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    /**
649     * Number of student conflicts caused by the initial assignment of this
650     * lecture
651     * @return number of student conflicts with the initial assignment of this class
652     */
653    public int countInitialStudentConflicts() {
654        Placement value = getInitialAssignment();
655        if (value == null)
656            return 0;
657        int studentConflictsSum = 0;
658        for (JenrlConstraint jenrl : jenrlConstraints()) {
659            Lecture another = jenrl.another(this);
660            if (another.getInitialAssignment() != null)
661                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric()))
662                    studentConflictsSum += jenrl.getJenrl();
663        }
664        return studentConflictsSum;
665    }
666
667    /**
668     * Table of student conflicts caused by the initial assignment of this
669     * lecture in format (another lecture, number)
670     * @return table of student conflicts with the initial assignment of this class
671     */
672    public Map<Lecture, Long> getInitialStudentConflicts() {
673        Placement value = getInitialAssignment();
674        if (value == null)
675            return null;
676        Map<Lecture, Long> ret = new HashMap<Lecture, Long>();
677        for (JenrlConstraint jenrl : jenrlConstraints()) {
678            Lecture another = jenrl.another(this);
679            if (another.getInitialAssignment() != null)
680                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric()))
681                    ret.put(another, jenrl.getJenrl());
682        }
683        return ret;
684    }
685
686    /**
687     * List of student conflicts caused by the initial assignment of this
688     * lecture
689     * @return a set of students in a conflict with the initial assignment of this class
690     */
691    public Set<Student> initialStudentConflicts() {
692        Placement value = getInitialAssignment();
693        if (value == null)
694            return null;
695        HashSet<Student> ret = new HashSet<Student>();
696        for (JenrlConstraint jenrl : jenrlConstraints()) {
697            Lecture another = jenrl.another(this);
698            if (another.getInitialAssignment() != null)
699                if (JenrlConstraint.isInConflict(value, another.getInitialAssignment(), getDistanceMetric()))
700                    ret.addAll(sameStudents(another));
701        }
702        return ret;
703    }
704
705    @Override
706    public void addContstraint(Constraint<Lecture, Placement> constraint) {
707        super.addContstraint(constraint);
708
709        if (constraint instanceof WeakeningConstraint)
710            iWeakeningConstraints.add(constraint);
711        
712        if (constraint instanceof FlexibleConstraint)
713            iFlexibleGroupConstraints.add((FlexibleConstraint) constraint);
714
715        if (constraint instanceof JenrlConstraint) {
716            JenrlConstraint jenrl = (JenrlConstraint) constraint;
717            Lecture another = jenrl.another(this);
718            if (another != null) {
719                iJenrlConstraints.add(jenrl);
720                another.iJenrlConstraints.add(jenrl);
721                iJenrlConstraintsHash.put(another, (JenrlConstraint) constraint);
722                another.iJenrlConstraintsHash.put(this, (JenrlConstraint) constraint);
723            }
724        } else if (constraint instanceof DepartmentSpreadConstraint)
725            iDeptSpreadConstraint = (DepartmentSpreadConstraint) constraint;
726        else if (constraint instanceof SpreadConstraint)
727            iSpreadConstraints.add((SpreadConstraint) constraint);
728        else if (constraint instanceof InstructorConstraint) {
729            InstructorConstraint ic = (InstructorConstraint) constraint;
730            if (ic.getResourceId() != null && ic.getResourceId().longValue() > 0)
731                iInstructorConstraints.add(ic);
732        } else if (constraint instanceof ClassLimitConstraint)
733            iClassLimitConstraint = (ClassLimitConstraint) constraint;
734        else if (constraint instanceof GroupConstraint) {
735            GroupConstraint gc = (GroupConstraint) constraint;
736            if (gc.canShareRoom()) {
737                iCanShareRoomGroupConstraints.add((GroupConstraint) constraint);
738            } else {
739                iGroupConstraints.add((GroupConstraint) constraint);
740                if (Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(gc.getPreference()))
741                        || Constants.sPreferenceRequired.equals(Constants
