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