reduce to 2 seconds

apps/ios/Shared/Model/ChatModel.swift

@@ -337,12 +337,10 @@ final class ChatModel: ObservableObject {
                 increaseUnreadCounter(user: currentUser!)
             }
             if i > 0 {
-                if chatId == nil {
-                    withAnimation { popChat_(i) }
-                } else if chatId == cInfo.id  {
+                if chatId == cInfo.id {
                     chatToTop = cInfo.id
                 } else {
-                    popChat_(i)
+                    popChatCollector.addChat(cInfo.id)
                 }
             }
         } else {
@@ -579,7 +577,7 @@ final class ChatModel: ObservableObject {
                     // update current chat
                     markChatItemRead_(itemIndex)
                     // update preview
-                    unreadCollector.decreaseUnreadCounter(chatIndex)
+                    unreadCollector.decreaseUnreadCounter(cInfo.id)
                 }
             }
         }
@@ -588,29 +586,76 @@ final class ChatModel: ObservableObject {
     private let unreadCollector = UnreadCollector()
 
     class UnreadCollector {
-        private let subject = PassthroughSubject<Int, Never>()
+        private let subject = PassthroughSubject<Void, Never>()
         private var bag = Set<AnyCancellable>()
-        private var dictionary = Dictionary<Int, Int>()
+        private var unreadCounts: [ChatId: Int] = [:]
 
         init() {
             subject
                 .debounce(for: 1, scheduler: DispatchQueue.main)
-                .sink { _ in
-                    self.dictionary.forEach { key, value in
-                        ChatModel.shared.decreaseUnreadCounter(key, by: value)
+                .sink {
+                    let m = ChatModel.shared
+                    for (chatId, count) in self.unreadCounts {
+                        if let i = m.getChatIndex(chatId) {
+                            m.decreaseUnreadCounter(i, by: count)
+                        }
                     }
-                    self.dictionary = Dictionary<Int, Int>()
+                    self.unreadCounts = [:]
                 }
                 .store(in: &bag)
         }
         
         // Only call from main thread
-        func decreaseUnreadCounter(_ chatIndex: Int) {
-            dictionary[chatIndex] = (dictionary[chatIndex] ?? 0) + 1
-            subject.send(chatIndex)
+        func decreaseUnreadCounter(_ chatId: ChatId) {
+            unreadCounts[chatId] = (unreadCounts[chatId] ?? 0) + 1
+            subject.send()
         }
     }
 
+    let popChatCollector = PopChatCollector()
+    
+    class PopChatCollector {
+        private let subject = PassthroughSubject<Void, Never>()
+        private var bag = Set<AnyCancellable>()
+        private var chatsToPop: [ChatId: Date] = [:]
+
+        init() {
+            subject
+                .throttle(for: 2, scheduler: DispatchQueue.main, latest: true)
+                .sink { self.popRecentChats() }
+                .store(in: &bag)
+        }
+
+        // Only call from main thread
+        func addChat(_ chatId: ChatId) {
+            chatsToPop[chatId] = Date.now
+            subject.send()
+        }
+                
+        func popRecentChats() {
+            let m = ChatModel.shared
+            var ixs: IndexSet = []
+            var chs: [(Chat, Date)] = []
+            // collect chats that received updates
+            for (chatId, ts) in chatsToPop {
+                if m.chatId != chatId, let i = m.getChatIndex(chatId) {
+                    ixs.insert(i)
+                    chs.append((m.chats[i], ts))
+                }
+            }
+            
+            // sort chats by timestamp in descending order
+            chs.sort { ch1, ch2 in ch1.1 > ch2.1 }
+
+            withAnimation {
+                m.chats.remove(atOffsets: ixs)
+                m.chats.insert(contentsOf: chs.map { $0.0 }, at: 0)
+            }
+
+            chatsToPop = [:]
+        }
+    }
+    
     private func markChatItemRead_(_ i: Int) {
         let meta = im.reversedChatItems[i].meta
         if case .rcvNew = meta.itemStatus {

apps/ios/Shared/Views/ChatList/ChatListView.swift

@@ -158,8 +158,8 @@ struct ChatListView: View {
                     .offset(x: -8)
                 }
             }
-            .onChange(of: chatModel.chatId) { _ in
-                if chatModel.chatId == nil, let chatId = chatModel.chatToTop {
+            .onChange(of: chatModel.chatId) { chId in
+                if chId == nil, let chatId = chatModel.chatToTop {
                     chatModel.chatToTop = nil
                     chatModel.popChat(chatId)
                 }