742                                .preferenceLevel2preference(gc.getPreference())))
743                    iHardGroupSoftConstraints.add((GroupConstraint) constraint);
744            }
745        }
746    }
747
748    @Override
749    public void removeContstraint(Constraint<Lecture, Placement> constraint) {
750        super.removeContstraint(constraint);
751
752        if (constraint instanceof WeakeningConstraint)
753            iWeakeningConstraints.remove(constraint);
754        
755        if (constraint instanceof FlexibleConstraint)
756            iFlexibleGroupConstraints.remove(constraint);
757
758        if (constraint instanceof JenrlConstraint) {
759            JenrlConstraint jenrl = (JenrlConstraint) constraint;
760            Lecture another = jenrl.another(this);
761            if (another != null) {
762                iJenrlConstraints.remove(jenrl);
763                another.iJenrlConstraints.remove(jenrl);
764                iJenrlConstraintsHash.remove(another);
765                another.iJenrlConstraintsHash.remove(this);
766            }
767        } else if (constraint instanceof GroupConstraint) {
768            iCanShareRoomGroupConstraints.remove(constraint);
769            iHardGroupSoftConstraints.remove(constraint);
770            iGroupConstraints.remove(constraint);
771        } else if (constraint instanceof DepartmentSpreadConstraint)
772            iDeptSpreadConstraint = null;
773        else if (constraint instanceof SpreadConstraint)
774            iSpreadConstraints.remove(constraint);
775        else if (constraint instanceof InstructorConstraint)
776            iInstructorConstraints.remove(constraint);
777        else if (constraint instanceof ClassLimitConstraint)
778            iClassLimitConstraint = null;
779    }
780
781    /** All JENRL constraints of this lecture 
782     * @param another another class
783     * @return a join enrollment constraint between this and the given class, if there is one 
784     **/
785    public JenrlConstraint jenrlConstraint(Lecture another) {
786        /*
787         * for (Enumeration e=iJenrlConstraints.elements();e.hasMoreElements();)
788         * { JenrlConstraint jenrl = (JenrlConstraint)e.nextElement(); if
789         * (jenrl.another(this).equals(another)) return jenrl; } return null;
790         */
791        return iJenrlConstraintsHash.get(another);
792    }
793
794    /** All JENRL constraints of this lecture
795     * @return list of all join enrollment constraints in which this lecture is involved
796     **/
797    public List<JenrlConstraint> jenrlConstraints() {
798        return iJenrlConstraints;
799    }
800
801    public int minClassLimit() {
802        return iMinClassLimit;
803    }
804
805    public int maxClassLimit() {
806        return iMaxClassLimit;
807    }
808
809    public int maxAchievableClassLimit() {
810        iLock.readLock().lock();
811        try {
812            if (iCacheMaxAchievableClassLimit != null) return iCacheMaxAchievableClassLimit.intValue();
813        } finally {
814            iLock.readLock().unlock();
815        }
816        iLock.writeLock().lock();
817        try {
818            if (iCacheMaxAchievableClassLimit != null) return iCacheMaxAchievableClassLimit.intValue();
819
820            int maxAchievableClassLimit = Math.min(maxClassLimit(), (int) Math.floor(maxRoomSize() / roomToLimitRatio()));
821
822            if (hasAnyChildren()) {
823
824                for (Long subpartId: getChildrenSubpartIds()) {
825                    int maxAchievableChildrenLimit = 0;
826
827                    for (Lecture child : getChildren(subpartId)) {
828                        maxAchievableChildrenLimit += child.maxAchievableClassLimit();
829                    }
830
831                    maxAchievableClassLimit = Math.min(maxAchievableClassLimit, maxAchievableChildrenLimit);
832                }
833            }
834
835            maxAchievableClassLimit = Math.max(minClassLimit(), maxAchievableClassLimit);
836            iCacheMaxAchievableClassLimit = new Integer(maxAchievableClassLimit);
837            return maxAchievableClassLimit;
838        } finally {
839            iLock.writeLock().unlock();
840        }
841    }
842
843    public int classLimit(Assignment<Lecture, Placement> assignment) {
844        if (minClassLimit() == maxClassLimit())
845            return minClassLimit();
846        return classLimit(assignment, null, null);
847    }
848
849    public int classLimit(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
850        Placement a = (assignment == null ? null : assignment.getValue(this));
851        if (value != null && value.variable().equals(this))
852            a = value;
