Fetch user relays, synchronously

app/services/nostr_manager/fetch_latest_event.rb

@@ -0,0 +1,59 @@
+module NostrManager
+  class FetchLatestEvent < NostrManagerService
+    TIMEOUT = 1
+
+    def initialize(filter:, relay_url:)
+      @filter = filter
+      @relay = new_relay(relay_url)
+      @client = Nostr::Client.new
+    end
+
+    def call
+      filter, client, relay = @filter, @client, @relay
+      latest_event = nil
+      mutex = Mutex.new
+      received_event = ConditionVariable.new
+      log_prefix = "[nostr][#{@relay.name}]"
+
+      thread = Thread.new do
+        client.on :connect do
+          client.subscribe(filter: filter)
+        end
+
+        client.on :error do |e|
+          Rails.logger.info "#{log_prefix} Error: #{e}"
+          Thread.current.exit
+        end
+
+        client.on :message do |m|
+          msg = JSON.parse(m) rescue nil
+          if msg && msg[0] == "EVENT" && msg[2]
+            puts "#{log_prefix} Event received: #{msg[2]["id"]}"
+            mutex.synchronize do
+              latest_event = msg[2]
+              received_event.signal
+            end
+          elsif msg && msg[0] == "EOSE"
+            Thread.current.exit
+          end
+        end
+
+        client.connect relay
+      end
+
+      begin
+        Timeout.timeout(TIMEOUT) do
+          mutex.synchronize do
+            received_event.wait(mutex) if latest_event.nil?
+          end
+        end
+      rescue Timeout::Error
+        puts "#{log_prefix} Timeout: No event received within #{TIMEOUT} seconds"
+      ensure
+        thread.exit
+      end
+
+      latest_event
+    end
+  end
+end