Factory Pattern

// ─── EXAMPLE 1 ──────────────────────────────────────────────────────────────
// WHAT WE ARE IMPLEMENTING:
// A notifications delivery framework routing alerts via Email, SMS, or Push
// channels.
//
// WHERE THE PATTERN FITS IN:
// NotificationFactory acts as the Creator. EmailNotificationFactory and
// SMSNotificationFactory represent Concrete Creators overriding the factory
// method to return matching product subclasses.
// ────────────────────────────────────────────────────────────────────────────
// --- Products ---
interface ParkingSpot {
    String getId();
    double getHourlyRate();
}

class CarSpot implements ParkingSpot {
    private final String id;
    public CarSpot(String id) { this.id = id; }
    public String getId() { return id; }
    public double getHourlyRate() { return 20.0; }
}

class BikeSpot implements ParkingSpot {
    private final String id;
    public BikeSpot(String id) { this.id = id; }
    public String getId() { return id; }
    public double getHourlyRate() { return 10.0; }
}

class TruckSpot implements ParkingSpot {
    private final String id;
    public TruckSpot(String id) { this.id = id; }
    public String getId() { return id; }
    public double getHourlyRate() { return 40.0; }
}

// --- Factory (centralized creation) ---
enum SpotType { CAR, BIKE, TRUCK }

class ParkingSpotFactory {
    public static ParkingSpot createSpot(SpotType type, String id) {
        return switch (type) {
            case CAR -> new CarSpot(id);
            case BIKE -> new BikeSpot(id);
            case TRUCK -> new TruckSpot(id);
        };
    }
}

// --- Client code ---
public class Main {
    public static void main(String[] args) {
        ParkingSpot carSpot = ParkingSpotFactory.createSpot(SpotType.CAR, "A1");
        ParkingSpot bikeSpot = ParkingSpotFactory.createSpot(SpotType.BIKE, "B2");

        System.out.println("Car spot: " + carSpot.getId() + " Rate: " + carSpot.getHourlyRate());
        System.out.println("Bike spot: " + bikeSpot.getId() + " Rate: " + bikeSpot.getHourlyRate());
    }
}