853        if (conflicts != null && a != null && conflicts.contains(a))
854            a = null;
855        int classLimit = (a == null ? maxAchievableClassLimit() : Math.min(maxClassLimit(), (int) Math.floor(a.getRoomSize() / roomToLimitRatio())));
856
857        if (!hasAnyChildren())
858            return classLimit;
859
860        for (Long subpartId: getChildrenSubpartIds()) {
861            int childrenClassLimit = 0;
862
863            for (Lecture child : getChildren(subpartId)) {
864                childrenClassLimit += child.classLimit(assignment, value, conflicts);
865            }
866
867            classLimit = Math.min(classLimit, childrenClassLimit);
868        }
869
870        return Math.max(minClassLimit(), classLimit);
871    }
872
873    public double roomToLimitRatio() {
874        return iRoomToLimitRatio;
875    }
876
877    public int minRoomUse() {
878        return Math.round(iMinClassLimit * iRoomToLimitRatio);
879    }
880
881    public int maxRoomUse() {
882        return Math.round(iMaxClassLimit * iRoomToLimitRatio);
883    }
884
885    @Override
886    public String toString() {
887        return getName();
888    }
889
890    /** Controlling Course Offering Department 
891     * @return department unique id
892     **/
893    public Long getDepartment() {
894        return iDept;
895    }
896
897    /** Controlling Course Offering Department 
898     * @param dept department unique id
899     **/
900    public void setDepartment(Long dept) {
901        iDept = dept;
902    }
903
904    /** Scheduler (Managing Department) 
905     * @return solver group unique id
906     **/
907    public Long getScheduler() {
908        return iScheduler;
909    }
910
911    /** Scheduler (Managing Department)
912     * @param scheduler solver group unique id 
913     **/
914    public void setScheduler(Long scheduler) {
915        iScheduler = scheduler;
916    }
917
918    /** Departmental spreading constraint 
919     * @return department spread constraint of this class, if any
920     **/
921    public DepartmentSpreadConstraint getDeptSpreadConstraint() {
922        return iDeptSpreadConstraint;
923    }
924
925    /** Instructor constraint 
926     * @return instructors of this class
927     **/
928    public List<InstructorConstraint> getInstructorConstraints() {
929        return iInstructorConstraints;
930    }
931
932    public ClassLimitConstraint getClassLimitConstraint() {
933        return iClassLimitConstraint;
934    }
935
936    public Set<SpreadConstraint> getSpreadConstraints() {
937        return iSpreadConstraints;
938    }
939    
940    public Set<FlexibleConstraint> getFlexibleGroupConstraints() {
941        return iFlexibleGroupConstraints;
942    }
943
944    public Set<Constraint<Lecture, Placement>> getWeakeningConstraints() {
945        return iWeakeningConstraints;
946    }
947
948    /** All room locations 
949     * @return possible rooms of this class
950     **/
951    public List<RoomLocation> roomLocations() {
952        return iRoomLocations;
953    }
954
955    /** All time locations 
956     * @return possible times of this class
957     **/
958    public List<TimeLocation> timeLocations() {
959        return iTimeLocations;
960    }
961
962    public int nrTimeLocations() {
963        int ret = 0;
964        for (TimeLocation time : iTimeLocations) {
965            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference())))
966                ret++;
967        }
968        return ret;
969    }
970
971    public int nrRoomLocations() {
972        int ret = 0;
973        for (RoomLocation room : iRoomLocations) {
974            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference())))
975                ret++;
976        }
977        return ret;
978    }
979
980    public long nrValues() {
981        int nrTimes = 0;
982        for (TimeLocation time: timeLocations())
983            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference())))
984                nrTimes ++;
985        int nrRooms = 0;
986        for (RoomLocation room : iRoomLocations)
987            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference())))
988                nrRooms ++;
989        long estNrValues = nrTimes;
990        if (getNrRooms() > 1 && getMaxRoomCombinations() > 0)
991            estNrValues *= Math.min(getMaxRoomCombinations(), ToolBox.binomial(nrRooms, getNrRooms()));
992        else
993            estNrValues *= ToolBox.binomial(nrRooms, getNrRooms());
994        return estNrValues;
995    }
996
997    public int nrValues(TimeLocation time) {
998        int ret = 0;
999        for (RoomLocation room : iRoomLocations) {
