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/*  Oxford University Date Converter
    Provides a class to manage conversion between term-time dates (expressed
    in weeks of term) and real-world dates that are usable outside the Oxford
    'bubble'. 

    Copyright (C) 2006 Rami R Chowdhury
    This script can be used under the terms of the GNU General Public License
    (http://www.gnu.org/copyleft/gpl.html) either version 2 or, at your opt-
    ion, any later version. I would in addition appreciate it if I were vis-
    ibly credited on any page that uses this code.
*/


function suffixate($num) {
    if ( ($num < 20) && ($num > 10) ) {
        return "${num}th"; // the *teens
    }
    $enum = $num % 10;
    switch ($enum) {
        case 1: return "${num}st";
        case 2: return "${num}nd";
        case 3: return "${num}rd";
        default: return "${num}th";
    }
}

class DateConverter {
    var $TermDates;
    var $TimeStamp;
    var $DaysOfWeek = Array ( "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" );
    var $MonthsOfYear = Array ( "", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");

    /* 
    A little documentation - variables called $timeArray are real-world date
    arrays, with "day", "month", and "year" elements. On the other hand the
    $oxfArray arrays contain "day", "week", "term", and "year" elements.
    */

    function DateConverter() {
        $this->TermDates = array();
        $this->TimeStamp = null;
    }

    function setTimeStamp($timeArray = null) {
        $tstamp = 0;
        if ($timeArray) {
            $tstamp = mktime(0, 1, 0, $timeArray['month'], $timeArray['day'], $timeArray['year'], 0);
        } else {
            $tstamp = time();
        }
        $this->TimeStamp = $tstamp;
    }

    function setTermDates($timeArray = null) {
        if ($this->TimeStamp == null) {
            $this->setTimeStamp($timeArray);
        }

        $feastDayStamp = mktime(0, 1, 0, 1, 13, date("Y", $this->TimeStamp), 0);
        $nFeastDayStamp = mktime(0, 1, 0, 1, 13, date("Y", $this->TimeStamp) + 1, 0);

        $hilaryStart = strtotime("next Sunday", $feastDayStamp);
        $nHilaryStart = strtotime("next Sunday", $nFeastDayStamp);

        $michaelmasStart = strtotime("-14 weeks", $nHilaryStart);
        $trinityStart = strtotime("+14 weeks", $hilaryStart);

        $this->TermDates['HilaryStart'] = strtotime("-2 weeks", $hilaryStart);
        $this->TermDates['HilaryEnd'] = strtotime("+10 weeks", $hilaryStart);

        $this->TermDates['MichaelmasStart'] = strtotime("-2 weeks", $michaelmasStart);
        $this->TermDates['MichaelmasEnd'] = strtotime("+10 weeks", $michaelmasStart);

        $this->TermDates['TrinityStart'] = strtotime("-2 weeks", $trinityStart);
        $this->TermDates['TrinityEnd'] = strtotime("+10 weeks", $trinityStart);
    }

    function toOxford($timeArray = null) {
        $this->setTimeStamp($timeArray);
        $this->setTermDates();

        $tstamp = $this->TimeStamp;
        $tDates = $this->TermDates;

        $oxfArray = array();

        if ( ($tstamp >= $tDates['HilaryStart']) && ($tstamp <= $tDates['HilaryEnd']) ) {
            $oxfArray['term'] = "Hilary Term";
            $oxfArray['week'] = (int) (( ($tstamp - $tDates['HilaryStart']) / 604800 ) ); // Accounting for 0th Week
        }
        elseif ( ($tstamp >= $tDates['TrinityStart']) && ($tstamp <= $tDates['TrinityEnd']) ) {
            $oxfArray['term'] = "Trinity Term";
            $oxfArray['week'] = (int) (( ($tstamp - $tDates['TrinityStart']) / 604800 ) );
        }
        elseif ( ($tstamp >= $tDates['MichaelmasStart']) && ($tstamp <= $tDates['MichaelmasEnd'])) {
            $oxfArray['term'] = "Michaelmas Term";
            $oxfArray['week'] = (int) (( ($tstamp - $tDates['MichaelmasStart']) / 604800 ) );
        }
        elseif ( ($tstamp >= $tDates['HilaryEnd']) && ($tstamp <= $tDates['TrinityStart']) ) {
            $oxfArray['term'] = "Easter Vacation";
            $oxfArray['week'] = (int) ( (($tstamp - $tDates['HilaryEnd']) / 604800) + 2 );
        }
        elseif ( ($tstamp >= $tDates['TrinityEnd']) && ($tstamp <= $tDates['MichaelmasStart']) ) {
            $oxfArray['term'] = "Long Vacation";
            $oxfArray['week'] = (int) ( (($tstamp - $tDates['TrinityEnd']) / 604800) + 2 );
        }
        elseif ( ($tstamp >= $tDates['MichaelmasEnd']) && ($tstamp <= $tDates['HilaryStart']) ) {
            $oxfArray['term'] = "Christmas Vacation";
            $oxfArray['week'] = (int) ( (($tstamp - $tDates['MichaelmasEnd']) / 604800) + 2 );
        }

        $oxfArray['day'] = date("w", $tstamp);
        $oxfArray['year'] = date("Y", $tstamp);
        return $oxfArray;
    }

    function toReal($oxfArray) {
        $this->setTimeStamp(Array( "day" => 1, "month" => 1, "year" => $oxfArray['year']));
        $this->setTermDates();

        $TermsLookup = Array (  "Hilary Term" => "HilaryStart",
                                "Trinity Term" => "TrinityStart",
                                "Michaelmas Term" => "MichaelmasStart",
                                "Easter Vacation" => "HilaryEnd", 
                                "Long Vacation" => "TrinityEnd",
                                "Christmas Vacation" => "MichaelmasEnd" );

        $TermStart = $this->TermDates[$TermsLookup[$oxfArray['term']]];
        //$TermStart = strtotime("+1 week", $TermStart); // As we start with -1st Week

        $week = ($oxfArray['week'] >= 0) ? "+$oxfArray[week]" : $oxfArray['week'];
        $RealTime = strtotime("$week weeks", $TermStart);
        $RealTime += ($oxfArray['day'] * 86400);
        
        $timeArray = array();
        $timeArray['day'] = date("d", $RealTime);
        $timeArray['month'] = date("m", $RealTime);
        $timeArray['year'] = date("Y", $RealTime);

        return $timeArray;
    }

}

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