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<?php
//--------------------------------------------------------------------------------------------------
// Utilities for our event-fetching scripts.
//
// Requires PHP 5.2.0 or higher.
//--------------------------------------------------------------------------------------------------
// PHP will fatal error if we attempt to use the DateTime class without this being set.
date_default_timezone_set('UTC');
class Event {
// Tests whether the given ISO8601 string has a time-of-day or not
const ALL_DAY_REGEX = '/^\d{4}-\d\d-\d\d$/'; // matches strings like "2013-12-29"
public $title;
public $allDay; // a boolean
public $start; // a DateTime
public $end; // a DateTime, or null
public $properties = array(); // an array of other misc properties
// Constructs an Event object from the given array of key=>values.
// You can optionally force the timeZone of the parsed dates.
public function __construct($array, $timeZone=null) {
$this->title = $array['title'];
if (isset($array['allDay'])) {
// allDay has been explicitly specified
$this->allDay = (bool)$array['allDay'];
}
else {
// Guess allDay based off of ISO8601 date strings
$this->allDay = preg_match(self::ALL_DAY_REGEX, $array['start']) &&
(!isset($array['end']) || preg_match(self::ALL_DAY_REGEX, $array['end']));
}
if ($this->allDay) {
// If dates are allDay, we want to parse them in UTC to avoid DST issues.
$timeZone = null;
}
// Parse dates
$this->start = parseDateTime($array['start'], $timeZone);
$this->end = isset($array['end']) ? parseDateTime($array['end'], $timeZone) : null;
// Record misc properties
foreach ($array as $name => $value) {
if (!in_array($name, array('title', 'allDay', 'start', 'end'))) {
$this->properties[$name] = $value;
}
}
}
// Returns whether the date range of our event intersects with the given all-day range.
// $rangeStart and $rangeEnd are assumed to be dates in UTC with 00:00:00 time.
public function isWithinDayRange($rangeStart, $rangeEnd) {
// Normalize our event's dates for comparison with the all-day range.
$eventStart = stripTime($this->start);
if (isset($this->end)) {
$eventEnd = stripTime($this->end); // normalize
}
else {
$eventEnd = $eventStart; // consider this a zero-duration event
}
// Check if the two whole-day ranges intersect.
return $eventStart < $rangeEnd && $eventEnd >= $rangeStart;
}
// Converts this Event object back to a plain data array, to be used for generating JSON
public function toArray() {
// Start with the misc properties (don't worry, PHP won't affect the original array)
$array = $this->properties;
$array['title'] = $this->title;
// Figure out the date format. This essentially encodes allDay into the date string.
if ($this->allDay) {
$format = 'Y-m-d'; // output like "2013-12-29"
}
else {
$format = 'c'; // full ISO8601 output, like "2013-12-29T09:00:00+08:00"
}
// Serialize dates into strings
$array['start'] = $this->start->format($format);
if (isset($this->end)) {
$array['end'] = $this->end->format($format);
}
return $array;
}
}
// Date Utilities
//----------------------------------------------------------------------------------------------
// Parses a string into a DateTime object, optionally forced into the given timeZone.
function parseDateTime($string, $timeZone=null) {
$date = new DateTime(
$string,
$timeZone ? $timeZone : new DateTimeZone('UTC')
// Used only when the string is ambiguous.
// Ignored if string has a timeZone offset in it.
);
if ($timeZone) {
// If our timeZone was ignored above, force it.
$date->setTimezone($timeZone);
}
return $date;
}
// Takes the year/month/date values of the given DateTime and converts them to a new DateTime,
// but in UTC.
function stripTime($datetime) {
return new DateTime($datetime->format('Y-m-d'));
}
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