001package org.cpsolver.coursett.model;
002
003import java.util.ArrayList;
004import java.util.Collection;
005import java.util.Collections;
006import java.util.Comparator;
007import java.util.Enumeration;
008import java.util.HashSet;
009import java.util.HashMap;
010import java.util.Iterator;
011import java.util.List;
012import java.util.Map;
013import java.util.Set;
014import java.util.concurrent.atomic.AtomicReference;
015import java.util.concurrent.locks.ReentrantReadWriteLock;
016
017import org.cpsolver.coursett.Constants;
018import org.cpsolver.coursett.constraint.ClassLimitConstraint;
019import org.cpsolver.coursett.constraint.DepartmentSpreadConstraint;
020import org.cpsolver.coursett.constraint.FlexibleConstraint;
021import org.cpsolver.coursett.constraint.GroupConstraint;
022import org.cpsolver.coursett.constraint.IgnoreStudentConflictsConstraint;
023import org.cpsolver.coursett.constraint.InstructorConstraint;
024import org.cpsolver.coursett.constraint.JenrlConstraint;
025import org.cpsolver.coursett.constraint.RoomConstraint;
026import org.cpsolver.coursett.constraint.SpreadConstraint;
027import org.cpsolver.coursett.criteria.StudentCommittedConflict;
028import org.cpsolver.coursett.criteria.StudentConflict;
029import org.cpsolver.ifs.assignment.Assignment;
030import org.cpsolver.ifs.assignment.context.AssignmentContext;
031import org.cpsolver.ifs.assignment.context.VariableWithContext;
032import org.cpsolver.ifs.constant.ConstantVariable;
033import org.cpsolver.ifs.model.Constraint;
034import org.cpsolver.ifs.model.GlobalConstraint;
035import org.cpsolver.ifs.model.WeakeningConstraint;
036import org.cpsolver.ifs.util.DistanceMetric;
037import org.cpsolver.ifs.util.ToolBox;
038
039
040/**
041 * Lecture (variable).
042 * 
043 * @version CourseTT 1.3 (University Course Timetabling)<br>
044 *          Copyright (C) 2006 - 2014 Tomas Muller<br>
045 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
046 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
047 * <br>
048 *          This library is free software; you can redistribute it and/or modify
049 *          it under the terms of the GNU Lesser General Public License as
050 *          published by the Free Software Foundation; either version 3 of the
051 *          License, or (at your option) any later version. <br>
052 * <br>
053 *          This library is distributed in the hope that it will be useful, but
054 *          WITHOUT ANY WARRANTY; without even the implied warranty of
055 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
056 *          Lesser General Public License for more details. <br>
057 * <br>
058 *          You should have received a copy of the GNU Lesser General Public
059 *          License along with this library; if not see
060 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
061 */
062
063public class Lecture extends VariableWithContext<Lecture, Placement, Lecture.LectureContext> implements ConstantVariable<Placement> {
064    private Long iClassId;
065    private Long iSolverGroupId;
066    private Long iSchedulingSubpartId;
067    private String iName;
068    private Long iDept;
069    private Long iScheduler;
070    private List<TimeLocation> iTimeLocations;
071    private List<RoomLocation> iRoomLocations;
072    private String iNote = null;
073
074    private int iMinClassLimit;
075    private int iMaxClassLimit;
076    private float iRoomToLimitRatio;
077    private int iNrRooms;
078    private int iOrd;
079    private double iWeight = 1.0;
080
081    private Set<Student> iStudents = new HashSet<Student>();
082    private DepartmentSpreadConstraint iDeptSpreadConstraint = null;
083    private Set<SpreadConstraint> iSpreadConstraints = new HashSet<SpreadConstraint>();
084    private Set<Constraint<Lecture, Placement>> iWeakeningConstraints = new HashSet<Constraint<Lecture, Placement>>();
085    private List<InstructorConstraint> iInstructorConstraints = new ArrayList<InstructorConstraint>();
086    private AtomicReference<Set<Long>> iIgnoreStudentConflictsWith = new AtomicReference<Set<Long>>();
087    private ClassLimitConstraint iClassLimitConstraint = null;
088
089    private Lecture iParent = null;
090    private HashMap<Long, List<Lecture>> iChildren = null;
091    private java.util.List<Lecture> iSameSubpartLectures = null;
092    private Configuration iParentConfiguration = null;
093
094    private List<JenrlConstraint> iJenrlConstraints = new ArrayList<JenrlConstraint>();
095    private HashMap<Lecture, JenrlConstraint> iJenrlConstraintsHash = new HashMap<Lecture, JenrlConstraint>();
096    private HashMap<Placement, Integer> iCommitedConflicts = new HashMap<Placement, Integer>();
097    private Set<GroupConstraint> iGroupConstraints = new HashSet<GroupConstraint>();
098    private Set<GroupConstraint> iHardGroupSoftConstraints = new HashSet<GroupConstraint>();
099    private Set<GroupConstraint> iCanShareRoomGroupConstraints = new HashSet<GroupConstraint>();
100    private Set<FlexibleConstraint> iFlexibleGroupConstraints = new HashSet<FlexibleConstraint>();    
101
102    public boolean iCommitted = false;
103
104    public static boolean sSaveMemory = false;
105    public static boolean sAllowBreakHard = false;
106    private int iMaxRoomCombinations = -1;
107
108    private Integer iCacheMinRoomSize = null;
109    private Integer iCacheMaxRoomSize = null;
110    private Integer iCacheMaxAchievableClassLimit = null;
111    
112    private final ReentrantReadWriteLock iLock = new ReentrantReadWriteLock();
113
114    /**
115     * Constructor
116     * 
117     * @param id class unique id
118     * @param solverGroupId solver group unique id 
119     * @param schedulingSubpartId  scheduling subpart unique id
120     * @param name class name
121     * @param timeLocations set of time locations
122     * @param roomLocations set of room location
123     * @param nrRooms number of rooms into which the class is to be assigned
124     * @param initialPlacement initial placement
125     * @param minClassLimit minimum class limit
126     * @param maxClassLimit maximum class limit
127     * @param room2limitRatio room ratio
128     */
129    public Lecture(Long id, Long solverGroupId, Long schedulingSubpartId, String name,
130            java.util.List<TimeLocation> timeLocations, java.util.List<RoomLocation> roomLocations, int nrRooms,
131            Placement initialPlacement, int minClassLimit, int maxClassLimit, double room2limitRatio) {
132        super(initialPlacement);
133        iClassId = id;
134        iSchedulingSubpartId = schedulingSubpartId;
135        iTimeLocations = new ArrayList<TimeLocation>(timeLocations);
136        iRoomLocations = new ArrayList<RoomLocation>(roomLocations);
137        iName = name;
138        iMinClassLimit = minClassLimit;
139        iMaxClassLimit = maxClassLimit;
140        iRoomToLimitRatio = (float)room2limitRatio;
141        iNrRooms = nrRooms;
142        iSolverGroupId = solverGroupId;
143    }
144
145    public Lecture(Long id, Long solverGroupId, String name) {
146        super(null);
147        iClassId = id;
148        iSolverGroupId = solverGroupId;
149        iName = name;
150    }
151
152    public Long getSolverGroupId() {
153        return iSolverGroupId;
154    }
155
156    /**
157     * Add active jenrl constraint (active mean that there is at least one
158     * student between its classes)
159     * @param assignment current assignment
160     * @param constr an active jenrl constraint
161     */
162    public void addActiveJenrl(Assignment<Lecture, Placement> assignment, JenrlConstraint constr) {
163        getContext(assignment).addActiveJenrl(constr);
164    }
165
166    /**
167     * Active jenrl constraints (active mean that there is at least one student
168     * between its classes)
169     * @param assignment current assignment
170     * @return set of active jenrl constraints
171     */
172    public Set<JenrlConstraint> activeJenrls(Assignment<Lecture, Placement> assignment) {
173        return getContext(assignment).activeJenrls();
174    }
175
176    /**
177     * Remove active jenrl constraint (active mean that there is at least one
178     * student between its classes)
179     * @param assignment current assignment
180     * @param constr an active jenrl constraint
181     */
182    public void removeActiveJenrl(Assignment<Lecture, Placement> assignment, JenrlConstraint constr) {
