Price Calculation

Povilas i notice the comment editor here is not very intuitive and its hard to paste/write a block of code. is there any way you can fix this?

Noticed an error with this if there isn't a vehicle already set on the $this->vehicle relation - would it be ideal to add $request validation in this function? Or was there a reason why you wouldn't add validation here?

   public function toArray($request)
   {
       $totalPrice = $this->total_price ?? ParkingPriceService::calculatePrice(
           $this->zone_id,
           $this->start_time,
           $this->stop_time
       );
 
       return [
           'id' => $this->id,
           'zone' => [
               'name' => $this->zone->name,
               'price_per_hour' => $this->zone->price_per_hour,
           ],
           'vehicle' => [
               'plate_number' => $this->vehicle->plate_number
           ],
           'start_time' => $this->start_time,
           'stop_time' => $this->stop_time,
           'total_price' => $totalPrice,
       ];
   }

I found that in our ParkingController class's stop() method, we didn't check if the parking stopped before updating its stop_time property, which could result in an incorrect price calculation if the /stop endpoint was triggered multiple times within different intervals.

This situation might be avoided in a frontend client by not allowing the user to click the stop button twice, however it cannot be totally avoided if the user hits the Api endpoint directly.

To resolve this issue, I added the following if statement to the top of ParkingController's stop() method:

if($parking->stop_time) {
return response()->json(['errors' => ['general' => ['Parking already stopped.']], ]
, Response::HTTP_UNPROCESSABLE_ENTITY);
}

I'm not sure if I'm overthinking the situation, but better safe than sorry.

In the variable $totalTimeByMinutes I had to add abs() so that it returns a positive value because otherwise it would return a negative $totalprice

public static function calculatePrice(int $zone_id, string $startTime, string $stopTime = null): int { $start = new Carbon($startTime); $stop = (!is_null($stopTime)) ? new Carbon($stopTime) : now();

    $totalTimeByMinutes = abs($stop->diffInMinutes($start));
 
    $priceByMinutes = Zone::find($zone_id)->price_per_hour / 60;
 
    $totalPrice = ceil($totalTimeByMinutes * $priceByMinutes);
 
    return $totalPrice;
}