Ping relays on resume, if there's an error then try to reconnect

This is an attempt to fix the fail-to-reconnect issues. Let's see if it works.

damus/ContentView.swift

@@ -59,6 +59,8 @@ struct ContentView: View {
         return keypair.privkey
     }
     
+    @Environment(\.scenePhase) var scenePhase
+    
     @State var status: String = "Not connected"
     @State var active_sheet: Sheets? = nil
     @State var damus_state: DamusState? = nil
@@ -403,6 +405,22 @@ struct ContentView: View {
         .onReceive(handle_notify(.unmute_thread)) { notif in
             home.filter_events()
         }
+        .onChange(of: scenePhase) { (phase: ScenePhase) in
+            switch phase {
+            case .background:
+                print("📙 DAMUS BACKGROUNDED")
+                break
+            case .inactive:
+                print("📙 DAMUS INACTIVE")
+                break
+            case .active:
+                print("📙 DAMUS ACTIVE")
+                guard let ds = damus_state else { return }
+                ds.pool.ping()
+            @unknown default:
+                break
+            }
+        }
         .onReceive(handle_notify(.local_notification)) { notif in
             
             guard let local = notif.object as? LossyLocalNotification,

damus/Nostr/RelayConnection.swift

@@ -42,6 +42,7 @@ final class RelayConnection {
     private(set) var isConnecting = false
     
     private(set) var last_connection_attempt: TimeInterval = 0
+    private(set) var last_pong: Date? = nil
     private(set) var backoff: TimeInterval = 1.0
     private lazy var socket = WebSocket(url.url)
     private var subscriptionToken: AnyCancellable?
@@ -54,6 +55,18 @@ final class RelayConnection {
         self.handleEvent = handleEvent
     }
     
+    func ping() {
+        socket.ping { err in
+            if let err {
+                self.isConnecting = false
+                self.isConnected = false
+                self.reconnect_with_backoff()
+            } else {
+                self.last_pong = .now
+            }
+        }
+    }
+    
     func connect(force: Bool = false) {
         if !force && (isConnected || isConnecting) {
             return
@@ -111,15 +124,14 @@ final class RelayConnection {
             DispatchQueue.main.async {
                 self.isConnected = false
                 self.isConnecting = false
-                self.reconnect()
+                self.reconnect_with_backoff()
             }
         case .error(let error):
             print("⚠️ Warning: RelayConnection (\(self.url)) error: \(error)")
             DispatchQueue.main.async {
                 self.isConnected = false
                 self.isConnecting = false
-                self.backoff *= 1.5
-                self.reconnect_in(after: self.backoff)
+                self.reconnect_with_backoff()
             }
         }
         DispatchQueue.main.async {
@@ -127,6 +139,11 @@ final class RelayConnection {
         }
     }
     
+    func reconnect_with_backoff() {
+        self.backoff *= 1.5
+        self.reconnect_in(after: self.backoff)
+    }
+    
     func reconnect() {
         guard !isConnecting else {
             return  // we're already trying to connect

damus/Nostr/RelayPool.swift

@@ -79,7 +79,13 @@ class RelayPool {
         self.handlers = handlers.filter { $0.sub_id != sub_id }
         print("removing \(sub_id) handler, current: \(handlers.count)")
     }
-
+    
+    func ping() {
+        for relay in relays {
+            relay.connection.ping()
+        }
+    }
+    
     func register_handler(sub_id: String, handler: @escaping (String, NostrConnectionEvent) -> ()) {
         for handler in handlers {
             // don't add duplicate handlers

damus/Nostr/WebSocket.swift

@@ -32,6 +32,10 @@ final class WebSocket: NSObject, URLSessionWebSocketDelegate {
         self.session = session
     }
     
+    func ping(receiveHandler: @escaping (Error?) -> Void) {
+        self.webSocketTask.sendPing(pongReceiveHandler: receiveHandler)
+    }
+    
     func connect() {
         resume()
     }