feat(contacts): show online status in user list (#131)

app/src/main/java/de/bollwerk/app/ui/messaging/UserListScreen.kt

@@ -11,7 +11,6 @@ import androidx.compose.foundation.lazy.items
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.outlined.Person
 import androidx.compose.material3.Badge
-import androidx.compose.material3.BadgedBox
 import androidx.compose.material3.Button
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -83,8 +82,10 @@ internal fun UserListScreen(
 
 @Composable
 private fun UserListItem(user: UserListItemDto, unreadCount: Int, onClick: () -> Unit) {
+    val statusText = formatOnlineStatus(user.lastSeen)
     ListItem(
         headlineContent = { Text(user.username) },
+        supportingContent = statusText?.let { { Text(it, style = MaterialTheme.typography.bodySmall) } },
         leadingContent = {
             Icon(imageVector = Icons.Outlined.Person, contentDescription = null)
         },
@@ -97,3 +98,23 @@ private fun UserListItem(user: UserListItemDto, unreadCount: Int, onClick: () ->
     )
     HorizontalDivider()
 }
+
+private fun formatOnlineStatus(lastSeen: Long?): String? {
+    if (lastSeen == null) return null
+    val now = System.currentTimeMillis()
+    if (now - lastSeen < ONLINE_THRESHOLD_MS) return "Verbunden"
+    val dt = java.util.Date(lastSeen)
+    val cal = java.util.Calendar.getInstance().apply { time = dt }
+    val todayCal = java.util.Calendar.getInstance()
+    val isToday = cal.get(java.util.Calendar.YEAR) == todayCal.get(java.util.Calendar.YEAR) &&
+        cal.get(java.util.Calendar.DAY_OF_YEAR) == todayCal.get(java.util.Calendar.DAY_OF_YEAR)
+    val timeFmt = java.text.SimpleDateFormat("HH:mm", java.util.Locale.GERMAN)
+    return if (isToday) {
+        "zuletzt online um ${timeFmt.format(dt)}"
+    } else {
+        val dateFmt = java.text.SimpleDateFormat("dd.MM.", java.util.Locale.GERMAN)
+        "zuletzt online am ${dateFmt.format(dt)} um ${timeFmt.format(dt)}"
+    }
+}
+
+private const val ONLINE_THRESHOLD_MS = 60_000L

app/src/main/java/de/bollwerk/app/ui/messaging/UserListViewModel.kt

@@ -5,10 +5,13 @@ import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import de.bollwerk.app.domain.repository.MessageRepository
 import de.bollwerk.shared.model.UserListItemDto
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import javax.inject.Inject
 
@@ -29,8 +32,30 @@ internal class UserListViewModel @Inject constructor(
     val unreadCounts: StateFlow<Map<String, Int>> = messageRepository.getUnreadCountsBySender()
         .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5000), emptyMap())
 
+    private var pollingJob: Job? = null
+
     init {
         loadUsers()
+        startPolling()
+    }
+
+    private fun startPolling() {
+        pollingJob = viewModelScope.launch {
+            while (isActive) {
+                delay(POLL_INTERVAL_MS)
+                refreshStatuses()
+            }
+        }
+    }
+
+    private suspend fun refreshStatuses() {
+        val result = messageRepository.fetchUsers()
+        if (result.isSuccess) {
+            val fresh = result.getOrDefault(emptyList())
+            _uiState.value = _uiState.value.copy(users = fresh)
+        } else {
+            android.util.Log.w(TAG, "Online-Status-Polling fehlgeschlagen: ${result.exceptionOrNull()?.message}")
+        }
     }
 
     private fun loadUsers() {
@@ -49,4 +74,9 @@ internal class UserListViewModel @Inject constructor(
     }
 
     fun retry() = loadUsers()
+
+    private companion object {
+        const val POLL_INTERVAL_MS = 30_000L
+        const val TAG = "UserListViewModel"
+    }
 }

server/src/main/kotlin/de/bollwerk/server/routes/UserRoutes.kt

@@ -25,9 +25,14 @@ internal fun Route.userRoutes(userRepository: UserRepository, webSocketManager:
                 HttpStatusCode.Unauthorized,
                 ErrorResponse(status = 401, message = "Unauthorized")
             )
+        val now = System.currentTimeMillis()
         val users = userRepository.listAll()
             .filter { it.id != principal.userId }
-            .map { UserListItemDto(id = it.id, username = it.username) }
+            .map { user ->
+                val online = webSocketManager.isOnline(user.id)
+                val lastSeen = if (online) now else webSocketManager.getLastSeen(user.id)
+                UserListItemDto(id = user.id, username = user.username, lastSeen = lastSeen)
+            }
         call.respond(HttpStatusCode.OK, users)
     }
 

server/src/main/kotlin/de/bollwerk/server/websocket/WebSocketManager.kt

@@ -13,17 +13,22 @@ import java.util.concurrent.CopyOnWriteArraySet
 internal class WebSocketManager {
 
     private val sessions = ConcurrentHashMap<String, CopyOnWriteArraySet<WebSocketSession>>()
+    private val lastSeenMap = ConcurrentHashMap<String, Long>()
 
     fun addSession(userId: String, session: WebSocketSession) {
-        sessions.getOrPut(userId) { CopyOnWriteArraySet() }.add(session)
+        sessions.computeIfAbsent(userId) { CopyOnWriteArraySet() }.add(session)
+        lastSeenMap[userId] = System.currentTimeMillis()
     }
 
     fun removeSession(userId: String, session: WebSocketSession) {
         sessions[userId]?.remove(session)
+        lastSeenMap[userId] = System.currentTimeMillis()
     }
 
     fun isOnline(userId: String): Boolean = sessions[userId]?.isNotEmpty() == true
 
+    fun getLastSeen(userId: String): Long? = lastSeenMap[userId]
+
     suspend fun notifyInventoryUpdated(userId: String, itemId: String) {
         val payload = buildJsonObject {
             put("type", "inventoryUpdated")

shared/src/main/kotlin/de/bollwerk/shared/model/UserListItemDto.kt

@@ -5,5 +5,6 @@ import kotlinx.serialization.Serializable
 @Serializable
 data class UserListItemDto(
     val id: String,
-    val username: String
+    val username: String,
+    val lastSeen: Long? = null
 )