183        getContext(assignment).removeActiveJenrl(constr);
184    }
185
186    /** Class id 
187     * @return class unique id
188     **/
189    public Long getClassId() {
190        return iClassId;
191    }
192
193    /**
194     * Scheduling subpart id
195     * @return scheduling subpart unique id
196     */
197    public Long getSchedulingSubpartId() {
198        return iSchedulingSubpartId;
199    }
200
201    /** Class name */
202    @Override
203    public String getName() {
204        return iName;
205    }
206
207    /** Class id */
208    @Override
209    public long getId() {
210        return iClassId.longValue();
211    }
212
213    /** Instructor name 
214     * @return list of instructor names
215     **/
216    public List<String> getInstructorNames() {
217        List<String> ret = new ArrayList<String>();
218        for (InstructorConstraint ic : iInstructorConstraints) {
219            ret.add(ic.getName());
220        }
221        return ret;
222    }
223
224    public String getInstructorName() {
225        StringBuffer sb = new StringBuffer();
226        for (InstructorConstraint ic : iInstructorConstraints) {
227            if (sb.length() > 0)
228                sb.append(", ");
229            sb.append(ic.getName());
230        }
231        return sb.toString();
232    }
233
234    /** List of enrolled students 
235     * @return list of enrolled students
236     **/
237    public Set<Student> students() {
238        return iStudents;
239    }
240
241    /**
242     * Total weight of all enrolled students
243     * @return sum of {@link Student#getOfferingWeight(Configuration)} of each enrolled student
244     */
245    public double nrWeightedStudents() {
246        double w = 0.0;
247        for (Student s : iStudents) {
248            w += s.getOfferingWeight(getConfiguration());
249        }
250        return w;
251    }
252
253    /** Add an enrolled student 
254     * @param assignment current assignment
255     * @param student a student to add
256     **/
257    public void addStudent(Assignment<Lecture, Placement> assignment, Student student) {
258        if (!iStudents.add(student))
259            return;
260        Placement value = (assignment == null ? null : assignment.getValue(this));
261        if (value != null && getModel() != null)
262            getModel().getCriterion(StudentCommittedConflict.class).inc(assignment, student.countConflictPlacements(value));
263        iLock.writeLock().lock();
264        iCommitedConflicts.clear();
265        iLock.writeLock().unlock();
266    }
267
268    /** 
269     * Remove an enrolled student
270     * @param assignment current assignment
271     * @param student a student to remove
272     */
273    public void removeStudent(Assignment<Lecture, Placement> assignment, Student student) {
274        if (!iStudents.remove(student))
275            return;
276        Placement value = (assignment == null ? null : assignment.getValue(this));
277        if (value != null && getModel() != null)
278            getModel().getCriterion(StudentCommittedConflict.class).inc(assignment, -student.countConflictPlacements(value));
279        iLock.writeLock().lock();
280        iCommitedConflicts.clear();
281        iLock.writeLock().unlock();
282    }
283
284    /** Returns true if the given student is enrolled 
285     * @param student a student
286     * @return true if the given student is enrolled in this class
287     **/
288    public boolean hasStudent(Student student) {
289        return iStudents.contains(student);
290    }
291
292    /** Set of lectures of the same class (only section is different) 
293     * @param sameSubpartLectures list of lectures of the same scheduling subpart 
294     **/
295    public void setSameSubpartLectures(List<Lecture> sameSubpartLectures) {
296        iSameSubpartLectures = sameSubpartLectures;
297    }
298
299    /** Set of lectures of the same class (only section is different) 
300     * @return list of lectures of the same scheduling subpart
301     **/
302    public List<Lecture> sameSubpartLectures() {
303        return iSameSubpartLectures;
304    }
305
306    /** List of students enrolled in this class as well as in the given class 
307     * @param lecture a lecture
308     * @return a set of students that are enrolled in both lectures 
309     **/
310    public Set<Student> sameStudents(Lecture lecture) {
311        JenrlConstraint jenrl = jenrlConstraint(lecture);
312        return (jenrl == null ? new HashSet<Student>() : jenrl.getStudents());
313    }
314
315    /** List of students of this class in conflict with the given assignment 
316     * @param assignment current assignment
317     * @param value given placement
318     * @return list of student conflicts
319     **/
320    public Set<Student> conflictStudents(Assignment<Lecture, Placement> assignment, Placement value) {
321        if (value == null)
322            return new HashSet<Student>();
323        if (value.equals(assignment.getValue(this)))
324            return conflictStudents(assignment);
325        Set<Student> ret = new HashSet<Student>();
326        for (JenrlConstraint jenrl : jenrlConstraints()) {
327            if (jenrl.jenrl(assignment, this, value) > 0)
328                ret.addAll(sameStudents(jenrl.another(this)));
329        }
330        return ret;
331    }
332
333    /**
334     * List of students of this class which are in conflict with any other
335     * assignment
336     * @param assignment current assignment
337     * @return list of student conflicts
338     */
339    public Set<Student> conflictStudents(Assignment<Lecture, Placement> assignment) {
340        Set<Student> ret = new HashSet<Student>();
341        Placement placement = assignment.getValue(this);
342        if (placement == null)
343            return ret;
344        for (JenrlConstraint jenrl : activeJenrls(assignment)) {
345            ret.addAll(sameStudents(jenrl.another(this)));
346        }
347        for (Student student : students()) {
348            if (student.countConflictPlacements(placement) > 0)
349                ret.add(student);
350        }
351        return ret;
352    }
353
354    /**
355     * Lectures different from this one, where it is student conflict of the
356     * given student between this and the lecture
357     * @param assignment current assignment
358     * @param student a student
359     * @return list of lectures with a student conflict 
360     */
361    public List<Lecture> conflictLectures(Assignment<Lecture, Placement> assignment, Student student) {
362        List<Lecture> ret = new ArrayList<Lecture>();
363        if (assignment.getValue(this) == null)
364            return ret;
365        for (JenrlConstraint jenrl : activeJenrls(assignment)) {
366            Lecture lect = jenrl.another(this);
367            if (lect.students().contains(student))
368                ret.add(lect);
369        }
370        return ret;
371    }
372
373    /** True if this lecture is in a student conflict with the given student 
374     * @param assignment current assignment
375     * @param student a student
376     * @return number of other lectures with a student conflict
377     **/
378    public int isInConflict(Assignment<Lecture, Placement> assignment, Student student) {
379        if (assignment.getValue(this) == null)
380            return 0;
381        int ret = 0;
382        for (JenrlConstraint jenrl : activeJenrls(assignment)) {
383            Lecture lect = jenrl.another(this);
384            if (lect.students().contains(student))
385                ret++;
386        }
387        return ret;
388    }
389    
390    private boolean isCacheDomain() {
391        return isCommitted() || (!sSaveMemory && (iNrRooms <= 1 || getMaxRoomCombinations() <= 0 || ToolBox.binomial(iRoomLocations.size(), iNrRooms) <= getMaxRoomCombinations()));
392    }
393    
394    /** Domain -- all combinations of room and time locations 
395     * @param assignment current assignment
396     * @param allowBreakHard breaking of hard constraints is allowed
397     * @return list of possible placements
398     **/
399    public List<Placement> computeValues(Assignment<Lecture, Placement> assignment, boolean allowBreakHard) {
400        List<Placement> values = new ArrayList<Placement>(iRoomLocations.size() * iTimeLocations.size());
