<?php

if ( !class_exists('FSO') )
    die('Framework SuperObject base class must be loaded to use its modules!');

/**
 * TermDates Class
 *
 * Class for converting between real dates and term/week dates.
 *
 * Adapted from the original code written by Rick Selby <rick@ystv.york.ac.uk>
 */
class TermDates extends FSO_Module
{
    const AUTUMN = 'aut';
    const SPRING = 'spr';
    const SUMMER = 'sum';

    private $termdb = null;     // database module to use
    private $yearWeeks = array();
    private $yearTerms = array();

    private $termTextAr = array(
        self::AUTUMN => 'Autumn',
        self::SPRING => 'Spring',
        self::SUMMER => 'Summer',
    );

    //  {{{ public function __construct( &$db )

    /**
     * Constructor
     *
     * Use database connection to load term data
     *
     * @param       FSO_DB_Module       $db
     * @return      void
     */
    public function __construct( &$db )
    {
        parent::__construct();
        $this->termdb =& $db;
        $result = $db->query('SELECT * FROM termDates ORDER BY year, week ASC');
        foreach ( $result->fetchAll(PDO::FETCH_ASSOC) as $row )
        {
            $this->yearWeeks[$row['year']][$row['week']] = $row['term'];
            $this->yearTerms[$row['year']][$row['term']] = $row['week'];
        }

        //  Set whether or not its termtime
        $term = $this->dateToTerm(time(), false);
        if ( empty($term) )
            define('TERMTIME', false);
        else
            define('TERMTIME', true);
    }

    //  }}}
    //  {{{ public function termText( $term )

    /**
     * Get the textual representation of a term name
     *
     * @param       string
     * @return      string
     */
    public function termText( $term )
    {
        return $this->termTextAr[$term];
    }

    //  }}}
    //  {{{ public function termArray()

    /**
     * Get the array of identifiers => real names for terms
     *
     * @return      array
     */
    public function termArray()
    {
        return $this->termTextAr;
    }

    //  }}}
    //  {{{ public function termToDate( $year, $term, $week, $day [, $hour = 0 [, $minute = 0]] )

    /**
     * Convert a year/term/week/day combination into a real date
     *
     *      year :  4-digit year representation
     *      term :  TermDates::AUTUMN, TermDates::SPRING or TermDates::SUMMER
     *      week :  1-10
     *      day  :  1 = Monday ... 7 = Sunday
     *
     * Returns a unix timestamp if inputs are valid
     */
    public function termToDate($year, $term, $week, $day, $hour = 0, $minute = 0)
    {
        if (!isset($this->yearTerms[$year][$term]))
            return false;

        $weekNum = $this->yearTerms[$year][$term] + ($week - 1);

        return $this->findDayOfWeek($year, $weekNum, $day, $hour, $minute);
    }

    //  }}}
    //  {{{ public function showTerm( [ $date = null ] )

    /**
     * Get the term that $date lies within (or the current date if not specified)
     *
     * @param       integer     $date
     * @return      string
     */
    public function showTerm($date = null)
    {
        $date = is_null($date) ? time() : $date;

        if ($termInfo = $this->dateToTerm($date, true))
            return $termInfo;
        else
            return $this->nextTerm($date);
    }

    //  }}}
    //  {{{ public function nextTerm( [ $date = null [, $tryNextYear = false] ] )

    /**
     * If we're in the holidays, this function will get the upcoming term details.
     * If we're in a term, it'll get the current term details. I believe.
     *
     * @param       integer     $date
     * @param       boolean     $tryNextYear
     * @return      array
     */
    public function nextTerm($date = null, $tryNextYear = false)
    {
        $date = is_null($date) ? time() : $date;

        $checkyear = date('Y', $date);
        $checkweek = date('W', $date);

        if ($this->yearWeeks[$checkyear])
        {
            $weeks = array_keys($this->yearWeeks[$checkyear]);
            $return = array();

            foreach ($weeks as $week)
                if (($week > $checkweek))
                {
                    $return['termText'] = $this->termText($this->yearWeeks[$checkyear][$week]);
                    $return['termRef'] = $this->yearWeeks[$checkyear][$week];
                    $return['year'] = $checkyear;

                    break;
                }

            if (sizeof($return) != 0)
                return $return;
            else
            {
                // only try one year ahead - we could recurse forever otherwise
                if (!$tryNextYear)
                    return $this->nextTerm(gmmktime (0,0,0,1,1,$checkyear+1), true);
                else
                    return false;
            }
        } else
            return false;
    }
    

    //  }}}
    //  {{{ public function lastTerm( [ $date = null [, $tryLastYear = false]] )