1000            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(room.getPreference()))
1001                    && (room.getRoomConstraint() == null || room.getRoomConstraint().isAvailable(this, time, getScheduler())))
1002                ret++;
1003        }
1004        return ret;
1005    }
1006
1007    public int nrValues(RoomLocation room) {
1008        int ret = 0;
1009        for (TimeLocation time : iTimeLocations) {
1010            if (!Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference()))
1011                    && (room.getRoomConstraint() == null || room.getRoomConstraint().isAvailable(this, time,getScheduler())))
1012                ret++;
1013        }
1014        return ret;
1015    }
1016
1017    public int nrValues(List<RoomLocation> rooms) {
1018        int ret = 0;
1019        for (TimeLocation time : iTimeLocations) {
1020            boolean available = true;
1021            for (RoomLocation room : rooms) {
1022                if (Constants.sPreferenceProhibited.equals(Constants.preferenceLevel2preference(time.getPreference()))
1023                        || (room.getRoomConstraint() != null && !room.getRoomConstraint().isAvailable(this, time,
1024                                getScheduler())))
1025                    available = false;
1026            }
1027            if (available)
1028                ret++;
1029        }
1030        return ret;
1031    }
1032
1033    public boolean allowBreakHard() {
1034        return sAllowBreakHard;
1035    }
1036
1037    public int getNrRooms() {
1038        return iNrRooms;
1039    }
1040
1041    public Lecture getParent() {
1042        return iParent;
1043    }
1044
1045    public void setParent(Lecture parent) {
1046        iParent = parent;
1047        iParent.addChild(this);
1048    }
1049
1050    public boolean hasParent() {
1051        return (iParent != null);
1052    }
1053
1054    public boolean hasChildren(Long subpartId) {
1055        return (iChildren != null && iChildren.get(subpartId) != null && !iChildren.get(subpartId).isEmpty());
1056    }
1057
1058    public boolean hasAnyChildren() {
1059        return (iChildren != null && !iChildren.isEmpty());
1060    }
1061
1062    public List<Lecture> getChildren(Long subpartId) {
1063        return iChildren.get(subpartId);
1064    }
1065
1066    public Set<Long> getChildrenSubpartIds() {
1067        return (iChildren == null ? null : iChildren.keySet());
1068    }
1069
1070    private void addChild(Lecture child) {
1071        if (iChildren == null)
1072            iChildren = new HashMap<Long, List<Lecture>>();
1073        List<Lecture> childrenThisSubpart = iChildren.get(child.getSchedulingSubpartId());
1074        if (childrenThisSubpart == null) {
1075            childrenThisSubpart = new ArrayList<Lecture>();
1076            iChildren.put(child.getSchedulingSubpartId(), childrenThisSubpart);
1077        }
1078        childrenThisSubpart.add(child);
1079    }
1080
1081    public boolean isSingleSection() {
1082        return (iSameSubpartLectures == null || iSameSubpartLectures.size() <= 1);
1083        /*
1084        if (iParent == null)
1085            return (iSameSubpartLectures == null || iSameSubpartLectures.size() <= 1);
1086        return (iParent.getChildren(getSchedulingSubpartId()).size() <= 1);
1087        */
1088    }
1089
1090    public java.util.List<Lecture> sameStudentsLectures() {
1091        return (hasParent() ? getParent().getChildren(getSchedulingSubpartId()) : sameSubpartLectures());
1092    }
1093
1094    public Lecture getChild(Student student, Long subpartId) {
1095        if (!hasAnyChildren())
1096            return null;
1097        List<Lecture> children = getChildren(subpartId);
1098        if (children == null)
1099            return null;
1100        for (Lecture child : children) {
1101            if (child.students().contains(student))
1102                return child;
1103        }
1104        return null;
1105    }
1106
1107    public int getCommitedConflicts(Placement placement) {
1108        iLock.readLock().lock();
1109        try {
1110            Integer ret = iCommitedConflicts.get(placement);
1111            if (ret != null) return ret;
1112        } finally {
1113            iLock.readLock().unlock();
1114        }
1115        iLock.writeLock().lock();
1116        try {
1117            int ret = placement.getCommitedConflicts();
1118            iCommitedConflicts.put(placement, ret);
1119            return ret;
1120        } finally {
1121            iLock.writeLock().unlock();
1122        }
1123    }
1124
1125    public Set<GroupConstraint> hardGroupSoftConstraints() {
1126        return iHardGroupSoftConstraints;
1127    }
1128
