Get number of occupied nights on Hotel System

Hello to everyone, I'm trying to get number of occupied nights in a given month for an Hotel System in Laravel.

In my DB I have arrival_date and departure_date. But if in the same date I have a checkout from one booking, and a checkin from on other one, I have to consider just one night.

I tried this, but it doesn't work:

public function occupancyRate()
{
    $startOfMonth = Carbon::now()->startOfMonth();
    $endOfMonth = Carbon::now()->endOfMonth();

 
    $totalNightsInMonth = $endOfMonth->diffInDays($startOfMonth) + 1; 

        $bookings = Booking::where(function ($query) use ($startOfMonth, $endOfMonth) {
        $query->whereBetween('arrival', [$startOfMonth, $endOfMonth])
            ->orWhereBetween('departure', [$startOfMonth, $endOfMonth])
            ->orWhere(function ($query) use ($startOfMonth, $endOfMonth) {
                $query->where('arrival', '<', $startOfMonth)
                    ->where('departure', '>', $endOfMonth);
            });
    })
    ->get();

$totalOccupiedNights = 0;

foreach ($bookings as $booking) {
    $arrival = Carbon::parse($booking->arrival);
    $departure = Carbon::parse($booking->departure);

    $nightsOfStay = $arrival->diffInDays($departure) + 1;

    $totalOccupiedNights += $nightsOfStay;
}

$occupancyRate = ($totalOccupiedNights / $totalNightsInMonth) * 100;

return $occupancyRate;
}