Horde_Icalendar_Vtimezone::parseChild PHP Method

    public function parseChild($child, $year)
    {
        $result['time'] = $result['end'] = 0;
        try {
            $t = $child->getAttribute('TZOFFSETFROM');
        } catch (Horde_Icalendar_Exception $e) {
            return array();
        }
        $result['from'] = ($t['hour'] * 60 * 60 + $t['minute'] * 60) * ($t['ahead'] ? 1 : -1);
        try {
            $t = $child->getAttribute('TZOFFSETTO');
        } catch (Horde_Icalendar_Exception $e) {
            return array();
        }
        $result['to'] = ($t['hour'] * 60 * 60 + $t['minute'] * 60) * ($t['ahead'] ? 1 : -1);
        try {
            $start = $child->getAttribute('DTSTART');
        } catch (Horde_Icalendar_Exception $e) {
            return array();
        }
        if (!is_int($start)) {
            return array();
        }
        $start = getdate($start);
        if ($start['year'] > $year) {
            return array();
        }
        $results = array();
        try {
            $rdates = $child->getAttributeValues('RDATE');
            foreach ($rdates as $rdate) {
                if ($rdate['year'] == $year || $rdate['year'] == $year - 1) {
                    $result['time'] = $result['end'] = gmmktime($start['hours'], $start['minutes'], $start['seconds'], $rdate['month'], $rdate['mday'], $rdate['year']);
                    $results[] = $result;
                }
            }
        } catch (Horde_Icalendar_Exception $e) {
        }
        try {
            $rrules = $child->getAttribute('RRULE');
        } catch (Horde_Icalendar_Exception $e) {
            if (!$results) {
                $result['time'] = $result['end'] = $start[0];
                $results[] = $result;
            }
            return $results;
        }
        $rrules = explode(';', $rrules);
        foreach ($rrules as $rrule) {
            $t = explode('=', $rrule);
            switch ($t[0]) {
                case 'FREQ':
                    if ($t[1] != 'YEARLY') {
                        return array();
                    }
                    break;
                case 'INTERVAL':
                    if ($t[1] != '1') {
                        return array();
                    }
                    break;
                case 'BYMONTH':
                    $month = intval($t[1]);
                    break;
                case 'BYDAY':
                    $len = strspn($t[1], '1234567890-+');
                    if ($len == 0) {
                        return array();
                    }
                    $weekday = substr($t[1], $len);
                    $weekdays = array('SU' => 0, 'MO' => 1, 'TU' => 2, 'WE' => 3, 'TH' => 4, 'FR' => 5, 'SA' => 6);
                    $weekday = $weekdays[$weekday];
                    $which = intval(substr($t[1], 0, $len));
                    break;
                case 'UNTIL':
                    $result['end'] = intval(substr($t[1], 0, 4));
                    break;
            }
        }
        if (empty($month) || !isset($weekday)) {
            return array();
        }
        // Get the timestamp for the first day of $month.
        $when = gmmktime($start['hours'], $start['minutes'], $start['seconds'], $month, 1, $year);
        // Get the day of the week for the first day of $month.
        $first_of_month_weekday = intval(gmstrftime('%w', $when));
        // Go to the first $weekday before first day of $month.
        if ($weekday >= $first_of_month_weekday) {
            $weekday -= 7;
        }
        $when -= ($first_of_month_weekday - $weekday) * 60 * 60 * 24;
        // If going backwards go to the first $weekday after last day
        // of $month.
        if ($which < 0) {
            do {
                $when += 60 * 60 * 24 * 7;
            } while (intval(gmstrftime('%m', $when)) == $month);
        }
        // Calculate $weekday number $which.
        $when += $which * 60 * 60 * 24 * 7;
        $result['time'] = $when;
        $results[] = $result;
        return $results;
    }