401        for (TimeLocation timeLocation : iTimeLocations) {
402            if (!allowBreakHard && Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(timeLocation.getPreference())))
403                continue;
404            if (timeLocation.getPreference() > 500)
405                continue;
406            boolean notAvailable = false;
407            for (InstructorConstraint ic : getInstructorConstraints()) {
408                if (!ic.isAvailable(this, timeLocation)) {
409                    notAvailable = true;
410                    break;
411                }
412            }
413            if (notAvailable)
414                continue;
415            if (iNrRooms == 0) {
416                Placement p = new Placement(this, timeLocation, (RoomLocation) null);
417                for (InstructorConstraint ic : getInstructorConstraints()) {
418                    if (!ic.isAvailable(this, p)) {
419                        notAvailable = true;
420                        break;
421                    }
422                }
423                if (notAvailable)
424                    continue;
425                p.setVariable(this);
426                if (sSaveMemory && !isValid(p))
427                    continue;
428                if (getInitialAssignment() != null && p.equals(getInitialAssignment()))
429                    setInitialAssignment(p);
430                // if (getAssignment() != null && getAssignment().equals(p)) iValue = getAssignment();
431                if (getBestAssignment() != null && getBestAssignment().equals(p))
432                    setBestAssignment(p, getBestAssignmentIteration());
433                values.add(p);
434            } else if (iNrRooms == 1) {
435                for (RoomLocation roomLocation : iRoomLocations) {
436                    if (!allowBreakHard && Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(roomLocation.getPreference()))) continue;
437                    if (roomLocation.getPreference() > 500) continue;
438                    if (roomLocation.getRoomConstraint() != null && !roomLocation.getRoomConstraint().isAvailable(this, timeLocation, getScheduler())) continue;
439                    Placement p = new Placement(this, timeLocation, roomLocation);
440                    p.setVariable(this);
441                    if (sSaveMemory && !isValid(p)) continue;
442                    if (getInitialAssignment() != null && p.equals(getInitialAssignment())) setInitialAssignment(p);
443                    if (getBestAssignment() != null && getBestAssignment().equals(p)) setBestAssignment(p, getBestAssignmentIteration());
444                    values.add(p);
445                }
446            } else {
447                if (getMaxRoomCombinations() > 0 && ToolBox.binomial(iRoomLocations.size(), iNrRooms) > getMaxRoomCombinations()) {
448                    if (getInitialAssignment() != null && getInitialAssignment().getNrRooms() == getNrRooms()) {
449                        Placement p = new Placement(this, timeLocation, new ArrayList<RoomLocation>(getInitialAssignment().getRoomLocations()));
450                        p.setVariable(this);
451                        if (p.equals(getInitialAssignment())) setInitialAssignment(p);
452                        values.add(p);
453                    }
454                    List<RoomLocation> available = new ArrayList<RoomLocation>(iRoomLocations.size());
455                    List<RoomLocation> other = new ArrayList<RoomLocation>(iRoomLocations.size());
456                    for (RoomLocation room: iRoomLocations) {
457                        if (room.getRoomConstraint() != null && !room.getRoomConstraint().isAvailable(this, timeLocation, getScheduler())) continue;
458                        if (Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference()))) continue;
459                        if (assignment != null && room.getRoomConstraint() != null && !room.getRoomConstraint().getContext(assignment).inConflict(this, timeLocation)) {
460                            available.add(room);
461                        } else {
462                            other.add(room);
463                        }
464                    }
465                    if (available.size() + other.size() < iNrRooms) continue;
466                    for (Enumeration<Collection<RoomLocation>> e = ToolBox.sample(available, other, iNrRooms, getMaxRoomCombinations()); e.hasMoreElements(); ) {
467                        Placement p = new Placement(this, timeLocation, new ArrayList<RoomLocation>(e.nextElement()));
468                        if (getInitialAssignment() != null && p.sameRooms(getInitialAssignment())) continue;
469                        p.setVariable(this);
470                        values.add(p);
471                    }
472                } else {
473                    List<RoomLocation> rooms = new ArrayList<RoomLocation>(iRoomLocations.size());
474                    for (RoomLocation room: iRoomLocations) {
475                        if (!allowBreakHard && Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference()))) continue;
476                        if (room.getRoomConstraint() != null && !room.getRoomConstraint().isAvailable(this, timeLocation, getScheduler())) continue;
477                        rooms.add(room);
478                    }
479                    if (rooms.size() < iNrRooms) continue;
480                    for (Enumeration<Collection<RoomLocation>> e = ToolBox.permutations(rooms, iNrRooms); e.hasMoreElements(); ) {
481                        Placement p = new Placement(this, timeLocation, new ArrayList<RoomLocation>(e.nextElement()));
482                        p.setVariable(this);
483                        if (sSaveMemory && !isValid(p)) continue;
484                        if (getInitialAssignment() != null && p.equals(getInitialAssignment())) setInitialAssignment(p);
485                        if (getBestAssignment() != null && getBestAssignment().equals(p)) setBestAssignment(p, getBestAssignmentIteration());
486                        values.add(p);
487                    }
488                }
489            }
490        }
491        return values;
492    }
493    
494    public void clearValueCache() {
495        super.setValues(null);
496    }
497
498    /** All values */
499    @Override
500    public List<Placement> values(Assignment<Lecture, Placement> assignment) {
501        if (super.values(assignment) == null) {
502            if (getInitialAssignment() != null && iTimeLocations.size() == 1 && iRoomLocations.size() == getNrRooms()) {
503                List<Placement> values = new ArrayList<Placement>(1);
504                values.add(getInitialAssignment());
505                setValues(values);
506                return values;
507            } else if (isCacheDomain()) {
508                List<Placement> values = computeValues(null, sAllowBreakHard); 
509                setValues(values);
510                return values;
511            } else {
512                return computeValues(assignment, sAllowBreakHard);
513            }
514        } else {
515            return super.values(assignment);
516        }
517    }
518
519    @Override
520    public boolean equals(Object o) {
521        if (o == null || !(o instanceof Lecture))
522            return false;
523        return getClassId().equals(((Lecture) o).getClassId());
524    }
525
526    /** Best time preference of this lecture */
527    private Double iBestTimePreferenceCache = null;
528
529    public double getBestTimePreference() {
530        if (iBestTimePreferenceCache == null) {
531            double ret = Double.MAX_VALUE;
532            for (TimeLocation time : iTimeLocations) {
533                ret = Math.min(ret, time.getNormalizedPreference());
534            }
535            iBestTimePreferenceCache = new Double(ret);
536        }
537        return iBestTimePreferenceCache.doubleValue();
538    }
539
540    /** Best room preference of this lecture 
541     * @return best room preference
542     **/
543    public int getBestRoomPreference() {
544        int ret = Integer.MAX_VALUE;
545        for (RoomLocation room : iRoomLocations) {
546            ret = Math.min(ret, room.getPreference());
547        }
548        return ret;
549    }
550
551    /**
