001package net.sf.cpsolver.studentsct.model;
002
003import java.util.List;
004
005import net.sf.cpsolver.ifs.model.Variable;
006
007/**
008 * Representation of a request of a student for a course(s) or a free time. This
009 * can be either {@link CourseRequest} or {@link FreeTimeRequest}. Each request
010 * contains id, priority, weight, and a student. A request can be also marked as
011 * alternative. <br>
012 * <br>
013 * For each student, all non-alternative requests should be satisfied (an
014 * enrollment is assigned to a request). If not, an alternative request can be
015 * assigned instead of a non-alternative course request. In the case when only
016 * one of two requests can be assigned, the one with the lowest priority is
017 * preferred. <br>
018 * <br>
019 * 
020 * @version StudentSct 1.2 (Student Sectioning)<br>
021 *          Copyright (C) 2007 - 2010 Tomáš Müller<br>
022 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
023 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
024 * <br>
025 *          This library is free software; you can redistribute it and/or modify
026 *          it under the terms of the GNU Lesser General Public License as
027 *          published by the Free Software Foundation; either version 3 of the
028 *          License, or (at your option) any later version. <br>
029 * <br>
030 *          This library is distributed in the hope that it will be useful, but
031 *          WITHOUT ANY WARRANTY; without even the implied warranty of
032 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
033 *          Lesser General Public License for more details. <br>
034 * <br>
035 *          You should have received a copy of the GNU Lesser General Public
036 *          License along with this library; if not see
037 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
038 */
039public abstract class Request extends Variable<Request, Enrollment> {
040    private long iId = -1;
041    private int iPriority = 0;
042    private boolean iAlternative = false;
043    private Student iStudent = null;
044    private double iWeight = 1.0;
045    /** True means that method {@link Request#values()} will cache its results. */
046    public static boolean sCacheValues = false;
047
048    /**
049     * Constructor
050     * 
051     * @param id
052     *            course/free time request unique id
053     * @param priority
054     *            request priority -- if there is a choice, request with lower
055     *            priority is more preferred to be assigned
056     * @param alternative
057     *            true if the request is alternative (alternative request can be
058     *            assigned instead of a non-alternative course requests, if it
059     *            is left unassigned)
060     * @param student
061     *            student to which this request belongs
062     */
063    public Request(long id, int priority, boolean alternative, Student student) {
064        iId = id;
065        iPriority = priority;
066        iAlternative = alternative;
067        iStudent = student;
068        iStudent.getRequests().add(this);
069    }
070
071    /** Request id */
072    @Override
073    public long getId() {
074        return iId;
075    }
076
077    /**
078     * Request priority -- if there is a choice, request with lower priority is
079     * more preferred to be assigned
080     */
081    public int getPriority() {
082        return iPriority;
083    }
084
085    /** Set request priority */
086    public void setPriority(int priority) {
087        iPriority = priority;
088    }
089
090    /**
091     * True, if the request is alternative (alternative request can be assigned
092     * instead of a non-alternative course requests, if it is left unassigned)
093     */
094    public boolean isAlternative() {
095        return iAlternative;
096    }
097
098    /** Student to which this request belongs */
099    public Student getStudent() {
100        return iStudent;
101    }
102
103    /**
104     * Compare to requests, non-alternative requests go first, otherwise use
105     * priority (a request with lower priority goes first)
106     */
107    @Override
108    public int compareTo(Request r) {
109        if (getStudent().getId() == r.getStudent().getId())
110            return (isAlternative() != r.isAlternative() ? isAlternative() ? 1 : -1 : getPriority() < r.getPriority() ? -1 : 1);
111        else
112            return getStudent().compareTo(r.getStudent());
113    }
114
115    /** Compute available enrollments */
116    public abstract List<Enrollment> computeEnrollments();
117
118    /**
119     * Domain of this variable -- list of available enrollments. Method
120     * {@link Request#computeEnrollments()} is used.
121     */
122    @Override
123    public List<Enrollment> values() {
124        List<Enrollment> values = super.values();
125        if (values != null)
126            return values;
127        values = computeEnrollments();
128        if (sCacheValues)
129            setValues(values);
130        return values;
131    }
132
133    /**
134     * Assign given enrollment to this request. This method also calls
135     * {@link Assignment#assigned(Enrollment)} on for all the assignments of the
136     * enrollment.
137     */
138    @Override
139    public void assign(long iteration, Enrollment enrollment) {
140        super.assign(iteration, enrollment);
141        for (Assignment a : enrollment.getAssignments()) {
142            a.assigned(enrollment);
143        }
144        if (enrollment.getConfig() != null)
145            enrollment.getConfig().assigned(enrollment);
146        if (enrollment.getCourse() != null)
147            enrollment.getCourse().assigned(enrollment);
148        if (enrollment.getReservation() != null)
149            enrollment.getReservation().assigned(enrollment);
150    }
151
152    /**
153     * Unassign currently assigned enrollment from this request. This method
154     * also calls {@link Assignment#unassigned(Enrollment)} on for all the
155     * assignments of the current enrollment.
156     */
157    @Override
158    public void unassign(long iteration) {
159        if (getAssignment() != null) {
160            Enrollment enrollment = getAssignment();
161            for (Assignment a : enrollment.getAssignments()) {
162                a.unassigned(enrollment);
163            }
164            if (enrollment.getConfig() != null)
165                enrollment.getConfig().unassigned(enrollment);
166            if (enrollment.getCourse() != null)
167                enrollment.getCourse().unassigned(enrollment);
168            if (enrollment.getReservation() != null)
169                enrollment.getReservation().unassigned(enrollment);
170        }
171        super.unassign(iteration);
172    }
173
174    /** Get bound, i.e., the value of the best possible enrollment */
175    public abstract double getBound();
176
177    /**
178     * Request weight, set by default to 1.0, defines the amount of space which
179     * will be taken in the section by this request.
180     */
181    public double getWeight() {
182        return iWeight;
183    }
184
185    /**
186     * Set request weight. It defines the amount of space which will be taken in
187     * the section by this request.
188     */
189    public void setWeight(double weight) {
190        iWeight = weight;
191    }
192
193    /** Return true if request is assigned. */
194    public boolean isAssigned() {
195        return getAssignment() != null;
196    }
197    
198    @Override
199    public int hashCode() {
200        return (int) (iId ^ (iId >>> 32) ^ getStudent().getId() ^ (getStudent().getId() >>> 32));
201    }
202    
203    @Override
204    public boolean equals(Object o) {
205        if (o == null || !(o instanceof Request)) return false;
206        return getId() == ((Request)o).getId() && getStudent().getId() == ((Request)o).getStudent().getId();
207    }
208
209}