1129    public Set<GroupConstraint> groupConstraints() {
1130        return iGroupConstraints;
1131    }
1132
1133    public int minRoomSize() {
1134        iLock.readLock().lock();
1135        try {
1136            if (iCacheMinRoomSize != null) return iCacheMinRoomSize.intValue();
1137        } finally {
1138            iLock.readLock().unlock();
1139        }
1140        iLock.writeLock().lock();
1141        try {
1142            if (iCacheMinRoomSize != null) return iCacheMinRoomSize.intValue();
1143            if (getNrRooms() <= 1) {
1144                int min = Integer.MAX_VALUE;
1145                for (RoomLocation r : roomLocations()) {
1146                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2)
1147                        min = Math.min(min, r.getRoomSize());
1148                }
1149                iCacheMinRoomSize = new Integer(min);
1150                return min;
1151            } else {
1152                List<RoomLocation> rooms = new ArrayList<RoomLocation>();
1153                for (RoomLocation r: roomLocations())
1154                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2)
1155                        rooms.add(r);
1156                Collections.sort(rooms, new Comparator<RoomLocation>() {
1157                    @Override
1158                    public int compare(RoomLocation r1, RoomLocation r2) {
1159                        if (r1.getRoomSize() < r2.getRoomSize()) return -1;
1160                        if (r1.getRoomSize() > r2.getRoomSize()) return 1;
1161                        return r1.compareTo(r2);
1162                    }
1163                });
1164                int min = rooms.isEmpty() ? 0 : rooms.get(Math.min(getNrRooms(), rooms.size()) - 1).getRoomSize();
1165                iCacheMinRoomSize = new Integer(min);
1166                return min;
1167            }
1168        } finally {
1169            iLock.writeLock().unlock();
1170        }
1171    }
1172
1173    public int maxRoomSize() {
1174        iLock.readLock().lock();
1175        try {
1176            if (iCacheMaxRoomSize != null) return iCacheMaxRoomSize.intValue();
1177        } finally {
1178            iLock.readLock().unlock();
1179        }
1180        iLock.writeLock().lock();
1181        try {
1182            if (iCacheMaxRoomSize != null) return iCacheMaxRoomSize.intValue();
1183            if (getNrRooms() <= 1) {
1184                int max = Integer.MIN_VALUE;
1185                for (RoomLocation r : roomLocations()) {
1186                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2) 
1187                        max = Math.max(max, r.getRoomSize());
1188                }
1189                iCacheMaxRoomSize = new Integer(max);
1190                return max;
1191            } else {
1192                List<RoomLocation> rooms = new ArrayList<RoomLocation>();
1193                for (RoomLocation r: roomLocations())
1194                    if (r.getPreference() <= Constants.sPreferenceLevelProhibited / 2) rooms.add(r);
1195                Collections.sort(rooms, new Comparator<RoomLocation>() {
1196                    @Override
1197                    public int compare(RoomLocation r1, RoomLocation r2) {
1198                        if (r1.getRoomSize() > r2.getRoomSize()) return -1;
1199                        if (r1.getRoomSize() < r2.getRoomSize()) return 1;
1200                        return r1.compareTo(r2);
1201                    }
1202                });
1203                int max = rooms.isEmpty() ? 0 : rooms.get(Math.min(getNrRooms(), rooms.size()) - 1).getRoomSize();
1204                iCacheMaxRoomSize = new Integer(max);
1205                return max;
1206            }
1207        } finally {
1208            iLock.writeLock().unlock();
1209        }
1210    }
1211
1212    public boolean canShareRoom() {
1213        return (!iCanShareRoomGroupConstraints.isEmpty());
1214    }
1215
1216    public boolean canShareRoom(Lecture other) {
1217        if (other.equals(this))
1218            return true;
1219        for (GroupConstraint gc : iCanShareRoomGroupConstraints) {
1220            if (gc.variables().contains(other))
1221                return true;
1222        }
1223        return false;
1224    }
1225
1226    public Set<GroupConstraint> canShareRoomConstraints() {
1227        return iCanShareRoomGroupConstraints;
1228    }
1229
1230    public boolean isSingleton() {
1231        return getNrRooms() == roomLocations().size() && timeLocations().size() == 1;
1232    }
1233
1234    public boolean isValid(Placement placement) {
1235        TimetableModel model = (TimetableModel) getModel();
1236        if (model == null)
1237            return true;