552     * Number of student conflicts caused by the given assignment of this
553     * lecture
554     * @param assignment current assignment
555     * @param value a placement
556     * @return number of student conflicts if assigned
557     */
558    public int countStudentConflicts(Assignment<Lecture, Placement> assignment, Placement value) {
559        int studentConflictsSum = 0;
560        for (JenrlConstraint jenrl : jenrlConstraints()) {
561            studentConflictsSum += jenrl.jenrl(assignment, this, value);
562        }
563        return studentConflictsSum;
564    }
565
566    public int countStudentConflictsOfTheSameProblem(Assignment<Lecture, Placement> assignment, Placement value) {
567        int studentConflictsSum = 0;
568        for (JenrlConstraint jenrl : jenrlConstraints()) {
569            if (!jenrl.isOfTheSameProblem())
570                continue;
571            studentConflictsSum += jenrl.jenrl(assignment, this, value);
572        }
573        return studentConflictsSum;
574    }
575
576    public int countHardStudentConflicts(Assignment<Lecture, Placement> assignment, Placement value) {
577        int studentConflictsSum = 0;
578        if (!isSingleSection())
579            return 0;
580        for (JenrlConstraint jenrl : jenrlConstraints()) {
581            if (!jenrl.areStudentConflictsHard())
582                continue;
583            studentConflictsSum += jenrl.jenrl(assignment, this, value);
584        }
585        return studentConflictsSum;
586    }
587
588    public int countCommittedStudentConflictsOfTheSameProblem(Assignment<Lecture, Placement> assignment, Placement value) {
589        int studentConflictsSum = 0;
590        for (JenrlConstraint jenrl : jenrlConstraints()) {
591            if (!jenrl.isOfTheSameProblem())
592                continue;
593            if (!jenrl.areStudentConflictsCommitted())
594                continue;
595            studentConflictsSum += jenrl.jenrl(assignment, this, value);
596        }
597        return studentConflictsSum;
598    }
599    
600    public int countCommittedStudentConflicts(Assignment<Lecture, Placement> assignment, Placement value) {
601        int studentConflictsSum = 0;
602        for (JenrlConstraint jenrl : jenrlConstraints()) {
603            if (!jenrl.areStudentConflictsCommitted())
604                continue;
605            studentConflictsSum += jenrl.jenrl(assignment, this, value);
606        }
607        return studentConflictsSum;
608    }
609
610    public int countHardStudentConflictsOfTheSameProblem(Assignment<Lecture, Placement> assignment, Placement value) {
611        int studentConflictsSum = 0;
612        for (JenrlConstraint jenrl : jenrlConstraints()) {
613            if (!jenrl.isOfTheSameProblem())
614                continue;
615            if (!jenrl.areStudentConflictsHard())
616                continue;
617            studentConflictsSum += jenrl.jenrl(assignment, this, value);
618        }
619        return studentConflictsSum;
620    }
621
622    public int countDistanceStudentConflicts(Assignment<Lecture, Placement> assignment, Placement value) {
623        int studentConflictsSum = 0;
624        for (JenrlConstraint jenrl : jenrlConstraints()) {
625            if (!jenrl.areStudentConflictsDistance(assignment, value))
626                continue;
627            studentConflictsSum += jenrl.jenrl(assignment, this, value);
628        }
629        return studentConflictsSum;
630    }
631
632    public int countDistanceStudentConflictsOfTheSameProblem(Assignment<Lecture, Placement> assignment, Placement value) {
633        int studentConflictsSum = 0;
634        for (JenrlConstraint jenrl : jenrlConstraints()) {
635            if (!jenrl.isOfTheSameProblem())
636                continue;
637            if (!jenrl.areStudentConflictsDistance(assignment, value))
638                continue;
639            studentConflictsSum += jenrl.jenrl(assignment, this, value);
640        }
641        return studentConflictsSum;
642    }
643    
644    private DistanceMetric getDistanceMetric() {
645        return ((TimetableModel)getModel()).getDistanceMetric();
646    }
647    
648    private int getStudentWorkDayLimit() {
649        return ((TimetableModel)getModel()).getStudentWorkDayLimit();
650    }
651
652    /**
653     * Number of student conflicts caused by the initial assignment of this
654     * lecture
655     * @return number of student conflicts with the initial assignment of this class
656     */
657    public int countInitialStudentConflicts() {
658        Placement value = getInitialAssignment();
659        if (value == null)
660            return 0;
661        int studentConflictsSum = 0;
662        for (JenrlConstraint jenrl : jenrlConstraints()) {
663            Lecture another = jenrl.another(this);
664            if (another.getInitialAssignment() != null)
665                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric(), getStudentWorkDayLimit()))
666                    studentConflictsSum += jenrl.getJenrl();
667        }
668        return studentConflictsSum;
669    }
670
671    /**
672     * Table of student conflicts caused by the initial assignment of this
673     * lecture in format (another lecture, number)
674     * @return table of student conflicts with the initial assignment of this class
675     */
676    public Map<Lecture, Long> getInitialStudentConflicts() {
677        Placement value = getInitialAssignment();
678        if (value == null)
679            return null;
680        Map<Lecture, Long> ret = new HashMap<Lecture, Long>();
681        for (JenrlConstraint jenrl : jenrlConstraints()) {
682            Lecture another = jenrl.another(this);
683            if (another.getInitialAssignment() != null)
684                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric(), getStudentWorkDayLimit()))
685                    ret.put(another, jenrl.getJenrl());
686        }
687        return ret;
688    }
689
690    /**
691     * List of student conflicts caused by the initial assignment of this
692     * lecture
693     * @return a set of students in a conflict with the initial assignment of this class
694     */
695    public Set<Student> initialStudentConflicts() {
696        Placement value = getInitialAssignment();
697        if (value == null)
698            return null;
699        HashSet<Student> ret = new HashSet<Student>();
700        for (JenrlConstraint jenrl : jenrlConstraints()) {
701            Lecture another = jenrl.another(this);
702            if (another.getInitialAssignment() != null)
703                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric(), getStudentWorkDayLimit()))
704                    ret.addAll(sameStudents(another));
705        }
706        return ret;
707    }
708
709    @Override
710    public void addContstraint(Constraint<Lecture, Placement> constraint) {
711        super.addContstraint(constraint);
712
713        if (constraint instanceof WeakeningConstraint)
714            iWeakeningConstraints.add(constraint);
715        
716        if (constraint instanceof FlexibleConstraint)
717            iFlexibleGroupConstraints.add((FlexibleConstraint) constraint);
718
719        if (constraint instanceof JenrlConstraint) {
720            JenrlConstraint jenrl = (JenrlConstraint) constraint;
721            Lecture another = jenrl.another(this);
722            if (another != null) {
723                iJenrlConstraints.add(jenrl);
724                another.iJenrlConstraints.add(jenrl);
725                iJenrlConstraintsHash.put(another, (JenrlConstraint) constraint);
726                another.iJenrlConstraintsHash.put(this, (JenrlConstraint) constraint);
727            }
728        } else if (constraint instanceof DepartmentSpreadConstraint)
729            iDeptSpreadConstraint = (DepartmentSpreadConstraint) constraint;
730        else if (constraint instanceof SpreadConstraint)
731            iSpreadConstraints.add((SpreadConstraint) constraint);
732        else if (constraint instanceof InstructorConstraint) {
733            InstructorConstraint ic = (InstructorConstraint) constraint;
734            if (ic.getResourceId() != null && ic.getResourceId().longValue() > 0)
735                iInstructorConstraints.add(ic);
736        } else if (constraint instanceof ClassLimitConstraint)
737            iClassLimitConstraint = (ClassLimitConstraint) constraint;
