/lib/Calendar/ICalendar.php

<?php

/*
 * Copyright © 2009 - 2010 Massachusetts Institute of Technology
 * Copyright © 2010 - 2013 Modo Labs Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * ICalendar
 * The ICal* classes in this file together partially implement RFC 2445.
 * @package ExternalData
 * @subpackage Calendar
 */

/**
 * ICalendar
 * @package Exceptions
 */
class ICalendarException extends KurogoDataException {
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
abstract class ICalObject {
    protected $classname;

    public function get_name() {
        return $this->classname;
    }

    public function set_attribute($attr, $value, $params=null) {
    }

    public function get_attribute($attr) {
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalTodo extends ICalObject {
    public function __construct() {
        $this->classname = 'VTODO';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalJournal extends ICalObject {
    public function __construct() {
        $this->classname = 'VJOURNAL';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalFreeBusy extends ICalObject {
    public function __construct() {
        $this->classname = 'VFREEBUSY';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalTimeZone extends ICalObject implements CalendarTimeZone {
    protected $tzid;
    
    public function getTZID() {
        return $this->tzid;
    }

    public function __construct() {
        $this->classname = 'VTIMEZONE';
    }

    public function set_attribute($attr, $value, $params=NULL) {
        switch ($attr) {
            case 'TZID':
                $this->tzid = $value;
                break;
        }
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalDaylight extends ICalTimeZone {
    public function __construct() {
        $this->classname = 'DAYLIGHT';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalStandard extends ICalTimeZone {
    public function __construct() {
        $this->classname = 'STANDARD';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalAlarm extends ICalObject {
    public function __construct() {
        $this->classname = 'VALARM';
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalEvent extends ICalObject implements KurogoObject, CalendarEvent {

    protected $uid;
    protected $sequence;
    protected $recurid = NULL;
    protected $range;
    protected $starttime;
    protected $summary;
    protected $description;
    protected $location;
    protected $geo;
    protected $tzid;
    protected $timezone;
    protected $url;
    protected $created;
    protected $updated;
    protected $dtstamp;
    protected $status;
    protected $transparency;
    protected $categories=array();
    protected $properties=array();
    protected $rrules=array();
    protected $exdates = array();
    protected $recurrence_exceptions = array();

    public function getEventCategories(TimeRange $range = null) {
        if($range && $this->range->contained_by($range)) {
            return $this->categories;
        }else {
            return $this->categories;
        }
        return array();
    }

    protected function standardAttributes() {
        return array(
            'summary', 
            'location', 
            'geo',
            'description', 
            'uid', 
            'start', 
            'end', 
            'url', 
            'categories',
            'datetime',
        );
    }

    public function filterItem($filters) {
        foreach ($filters as $filter=>$value) {
            switch ($filter)
            {
                case 'search': //case insensitive
                    return  (stripos($this->getTitle(), $value)!==FALSE);
                    break;
                case 'category': //case insensitive
                    if (!in_array(strtolower($value), array_map('strtolower', $this->categories))) {
                        return false;
                    }
                    break;
            }
        }   
        
        return true;     
    }

    public function get_tzid() {
        return $this->tzid;
    }
    
    public function get_timezone() {
        return $this->timezone;
    }
    
    public function getID() {
        return $this->uid;
    }

    public function get_uid() {
        return $this->uid;
    }

    public function get_recurid() {
        return $this->recurid;
    }
    
    public function isAllDay() {
        return $this->range instanceOf DayRange;
    }

    public function getRange() {
        return $this->range;
    }

    public function get_range() {
        return $this->range;
    }

    public function get_series_range() {
        return new TimeRange($this->get_start(), $this->get_end());
    }

    public function get_start() {
        return $this->range->get_start();
    }

    public function set_start($timestamp, $dayOnly=false) {
        if (!$this->range) {
            throw new KurogoDataException("set_start called before range is initialized");
        }
        $this->range->set_start($timestamp);
        $this->starttime = $timestamp;
    }

    public function get_end() {
        return $this->range->get_end();
    }

    public function set_end($timestamp, $dayOnly=false) {
        if (!$this->range) {
            throw new KurogoDataException("set_end called before range is initialized");
        }
        $start = $this->range->get_start();
        
        if ($timestamp < $start) {
            // if the end time is an all day time then just use the start time.
            if ($dayOnly) {
                $timestamp = $start;
            } else {
            	//ignore end time if it's later
            	return false;
            }
        }
            
