Example1.cs

namespace RouteExample2;

public class Route
{
    public Guid RouteId { get; }
    public string Name { get; }
    
    public int AlarmCount => Locations.Sum(x => x.VendingMachine?.NewAlarms.Count ?? 0);
    public DateTime LastAlarmDate => Locations.Max(x => x.VendingMachine?.NewAlarms.Max(y => y.Date) ?? DateTime.MinValue);
    
    private List<Location> Locations { get; } = new();

    public Route(Guid routeId, string name)
    {
        RouteId = routeId;
        Name = name;
    }
    
    public Guid AddLocation(string name, LatLong coords)
    {
        var locationId = Guid.NewGuid();
        Locations.Add(new Location(locationId, name, coords));
        return locationId;
    }

    public Guid AddVendingMachineToLocation(Guid locationId)
    {
        var location = Locations.SingleOrDefault(x => x.LocationId == locationId);
        if (location == null)
        {
            throw new InvalidOperationException("Location is not associated to route.");
        }

        var vendingMachineId = Guid.NewGuid();
        location.AssociateVendingMachine(new VendingMachine(vendingMachineId));
        return vendingMachineId;
    }
    
    public void Alarm(Guid vendingMachineId, DateTime date)
    {
        var location = Locations.SingleOrDefault(x => x.VendingMachine != null && x.VendingMachine.VendingMachineId == vendingMachineId);
        if (location == null)
        {
            throw new InvalidOperationException("Vending machine is not associated to route.");
        }
        
        location.VendingMachine!.AddAlarm(location.LocationId, date);
    }
}

public class Location
{
    public Guid LocationId { get; }
    public string Name { get; }
    public LatLong Coords{ get; }
    public VendingMachine? VendingMachine { get; private set; }

    public Location(Guid locationId, string name, LatLong coords)
    {
        LocationId = locationId;
        Name = name;
        Coords = coords;
    }

    public void AssociateVendingMachine(VendingMachine vendingMachine)
    {
        VendingMachine = vendingMachine;
    }
}

public class VendingMachine
{
    public Guid VendingMachineId { get; }
    public List<AlarmTriggered> NewAlarms { get; } = new();

    public VendingMachine(Guid vendingMachine)
    {
        VendingMachineId = vendingMachine;
    }

    public void AddAlarm(Guid locationId, DateTime dateTime)
    {
        NewAlarms.Add(new AlarmTriggered(VendingMachineId, locationId, dateTime));
    }
}

public record LatLong(double Lat, double Lng);
public record AlarmTriggered(Guid VendingMachineId, Guid LocationId, DateTime Date);

public class Example
{
    public void Usage()
    {
        var route = new Route(Guid.NewGuid(), "Route 1");
        
        var locationId = route.AddLocation("Location 1", new LatLong(1, 1));
        var vendingMachineId = route.AddVendingMachineToLocation(locationId);
        
        route.Alarm(vendingMachineId, DateTime.UtcNow);
    }
}