Implements signals

kordophone2/ChatTranscriptView.swift

@@ -11,6 +11,8 @@ struct ChatTranscriptView: View
 {
     @Binding var model: ViewModel
     
+    @Environment(\.xpcClient) private var xpcClient
+    
     var body: some View {
         ScrollView {
             LazyVStack(spacing: 17.0) {
@@ -18,11 +20,26 @@ struct ChatTranscriptView: View
                     MessageCellView(message: message)
                         .id(message.id)
                         .scaleEffect(CGSize(width: 1.0, height: -1.0))
+                        .transition(
+                            .push(from: .bottom)
+                            .combined(with: .opacity)
+                        )
                 }
             }
             .padding()
         }
         .scaleEffect(CGSize(width: 1.0, height: -1.0))
+        .task { await watchForMessageListChanges() }
+    }
+    
+    private func watchForMessageListChanges() async {
+        for await event in xpcClient.eventStream() {
+            if case let .messagesUpdated(conversationId) = event {
+                if conversationId == model.displayedConversation {
+                    model.setNeedsReload()
+                }
+            }
+        }
     }
     
     // MARK: - Types
@@ -32,7 +49,8 @@ struct ChatTranscriptView: View
     {
         var messages: [Display.Message]
         var displayedConversation: Display.Conversation.ID? = nil
-        
+        var needsReload: Bool = true
+
         init(messages: [Display.Message] = []) {
             self.messages = messages
             observeDisplayedConversation()
@@ -45,21 +63,37 @@ struct ChatTranscriptView: View
                 Task { @MainActor [weak self] in
                     guard let self else { return }
                     
-                    await loadMessages()
+                    setNeedsReload()
                     observeDisplayedConversation()
                 }
             }
         }
+
+        func setNeedsReload() {
+            needsReload = true
+            Task { @MainActor [weak self] in
+                guard let self else { return }
+                await reloadMessages()
+            }
+        }
         
-        private func loadMessages() async {
-            self.messages = []
+        func reloadMessages() async {
+            guard needsReload else { return }
+            needsReload = false
             
             guard let displayedConversation else { return }
             
             do {
                 let client = XPCClient()
-                let messages = try await client.getMessages(conversationId: displayedConversation)
-                self.messages = messages.map { Display.Message(from: $0) }
+                let clientMessages = try await client.getMessages(conversationId: displayedConversation)
+                    .map { Display.Message(from: $0) }
+                
+                let newMessages = Set(clientMessages).subtracting(Set(self.messages))
+                
+                let animation: Animation? = newMessages.count == 1 ? .default : nil
+                withAnimation(animation) {
+                    self.messages = clientMessages
+                }
             } catch {
                 print("Message fetch error: \(error)")
             }