/// <summary>
/// Adds a child service to the <see cref="Services"/> collection.
/// </summary>
/// <param name="service">The <see cref="SsdpService"/> instance to add.</param>
/// <remarks>
/// <para>If the device is already a member of the <see cref="Services"/> collection, this method does nothing.</para>
/// <para>Also sets the <see cref="SsdpService.RootDevice"/> property of the added device and all descendant devices to the
/// relevant <see cref="SsdpRootDevice"/> instance.</para>
/// </remarks>
/// <exception cref="ArgumentNullException">Thrown if the <paramref name="service"/> argument is null.</exception>
/// <exception cref="InvalidOperationException">Thrown if the <paramref name="service"/> is already associated with a different
/// <see cref="SsdpRootDevice"/> instance than used in this tree. Can occur if you try to add the same device instance to more than
/// one tree. Also thrown if you try to add a device to itself.</exception>
public void AddService(SsdpService service)
{
if (service == null)
{
throw new ArgumentNullException(nameof(service));
}
SsdpDevice thisRootDevice = GetRootDevice();
if (service.RootDevice != null && !service.RootDevice.Equals(thisRootDevice))
{
throw new InvalidOperationException("This device is already associated with a different root device (has been added as a child in another branch).");
}
if (service == this)
{
throw new InvalidOperationException("Can't add device to itself.");
}
lock (_services)
{
service.RootDevice = (SsdpRootDevice)thisRootDevice;
if (!_services.Contains(service))
{
_services.Add(service);
}
}
}
/// <summary>
/// Returns the root device of this object.
/// </summary>
/// <returns>Root device in the structure.</returns>
public SsdpRootDevice GetRootDevice()
{
SsdpDevice?rootDevice = this switch
{
SsdpRootDevice root => root,
SsdpService embedded => embedded.RootDevice,
_ => null
};
if (rootDevice == null)
{
throw new NullReferenceException("Root device cannot be null.");
}
return((SsdpRootDevice)rootDevice);
}
