Limit number of relays to publish zap receipts to

app/models/setting.rb

@@ -169,6 +169,9 @@ class Setting < RailsSettings::Base
   field :nostr_public_key, type: :string,
     default: ENV["NOSTR_PUBLIC_KEY"].presence
 
+  field :nostr_zaps_relay_limit, type: :integer,
+    default: 12
+
   #
   # OpenCollective
   #

app/services/nostr_manager/publish_zap_receipt.rb

@@ -7,8 +7,7 @@ module NostrManager
     def call
       tags = parse_tags(@zap.request_event.tags)
 
-      # TODO limit to 15 or so relays
-      tags[:relays].each do |relay_url|
+      tags[:relays].take(Setting.nostr_zaps_relay_limit).each do |relay_url|
         if @delayed
           NostrPublishEventJob.perform_later(event: @zap.receipt, relay: relay_url)
         else

app/views/admin/settings/services/_nostr.html.erb

@@ -19,5 +19,15 @@
         title: "Public key",
         description: "The corresponding public key of the accounts service"
       ) %>
-<% end %>
 </ul>
+</section>
+<section>
+<h3>Zaps</h3>
+<ul role="list">
+  <%= render FormElements::FieldsetResettableSettingComponent.new(
+        key: :nostr_zaps_relay_limit,
+        title: "Relay limit",
+        description: "The maximum number of relays to publish zap receipts to"
+      ) %>
+</ul>
+<% end %>

spec/services/nostr_manager/publish_zap_receipt_spec.rb

@@ -6,11 +6,35 @@ RSpec.describe NostrManager::PublishZapReceipt, type: :model do
 
   describe "Default/delayed execution" do
     it "publishes zap receipts to all requested relays" do
-      2.times do
-        expect(NostrPublishEventJob).to receive(:perform_later).and_return(true)
-      end
+      expect(NostrPublishEventJob).to receive(:perform_later)
+        .exactly(2).times.and_return(true)
 
       described_class.call(zap: zap)
     end
+
+    context "with a long relay list" do
+      before do
+        relays = zap.request["tags"].find { |t| t.first == "relays" }
+        [
+          "wss://aegonstargaryen.example.com", "wss://visenya.example.com",
+          "wss://rhaenys.example.com", "wss://housevelaryon.example.com",
+          "wss://aemond.example.com", "wss://jaehaerys.example.com",
+          "wss://daenerys.example.com", "wss://corlys.example.com",
+          "wss://laenor.example.com", "wss://alysanne.example.com",
+          "wss://balerion.example.com", "wss://meraxes.example.com",
+          "wss://vhaegar.example.com", "wss://vermax.example.com",
+          "wss://caraxes.example.com"
+        ].each do |url|
+          relays << url
+        end
+      end
+
+      it "limits publishing attempts to the first 12 relays" do
+        expect(NostrPublishEventJob).to receive(:perform_later)
+          .exactly(12).times.and_return(true)
+
+        described_class.call(zap: zap)
+      end
+    end
   end
 end