        $this->range->set_end($timestamp);
    }

    public function get_summary() {
        return $this->summary;
    }
    
    public function getTitle() {
        return $this->summary;
    }

    public function get_url() {
        return $this->url;
    }

    public function get_description() {
        return $this->description;
    }

    public function get_location() {
        return $this->location;
    }
    
    public function get_location_coordinates() {
        $coords = false;
        $parts = explode(';', $this->geo);
        if (count($parts) == 2) {
            $coords = array(
                'lat' => floatval($parts[0]),
                'lon' => floatval($parts[1]),
            );
        }
        return $coords;
    }

    public function get_categories() {
        return $this->categories;
    }

    public function is_recurring() {
        return count($this->rrules)>0;
    }

    /* returns an array of occurrences that occur in the given range */
    public function getOccurrencesInRange(TimeRange $range, $limit=null) {
        $occurrences = array();

        /* check the "base" event */    
        if ($this->range->overlaps($range)) {
            $occurrences[$this->get_start()] = $this;
        }

        foreach ($this->rrules as $rrule) {
            foreach ($rrule->occurrences($this, $range, $limit) as $occurrence) {
                if (!in_array($occurrence->get_start(), $this->exdates)) {
                    $occurrences[$occurrence->get_start()] = $occurrence;
                }
            }
        }

        ksort($occurrences);
        return array_values($occurrences);
    }

    public function overlaps(TimeRange $range) {
        return $this->range->overlaps($range);
    }

    public function contains(TimeRange $range) {
        return $this->range->contains($range);
    }

    public function contained_by(TimeRange $range) {
        return $this->range->contained_by($range);
    }

    public function get_attribute($attr) {
        if (in_array($attr, $this->standardAttributes())) {
            if ($attr == 'datetime') {
                return $this->range;
            } else {
                $method = "get_$attr";
                return $this->$method();
            }
        } else {
            return isset($this->properties[$attr]) ? $this->properties[$attr] : null;
        }
    }

    public function get_all_attributes() {
        return array_merge($this->standardAttributes(), array_keys($this->properties));
    }

    public function setRange(TimeRange $range) {
        $this->range = $range;
        $this->starttime = $range->get_start();
    }

    public function setSummary($summary) {
        $this->summary = $summary;
    }

    public function setDescription($description) {
        $this->description = TextFormatter::linkify($description);
    }

    public function setUID($uid) {
        $this->uid = $uid;
    }

    public function setLocation($location) {
        $this->location = $location;
    }
    
    public function setLocationCoordinates($coordinates) {
        if (count($coordinates) == 2) {
            $this->geo = implode(';', array_values($coordinates));
        }
    }

    private static function timezoneFilter($tzid) {
    	static $timezoneMap;
    	if (!$timezoneMap) {
    		$timezoneMap = Kurogo::getSiteSection('timezones');
    	}
    	return Kurogo::arrayVal($timezoneMap, $tzid, $tzid);
    }
    
    private static function getTimezoneForID($tzid) {
        $tzid = self::timezoneFilter($tzid);
        try {
            $timezone = new DateTimeZone($tzid);
        } catch (Exception $e) {
            Kurogo::log(LOG_WARNING, "Invalid timezone $tzid found when processing calendar", 'data');
            $timezone = null;
        }
        return $timezone;
    }

    /**
     * reset the end time when the start time is less than the start time
     */
    protected function rectifyRange() {
        if ($this->range) {
            $start = $this->range->get_start();
            $end = $this->range->get_end();
            if ($end < $start) {
                $this->range->set_end($start);
            }
        }
    }
    