1238        if (model.hasConstantVariables()) {
1239            for (Placement confPlacement : model.conflictValuesSkipWeakeningConstraints(model.getEmptyAssignment(), placement)) {
1240                Lecture lecture = confPlacement.variable();
1241                if (lecture.isCommitted())
1242                    return false;
1243                if (confPlacement.equals(placement))
1244                    return false;
1245            }
1246        } else {
1247            Set<Placement> conflicts = new HashSet<Placement>();
1248            for (Constraint<Lecture, Placement> constraint : hardConstraints()) {
1249                if (constraint instanceof WeakeningConstraint) continue;
1250                constraint.computeConflicts(model.getEmptyAssignment(), placement, conflicts);
1251            }
1252            for (GlobalConstraint<Lecture, Placement> constraint : model.globalConstraints()) {
1253                if (constraint instanceof WeakeningConstraint) continue;
1254                constraint.computeConflicts(model.getEmptyAssignment(), placement, conflicts);
1255            }
1256            if (conflicts.contains(placement))
1257                return false;
1258        }
1259        return true;
1260    }
1261
1262    public String getNotValidReason(Assignment<Lecture, Placement> assignment, Placement placement, boolean useAmPm) {
1263        TimetableModel model = (TimetableModel) getModel();
1264        if (model == null)
1265            return "no model for class " + getName();
1266        Map<Constraint<Lecture, Placement>, Set<Placement>> conflictConstraints = model.conflictConstraints(assignment, placement);
1267        for (Map.Entry<Constraint<Lecture, Placement>, Set<Placement>> entry : conflictConstraints.entrySet()) {
1268            Constraint<Lecture, Placement> constraint = entry.getKey();
1269            Set<Placement> conflicts = entry.getValue();
1270            String cname = constraint.getName();
1271            if (constraint instanceof RoomConstraint) {
1272                cname = "Room " + constraint.getName();
1273            } else if (constraint instanceof InstructorConstraint) {
1274                cname = "Instructor " + constraint.getName();
1275            } else if (constraint instanceof GroupConstraint) {
1276                cname = "Distribution " + constraint.getName();
1277            } else if (constraint instanceof DepartmentSpreadConstraint) {
1278                cname = "Balancing of department " + constraint.getName();
1279            } else if (constraint instanceof SpreadConstraint) {
1280                cname = "Same subpart spread " + constraint.getName();
1281            } else if (constraint instanceof ClassLimitConstraint) {
1282                cname = "Class limit " + constraint.getName();
1283            }
1284            for (Placement confPlacement : conflicts) {
1285                Lecture lecture = confPlacement.variable();
1286                if (lecture.isCommitted()) {
1287                    return placement.getLongName(useAmPm) + " conflicts with " + lecture.getName() + " "
1288                            + confPlacement.getLongName(useAmPm) + " due to constraint " + cname;
1289                }
1290                if (confPlacement.equals(placement)) {
1291                    return placement.getLongName(useAmPm) + " is not valid due to constraint " + cname;
1292                }
1293            }
1294        }
1295        return null;
1296    }
1297    
1298    @Deprecated
1299    public String getNotValidReason(Assignment<Lecture, Placement> assignment, Placement placement) {
1300        return getNotValidReason(assignment, placement, true);
1301    }
1302
1303    public void purgeInvalidValues(boolean interactiveMode) {
1304        if (isCommitted() || sSaveMemory) return;
1305        TimetableModel model = (TimetableModel) getModel();
1306        if (model == null)
1307            return;
1308        List<Placement> newValues = new ArrayList<Placement>(values(null).size());
1309        for (Placement placement : values(null)) {
1310            if (placement.isValid())
1311                newValues.add(placement);
1312        }
1313        if (!interactiveMode && newValues.size() != values(null).size()) {
1314            for (Iterator<TimeLocation> i = timeLocations().iterator(); i.hasNext();) {
1315                TimeLocation timeLocation = i.next();
1316                boolean hasPlacement = false;
1317                for (Placement placement : newValues) {
1318                    if (timeLocation.equals(placement.getTimeLocation())) {
1319                        hasPlacement = true;
1320                        break;