738        else if (constraint instanceof GroupConstraint) {
739            GroupConstraint gc = (GroupConstraint) constraint;
740            if (gc.canShareRoom()) {
741                iCanShareRoomGroupConstraints.add((GroupConstraint) constraint);
742            } else {
743                iGroupConstraints.add((GroupConstraint) constraint);
744                if (Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(gc.getPreference()))
745                        || Constants.sPreferenceRequired.equals(Constants
746                                .preferenceLevel2preference(gc.getPreference())))
747                    iHardGroupSoftConstraints.add((GroupConstraint) constraint);
748            }
749        }
750    }
751
752    @Override
753    public void removeContstraint(Constraint<Lecture, Placement> constraint) {
754        super.removeContstraint(constraint);
755
756        if (constraint instanceof WeakeningConstraint)
757            iWeakeningConstraints.remove(constraint);
758        
759        if (constraint instanceof FlexibleConstraint)
760            iFlexibleGroupConstraints.remove(constraint);
761
762        if (constraint instanceof JenrlConstraint) {
763            JenrlConstraint jenrl = (JenrlConstraint) constraint;
764            Lecture another = jenrl.another(this);
765            if (another != null) {
766                iJenrlConstraints.remove(jenrl);
767                another.iJenrlConstraints.remove(jenrl);
768                iJenrlConstraintsHash.remove(another);
769                another.iJenrlConstraintsHash.remove(this);
770            }
771        } else if (constraint instanceof GroupConstraint) {
772            iCanShareRoomGroupConstraints.remove(constraint);
773            iHardGroupSoftConstraints.remove(constraint);
774            iGroupConstraints.remove(constraint);
775        } else if (constraint instanceof DepartmentSpreadConstraint)
776            iDeptSpreadConstraint = null;
777        else if (constraint instanceof SpreadConstraint)
778            iSpreadConstraints.remove(constraint);
779        else if (constraint instanceof InstructorConstraint)
780            iInstructorConstraints.remove(constraint);
781        else if (constraint instanceof ClassLimitConstraint)
782            iClassLimitConstraint = null;
783    }
784
785    /** All JENRL constraints of this lecture 
786     * @param another another class
787     * @return a join enrollment constraint between this and the given class, if there is one 
788     **/
789    public JenrlConstraint jenrlConstraint(Lecture another) {
790        /*
791         * for (Enumeration e=iJenrlConstraints.elements();e.hasMoreElements();)
792         * { JenrlConstraint jenrl = (JenrlConstraint)e.nextElement(); if
793         * (jenrl.another(this).equals(another)) return jenrl; } return null;
794         */
795        return iJenrlConstraintsHash.get(another);
796    }
797
798    /** All JENRL constraints of this lecture
799     * @return list of all join enrollment constraints in which this lecture is involved
800     **/
801    public List<JenrlConstraint> jenrlConstraints() {
802        return iJenrlConstraints;
803    }
804
805    public int minClassLimit() {
806        return iMinClassLimit;
807    }
808
809    public int maxClassLimit() {
810        return iMaxClassLimit;
811    }
812
813    public int maxAchievableClassLimit() {
814        iLock.readLock().lock();
815        try {
816            if (iCacheMaxAchievableClassLimit != null) return iCacheMaxAchievableClassLimit.intValue();
817        } finally {
818            iLock.readLock().unlock();
819        }
820        iLock.writeLock().lock();
821        try {
822            if (iCacheMaxAchievableClassLimit != null) return iCacheMaxAchievableClassLimit.intValue();
823
824            int maxAchievableClassLimit = Math.min(maxClassLimit(), (int) Math.floor(maxRoomSize() / roomToLimitRatio()));
825
826            if (hasAnyChildren()) {
827
828                for (Long subpartId: getChildrenSubpartIds()) {
829                    int maxAchievableChildrenLimit = 0;
830
831                    for (Lecture child : getChildren(subpartId)) {
832                        maxAchievableChildrenLimit += child.maxAchievableClassLimit();
833                    }
834
835                    maxAchievableClassLimit = Math.min(maxAchievableClassLimit, maxAchievableChildrenLimit);
836                }
837            }
838
839            maxAchievableClassLimit = Math.max(minClassLimit(), maxAchievableClassLimit);
840            iCacheMaxAchievableClassLimit = new Integer(maxAchievableClassLimit);
841            return maxAchievableClassLimit;
842        } finally {
843            iLock.writeLock().unlock();
844        }
845    }
846
847    public int classLimit(Assignment<Lecture, Placement> assignment) {
848        if (minClassLimit() == maxClassLimit())
849            return minClassLimit();
850        return classLimit(assignment, null, null);
851    }
852
853    public int classLimit(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
854        Placement a = (assignment == null ? null : assignment.getValue(this));
855        if (value != null && value.variable().equals(this))
856            a = value;
857        if (conflicts != null && a != null && conflicts.contains(a))
858            a = null;
859        int classLimit = (a == null ? maxAchievableClassLimit() : Math.min(maxClassLimit(), (int) Math.floor(a.getRoomSize() / roomToLimitRatio())));
860
861        if (!hasAnyChildren())
862            return classLimit;
863
864        for (Long subpartId: getChildrenSubpartIds()) {
865            int childrenClassLimit = 0;
866
867            for (Lecture child : getChildren(subpartId)) {
868                childrenClassLimit += child.classLimit(assignment, value, conflicts);
869            }
870
871            classLimit = Math.min(classLimit, childrenClassLimit);
872        }
873
874        return Math.max(minClassLimit(), classLimit);
875    }
876
877    public double roomToLimitRatio() {
878        return iRoomToLimitRatio;
879    }
880
881    public int minRoomUse() {
882        return iNrRooms == 0 ? 0 : Math.round(iMinClassLimit * iRoomToLimitRatio);
883    }
884
885    public int maxRoomUse() {
886        return iNrRooms == 0 ? 0 : Math.round(iMaxClassLimit * iRoomToLimitRatio);
887    }
888
889    @Override
890    public String toString() {
891        return getName();
892    }
893
894    /** Controlling Course Offering Department 
895     * @return department unique id
896     **/
897    public Long getDepartment() {
898        return iDept;
899    }
900
901    /** Controlling Course Offering Department 
902     * @param dept department unique id
903     **/
904    public void setDepartment(Long dept) {
905        iDept = dept;
906    }
907
908    /** Scheduler (Managing Department) 
909     * @return solver group unique id
910     **/
911    public Long getScheduler() {
912        return iScheduler;
913    }
914
915    /** Scheduler (Managing Department)
916     * @param scheduler solver group unique id 
917     **/
918    public void setScheduler(Long scheduler) {
919        iScheduler = scheduler;
920    }
921
922    /** Departmental spreading constraint 
923     * @return department spread constraint of this class, if any
924     **/
925    public DepartmentSpreadConstraint getDeptSpreadConstraint() {
926        return iDeptSpreadConstraint;
927    }
928
929    /** Instructor constraint 
930     * @return instructors of this class
931     **/
932    public List<InstructorConstraint> getInstructorConstraints() {
933        return iInstructorConstraints;
934    }
935
936    public ClassLimitConstraint getClassLimitConstraint() {
937        return iClassLimitConstraint;
938    }
939
940    public Set<SpreadConstraint> getSpreadConstraints() {
941        return iSpreadConstraints;
942    }
943    
944    public Set<FlexibleConstraint> getFlexibleGroupConstraints() {
945        return iFlexibleGroupConstraints;
946    }
947
948    public Set<Constraint<Lecture, Placement>> getWeakeningConstraints() {
949        return iWeakeningConstraints;
950    }
951
952    /** All room locations 
953     * @return possible rooms of this class
954     **/
955    public List<RoomLocation> roomLocations() {
956        return iRoomLocations;
957    }
958
959    /** All time locations 
