public function overlap(DayTime $b)
{
// Seconds from commencement of the week;
$selfMinutes = $this->getDay() * self::MINUTES_IN_DAY + $this->getHour() * self::MINUTES_IN_HOUR + $this->getMinute();
$bMinutes = $b->getDay() * self::MINUTES_IN_DAY + $b->getHour() * self::MINUTES_IN_HOUR + $b->getMinute();
if ($selfMinutes > $bMinutes) {
// I start before the other does
return min($bMinutes + $b->getDuration(), $selfMinutes + $this->getDuration()) - $selfMinutes;
}
// Does this DayTime end overlap with the $b period?
if ($selfMinutes + $this->getDuration() < $bMinutes) {
// No overlap - return 0;
return 0;
}
$selfEnd = $selfMinutes + $this->getDuration();
$bEnd = $bMinutes + $b->getDuration();
if ($selfEnd < $bEnd) {
// I end before $b ends
return $bMinutes + ($bEnd - $selfEnd);
}
return $b->getDuration();
}
public static function getWeekdayDate($which, $weekday, $month, $year = null)
{
if ($month instanceof DayTime) {
$year = $month->getYear();
$month = $month->getMonth();
}
$which = min(5, max(1, (int) $which)) - 1;
$wdOf1st = (int) date("N", strtotime("{$year}-{$month}-01"));
$firstWd = 1 + ($weekday + 7 - $wdOf1st) % 7;
if ($which <= 3) {
return $which * 7 + $firstWd;
} else {
if ($which * 7 + $firstWd <= DayTime::daysInMonth($month, $year)) {
return $which * 7 + $firstWd;
} else {
return $firstWd + 7 * 3;
}
}
}