1321                    }
1322                }
1323                if (!hasPlacement)
1324                    i.remove();
1325            }
1326            for (Iterator<RoomLocation> i = roomLocations().iterator(); i.hasNext();) {
1327                RoomLocation roomLocation = i.next();
1328                boolean hasPlacement = false;
1329                for (Placement placement : newValues) {
1330                    if (placement.isMultiRoom()) {
1331                        if (placement.getRoomLocations().contains(roomLocation)) {
1332                            hasPlacement = true;
1333                            break;
1334                        }
1335                    } else {
1336                        if (roomLocation.equals(placement.getRoomLocation())) {
1337                            hasPlacement = true;
1338                            break;
1339                        }
1340                    }
1341                }
1342                if (!hasPlacement)
1343                    i.remove();
1344            }
1345        }
1346        setValues(newValues);
1347    }
1348
1349    public void setCommitted(boolean committed) {
1350        iCommitted = committed;
1351    }
1352
1353    public boolean isCommitted() {
1354        return iCommitted;
1355    }
1356
1357    @Override
1358    public boolean isConstant() {
1359        return iCommitted;
1360    }
1361    
1362    @Override
1363    public Placement getConstantValue() {
1364        return (isCommitted() ? getInitialAssignment() : null);
1365    }
1366    
1367    public void setConstantValue(Placement value) {
1368        setInitialAssignment(value);
1369    }
1370
1371    public int getSpreadPenalty(Assignment<Lecture, Placement> assignment) {
1372        int spread = 0;
1373        for (SpreadConstraint sc : getSpreadConstraints()) {
1374            spread += sc.getPenalty(assignment);
1375        }
1376        return spread;
1377    }
1378
1379    @Override
1380    public int hashCode() {
1381        return getClassId().hashCode();
1382    }
1383
1384    public Configuration getConfiguration() {
1385        Lecture lecture = this;
1386        while (lecture.getParent() != null)
1387            lecture = lecture.getParent();
1388        return lecture.iParentConfiguration;
1389    }
1390
1391    public void setConfiguration(Configuration configuration) {
1392        Lecture lecture = this;
1393        while (lecture.getParent() != null)
1394            lecture = lecture.getParent();
1395        lecture.iParentConfiguration = configuration;
1396        configuration.addTopLecture(lecture);
1397    }
1398
1399    private int[] iMinMaxRoomPreference = null;
1400
1401    public int[] getMinMaxRoomPreference() {
1402        iLock.readLock().lock();
1403        try {
1404            if (iMinMaxRoomPreference != null) return iMinMaxRoomPreference;
1405        } finally {
1406            iLock.readLock().unlock();
1407        }
1408        iLock.writeLock().lock();
1409        try {
1410            if (iMinMaxRoomPreference != null) return iMinMaxRoomPreference;
1411
1412            if (getNrRooms() <= 0 || roomLocations().isEmpty()) {
1413                iMinMaxRoomPreference = new int[] { 0, 0 };
1414            } else {
1415                Integer minRoomPref = null, maxRoomPref = null;
1416                for (RoomLocation r : roomLocations()) {
1417                    int pref = r.getPreference();
1418                    if (pref >= Constants.sPreferenceLevelRequired / 2 && pref <= Constants.sPreferenceLevelProhibited / 2) {
1419                        minRoomPref = (minRoomPref == null ? pref : Math.min(minRoomPref, pref));
1420                        maxRoomPref = (maxRoomPref == null ? pref : Math.max(maxRoomPref, pref));
1421                    }
1422                }
1423                iMinMaxRoomPreference = new int[] { minRoomPref == null ? 0 : minRoomPref, maxRoomPref == null ? 0 : maxRoomPref };
1424            }
1425
1426            return iMinMaxRoomPreference;
1427        } finally {
1428            iLock.writeLock().unlock();
1429        }
1430    }
1431
1432    private double[] iMinMaxTimePreference = null;
1433
1434    public double[] getMinMaxTimePreference() {
1435        iLock.readLock().lock();
1436        try {
1437            if (iMinMaxTimePreference != null) return iMinMaxTimePreference;
1438        } finally {
1439            iLock.readLock().unlock();
1440        }
1441        iLock.writeLock().lock();
1442        try {
1443            if (iMinMaxTimePreference != null) return iMinMaxTimePreference;
1444
1445            Double minTimePref = null, maxTimePref = null;
1446            for (TimeLocation t : timeLocations()) {