960     * @return possible times of this class
961     **/
962    public List<TimeLocation> timeLocations() {
963        return iTimeLocations;
964    }
965
966    public int nrTimeLocations() {
967        int ret = 0;
968        for (TimeLocation time : iTimeLocations) {
969            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference())))
970                ret++;
971        }
972        return ret;
973    }
974
975    public int nrRoomLocations() {
976        int ret = 0;
977        for (RoomLocation room : iRoomLocations) {
978            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference())))
979                ret++;
980        }
981        return ret;
982    }
983
984    public long nrValues() {
985        int nrTimes = 0;
986        for (TimeLocation time: timeLocations())
987            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference())))
988                nrTimes ++;
989        int nrRooms = 0;
990        for (RoomLocation room : iRoomLocations)
991            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference())))
992                nrRooms ++;
993        long estNrValues = nrTimes;
994        if (getNrRooms() > 1 && getMaxRoomCombinations() > 0)
995            estNrValues *= Math.min(getMaxRoomCombinations(), ToolBox.binomial(nrRooms, getNrRooms()));
996        else
997            estNrValues *= ToolBox.binomial(nrRooms, getNrRooms());
998        return estNrValues;
999    }
1000
1001    public int nrValues(TimeLocation time) {
1002        int ret = 0;
1003        for (RoomLocation room : iRoomLocations) {
1004            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference()))
1005                    && (room.getRoomConstraint() == null || room.getRoomConstraint().isAvailable(this, time, getScheduler())))
1006                ret++;
1007        }
1008        return ret;
1009    }
1010
1011    public int nrValues(RoomLocation room) {
1012        int ret = 0;
1013        for (TimeLocation time : iTimeLocations) {
1014            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference()))
1015                    && (room.getRoomConstraint() == null || room.getRoomConstraint().isAvailable(this, time,getScheduler())))
1016                ret++;
1017        }
1018        return ret;
1019    }
1020
1021    public int nrValues(List<RoomLocation> rooms) {
1022        int ret = 0;
1023        for (TimeLocation time : iTimeLocations) {
1024            boolean available = true;
1025            for (RoomLocation room : rooms) {
1026                if (Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference()))
1027                        || (room.getRoomConstraint() != null && !room.getRoomConstraint().isAvailable(this, time,
1028                                getScheduler())))
1029                    available = false;
1030            }
1031            if (available)
1032                ret++;
1033        }
1034        return ret;
1035    }
1036
1037    public boolean allowBreakHard() {
1038        return sAllowBreakHard;
1039    }
1040
1041    public int getNrRooms() {
1042        return iNrRooms;
1043    }
1044
1045    public Lecture getParent() {
1046        return iParent;
1047    }
1048
1049    public void setParent(Lecture parent) {
1050        iParent = parent;
1051        iParent.addChild(this);
1052    }
1053
1054    public boolean hasParent() {
1055        return (iParent != null);
1056    }
1057
1058    public boolean hasChildren(Long subpartId) {
1059        return (iChildren != null && iChildren.get(subpartId) != null && !iChildren.get(subpartId).isEmpty());
1060    }
1061
1062    public boolean hasAnyChildren() {
1063        return (iChildren != null && !iChildren.isEmpty());
1064    }
1065
1066    public List<Lecture> getChildren(Long subpartId) {
1067        return iChildren.get(subpartId);
1068    }
1069
1070    public Set<Long> getChildrenSubpartIds() {
1071        return (iChildren == null ? null : iChildren.keySet());
1072    }
1073    
1074    public Map<Long, List<Lecture>> getChildren() {
1075        return iChildren;
1076    }
1077
1078    private void addChild(Lecture child) {
1079        if (iChildren == null)
1080            iChildren = new HashMap<Long, List<Lecture>>();
1081        List<Lecture> childrenThisSubpart = iChildren.get(child.getSchedulingSubpartId());
1082        if (childrenThisSubpart == null) {
1083            childrenThisSubpart = new ArrayList<Lecture>();
1084            iChildren.put(child.getSchedulingSubpartId(), childrenThisSubpart);
1085        }
1086        childrenThisSubpart.add(child);
1087    }
1088
1089    public boolean isSingleSection() {
1090        return (iSameSubpartLectures == null || iSameSubpartLectures.size() <= 1);
1091        /*
1092        if (iParent == null)
1093            return (iSameSubpartLectures == null || iSameSubpartLectures.size() <= 1);
1094        return (iParent.getChildren(getSchedulingSubpartId()).size() <= 1);
1095        */
1096    }
1097
1098    public java.util.List<Lecture> sameStudentsLectures() {
1099        return (hasParent() ? getParent().getChildren(getSchedulingSubpartId()) : sameSubpartLectures());
1100    }
1101
1102    public Lecture getChild(Student student, Long subpartId) {
1103        if (!hasAnyChildren())
1104            return null;
1105        List<Lecture> children = getChildren(subpartId);
1106        if (children == null)
1107            return null;
1108        for (Lecture child : children) {
1109            if (child.students().contains(student))
1110                return child;
1111        }
1112        return null;
1113    }
1114
1115    public int getCommitedConflicts(Placement placement) {
1116        iLock.readLock().lock();
1117        try {
1118            Integer ret = iCommitedConflicts.get(placement);
1119            if (ret != null) return ret;
1120        } finally {
1121            iLock.readLock().unlock();
1122        }
1123        iLock.writeLock().lock();
1124        try {
1125            int ret = placement.getCommitedConflicts();
1126            iCommitedConflicts.put(placement, ret);
1127            return ret;
1128        } finally {
1129            iLock.writeLock().unlock();
1130        }
1131    }
1132
1133    public Set<GroupConstraint> hardGroupSoftConstraints() {
1134        return iHardGroupSoftConstraints;
1135    }
1136
1137    public Set<GroupConstraint> groupConstraints() {
1138        return iGroupConstraints;
1139    }
1140
1141    public int minRoomSize() {
1142        iLock.readLock().lock();
1143        try {
1144            if (iCacheMinRoomSize != null) return iCacheMinRoomSize.intValue();
1145        } finally {
1146            iLock.readLock().unlock();
1147        }
1148        iLock.writeLock().lock();
1149        try {
1150            if (iCacheMinRoomSize != null) return iCacheMinRoomSize.intValue();
1151            if (getNrRooms() <= 1) {
1152                int min = Integer.MAX_VALUE;
1153                for (RoomLocation r : roomLocations()) {
1154                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2)
1155                        min = Math.min(min, r.getRoomSize());
1156                }
1157                iCacheMinRoomSize = new Integer(min);
1158                return min;
1159            } else {
1160                List<RoomLocation> rooms = new ArrayList<RoomLocation>();
1161                for (RoomLocation r: roomLocations())
1162                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2)
1163                        rooms.add(r);
1164                Collections.sort(rooms, new Comparator<RoomLocation>() {
1165                    @Override
1166                    public int compare(RoomLocation r1, RoomLocation r2) {
1167                        if (r1.getRoomSize() < r2.getRoomSize()) return -1;
1168                        if (r1.getRoomSize() > r2.getRoomSize()) return 1;
1169                        return r1.compareTo(r2);
1170                    }
1171                });
1172                int min = rooms.isEmpty() ? 0 : rooms.get(Math.min(getNrRooms(), rooms.size()) - 1).getRoomSize();
1173                iCacheMinRoomSize = new Integer(min);
1174                return min;
1175            }
1176        } finally {
1177            iLock.writeLock().unlock();
1178        }
1179    }
1180
1181    public int maxRoomSize() {
1182        iLock.readLock().lock();
