better handling of connection errors

QueueCube/API.swift

@@ -9,7 +9,7 @@ import Foundation
 
 struct MediaItem: Codable
 {
-    let filename: String
+    let filename: String?
     let title: String?
     let id: Int
     
@@ -109,40 +109,65 @@ struct API
             .post()
     }
     
-    public func events() async throws -> AsyncStream<Event> {
+    public func events() async throws -> AsyncStream<StreamEvent> {
         return AsyncStream { continuation in
-            let url = request()
+            var websocketTask: URLSessionWebSocketTask = spawnWebsocketTask(with: continuation)
-                .path("/events")
-                .websocket()
-            
-            let websocketTask = URLSession.shared.webSocketTask(with: url)
-            websocketTask.resume()
             
             Task {
-                do {
+                while true {
-                    let event = { (data: Data) in
+                    try await Task.sleep(for: .seconds(5))
-                        try JSONDecoder().decode(Event.self, from: data)
-                    }
                     
-                    while websocketTask.state == .running {
+                    websocketTask.sendPing { error in
-                        switch try await websocketTask.receive() {
+                        if let error {
-                        case .string(let string):
+                            print("Ping error: \(error). Trying to reconnect.")
-                            let event = try event(string.data(using: .utf8)!)
+                            continuation.yield(.error(.websocketError(error)))
-                            continuation.yield(event)
+                            websocketTask = spawnWebsocketTask(with: continuation)
-                        case .data(let data):
+                        } else {
-                            let event = try event(data)
+                            continuation.yield(.event(Event(type: .receivedWebsocketPong)))
-                            continuation.yield(event)
-                        default:
-                            break
                         }
                     }
-                } catch {
-                    print("Websocket Error: \(error)")
                 }
             }
         }
     }
     
+    private func spawnWebsocketTask(
+        with continuation: AsyncStream<StreamEvent>.Continuation
+    ) -> URLSessionWebSocketTask
+    {
+        let url = request()
+            .path("/events")
+            .websocket()
+        
+        let websocketTask = URLSession.shared.webSocketTask(with: url)
+        websocketTask.resume()
+        
+        Task {
+            do {
+                let event = { (data: Data) in
+                    try JSONDecoder().decode(Event.self, from: data)
+                }
+                
+                while websocketTask.state == .running {
+                    switch try await websocketTask.receive() {
+                    case .string(let string):
+                        let event = try event(string.data(using: .utf8)!)
+                        continuation.yield(.event(event))
+                    case .data(let data):
+                        let event = try event(data)
+                        continuation.yield(.event(event))
+                    default:
+                        break
+                    }
+                }
+            } catch {
+                print("Websocket Error: \(error)")
+            }
+        }
+        
+        return websocketTask
+    }
+    
     private func request() -> RequestBuilder {
         RequestBuilder(url: baseURL)
     }
@@ -152,6 +177,12 @@ struct API
     enum Error: Swift.Error
     {
         case apiNotConfigured
+        case websocketError(Swift.Error)
+    }
+    
+    enum StreamEvent {
+        case event(Event)
+        case error(API.Error)
     }
     
     struct Event: Decodable
@@ -169,6 +200,9 @@ struct API
             case favoritesUpdate     = "favorites_update"
             case metadataUpdate      = "metadata_update"
             case mpdUpdate           = "mpd_update"
+            
+            // Private UI events
+            case receivedWebsocketPong
         }
     }
 }

QueueCube/ContentView.swift

@@ -73,8 +73,14 @@ extension ContentView
         do {
             if what.contains(.nowPlaying) {
                 let nowPlaying = try await api.fetchNowPlayingInfo()
-                model.nowPlayingViewModel.title = nowPlaying.playingItem?.title ?? "??"
+                if let nowPlayingItem = nowPlaying.playingItem, let title = nowPlayingItem.title {
-                model.nowPlayingViewModel.subtitle = nowPlaying.playingItem?.filename ?? "??"
+                    model.nowPlayingViewModel.title = title
+                    model.nowPlayingViewModel.subtitle = nowPlayingItem.filename ?? ""
+                } else {
+                    model.nowPlayingViewModel.title = "(Not Playing)"
+                    model.nowPlayingViewModel.subtitle = ""
+                }
+                
                 model.nowPlayingViewModel.isPlaying = !nowPlaying.isPaused
                 model.nowPlayingViewModel.volume = Double(nowPlaying.volume) / 100.0
                 model.playlistModel.isPlaying = !nowPlaying.isPaused
@@ -86,14 +92,17 @@ extension ContentView
                     PlaylistItem(
                         index: idx,
                         id: String(mediaItem.id),
-                        title: mediaItem.title ?? mediaItem.filename,
+                        title: mediaItem.title ?? mediaItem.filename ?? "<null>",
-                        filename: mediaItem.filename,
+                        filename: mediaItem.filename ?? "<null>",
                         isCurrent: mediaItem.current ?? false
                     )
                 }
             }
+            
+            model.connectionError = nil
         } catch {
             print("Error refreshing content: \(error)")
+            model.connectionError = error
         }
     }
     