    public function set_attribute($attr, $value, $params=NULL) {
        switch ($attr) {
            case 'UID':
                $this->setUID($value);
                break;
            case 'RECURRENCE-ID':
                $this->recurid = $value;
                break;
            case 'DESCRIPTION':
                $this->setDescription(iCalendar::ical_unescape_text($value));
                break;
            case 'LOCATION':
                $this->setLocation(iCalendar::ical_unescape_text($value));
                break;
            case 'GEO':
                if (is_array($value)) {
                    $this->setLocationCoordinates($value);
                } else if (is_string($value)) {
                    $this->geo = $value;
                }
                break;
            case 'SUMMARY':
                $this->setSummary(iCalendar::ical_unescape_text($value));
                break;
            case 'CATEGORIES':
                $categories = explode(',', $value);
                $this->categories = array();
                foreach ($categories as $category) {
                    $this->categories[] = trim(iCalendar::ical_unescape_text($category));
                }
                break;
            case 'URL':
                $this->url = iCalendar::ical_unescape_text($value);
                break;
            case 'SEQUENCE':
                $this->sequence = $value;
                break;
            case 'STATUS':
                $this->status = $value;
                break;
            case 'CREATED':
                if (array_key_exists('TZID', $params)) {
                    $timezone = self::getTimezoneForID($params['TZID']);
                    $datetime = new DateTime($value, $timezone);
                } else {
                    $datetime = new DateTime($value);
                }
                $this->created = $datetime->format('U');
                break;
            case 'LAST-MODIFIED':
                if (array_key_exists('TZID', $params)) {
                    $timezone = self::getTimezoneForID($params['TZID']);
                    $datetime = new DateTime($value, $timezone);
                } else {
                    $datetime = new DateTime($value);
                }
                $this->updated = $datetime->format('U');
                break;
            case 'DTSTAMP':
                if (array_key_exists('TZID', $params)) {
                    $timezone = self::getTimezoneForID($params['TZID']);
                    $datetime = new DateTime($value, $timezone);
                } else {
                    $datetime = new DateTime($value);
                }
                $this->dtstamp = $datetime->format('U');
                break;
            case 'DTSTART':
                // set the event timezone if it's present in the start time
                if (array_key_exists('TZID', $params)) {
                	if ($timezone = self::getTimezoneForID($params['TZID'])) {
						$this->timezone = $timezone;
						$this->tzid = $timezone->getName();
					}
                }
            case 'DTEND':
                $dayOnly = false;

            case 'DTEND':

                //reset the system timezone to calculate the timestamp
                if ($this->tzid) {
                    $old_timezone = date_default_timezone_get();
                    date_default_timezone_set($this->tzid);
                    $datetime = new DateTime($value, $this->timezone);
                } else {
                    $datetime = new DateTime($value);
                }

                $t = strpos($value, 'T');
                // if there is no "T" or if the "T" is at the end
                if ( ($t === FALSE) || ($t == (strlen($value)-1))) {
                    $dayOnly = true;
                }

                $timestamp = $datetime->format('U');

                if ($this->tzid) {
                    date_default_timezone_set($old_timezone);
                }
                
                if ($attr=='DTEND') {
                    if ($dayOnly) {
                        // make all day events end at 11:59:59 so they don't overlap next day
                        $timestamp -= 1;
                    }
                }

                if (!$this->range) {
                    $range = $dayOnly ? new DayRange($timestamp, null, $this->tzid) : new TimeRange($timestamp, null, $this->tzid);
                    $this->setRange($range);

                    if (isset($this->properties['duration'])) {
                        $this->range->set_icalendar_duration($this->properties['duration']);
                        unset($this->properties['duration']);
                    }
                }

                switch ($attr)
                {
                    case 'DTSTART':
                        $this->set_start($timestamp, $dayOnly);
                        break;
                    case 'DTEND':
                        $this->set_end($timestamp, $dayOnly);
                        break;
                }
                break;
            case 'TRANSP':
                $this->transparency = $value;
                break;
            case 'DURATION':
                if ($this->range) {
                    $this->range->set_icalendar_duration($value);
                } else {
                    $this->properties['duration'] = $value;
                }
                break;
            case 'RRULE':
                $this->add_rrule($value);
                break;
            case 'EXDATE':
                if (array_key_exists('TZID', $params)) {
                    $timezone = self::getTimezoneForID($params['TZID']);
                    $datetime = new DateTime($value, $timezone);
                } else {
                    $datetime = new DateTime($value);
                }

                $this->exdates[] = $datetime->format('U'); // start time
                break;
            case 'TZID': // this only gets called by ICalendar::__construct
                if ($timezone = self::getTimezoneForID($value)) {
					$this->timezone = $timezone;
					$this->tzid = $timezone->getName();
				}
                break;
            default:
                $this->properties[$attr] = iCalendar::ical_unescape_text($value);
                break;
        }
    }

    protected function increment_set($set) {
        return array_map(
            $this->incrementor,
            $set,
            array_fill(0, count($set), $this->interval)
        );
    }

    public function clear_rrules() {
        $this->rrules = array();
    }

    protected function add_rrule($rrule_string) {
        $rrule = new ICalRecurrenceRule($rrule_string);
        $this->rrules[] = $rrule;

        return;
    }

    private function addLine(&$string, $prop, $value) {
        $string .= sprintf("%s:%s\n", $prop, iCalendar::ical_escape_text($value));
    }