1183        try {
1184            if (iCacheMaxRoomSize != null) return iCacheMaxRoomSize.intValue();
1185        } finally {
1186            iLock.readLock().unlock();
1187        }
1188        iLock.writeLock().lock();
1189        try {
1190            if (iCacheMaxRoomSize != null) return iCacheMaxRoomSize.intValue();
1191            if (getNrRooms() <= 1) {
1192                int max = Integer.MIN_VALUE;
1193                for (RoomLocation r : roomLocations()) {
1194                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2) 
1195                        max = Math.max(max, r.getRoomSize());
1196                }
1197                iCacheMaxRoomSize = new Integer(max);
1198                return max;
1199            } else {
1200                List<RoomLocation> rooms = new ArrayList<RoomLocation>();
1201                for (RoomLocation r: roomLocations())
1202                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2) rooms.add(r);
1203                Collections.sort(rooms, new Comparator<RoomLocation>() {
1204                    @Override
1205                    public int compare(RoomLocation r1, RoomLocation r2) {
1206                        if (r1.getRoomSize() > r2.getRoomSize()) return -1;
1207                        if (r1.getRoomSize() < r2.getRoomSize()) return 1;
1208                        return r1.compareTo(r2);
1209                    }
1210                });
1211                int max = rooms.isEmpty() ? 0 : rooms.get(Math.min(getNrRooms(), rooms.size()) - 1).getRoomSize();
1212                iCacheMaxRoomSize = new Integer(max);
1213                return max;
1214            }
1215        } finally {
1216            iLock.writeLock().unlock();
1217        }
1218    }
1219
1220    public boolean canShareRoom() {
1221        return (!iCanShareRoomGroupConstraints.isEmpty());
1222    }
1223
1224    public boolean canShareRoom(Lecture other) {
1225        if (other.equals(this))
1226            return true;
1227        for (GroupConstraint gc : iCanShareRoomGroupConstraints) {
1228            if (gc.variables().contains(other))
1229                return true;
1230        }
1231        return false;
1232    }
1233
1234    public Set<GroupConstraint> canShareRoomConstraints() {
1235        return iCanShareRoomGroupConstraints;
1236    }
1237
1238    public boolean isSingleton() {
1239        return getNrRooms() == roomLocations().size() && timeLocations().size() == 1;
1240    }
1241
1242    public boolean isValid(Placement placement) {
1243        TimetableModel model = (TimetableModel) getModel();
1244        if (model == null)
1245            return true;
1246        if (model.hasConstantVariables()) {
1247            for (Placement confPlacement : model.conflictValuesSkipWeakeningConstraints(model.getEmptyAssignment(), placement)) {
1248                Lecture lecture = confPlacement.variable();
1249                if (lecture.isCommitted())
1250                    return false;
1251                if (confPlacement.equals(placement))
1252                    return false;
1253            }
1254        } else {
1255            Set<Placement> conflicts = new HashSet<Placement>();
1256            for (Constraint<Lecture, Placement> constraint : hardConstraints()) {
1257                if (constraint instanceof WeakeningConstraint) continue;
1258                constraint.computeConflicts(model.getEmptyAssignment(), placement, conflicts);
1259            }
1260            for (GlobalConstraint<Lecture, Placement> constraint : model.globalConstraints()) {
1261                if (constraint instanceof WeakeningConstraint) continue;
1262                constraint.computeConflicts(model.getEmptyAssignment(), placement, conflicts);
1263            }
1264            if (conflicts.contains(placement))
1265                return false;
1266        }
1267        return true;
1268    }
1269
1270    public String getNotValidReason(Assignment<Lecture, Placement> assignment, Placement placement, boolean useAmPm) {
1271        TimetableModel model = (TimetableModel) getModel();
1272        if (model == null)
1273            return "no model for class " + getName();
1274        Map<Constraint<Lecture, Placement>, Set<Placement>> conflictConstraints = model.conflictConstraints(assignment, placement);
1275        for (Map.Entry<Constraint<Lecture, Placement>, Set<Placement>> entry : conflictConstraints.entrySet()) {
1276            Constraint<Lecture, Placement> constraint = entry.getKey();
1277            Set<Placement> conflicts = entry.getValue();
1278            String cname = constraint.getName();
1279            if (constraint instanceof RoomConstraint) {
1280                cname = "Room " + constraint.getName();
1281            } else if (constraint instanceof InstructorConstraint) {
1282                cname = "Instructor " + constraint.getName();
1283            } else if (constraint instanceof GroupConstraint) {
1284                cname = "Distribution " + constraint.getName();
1285            } else if (constraint instanceof DepartmentSpreadConstraint) {
1286                cname = "Balancing of department " + constraint.getName();
1287            } else if (constraint instanceof SpreadConstraint) {
1288                cname = "Same subpart spread " + constraint.getName();
1289            } else if (constraint instanceof ClassLimitConstraint) {
1290                cname = "Class limit " + constraint.getName();
1291            }
1292            for (Placement confPlacement : conflicts) {
1293                Lecture lecture = confPlacement.variable();
1294                if (lecture.isCommitted()) {
1295                    return placement.getLongName(useAmPm) + " conflicts with " + lecture.getName() + " "
1296                            + confPlacement.getLongName(useAmPm) + " due to constraint " + cname;
1297                }
1298                if (confPlacement.equals(placement)) {
1299                    return placement.getLongName(useAmPm) + " is not valid due to constraint " + cname;
1300                }
1301            }
1302        }
1303        return null;
1304    }
1305    
1306    @Deprecated
1307    public String getNotValidReason(Assignment<Lecture, Placement> assignment, Placement placement) {
1308        return getNotValidReason(assignment, placement, true);
1309    }
1310
1311    public void purgeInvalidValues(boolean interactiveMode) {
1312        if (isCommitted() || sSaveMemory) return;
1313        TimetableModel model = (TimetableModel) getModel();
1314        if (model == null)
1315            return;
1316        List<Placement> newValues = new ArrayList<Placement>(values(null).size());
1317        for (Placement placement : values(null)) {
1318            if (placement.isValid())
1319                newValues.add(placement);
1320        }
1321        if (!interactiveMode && newValues.size() != values(null).size()) {
1322            for (Iterator<TimeLocation> i = timeLocations().iterator(); i.hasNext();) {
1323                TimeLocation timeLocation = i.next();
1324                boolean hasPlacement = false;
1325                for (Placement placement : newValues) {
1326                    if (timeLocation.equals(placement.getTimeLocation())) {
1327                        hasPlacement = true;
1328                        break;
1329                    }
1330                }
1331                if (!hasPlacement)
1332                    i.remove();
1333            }
1334            for (Iterator<RoomLocation> i = roomLocations().iterator(); i.hasNext();) {
1335                RoomLocation roomLocation = i.next();
1336                boolean hasPlacement = false;
1337                for (Placement placement : newValues) {
1338                    if (placement.isMultiRoom()) {
1339                        if (placement.getRoomLocations().contains(roomLocation)) {
1340                            hasPlacement = true;
1341                            break;
1342                        }
1343                    } else {
1344                        if (roomLocation.equals(placement.getRoomLocation())) {
1345                            hasPlacement = true;
1346                            break;
1347                        }
1348                    }
1349                }
1350                if (!hasPlacement)
1351                    i.remove();
