android: changing a chat on user change

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/App.kt

@@ -32,8 +32,7 @@ import chat.simplex.res.MR
 import dev.icerock.moko.resources.compose.painterResource
 import dev.icerock.moko.resources.compose.stringResource
 import kotlinx.coroutines.*
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.*
 
 data class SettingsViewState(
   val userPickerState: MutableStateFlow<AnimatedViewState>,
@@ -194,24 +193,27 @@ fun AndroidScreen(settingsState: SettingsViewState) {
       StartPartOfScreen(settingsState)
     }
     val scope = rememberCoroutineScope()
-    val onComposed: () -> Unit = {
+    val onComposed: suspend (chatId: String?) -> Unit = { chatId ->
+      // coroutine, scope and join() because:
+      // - it should be run from coroutine to wait until this function finishes
+      // - without using scope.launch it throws CancellationException when changing user
+      // - join allows to wait until completion
       scope.launch {
         offset.animateTo(
-          if (chatModel.chatId.value == null) 0f else maxWidth.value,
+          if (chatId == null) 0f else maxWidth.value,
           chatListAnimationSpec()
         )
-        if (offset.value == 0f) {
-          currentChatId = null
-        }
-      }
+      }.join()
     }
     LaunchedEffect(Unit) {
       launch {
         snapshotFlow { chatModel.chatId.value }
           .distinctUntilChanged()
           .collect {
-            if (it != null) currentChatId = it
-            else onComposed()
+            if (it == null) {
+              onComposed(null)
+            }
+            currentChatId = it
           }
       }
     }

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

@@ -43,7 +43,7 @@ import java.net.URI
 import kotlin.math.sign
 
 @Composable
-fun ChatView(chatId: String, chatModel: ChatModel, onComposed: () -> Unit) {
+fun ChatView(chatId: String, chatModel: ChatModel, onComposed: suspend (chatId: String) -> Unit) {
   val activeChat = remember { mutableStateOf(chatModel.chats.firstOrNull { chat -> chat.chatInfo.id == chatId }) }
   val searchText = rememberSaveable { mutableStateOf("") }
   val user = chatModel.currentUser.value
@@ -66,12 +66,11 @@ fun ChatView(chatId: String, chatModel: ChatModel, onComposed: () -> Unit) {
     launch {
       snapshotFlow { chatModel.chatId.value }
         .distinctUntilChanged()
+        .filter { it != null && activeChat.value?.id != it }
         .collect { chatId ->
-          if (activeChat.value?.id != chatId && chatId != null) {
-            // Redisplay the whole hierarchy if the chat is different to make going from groups to direct chat working correctly
-            // Also for situation when chatId changes after clicking in notification, etc
-            activeChat.value = chatModel.getChat(chatId)
-          }
+          // Redisplay the whole hierarchy if the chat is different to make going from groups to direct chat working correctly
+          // Also for situation when chatId changes after clicking in notification, etc
+          activeChat.value = chatModel.getChat(chatId!!)
           markUnreadChatAsRead(activeChat, chatModel)
         }
     }
@@ -91,7 +90,7 @@ fun ChatView(chatId: String, chatModel: ChatModel, onComposed: () -> Unit) {
       }
         .distinctUntilChanged()
         // Only changed chatInfo is important thing. Other properties can be skipped for reducing recompositions
-        .filter { it?.chatInfo != activeChat.value?.chatInfo && it != null }
+        .filter { it != null && it?.chatInfo != activeChat.value?.chatInfo }
         .collect { activeChat.value = it }
     }
   }
@@ -422,7 +421,7 @@ fun ChatLayout(
   markRead: (CC.ItemRange, unreadCountAfter: Int?) -> Unit,
   changeNtfsState: (Boolean, currentValue: MutableState<Boolean>) -> Unit,
   onSearchValueChanged: (String) -> Unit,
-  onComposed: () -> Unit,
+  onComposed: suspend (chatId: String) -> Unit,
 ) {
   val scope = rememberCoroutineScope()
   val attachmentDisabled = remember { derivedStateOf { composeState.value.attachmentDisabled } }
@@ -672,7 +671,7 @@ fun BoxWithConstraintsScope.ChatItemsList(
   showItemDetails: (ChatInfo, ChatItem) -> Unit,
   markRead: (CC.ItemRange, unreadCountAfter: Int?) -> Unit,
   setFloatingButton: (@Composable () -> Unit) -> Unit,
-  onComposed: () -> Unit,
+  onComposed: suspend (chatId: String) -> Unit,
 ) {
   val listState = rememberLazyListState()
   val scope = rememberCoroutineScope()
@@ -703,13 +702,13 @@ fun BoxWithConstraintsScope.ChatItemsList(
       scope.launch { listState.animateScrollToItem(kotlin.math.min(reversedChatItems.lastIndex, index + 1), -maxHeightRounded) }
     }
   }
-  LaunchedEffect(Unit) {
+  LaunchedEffect(chat.id) {
     var stopListening = false
     snapshotFlow { listState.layoutInfo.visibleItemsInfo.lastIndex }
       .distinctUntilChanged()
       .filter { !stopListening }
       .collect {
-        onComposed()
+        onComposed(chat.id)
         stopListening = true
       }
   }