    /**
     * Add an ICalEvent as an Exception to the recurrence pattern of a repeating
     * event.
     */
    public function addRecurenceException(ICalEvent $recurrence_exception) {
        $this->recurrence_exceptions[] = $recurrence_exception;
    }

    /**
     * Answer an ICalEvent that is an exception to the normal recurrence pattern
     * if one exists for the start-time given. null if none match.
     * @param int $time
     * @return mixed ICalEvent or null
     */
    public function getRecurrenceException($time) {
        $recurrence_id = strftime("%Y%m%dT%H%M%S",$time);
        foreach ($this->recurrence_exceptions as $exception) {
            // Some ical feeds only have the %Y%m%d portion for DTSTART/DTEND (Google Calendar feeds),
            // so first check for an exact match, then try adding a T000000 time and check again.
            if (($exception->get_recurid() == $recurrence_id) || ($exception->get_recurid().'T000000' == $recurrence_id)){
                return $exception;
            }
        }
        return null;
    }

    public function outputICS() {
        $output_string = '';
        $this->addLine($output_string, "BEGIN", 'VEVENT');
        if ($this->uid) {
            $this->addLine($output_string, "UID", $this->uid);
        }

        if ($this->summary) {
            $this->addLine($output_string, "SUMMARY", $this->summary);
        }

        if ($this->location) {
            $this->addLine($output_string, "LOCATION", $this->location);
        }

        if ($this->geo) {
            $this->addLine($output_string, "GEO", $this->geo);
        }

        if ($this->description) {
            $this->addLine($output_string, "DESCRIPTION", $this->description);
        }

        if ($this->range) {
            if ($this->range instanceOf DayRange)  {
                $this->addLine($output_string, "DTSTART", date('Ymd', $this->range->get_start()));
                $this->addLine($output_string, "DTEND", date('Ymd', $this->range->get_end()));
            } else {
                $this->addLine($output_string, "DTSTART", strftime('%Y%m%dT%H%M%S', $this->range->get_start()));
                $this->addLine($output_string, "DTEND", strftime('%Y%m%dT%H%M%S', $this->range->get_end()));
            }
        }

        $this->addLine($output_string, 'END', 'VEVENT');
        return $output_string;
    }
    
    public function init($args) {
    }

    public function __construct($summary=NULL, TimeRange $range=NULL) {
        $this->classname = 'VEVENT';
        if ($summary !== NULL) {
            $this->summary = $summary;
        }
        if ($range !== NULL) {
            $this->range = $range;
        }
    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalRecurrenceRule extends ICalObject {
    const MAX_OCCURRENCES = PHP_INT_MAX; // provided as a safety net
    protected $classname = 'RECURRENCE';
    protected $type;
    protected $limit = -1;
    protected $limitType = 'COUNT';
    protected $interval = 1;
    protected $occurs_by_list = array();
    protected $occurs_by_day = array();
    protected $wkst;
    private static $dayIndex = Array('SU'=>0, 'MO'=>1, 'TU'=>2, 'WE'=>3, 'TH'=>4, 'FR'=>5, 'SA'=>6 );
    private $dayString = array(
        'SU' => 'Sunday',
        'MO' => 'Monday',
        'TU' => 'Tuesday',
        'WE' => 'Wednesday',
        'TH' => 'Thursday',
        'FR' => 'Friday',
        'SA' => 'Saturday'
    );

    private $frequencies = Array(
        'SECONDLY',
        'MINUTELY',
        'HOURLY',
        'DAILY',
        'WEEKLY',
        'MONTHLY',
        'YEARLY'
    );

    function __construct($rule_string) {
        $rules = explode(';', $rule_string);

        foreach ($rules as $rule) {
            $namevalue = explode('=', $rule);
            $rulename = $namevalue[0];
            $rulevalue = $namevalue[1];
            switch ($rulename) {
                case 'FREQ': // always present
                    if (in_array($rulevalue, $this->frequencies)) {
                        $this->type = $rulevalue;
                    } else {
                        throw new ICalendarException("Invalid frequency $rulevalue");
                    }

