Improve scroll to bottom behavior of chat panel

Author: intitni

Core/Sources/ChatGPTChatTab/Chat.swift

@@ -226,9 +226,13 @@ struct Chat: ReducerProtocol {
                             cancellable.cancel()
                         }
                     }
-                    for await _ in stream {
+                    let debouncedHistoryChange = TimedDebounceFunction(duration: 0.2) {
                         await send(.historyChanged)
                     }
+                    
+                    for await _ in stream {
+                        await debouncedHistoryChange()
+                    }
                 }.cancellable(id: CancelID.observeHistoryChange(id), cancelInFlight: true)
 
             case .observeIsReceivingMessageChange:
@@ -450,3 +454,33 @@ struct ChatMenu: ReducerProtocol {
     }
 }
 
+private actor TimedDebounceFunction {
+    let duration: TimeInterval
+    let block: () async -> Void
+
+    var task: Task<Void, Error>?
+    var lastFireTime: Date = .init(timeIntervalSince1970: 0)
+
+    init(duration: TimeInterval, block: @escaping () async -> Void) {
+        self.duration = duration
+        self.block = block
+    }
+
+    func callAsFunction() async {
+        task?.cancel()
+        if lastFireTime.timeIntervalSinceNow < -duration {
+            await fire()
+            task = nil
+        } else {
+            task = Task.detached { [weak self, duration] in
+                try await Task.sleep(nanoseconds: UInt64(duration * 1_000_000_000))
+                await self?.fire()
+            }
+        }
+    }
+    
+    func fire() async {
+        lastFireTime = Date()
+        await block()
+    }
+}

Core/Sources/ChatGPTChatTab/ChatPanel.swift

@@ -228,7 +228,10 @@ struct ChatPanelMessages: View {
                             if isInitialLoad {
                                 isInitialLoad = false
                             }
-                            scrollToBottom()
+                            Task {
+                                await Task.yield()
+                                scrollToBottom()
+                            }
                         }
                     }
             }