    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}