                    break;
                case 'INTERVAL':
                    $this->interval = $rulevalue;
                    break;
                case 'UNTIL':
                    $this->limitType = 'UNTIL';
                    $datetime = new DateTime($rulevalue);
                    $this->limit = $datetime->format('U');
                    break;
                case 'COUNT':
                    $limitType = 'COUNT';
                    $this->limit = $rulevalue;
                    break;
                case 'BYDAY':
                    if ($this->type == 'WEEKLY') {
                        $this->type = 'WEEKLY-BYDAY';
                        $this->occurs_by_day = array();
                        foreach (explode(',', $rulevalue) as $day) {
                            $this->occurs_by_day[self::$dayIndex[$day]] = $day;
                        }
                        ksort($this->occurs_by_day);
                        break;
                    } else if($this->type == 'MONTHLY'){
                    	$this->occurs_by_list = array('BYDAY'=>$rulevalue);
                    }
                case 'WKST':
                    $this->wkst = array_key_exists($rulevalue, self::$dayIndex) ? $rulevalue : '';
                    break;
                case (substr($rulename, 0, 2) == 'BY'):
                    $this->occurs_by_list[$rulename] = $rulevalue;
                    break;
                default:
                    throw new ICalendarException("Unknown recurrence rule property $rulename found");
                    break;
            }
        }

        if (empty($this->type)) {
            throw new ICalendarException("Invalid Frequency");
        }
    }

    private function nextIncrement($time, $type, $interval = 1, $tzid = null) {
        //remember the initial time
        $startTime = $time;

        //keep the current timezone
        if ($tzid) {
            $old_timezone = date_default_timezone_get();
            date_default_timezone_set($tzid);
        }
        
        switch ($type) {
            case 'SECONDLY': 
                $time += $interval; 
                break;
            case 'MINUTELY': 
                $time += ($interval * 60); 
                break;
            case 'HOURLY'  : 
                $time += ($interval * 3600);
                break;
            case 'DAILY':
                $hour = date('H', $time);
                $minute = date('i', $time);
                $second = date('s', $time);
                for ($i=0; $i<$interval; $i++) {
                    //can't assume 24 "hours" in a day due to daylight savings. start at midnight and add 28 hours to be in the next day
                    $timestamp = mktime(0,0,0, date('m', $time), date('d', $time), date('Y', $time)) + 100800; 
                    $time =  mktime($hour, $minute, $second, date('m', $timestamp), date('d', $timestamp), date('Y', $timestamp));
                }
                break;
            case 'WEEKLY':
                $time = self::nextIncrement($time, 'DAILY', 7*$interval, $tzid);
                break;
            case 'WEEKLY-BYDAY':
                $current_day = strtoupper(substr(date('D', $time), 0,2));

                // Loop through the days and find the next one.
                reset($this->occurs_by_day);
                //check the wkst to resort the occurs_by_day 
                if ($interval > 1 && $this->wkst && self::$dayIndex[$this->wkst] > 0 && isset($this->occurs_by_day[0])) {
                    array_shift($this->occurs_by_day);
                    $this->occurs_by_day[7] = 'SU';
                }
                
                $day = current($this->occurs_by_day);
                while ($day) {
                    if ($day == $current_day) {
                        $next_day = next($this->occurs_by_day);
                        if ($next_day) {
                            $offset = self::$dayIndex[$next_day] - self::$dayIndex[$current_day];
                            $time = self::nextIncrement($time, 'DAILY', $offset, $tzid);
                        }
                        // If we have reached the end of the sequence, use the beginning and add 7
                        else {
                            reset($this->occurs_by_day);
                            $next_day = current($this->occurs_by_day);
                            $offset = 7 + self::$dayIndex[$next_day] - self::$dayIndex[$current_day];
                            $time = self::nextIncrement($time, 'DAILY', $offset + (($interval - 1) * 7), $tzid);
                        }
                        break;
                    }
                    $day = next($this->occurs_by_day);
                }
                //$time = self::nextIncrement($time, 'DAILY', $offset*$interval, $tzid);
                break;
            case 'MONTHLY':
            	$time = mktime(date('H', $time), date('i', $time), date('s', $time), date('m', $time)+$interval, date('d', $time), date('Y', $time));
                break;
            case 'YEARLY':
                $time = mktime(date('H', $time), date('i', $time), date('s', $time), date('m', $time), date('d', $time), date('Y', $time)+$interval);
                break;
            default:
                throw new ICalendarException("Invalid type $type");
        }

