope that it will be useful, but
027 *          WITHOUT ANY WARRANTY; without even the implied warranty of
028 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
029 *          Lesser General Public License for more details. <br>
030 * <br>
031 *          You should have received a copy of the GNU Lesser General Public
032 *          License along with this library; if not see
033 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
034 */
035
036public class ClassLimitConstraint extends Constraint<Lecture, Placement> {
037    private int iClassLimit = 0;
038    private Lecture iParent = null;
039    private String iName = null;
040    boolean iEnabled = true;
041
042    private int iClassLimitDelta = 0;
043
044    public ClassLimitConstraint(int classLimit, String name) {
045        iClassLimit = classLimit;
046        iName = name;
047    }
048
049    public ClassLimitConstraint(Lecture parent, String name) {
050        iParent = parent;
051        iName = name;
052    }
053
054    public int getClassLimitDelta() {
055        return iClassLimitDelta;
056    }
057
058    public void setClassLimitDelta(int classLimitDelta) {
059        iClassLimitDelta = classLimitDelta;
060    }
061
062    public int classLimit() {
063        return (iParent == null ? iClassLimit + iClassLimitDelta : iParent.minClassLimit() + iClassLimitDelta);
064    }
065
066    public Lecture getParentLecture() {
067        return iParent;
068    }
069
070    public int currentClassLimit(Placement value, Set<Placement> conflicts) {
071        int limit = 0;
072        for (Lecture lecture : variables()) {
073            limit += lecture.classLimit(value, conflicts);
074        }
075        return limit;
076    }
077
078    @Override
079    public void computeConflicts(Placement value, Set<Placement> conflicts) {
080        if (!iEnabled)
081            return;
082        int currentLimit = currentClassLimit(value, conflicts);
083        int classLimit = classLimit();
084        if (currentLimit < classLimit) {
085            // System.out.println(getName()+"> "+currentLimit+"<"+classLimit+" ("+value+")");
086            TreeSet<Placement> adepts = new TreeSet<Placement>(new ClassLimitComparator());
087            computeAdepts(adepts, variables(), value, conflicts);
088            addParentAdepts(adepts, iParent, value, conflicts);
089            // System.out.println(" -- found "+adepts.size()+" adepts");
090            for (Placement adept : adepts) {
091                // System.out.println("   -- selected "+adept);
092                conflicts.add(adept);
093                currentLimit = currentClassLimit(value, conflicts);
094                // System.out.println("   -- new current limit "+currentLimit);
095                if (currentLimit >= classLimit)
096                    break;
097            }
098            // System.out.println(" -- done (currentLimit="+currentLimit+", classLimit="+classLimit+")");
099        }
100
101        if (currentLimit < classLimit)
102            conflicts.add(value);
103
104        if (iParent != null && iParent.getClassLimitConstraint() != null)
105            iParent.getClassLimitConstraint().computeConflicts(value, conflicts);
106    }
107
108    public void computeAdepts(Collection<Placement> adepts, List<Lecture> variables, Placement value,
109            Set<Placement> conflicts) {
110        for (Lecture lecture : variables) {
111            if (lecture.isCommitted()) continue;
112            Placement placement = lecture.getAssignment();
113            if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
114                adepts.add(placement);
115            }
116            if (lecture.hasAnyChildren()) {
117                for (Long subpartId: lecture.getChildrenSubpartIds()) {
118                    computeAdepts(adepts, lecture.getChildren(subpartId), value, conflicts);
119                }
120            }
121
122        }
123    }
124
125    public void addParentAdepts(Collection<Placement> adepts, Lecture parent, Placement value, Set<Placement> conflicts) {
126        if (parent == null || parent.isCommitted() || parent.minClassLimit() == parent.maxClassLimit())
127            return;
128        Placement placement = parent.getAssignment();
129        if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
130            adepts.add(placement);
131        }
132        addParentAdepts(adepts, parent.getParent(), value, conflicts);
133    }
134
135    @Override
136    public boolean inConflict(Placement value) {
137        if (!iEnabled)
138            return false;
139        int currentLimit = currentClassLimit(value, null);
140        int classLimit = classLimit();
141        if (currentLimit < classLimit)
142            return true;
143
144        if (iParent != null && iParent.getClassLimitConstraint() != null)
145            return iParent.getClassLimitConstraint().inConflict(value);
146
147        return false;
148    }
149
150    @Override
151    public String getName() {
152        return iName;
153    }
154
155    private static class ClassLimitComparator implements Comparator<Placement> {
156        @Override
157        public int compare(Placement p1, Placement p2) {
158            Lecture l1 = p1.variable();
159            Lecture l2 = p2.variable();
160            int cl1 = Math.min(l1.maxClassLimit(), (int) Math.floor(p1.getRoomSize() / l1.roomToLimitRatio()));
161            int cl2 = Math.min(l2.maxClassLimit(), (int) Math.floor(p2.getRoomSize() / l2.roomToLimitRatio()));
162            int cmp = -Double.compare(l1.maxAchievableClassLimit() - cl1, l2.maxAchievableClassLimit() - cl2);
163            if (cmp != 0)
164                return cmp;
165            return l1.getClassId().compareTo(l2.getClassId());
166        }
167    }
168
169    public void setEnabled(boolean enabled) {
170        iEnabled = enabled;
171    }
172
173    public boolean isEnabled() {
174        return iEnabled;
175    }
176
177    @Override
178    public String toString() {
179        return "Class-limit " + getName();
180    }
181
182}