Reset indicator after leaving chat

Author: FelberMartin

feature/metis/conversation/src/main/kotlin/de/tum/informatics/www1/artemis/native_app/feature/metis/conversation/ui/ConversationScreen.kt

@@ -10,6 +10,7 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.material3.VerticalDivider
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
@@ -50,6 +51,10 @@ fun ConversationScreen(
         viewModel.updateOpenedThread(threadPostId)
     }
 
+    DisposableEffect(viewModel) {
+        onDispose { viewModel.chatListUseCase.resetLastAlreadyReadPostId() }
+    }
+
     val showThread by remember(threadPostId) {
         mutableStateOf(threadPostId != null)
     }

feature/metis/conversation/src/main/kotlin/de/tum/informatics/www1/artemis/native_app/feature/metis/conversation/ui/chatlist/ConversationChatListUseCase.kt

@@ -120,6 +120,10 @@ class ConversationChatListUseCase(
     // We store this in addition to the unreadPostCount, because as new posts come in, the unreadPostCount will become outdated.
     private var lastAlreadyReadPostId: Long? = null
 
+    fun resetLastAlreadyReadPostId() {
+        lastAlreadyReadPostId = null
+    }
+
     @OptIn(ExperimentalPagingApi::class)
     val postPagingData: Flow<PagingData<ChatListItem>> =
         pagingDataInput.flatMapLatest { pagingDataInput ->