Add stateInWhileSubscribed extension (#3456)

core/ui/src/main/kotlin/org/meshtastic/core/ui/qr/ScannedQrCodeViewModel.kt

@@ -21,12 +21,11 @@ import android.os.RemoteException
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
-import kotlinx.coroutines.flow.SharingStarted
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import org.meshtastic.core.data.repository.RadioConfigRepository
 import org.meshtastic.core.proto.getChannelList
 import org.meshtastic.core.service.ServiceRepository
+import org.meshtastic.core.ui.viewmodel.stateInWhileSubscribed
 import org.meshtastic.proto.AppOnlyProtos
 import org.meshtastic.proto.ChannelProtos
 import org.meshtastic.proto.ConfigProtos.Config
@@ -44,19 +43,10 @@ constructor(
     private val serviceRepository: ServiceRepository,
 ) : ViewModel() {
 
-    val channels =
-        radioConfigRepository.channelSetFlow.stateIn(
-            viewModelScope,
-            SharingStarted.WhileSubscribed(5_000L),
-            channelSet {},
-        )
+    val channels = radioConfigRepository.channelSetFlow.stateInWhileSubscribed(initialValue = channelSet {})
 
     private val localConfig =
-        radioConfigRepository.localConfigFlow.stateIn(
-            viewModelScope,
-            SharingStarted.WhileSubscribed(5_000L),
-            LocalConfig.getDefaultInstance(),
-        )
+        radioConfigRepository.localConfigFlow.stateInWhileSubscribed(initialValue = LocalConfig.getDefaultInstance())
 
     /** Set the radio config (also updates our saved copy in preferences). */
     fun setChannels(channelSet: AppOnlyProtos.ChannelSet) = viewModelScope.launch {

core/ui/src/main/kotlin/org/meshtastic/core/ui/share/SharedContactViewModel.kt

@@ -20,14 +20,13 @@ package org.meshtastic.core.ui.share
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
-import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import org.meshtastic.core.data.repository.NodeRepository
 import org.meshtastic.core.database.model.Node
 import org.meshtastic.core.service.ServiceAction
 import org.meshtastic.core.service.ServiceRepository
+import org.meshtastic.core.ui.viewmodel.stateInWhileSubscribed
 import org.meshtastic.proto.AdminProtos
 import javax.inject.Inject
 
@@ -40,13 +39,7 @@ constructor(
 ) : ViewModel() {
 
     val unfilteredNodes: StateFlow<List<Node>> =
-        nodeRepository
-            .getNodes()
-            .stateIn(
-                scope = viewModelScope,
-                started = SharingStarted.WhileSubscribed(5_000),
-                initialValue = emptyList(),
-            )
+        nodeRepository.getNodes().stateInWhileSubscribed(initialValue = emptyList())
 
     fun addSharedContact(sharedContact: AdminProtos.SharedContact) =
         viewModelScope.launch { serviceRepository.onServiceAction(ServiceAction.ImportContact(sharedContact)) }

core/ui/src/main/kotlin/org/meshtastic/core/ui/viewmodel/ViewModelExtensions.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2025 Meshtastic LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+@file:Suppress("Wrapping", "UnusedImports", "SpacingAroundColon")
+
+package org.meshtastic.core.ui.viewmodel
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.stateIn
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.seconds
+
+/**
+ * Extension for converting a [Flow] to a [StateFlow] in a [ViewModel] context.
+ *
+ * @param initialValue the initial value of the state flow
+ * @param stopTimeout configures a delay between the disappearance of the last subscriber and the stopping of the
+ *   sharing coroutine.
+ */
+context(viewModel: ViewModel)
+fun <T> Flow<T>.stateInWhileSubscribed(initialValue: T, stopTimeout: Duration = 5.seconds): StateFlow<T> = stateIn(
+    scope = viewModel.viewModelScope,
+    started = SharingStarted.WhileSubscribed(stopTimeoutMillis = stopTimeout.inWholeMilliseconds),
+    initialValue = initialValue,
+)