    /**
     * This will get the previous term details (see Officers Reports for use)
     *
     * @param       integer     $date
     * @param       boolean     $tryLastYear
     * @return      array
     */
    public function lastTerm($date = null, $tryLastYear = false)
    {
        $date = is_null($date) ? time() : $date;

        $checkyear = date('Y', $date);
        $checkweek = date('W', $date);

        if ($this->yearWeeks[$checkyear])
        {
            $weeks = array_keys($this->yearWeeks[$checkyear]);
            $return = array();

            foreach ($weeks as $week)
                if (($week + 10 <= $checkweek))
                {
                    $return['termText'] = $this->termText($this->yearWeeks[$checkyear][$week]);
                    $return['termRef'] = $this->yearWeeks[$checkyear][$week];
                    $return['year'] = $checkyear;
                }

            if (sizeof($return) != 0)
                return $return;
            else
            {
                // only try one year back - we could recurse forever otherwise
                if (!$tryLastYear)
                    return $this->lastTerm(gmmktime (0,0,0,12,31,$checkyear-1), true);
                else
                    return false;
            }
        } else
            return false;
    }
    

    //  }}}
    //  {{{ public function dateToTerm( $date [, $extraWeek = false] )

    /**
     * Convert a real date into an array of year/term/week details
     *
     * @param       integer     $date
     * @param       boolean     $extraWeek
     * @return      array
     */
    public function dateToTerm($date, $extraWeek = false)
    {
        $checkyear = date('Y', $date);
        $checkweek = date('W', $date);

        $weekRange = ($extraWeek ? 11 : 10);

        if ($this->yearWeeks[$checkyear])
        {
            $weeks = array_keys($this->yearWeeks[$checkyear]);
            $return = array();

            foreach ($weeks as $week)
                if (($week <= $checkweek) && ($week + $weekRange > $checkweek))
                {
                    $return['termText'] = $this->termText($this->yearWeeks[$checkyear][$week]);
                    $return['termRef'] = $this->yearWeeks[$checkyear][$week];
                    $return['year'] = date('Y', $date);
                    $termWeek = ($checkweek - $week + 1);
                    if (!$extraWeek || ($termWeek < 11))
                    {
                        $return['week'] = $termWeek;
                        $return['day'] = date('N', $date);
                    }
                    break;
                }

            if (sizeof($return) != 0)
                return $return;
            else
                return false;
        } else
            return false;
    }

    //  }}}
    //  {{{ public function findDayOfWeek( $year, $week, $day [, $hour = 0 [, $minute = 0 ]] )

    /**
     * Takes a year, week number, and day [mon, tues etc], and returns the timestamp for that day
     *
     * @param       integer     $year
     * @param       integer     $week
     * @param       integer     $day
     * @param       integer     $hour
     * @param       integer     $minute
     * @return      integer
     */
    public function findDayOfWeek($year, $week, $day, $hour = 0, $minute = 0)
    {
	    // day: 0=Sunday...6=Saturday
        // 1 	Monday 	0-53 	with more than 3 days this year

        // find out which day Jan 1st is
        $firstday = gmdate('N', strtotime($year.'-01-01'));

        /* if first day is Mon to Thurs - day 1 is in week 1)
                  Day | firstSunday
                --------------------
                Mon 1 |  0  (the 31st Dec)
                Tue 2 | -1  (the 30th Dec)
                Wed 3 | -2
                Thr 4 | -3
                Fri 5 |  3  (the 3rd Jan)
                Sat 6 |  2
                Sun 7 |  1
         */

        if ($firstday <= 4)
        {
            $firstSunday = 1 - $firstday;
        } else {
            $firstSunday = 8 - $firstday;
        }

        // get day in January for first day that we're looking for
        $firstWhichDay = $firstSunday + $day;
        // if the first day is still not a valid day, jump to week 2
        if ($firstWhichDay < 1)
        {
            // but if we want week one, it's not this year, so fail.
            if ($week == 1)
                return 0;

            // increment day and decrement week accordingly
            $firstWhichDay += 7;
            $week--;
        }

        // calculate seconds in a week
        $oneweek = 60*60*24*7;

        // do the calculation. 
        return strtotime($year.'-01-'.$firstWhichDay) // timestamp of the day in week 1
            + (($week - 1) * $oneweek) // plus number of seconds to get to correct week
            + (60 * 60 * $hour) // plus hours
            + (60 * $minute); // plus minutes
    }

    //  }}}
    
    //  {{{ compatibility stuff

    /**
     * The term* calls to make this version call-compatible with the original
     */
    public function termAutumn() { return self::AUTUMN; }
    public function termSpring() { return self::SPRING; }
    public function termSummer() { return self::SUMMER; }

    //  }}}
}

?>