android, desktop: throttle items moving around in chat list too often (#4617)

* android, desktop: throttle items moving around in chat list too often

* test

* Revert "test"

This reverts commit 82db198ed9.

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/ChatModel.kt

@@ -19,6 +19,8 @@ import chat.simplex.res.MR
 import dev.icerock.moko.resources.ImageResource
 import dev.icerock.moko.resources.StringResource
 import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.flow.internal.ChannelFlow
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.datetime.*
@@ -301,9 +303,7 @@ object ChatModel {
           else
             chat.chatStats
         )
-        if (i > 0) {
-          chats.add(index = 0, chats.removeAt(i))
-        }
+        popChatCollector.addChat(chat.remoteHostId, chat.id)
       } else {
         addChat(Chat(remoteHostId = rhId, chatInfo = cInfo, chatItems = arrayListOf(cItem)))
       }
@@ -421,6 +421,32 @@ object ChatModel {
       }
     }
 
+    private val popChatCollector = PopChatCollector()
+
+    class PopChatCollector {
+      private val subject = MutableSharedFlow<Unit>()
+
+      init {
+        withLongRunningApi {
+          subject
+            .throttleLatest(2000)
+            .collect {
+              withChats {
+                chats.replaceAll(chats.value.sortedByDescending { it.popTs })
+              }
+            }
+        }
+      }
+
+      suspend fun addChat(remoteHostId: Long?, chatId: ChatId) {
+        val index = getChatIndex(remoteHostId, chatId)
+        if (index >= 0) {
+          chats.value[index].popTs = Clock.System.now()
+          subject.emit(Unit)
+        }
+      }
+    }
+
     fun markChatItemsRead(remoteHostId: Long?, chatInfo: ChatInfo, range: CC.ItemRange? = null, unreadCountAfter: Int? = null) {
       val cInfo = chatInfo
       val markedRead = markItemsReadInCurrentChat(chatInfo, range)
@@ -847,6 +873,9 @@ data class Chat(
   val chatItems: List<ChatItem>,
   val chatStats: ChatStats = ChatStats()
 ) {
+  @Transient
+  var popTs: Instant? = null
+
   val nextSendGrpInv: Boolean
     get() = when (chatInfo) {
       is ChatInfo.Direct -> chatInfo.contact.nextSendGrpInv

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/helpers/Utils.kt

@@ -16,6 +16,7 @@ import chat.simplex.res.MR
 import com.charleskorn.kaml.decodeFromStream
 import dev.icerock.moko.resources.StringResource
 import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.*
 import kotlinx.serialization.encodeToString
 import java.io.*
 import java.net.URI
@@ -535,6 +536,13 @@ fun TextUnit.toDp(): Dp {
   return Dp(value * LocalDensity.current.fontScale)
 }
 
+fun <T> Flow<T>.throttleLatest(delayMillis: Long): Flow<T> = this
+  .conflate()
+  .transform {
+    emit(it)
+    delay(delayMillis)
+  }
+
 @Composable
 fun DisposableEffectOnGone(always: () -> Unit = {}, whenDispose: () -> Unit = {}, whenGone: () -> Unit) {
   DisposableEffect(Unit) {