Support onchain for prism

Plugins/BTCPayServer.Plugins.Prism/LNURLPrismDestinationValidator.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Threading.Tasks;
+using BTCPayServer.Abstractions.Contracts;
+using BTCPayServer.Payments;
+
+namespace BTCPayServer.Plugins.Prism;
+
+public class LNURLPrismDestinationValidator : IPluginHookFilter
+{
+    public string Hook => "prism-destination-validate";
+
+    public Task<object> Execute(object args)
+    {
+        if (args is not string args1) return Task.FromResult(args);
+
+        try
+        {
+            LNURL.LNURL.ExtractUriFromInternetIdentifier(args1);
+            return Task.FromResult<object>(new PrismDestinationValidationResult()
+            {
+                Success = true,
+                PaymentMethod = new PaymentMethodId("BTC", PaymentTypes.LNURLPay)
+            });
+        }
+        catch (Exception e)
+        {
+            try
+            {
+                LNURL.LNURL.Parse(args1, out var tag);
+                return Task.FromResult<object>(new PrismDestinationValidationResult()
+                {
+                    Success = true,
+                    PaymentMethod = new PaymentMethodId("BTC", PaymentTypes.LNURLPay)
+                });
+            }
+            catch (Exception)
+            {
+            }
+        }
+
+        return Task.FromResult(args);
+    }
+}
+
+public class PrismDestinationValidationResult
+{
+    public bool Success { get; set; }
+    public PaymentMethodId PaymentMethod { get; set; }
+}