001package org.cpsolver.studentsct.heuristics.studentord;
002
003import org.cpsolver.ifs.util.DataProperties;
004import org.cpsolver.studentsct.model.CourseRequest;
005import org.cpsolver.studentsct.model.Request;
006import org.cpsolver.studentsct.model.Student;
007
008/**
009 * Return the given set of students in an order of average course request
010 * time stamp {@link CourseRequest#getTimeStamp()}. If the time stamp
011 * is the same (or not set), fall back to the number of choices
012 * (student with fewer choices first).
013 * 
014 * @author  Tomáš Müller
015 * @version StudentSct 1.3 (Student Sectioning)<br>
016 *          Copyright (C) 2007 - 2019 Tomáš Müller<br>
017 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
018 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
019 * <br>
020 *          This library is free software; you can redistribute it and/or modify
021 *          it under the terms of the GNU Lesser General Public License as
022 *          published by the Free Software Foundation; either version 3 of the
023 *          License, or (at your option) any later version. <br>
024 * <br>
025 *          This library is distributed in the hope that it will be useful, but
026 *          WITHOUT ANY WARRANTY; without even the implied warranty of
027 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
028 *          Lesser General Public License for more details. <br>
029 * <br>
030 *          You should have received a copy of the GNU Lesser General Public
031 *          License along with this library; if not see
032 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
033 */
034public class StudentByRequestDate extends StudentChoiceOrder {
035    
036    public StudentByRequestDate(DataProperties config) {
037        super(config);
038    }
039    
040    public Long getRequestDate(Student s) {
041        long total = 0, cnt = 0;
042        for (Request r: s.getRequests()) {
043            if (r instanceof CourseRequest) {
044                CourseRequest cr = (CourseRequest)r;
045                if (cr.getTimeStamp() != null) {
046                    total += cr.getTimeStamp();
047                    cnt ++;
048                }
049            }
050        }
051        if (cnt > 0)
052            return total / cnt;
053        return Long.MAX_VALUE;
054    }
055    
056    @Override
057    public int compare(Student s1, Student s2) {
058        int cmp = getRequestDate(s1).compareTo(getRequestDate(s2));
059        if (cmp != 0) return (isReverse() ? -1 : 1) * cmp;
060        return - super.compare(s1, s2);
061    }
062}