sealed class Program
{
  public static void Main(string[] args)
  {
    var app = new App();

    var snsStack = new SnsStack(app, "Sns", new StackProps
    {
        Env = new Environment
        {
            Account = "XXXXXXXXXXXX",
            Region = "us-east-1",
        }
    });
    
    var lambdaStack = new LambdaStack(app, "Lambda", new StackProps
    {
        Env = new Environment
        {
            Account = "XXXXXXXXXXXX",
            Region = "us-west-2",
        }
    }, snsStack);
}

public class SnsStack : Stack
{
    public readonly ITopic Topic;

    public SnsStack(Construct scope, string id, StackProps props) : base(scope, id, props)
    {
        Topic = new Topic(this, "Topic", new TopicProps { TopicName = PhysicalName.GENERATE_IF_NEEDED, });
    }
}

public class LambdaStack : Stack
{
    public readonly IFunction Function;

    internal LambdaStack(Construct scope, string id, StackProps props, SnsStack snsStack) : base(scope, id, props)
    {
        Function = new PythonFunction(this, "Function", new PythonFunctionProps
        {
            Entry = "src/CdkSnsCrossRegion/Function",
        });

        snsStack.Topic.AddSubscription(new LambdaSubscription(Function));
    }
}