1447                double npref = t.getNormalizedPreference();
1448                int pref = t.getPreference();
1449                if (pref >= Constants.sPreferenceLevelRequired / 2 && pref <= Constants.sPreferenceLevelProhibited / 2) {
1450                    minTimePref = (minTimePref == null ? npref : Math.min(minTimePref, npref));
1451                    maxTimePref = (maxTimePref == null ? npref : Math.max(maxTimePref, npref));
1452                }
1453            }
1454            iMinMaxTimePreference = new double[] { minTimePref == null ? 0.0 : minTimePref, maxTimePref == null ? 0.0 : maxTimePref };
1455            
1456            return iMinMaxTimePreference;
1457        } finally {
1458            iLock.writeLock().unlock();
1459        }
1460    }
1461
1462    public void setOrd(int ord) {
1463        iOrd = ord;
1464    }
1465
1466    public int getOrd() {
1467        return iOrd;
1468    }
1469
1470    @Override
1471    public int compareTo(Lecture o) {
1472        int cmp = Double.compare(getOrd(), o.getOrd());
1473        if (cmp != 0)
1474            return cmp;
1475        return super.compareTo(o);
1476    }
1477
1478    public String getNote() {
1479        return iNote;
1480    }
1481
1482    public void setNote(String note) {
1483        iNote = note;
1484    }
1485    
1486    public boolean areStudentConflictsHard(Lecture other) {
1487        return StudentConflict.hard(this, other);
1488    }
1489    
1490    public void clearIgnoreStudentConflictsWithCache() {
1491        iIgnoreStudentConflictsWith.set(null);
1492    }
1493    
1494    /**
1495     * Returns true if there is {@link IgnoreStudentConflictsConstraint} between the two lectures.
1496     * @param other another class
1497     * @return true if student conflicts between this and the given calls are to be ignored
1498     */
1499   public boolean isToIgnoreStudentConflictsWith(Lecture other) {
1500       Set<Long> cache = iIgnoreStudentConflictsWith.get();
1501       if (cache != null)
1502           return cache.contains(other.getClassId());
1503       cache = new HashSet<Long>();
1504       for (Constraint<Lecture, Placement> constraint: constraints()) {
1505           if (constraint instanceof IgnoreStudentConflictsConstraint)
1506               for (Lecture x: constraint.variables()) {
1507                   if (!x.equals(this)) cache.add(x.getClassId());
1508               }
1509       }
1510       iIgnoreStudentConflictsWith.set(cache);
1511       return cache.contains(other);
1512    }
1513   
1514   /**
1515    * Get class weight. This weight is used with the criteria. E.g., class that is not meeting all the
1516    * semester can have a lower weight. Defaults to 1.0
1517    * @return class weight
1518    */
1519   public double getWeight() { return iWeight; }
1520   /**
1521    * Set class weight. This weight is used with the criteria. E.g., class that is not meeting all the
1522    * semester can have a lower weight.
1523    * @param weight class weight
1524    */
1525   public void setWeight(double weight) { iWeight = weight; }
1526   
1527   @Override
1528   public LectureContext createAssignmentContext(Assignment<Lecture, Placement> assignment) {
1529       return new LectureContext();
1530   }
1531
1532   public class LectureContext implements AssignmentContext {
1533       private Set<JenrlConstraint> iActiveJenrls = new HashSet<JenrlConstraint>();
1534 
1535       /**
1536        * Add active jenrl constraint (active mean that there is at least one
1537        * student between its classes)
1538        * @param constr active join enrollment constraint 
1539        */
1540       public void addActiveJenrl(JenrlConstraint constr) {
1541           iActiveJenrls.add(constr);
1542       }
1543
1544       /**
1545        * Active jenrl constraints (active mean that there is at least one student
1546        * between its classes)
1547        * @return set of active join enrollment constraints
1548        */
1549       public Set<JenrlConstraint> activeJenrls() {
1550           return iActiveJenrls;
1551       }
1552
1553       /**
1554        * Remove active jenrl constraint (active mean that there is at least one
1555        * student between its classes)
1556        * @param constr active join enrollment constraint
1557        */
1558       public void removeActiveJenrl(JenrlConstraint constr) {
1559           iActiveJenrls.remove(constr);
1560       }
1561   }
1562   
1563   public int getMaxRoomCombinations() {
1564       return iMaxRoomCombinations;
1565   }
1566   
1567   public void setMaxRoomCombinations(int maxRoomCombinations) {
1568       iMaxRoomCombinations = maxRoomCombinations;
1569   }
1570}