001package org.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 org.cpsolver.coursett.model.Lecture;
010import org.cpsolver.coursett.model.Placement;
011import org.cpsolver.ifs.assignment.Assignment;
012import org.cpsolver.ifs.model.Constraint;
013
014
015/**
016 * Class limit constraint.
017 * 
018 * @version CourseTT 1.3 (University Course Timetabling)<br>
019 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
022 * <br>
023 *          This library is free software; you can redistribute it and/or modify
024 *          it under the terms of the GNU Lesser General Public License as
025 *          published by the Free Software Foundation; either version 3 of the
026 *          License, or (at your option) any later version. <br>
027 * <br>
028 *          This library is distributed in the hope that it will be useful, but
029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
031 *          Lesser General Public License for more details. <br>
032 * <br>
033 *          You should have received a copy of the GNU Lesser General Public
034 *          License along with this library; if not see
035 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
036 */
037
038public class ClassLimitConstraint extends Constraint<Lecture, Placement> {
039    private int iClassLimit = 0;
040    private Lecture iParent = null;
041    private String iName = null;
042    boolean iEnabled = true;
043
044    private int iClassLimitDelta = 0;
045
046    public ClassLimitConstraint(int classLimit, String name) {
047        iClassLimit = classLimit;
048        iName = name;
049    }
050
051    public ClassLimitConstraint(Lecture parent, String name) {
052        iParent = parent;
053        iName = name;
054    }
055
056    public int getClassLimitDelta() {
057        return iClassLimitDelta;
058    }
059
060    public void setClassLimitDelta(int classLimitDelta) {
061        iClassLimitDelta = classLimitDelta;
062    }
063
064    public int classLimit() {
065        return (iParent == null ? iClassLimit + iClassLimitDelta : iParent.minClassLimit() + iClassLimitDelta);
066    }
067
068    public Lecture getParentLecture() {
069        return iParent;
070    }
071
072    public int currentClassLimit(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
073        int limit = 0;
074        for (Lecture lecture : variables()) {
075            limit += lecture.classLimit(assignment, value, conflicts);
076        }
077        return limit;
078    }
079
080    @Override
081    public void computeConflicts(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
082        if (!iEnabled)
083            return;
084        int currentLimit = currentClassLimit(assignment, value, conflicts);
085        int classLimit = classLimit();
086        if (currentLimit < classLimit) {
087            // System.out.println(getName()+"> "+currentLimit+"<"+classLimit+" ("+value+")");
088            TreeSet<Placement> adepts = new TreeSet<Placement>(new ClassLimitComparator());
089            computeAdepts(assignment, adepts, variables(), value, conflicts);
090            addParentAdepts(assignment, adepts, iParent, value, conflicts);
091            // System.out.println(" -- found "+adepts.size()+" adepts");
092            for (Placement adept : adepts) {
093                // System.out.println("   -- selected "+adept);
094                conflicts.add(adept);
095                currentLimit = currentClassLimit(assignment, value, conflicts);
096                // System.out.println("   -- new current limit "+currentLimit);
097                if (currentLimit >= classLimit)
098                    break;
099            }
100            // System.out.println(" -- done (currentLimit="+currentLimit+", classLimit="+classLimit+")");
101        }
102
103        if (currentLimit < classLimit)
104            conflicts.add(value);
105
106        if (iParent != null && iParent.getClassLimitConstraint() != null)
107            iParent.getClassLimitConstraint().computeConflicts(assignment, value, conflicts);
108    }
109
110    public void computeAdepts(Assignment<Lecture, Placement> assignment, Collection<Placement> adepts, List<Lecture> variables, Placement value,
111            Set<Placement> conflicts) {
112        for (Lecture lecture : variables) {
113            if (lecture.isCommitted()) continue;
114            Placement placement = assignment.getValue(lecture);
115            if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
116                adepts.add(placement);
117            }
118            if (lecture.hasAnyChildren()) {
119                for (Long subpartId: lecture.getChildrenSubpartIds()) {
120                    computeAdepts(assignment, adepts, lecture.getChildren(subpartId), value, conflicts);
121                }
122            }
123
124        }
125    }
126
127    public void addParentAdepts(Assignment<Lecture, Placement> assignment, Collection<Placement> adepts, Lecture parent, Placement value, Set<Placement> conflicts) {
128        if (parent == null || parent.isCommitted() || parent.minClassLimit() == parent.maxClassLimit())
129            return;
130        Placement placement = assignment.getValue(parent);
131        if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
132            adepts.add(placement);
133        }
134        addParentAdepts(assignment, adepts, parent.getParent(), value, conflicts);
135    }
136
137    @Override
138    public boolean inConflict(Assignment<Lecture, Placement> assignment, Placement value) {
139        if (!iEnabled)
140            return false;
141        int currentLimit = currentClassLimit(assignment, value, null);
142        int classLimit = classLimit();
143        if (currentLimit < classLimit)
144            return true;
145
146        if (iParent != null && iParent.getClassLimitConstraint() != null)
147            return iParent.getClassLimitConstraint().inConflict(assignment, value);
148
149        return false;
150    }
151
152    @Override
153    public String getName() {
154        return iName;
155    }
156
157    private static class ClassLimitComparator implements Comparator<Placement> {
158        @Override
159        public int compare(Placement p1, Placement p2) {
160            Lecture l1 = p1.variable();
161            Lecture l2 = p2.variable();
162            int cl1 = Math.min(l1.maxClassLimit(), (int) Math.floor(p1.getRoomSize() / l1.roomToLimitRatio()));
163            int cl2 = Math.min(l2.maxClassLimit(), (int) Math.floor(p2.getRoomSize() / l2.roomToLimitRatio()));
164            int cmp = -Double.compare(l1.maxAchievableClassLimit() - cl1, l2.maxAchievableClassLimit() - cl2);
165            if (cmp != 0)
166                return cmp;
167            return l1.getClassId().compareTo(l2.getClassId());
168        }
169    }
170
171    public void setEnabled(boolean enabled) {
172        iEnabled = enabled;
173    }
174
175    public boolean isEnabled() {
176        return iEnabled;
177    }
178
179    @Override
180    public String toString() {
181        return "Class-limit " + getName();
182    }
183
184}