/**
* Grok the TZID and return an offset in seconds from UTC for this
* date and time.
*/
function _parseTZID($date, $time, $tzid)
{
$vtimezone = $this->_container->findComponentByAttribute('vtimezone', 'TZID', $tzid);
if (!$vtimezone) {
return false;
}
$change_times = array();
foreach ($vtimezone->getComponents() as $o) {
$t = $vtimezone->parseChild($o, $date['year']);
if ($t !== false) {
$change_times[] = $t;
}
}
if (!$change_times) {
return false;
}
sort($change_times);
// Time is arbitrarily based on UTC for comparison.
$t = @gmmktime($time['hour'], $time['minute'], $time['second'], $date['month'], $date['mday'], $date['year']);
if ($t < $change_times[0]['time']) {
return $change_times[0]['from'];
}
for ($i = 0, $n = count($change_times); $i < $n - 1; $i++) {
if ($t >= $change_times[$i]['time'] && $t < $change_times[$i + 1]['time']) {
return $change_times[$i]['to'];
}
}
if ($t >= $change_times[$n - 1]['time']) {
return $change_times[$n - 1]['to'];
}
return false;
}
