OOP Concepts

public enum SpotSize { Regular, Motorcycle, Large }

public class ParkingLot
{
  public bool ParkVehicle(Vehicle vehicle)
  {
    var vehicleSize = vehicle.Type switch {
      "car" => SpotSize.Regular,
      "motorcycle" => SpotSize.Motorcycle,
      "truck" => SpotSize.Large
    };

    var spot = FindAvailableSpotBySize(vehicleSize);
    if (spot is null)
      return false;

    spot.Occupy(vehicle);
    return true;
  }
}

public enum SpotSize { Regular, Motorcycle, Large }

public abstract record IVehicle(SpotSize SpotSize);
public record Car() : IVehicle(SpotSize.Regular);
public record Motorcycle() : IVehicle(SpotSize.Motorcycle);
public record Truck() : IVehicle(SpotSize.Large);

public class ParkingLot
{
  public bool ParkVehicle(IVehicle vehicle)
  {
    var spot = FindAvailableSpotBySize(vehicle.SpotSize);
    if (spot is null)
      return false;

    spot.Occupy(vehicle);
    return true;
  }
}

record struct Order(double Total, ...);

public class StripeApi
{
  public void SetApiKey(string key) { ... }
  public void CreateCharge(double amount) { ... }
}

public class OrderService
{
  public string ApiKey = string.Empty;

  public void Checkout(Order order)
  {
    var stripe = new StripeApi();
    stripe.SetApiKey(ApiKey);
    stripe.CreateCharge(order.Total);
  }
}

record struct Order(double Total, ...);

interface IPaymentMethod
{
  void Process(double amount);
}

public class StripePaymentMethod : IPaymentMethod
{
  StripePaymentMethod(string apiKey);
  void Process(double amount) { ... }
}

public class OrderService
{
  public void Checkout(IPaymentMethod paymentMethod, Order order) =>
    paymentMethod.Process(order);
}