@@ -101,9 +110,14 @@ extension ContentView
         guard let api = model.api else { return }
         
         do {
-            for await event in try await api.events() {
+            for await streamEvent in try await api.events() {
-                print("Got event: \(event.type)")
+                switch streamEvent {
-                await handle(event: event)
+                    case .event(let event):
+                        model.connectionError = nil
+                        await handle(event: event)
+                    case .error(let error):
+                        model.connectionError = error
+                }
             }
         } catch {
             print("Events error: \(error)")
@@ -123,6 +137,13 @@ extension ContentView
         case .mpdUpdate:
             await refresh([.playlist, .nowPlaying])
         
+        case .receivedWebsocketPong:
+            // This means we're online.
+            if model.connectionError != nil {
+                model.connectionError = nil
+                await refresh([.playlist, .nowPlaying])
+            }
+            
         default:
             break
         }
@@ -134,6 +155,8 @@ class MainViewModel
 {
     var api = API.fromSettings()
     
+    var connectionError: Error? = nil
+    
     var playlistModel       = PlaylistViewModel()
     var nowPlayingViewModel = NowPlayingViewModel()
     var addMediaViewModel   = AddMediaBarViewModel()
@@ -164,12 +187,10 @@ struct MainView: View
             VStack {
                 NowPlayingView(model: model.nowPlayingViewModel)
                     .padding()
-                    .disabled(showConfigurationDialog)
+                    .disabled(showConfigurationDialog || model.connectionError != nil)
                 
                 if showConfigurationDialog {
-                    Spacer()
+                    ContentPlaceholderView {
-                    
-                    ContentUnavailableView {
                         Image(systemName: "server.rack")
                         Text(.notConfigured)
                     } actions: {
@@ -179,8 +200,11 @@ struct MainView: View
                             Text(.settings)
                         }
                     }
-                    
+                } else if model.connectionError != nil {
-                    Spacer()
+                    ContentPlaceholderView {
+                        Image(systemName: "exclamationmark.triangle.fill")
+                        Text(.connectionError)
+                    }
                 } else {
                     PlaylistView(model: model.playlistModel)
                         .frame(maxWidth: 640.0)
@@ -199,3 +223,26 @@ struct MainView: View
         
     }
 }
+
+struct ContentPlaceholderView<Label, Actions>: View
+    where Label: View, Actions: View
+{
+    let label: Label
+    let actions: Actions
+    
+    init(@ViewBuilder label: () -> Label, @ViewBuilder actions: () -> Actions = { EmptyView() }) {
+        self.label = label()
+        self.actions = actions()
+    }
+    
+    var body: some View {
+        Spacer()
+        
+        ContentUnavailableView {
+            label
+                .imageScale(.large)
+        } actions: { actions }
+        
+        Spacer()
+    }
+}

QueueCube/Localizable/Localizable.xcstrings

@@ -31,6 +31,16 @@
         }
       }
     },
+    "CONNECTION_ERROR" : {
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Connection Error"
+          }
+        }
+      }
+    },
     "DONE" : {
       "localizations" : {
         "en" : {

QueueCube/Localizable/Strings.swift

@@ -21,4 +21,5 @@ extension LocalizedStringKey
     static let configuration    = LocalizedStringKey("CONFIGURATION")
     static let validating       = LocalizedStringKey("VALIDATING")
     static let general          = LocalizedStringKey("GENERAL")
+    static let connectionError  = LocalizedStringKey("CONNECTION_ERROR")
 }