1352            }
1353        }
1354        setValues(newValues);
1355    }
1356
1357    public void setCommitted(boolean committed) {
1358        iCommitted = committed;
1359    }
1360
1361    public boolean isCommitted() {
1362        return iCommitted;
1363    }
1364
1365    @Override
1366    public boolean isConstant() {
1367        return iCommitted;
1368    }
1369    
1370    @Override
1371    public Placement getConstantValue() {
1372        return (isCommitted() ? getInitialAssignment() : null);
1373    }
1374    
1375    public void setConstantValue(Placement value) {
1376        setInitialAssignment(value);
1377    }
1378
1379    public int getSpreadPenalty(Assignment<Lecture, Placement> assignment) {
1380        int spread = 0;
1381        for (SpreadConstraint sc : getSpreadConstraints()) {
1382            spread += sc.getPenalty(assignment);
1383        }
1384        return spread;
1385    }
1386
1387    @Override
1388    public int hashCode() {
1389        return getClassId().hashCode();
1390    }
1391
1392    public Configuration getConfiguration() {
1393        Lecture lecture = this;
1394        while (lecture.getParent() != null)
1395            lecture = lecture.getParent();
1396        return lecture.iParentConfiguration;
1397    }
1398
1399    public void setConfiguration(Configuration configuration) {
1400        Lecture lecture = this;
1401        while (lecture.getParent() != null)
1402            lecture = lecture.getParent();
1403        lecture.iParentConfiguration = configuration;
1404        configuration.addTopLecture(lecture);
1405    }
1406
1407    private int[] iMinMaxRoomPreference = null;
1408
1409    public int[] getMinMaxRoomPreference() {
1410        iLock.readLock().lock();
1411        try {
1412            if (iMinMaxRoomPreference != null) return iMinMaxRoomPreference;
1413        } finally {
1414            iLock.readLock().unlock();
1415        }
1416        iLock.writeLock().lock();
1417        try {
1418            if (iMinMaxRoomPreference != null) return iMinMaxRoomPreference;
1419
1420            if (getNrRooms() <= 0 || roomLocations().isEmpty()) {
1421                iMinMaxRoomPreference = new int[] { 0, 0 };
1422            } else {
1423                Integer minRoomPref = null, maxRoomPref = null;
1424                for (RoomLocation r : roomLocations()) {
1425                    int pref = r.getPreference();
1426                    if (pref >= Constants.sPreferenceLevelRequired / 2 && pref <= Constants.sPreferenceLevelProhibited / 2) {
1427                        minRoomPref = (minRoomPref == null ? pref : Math.min(minRoomPref, pref));
1428                        maxRoomPref = (maxRoomPref == null ? pref : Math.max(maxRoomPref, pref));
1429                    }
1430                }
1431                iMinMaxRoomPreference = new int[] { minRoomPref == null ? 0 : minRoomPref, maxRoomPref == null ? 0 : maxRoomPref };
1432            }
1433
1434            return iMinMaxRoomPreference;
1435        } finally {
1436            iLock.writeLock().unlock();
1437        }
1438    }
1439
1440    private double[] iMinMaxTimePreference = null;
1441
1442    public double[] getMinMaxTimePreference() {
1443        iLock.readLock().lock();
1444        try {
1445            if (iMinMaxTimePreference != null) return iMinMaxTimePreference;
1446        } finally {
1447            iLock.readLock().unlock();
1448        }
1449        iLock.writeLock().lock();
1450        try {
1451            if (iMinMaxTimePreference != null) return iMinMaxTimePreference;
1452
1453            Double minTimePref = null, maxTimePref = null;
1454            for (TimeLocation t : timeLocations()) {
1455                double npref = t.getNormalizedPreference();
1456                int pref = t.getPreference();
1457                if (pref >= Constants.sPreferenceLevelRequired / 2 && pref <= Constants.sPreferenceLevelProhibited / 2) {
1458                    minTimePref = (minTimePref == null ? npref : Math.min(minTimePref, npref));
1459                    maxTimePref = (maxTimePref == null ? npref : Math.max(maxTimePref, npref));
1460                }
1461            }
1462            iMinMaxTimePreference = new double[] { minTimePref == null ? 0.0 : minTimePref, maxTimePref == null ? 0.0 : maxTimePref };
1463            
1464            return iMinMaxTimePreference;
1465        } finally {
1466            iLock.writeLock().unlock();
1467        }
1468    }
1469
1470    public void setOrd(int ord) {
1471        iOrd = ord;
1472    }
1473
1474    public int getOrd() {
1475        return iOrd;
1476    }
1477
1478    @Override
1479    public int compareTo(Lecture o) {
1480        int cmp = Double.compare(getOrd(), o.getOrd());
1481        if (cmp != 0)
1482            return cmp;
1483        return super.compareTo(o);
1484    }
1485
1486    public String getNote() {
1487        return iNote;
1488    }
1489
1490    public void setNote(String note) {
1491        iNote = note;
1492    }
1493    
1494    public boolean areStudentConflictsHard(Lecture other) {
1495        return StudentConflict.hard(this, other);
1496    }
1497    
1498    public void clearIgnoreStudentConflictsWithCache() {
1499        iIgnoreStudentConflictsWith.set(null);
1500    }
1501    
1502    /**
1503     * Returns true if there is {@link IgnoreStudentConflictsConstraint} between the two lectures.
1504     * @param other another class
1505     * @return true if student conflicts between this and the given calls are to be ignored
1506     */
1507   public boolean isToIgnoreStudentConflictsWith(Lecture other) {
1508       Set<Long> cache = iIgnoreStudentConflictsWith.get();
1509       if (cache != null)
1510           return cache.contains(other.getClassId());
1511       cache = new HashSet<Long>();
1512       for (Constraint<Lecture, Placement> constraint: constraints()) {
1513           if (constraint instanceof IgnoreStudentConflictsConstraint)
1514               for (Lecture x: constraint.variables()) {
1515                   if (!x.equals(this)) cache.add(x.getClassId());
1516               }
1517       }
1518       iIgnoreStudentConflictsWith.set(cache);
1519       return cache.contains(other.getClassId());
1520    }
1521   
1522   /**
1523    * Get class weight. This weight is used with the criteria. E.g., class that is not meeting all the
1524    * semester can have a lower weight. Defaults to 1.0
1525    * @return class weight
1526    */
1527   public double getWeight() { return iWeight; }
1528   /**
1529    * Set class weight. This weight is used with the criteria. E.g., class that is not meeting all the
1530    * semester can have a lower weight.
1531    * @param weight class weight
1532    */
1533   public void setWeight(double weight) { iWeight = weight; }
1534   
1535   @Override
1536   public LectureContext createAssignmentContext(Assignment<Lecture, Placement> assignment) {
1537       return new LectureContext();
1538   }
1539
1540   public class LectureContext implements AssignmentContext {
1541       private Set<JenrlConstraint> iActiveJenrls = new HashSet<JenrlConstraint>();
1542 
1543       /**
1544        * Add active jenrl constraint (active mean that there is at least one
1545        * student between its classes)
1546        * @param constr active join enrollment constraint 
1547        */
1548       public void addActiveJenrl(JenrlConstraint constr) {
1549           iActiveJenrls.add(constr);
1550       }
1551
1552       /**
1553        * Active jenrl constraints (active mean that there is at least one student
1554        * between its classes)
1555        * @return set of active join enrollment constraints
1556        */
1557       public Set<JenrlConstraint> activeJenrls() {
1558           return iActiveJenrls;
1559       }
1560
1561       /**
1562        * Remove active jenrl constraint (active mean that there is at least one
1563        * student between its classes)
1564        * @param constr active join enrollment constraint
1565        */
1566       public void removeActiveJenrl(JenrlConstraint constr) {
1567           iActiveJenrls.remove(constr);
1568       }
1569   }
1570   
1571   public int getMaxRoomCombinations() {
1572       return iMaxRoomCombinations;
1573   }
1574   
1575   public void setMaxRoomCombinations(int maxRoomCombinations) {
1576       iMaxRoomCombinations = maxRoomCombinations;
1577   }
1578}