Zaps

NostrStreamer/Extensions.cs

@@ -18,6 +18,11 @@ public static class Extensions
         return NostrPrivateKey.FromBech32(cfg.PrivateKey).DerivePublicKey().Hex;
     }
     
+    public static NostrPrivateKey GetPrivateKey(this Config cfg)
+    {
+        return NostrPrivateKey.FromBech32(cfg.PrivateKey);
+    }
+
     public static List<Variant> GetVariants(this IngestEndpoint ep)
     {
         return ep.Capabilities

NostrStreamer/Program.cs

@@ -46,6 +46,7 @@ internal static class Program
         services.AddSingleton<INostrClient>(s => s.GetRequiredService<NostrMultiWebsocketClient>());
         services.AddSingleton<NostrListener>();
         services.AddHostedService<NostrListenerLifetime>();
+        services.AddTransient<ZapService>();
         
         // streaming services
         services.AddTransient<SrsApi>();

NostrStreamer/Services/LndInvoiceStream.cs

@@ -43,6 +43,7 @@ public class LndInvoicesStream : BackgroundService
                     {
                         using var scope = _scopeFactory.CreateScope();
                         var db = scope.ServiceProvider.GetRequiredService<StreamerContext>();
+                        var zapService = scope.ServiceProvider.GetRequiredService<ZapService>();
 
                         try
                         {
@@ -56,6 +57,10 @@ public class LndInvoicesStream : BackgroundService
                                 payment.IsPaid = true;
                                 payment.User.Balance += (long)(payment.Amount * 1000L);
                                 await db.SaveChangesAsync(stoppingToken);
+                                if (!string.IsNullOrEmpty(payment.Nostr))
+                                {
+                                    zapService.HandlePaid(payment.Invoice, payment.Nostr);
+                                }
                             }
                         }
                         catch (Exception ex)

NostrStreamer/Services/ZapService.cs

@@ -0,0 +1,60 @@
+using Newtonsoft.Json;
+using Nostr.Client.Client;
+using Nostr.Client.Messages;
+using Nostr.Client.Requests;
+
+namespace NostrStreamer.Services;
+
+public class ZapService
+{
+    private readonly ILogger<ZapService> _logger;
+    private readonly Config _config;
+    private readonly INostrClient _nostrClient;
+
+    public ZapService(ILogger<ZapService> logger, Config config, INostrClient nostrClient)
+    {
+        _logger = logger;
+        _config = config;
+        _nostrClient = nostrClient;
+    }
+
+    public void HandlePaid(string pr, string? zapRequest)
+    {
+        try
+        {
+            if (string.IsNullOrEmpty(zapRequest)) return;
+
+            var zapNote = JsonConvert.DeserializeObject<NostrEvent>(zapRequest);
+            if (zapNote == default)
+            {
+                _logger.LogWarning("Could not parse zap note {note}", zapRequest);
+                return;
+            }
+
+            var key = _config.GetPrivateKey();
+            var pubKey = key.DerivePublicKey().Hex;
+            var tags = zapNote.Tags!.Where(a => a.TagIdentifier?.Length == 1).ToList();
+            tags.Add(new("bolt11", pr));
+            tags.Add(new("description", zapRequest));
+
+            var zapReceipt = new NostrEvent()
+            {
+                Kind = NostrKind.Zap,
+                CreatedAt = DateTime.UtcNow,
+                Pubkey = pubKey,
+                Content = zapNote.Content,
+                Tags = new(tags.ToArray())
+            };
+
+            var zapReceiptSigned = zapReceipt.Sign(key);
+
+            var jsonZap = JsonConvert.SerializeObject(zapReceiptSigned);
+            _logger.LogInformation("Created tip receipt {json}", jsonZap);
+            _nostrClient.Send(new NostrEventRequest(zapReceiptSigned));
+        }
+        catch (Exception e)
+        {
+            _logger.LogError(e, "Failed to handle zap");
+        }
+    }
+}