        //restore the old timezone
        if ($tzid) {
            date_default_timezone_set($old_timezone);
        }

        //ensure that the time has changed
        if ($time == $startTime) {
            throw new KurogoDataException("nextIncrement was the same when parsing a recurring event rule. There is likely a bug in the iCalendar code. Please report this behavior");
        }

        return $this->affectRules($time, $tzid);
    }

    private function affectRules($time, $tzid) {

        if(empty($this->occurs_by_list)) {
            return $time;
        }

        //keep the current timezone
        if ($tzid) {
            $old_timezone = date_default_timezone_get();
            date_default_timezone_set($tzid);
        }

        foreach($this->occurs_by_list as $rule => $val) {
            switch($rule) {
                case 'BYDAY':
                    $n = substr($val, 0, -2);
                    $day = substr($val, -2);
                    if ($n < 0) {
                        $firstday = mktime(date('H', $time), date('i', $time), date('s', $time), date('m', $time) + 1, 1, date('Y', $time));
                        $time = strtotime($n . " " . $this->dayString[$day], $firstday);
                    } else {
                        $firstday = mktime(date('H', $time), date('i', $time), date('s', $time), date('m', $time), 1, date('Y', $time));
                        $time = strtotime($n . " " . $this->dayString[$day], $firstday);
                    }
                    break;
                case 'BYMONTH':
                    $time = mktime(date('H', $time), date('i', $time), date('s', $time), $val, date('d', $time), date('Y', $time));
                    break;
                case 'BYSECOND':
                    $time = mktime(date('H', $time), date('i', $time), $val, date('m', $time), date('d', $time), date('Y', $time));
                    break;
                case 'BYMINUTE':
                    $time = mktime(date('H', $time), $val, date('s', $time), date('m', $time), date('d', $time), date('Y', $time));
                    break;
                case 'BYHOUR':
                    $time = mktime($val, date('i', $time), date('s', $time), date('m', $time), date('d', $time), date('Y', $time));
                    break;
                case 'BYMONTHDAY':
                    $time = mktime(date('H', $time), date('i', $time), date('s', $time), date('m', $time), $val, date('Y', $time));
                    break;
                case 'BYYEARDAY':
                    $firstday = mktime(date('H', $time), date('i', $time), date('s', $time), 1, 1, date('Y', $time));
                    $time = strtotime($val . " day", $firstday);
                    break;
                case 'BYWEEKNO':
                case 'BYSETPOS':
                case 'WKST':
                    throw new ICalendarException("$rule Not handled yet");
                    break;
                default:
            }
        }
        
        //restore the timezone
        if ($tzid) {
            date_default_timezone_set($old_timezone);
        }
        
        return $time;
    }

    /* takes an event and range as parmeters and returns an array of occurrences DOES NOT include the original event */
    function occurrences(ICalEvent $event, TimeRange $range=null, $max=null) {
        $occurrences = array();
        $time = $event->get_start();
        $diff = $event->get_end()-$event->get_start();
        $limitType = $this->limitType;
        $limit = $this->limit;
        $count = 0;

        //    echo date('m/d/Y H:i:s', $time) . "<br>\n";

        $time = $this->nextIncrement($time, $this->type, $this->interval, $event->get_tzid());
        while ($time <= $range->get_end()) {
            //      echo date('m/d/Y H:i:s', $time) . "<br>\n";
            if ( ($limitType=='UNTIL') && ($time > $limit) ) {
                break;
            }
            $occurrence_range = new TimeRange($time, $time + $diff);
            if ($occurrence_range->overlaps($range)) {
                if ($recurrence_exception = $event->getRecurrenceException($time)) {
                    $occurrence = clone $recurrence_exception;
                } else {
                    $occurrence = clone $event;
                    $occurrence->setRange($occurrence_range);
                    $occurrence->clear_rrules();
                    $recurrence_id = strftime("%Y%m%dT%H%M%S",$time);
                    if ($tzid = $occurrence->get_tzid()) {
                        $recurrence_id = sprintf("TZID=%s:%s", $tzid, $recurrence_id);
                    }
                    $occurrence->set_attribute('RECURRENCE-ID', $recurrence_id);
                }
                $occurrences[] = $occurrence;
            }
            if ( ($limitType=='COUNT') && ($count < $limit) ) {
                break;
            }
            if ( $count > ICalRecurrenceRule::MAX_OCCURRENCES) {
                break;
            }
            if ( !is_null($max) && count($occurrences)>=$max) {
                break;
            }
            $time = $this->nextIncrement($time, $this->type, $this->interval, $event->get_tzid());
            $count++;
        }

        return $occurrences;

    }
}

/**
 * @package ExternalData
 * @subpackage Calendar
 */
class ICalendar extends ICalObject implements CalendarInterface {
    protected $properties;
    protected $timezone = NULL;
    protected $events=array();
    protected $eventStartTimes=array();
    protected $recurrence_exceptions = array();
    protected $initArgs=array();
    
    public function setTimezone(CalendarTimeZone $timezone) {
        $this->timezone = $timezone;
    }

    public function getTimezone() {
        return $this->timezone;
    }

    public function add_event(CalendarEvent $event) {
        if (!$event instanceOf ICalEvent) {
            throw new KurogoConfigurationException(gettype($event) . " must be a subclass of ICalEvent");
        }
        
        $uid = $event->get_uid();
        if (is_null($event->get_recurid())) {
            $this->events[$uid] = $event;

            // use event start times so we can return events in starting order
            $this->eventStartTimes[$uid] = $event->get_start();

            // Add any stored exceptions to the event.
            if (isset($this->recurrence_exceptions[$uid])) {
                foreach ($this->recurrence_exceptions[$uid] as $exception) {
                    $this->events[$uid]->addRecurenceException($exception);
                }
            }
        } else {
            // If the event already exists, add the exception to it.
            if (isset($this->events[$uid])) {
                $this->events[$uid]->addRecurenceException($event);
            }
            // Otherwise, store up a list of exceptions for addition to the event
            // when its added.
            else {
                if (!isset($this->recurrence_exceptions[$uid]))
                    $this->recurrence_exceptions[$uid] = array();

                $this->recurrence_exceptions[$uid][] = $event;
            }
        }
    }

    public function getEvents() {
        return $this->events;
    }

    public function getEvent($id) {
        return isset($this->events[$id]) ? $this->events[$id] : null;
    }

    /* returns an array of events keyed by uid containing an array of occurrences keyed by start time */
    public function getEventsInRange(TimeRange $range=null, $limit=null, $filters=null) {

        $occurrences = array();
        $filters = is_array($filters) ? $filters : array();

        foreach ($this->eventStartTimes as $id => $startTime) {
            $event = $this->events[$id];
            if ($event->filterItem($filters)) {
                $occurrences = array_merge($occurrences, $event->getOccurrencesInRange($range, $limit));
            }
        }

        usort($occurrences, array($this, "sort_events"));
        
        // in some case, it doesn't work properly if we just sort $this->eventStartTimes
        return $occurrences;
    }

    private function sort_events($a, $b) {
        $startA = $a->get_start();
        $startB = $b->get_start();
        if ($startA == $startB) {
            return 0;
        }
        return ($startA < $startB) ? -1 : 1;
    }

    public function set_attribute($attr, $value, $params=null) {
        $this->properties[$attr] = $value;
    }

    public function init($args) {
        $this->initArgs = $args;
    }
    

    public function __construct($url=FALSE) {
        $this->properties = Array();
        $this->events = Array();
        $this->classname = 'VCALENDAR';
    }

    private function addLine(&$string, $prop, $value) {
        $string .= sprintf("%s:%s\n", $prop, self::ical_escape_text($value));
    }

    public function ical_escape_text($text) {
        $text = str_replace(array("\"","\\",",",";","\n"), array("DQUOTE","\\\\", "\,","\;","\\n"), $text);
        return $text;
    }

    public static function ical_unescape_text($text) {
        $text = str_replace(array("DQUOTE","\\\\", "\,","\;","\\n","\\r"), array("\"","\\",",",";","\n",""), $text);
        return $text;
    }

    public function outputICS() {
        $output_string = '';
        $this->addLine($output_string, 'BEGIN','VCALENDAR');
        $this->addLine($output_string, 'CALSCALE','GREGORIAN');
        foreach ($this->events as $event) {
            $output_string .= $event->outputICS();
        }

        $output_string .= 'END:VCALENDAR';
        return $output_string;
    }
}