Add MatrixClient.totalUnreadCountFlow() extension

Extract the logic to observe the total unread count of a MatrixClient, refreshed on each sync
heartbeat, to a shared extension and use it in HomePresenter and PreferencesRootPresenter.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

features/home/impl/src/main/kotlin/io/element/android/features/home/impl/HomePresenter.kt

@@ -14,7 +14,6 @@ import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableIntStateOf
-import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
@@ -33,16 +32,12 @@ import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.indicator.api.IndicatorService
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.matrix.api.sync.SyncService
+import io.element.android.libraries.matrix.api.totalUnreadCountFlow
 import io.element.android.libraries.sessionstorage.api.SessionStore
 import kotlinx.collections.immutable.persistentListOf
-import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.debounce
 import kotlinx.coroutines.flow.filter
-import kotlinx.coroutines.flow.mapLatest
 import kotlinx.coroutines.launch
-import kotlin.time.Duration.Companion.milliseconds
 
 @Inject
 class HomePresenter(
@@ -59,20 +54,13 @@ class HomePresenter(
 ) : Presenter<HomeState> {
     private val currentUserWithNeighborsBuilder = CurrentUserWithNeighborsBuilder()
 
-    @OptIn(FlowPreview::class, ExperimentalCoroutinesApi::class)
     @Composable
     override fun present(): HomeState {
         val coroutineState = rememberCoroutineScope()
         val matrixUser by client.userProfile.collectAsState()
-
-        val totalUnreadCount by produceState(client.totalUnreadCount().getOrDefault(0).toInt()) {
-            syncService.heartBeat
-                // Delay the heartbeat so the SDK has time to update the unread count before we read it.
-                .debounce(100.milliseconds)
-                .mapLatest { client.totalUnreadCount().getOrDefault(0).toInt() }
-                .collect { value = it }
-        }
-
+        val totalUnreadCount by remember { client.totalUnreadCountFlow() }
+            // The initial value is only used for the first composition, remember it to avoid calling the SDK on every recomposition.
+            .collectAsState(initial = remember { client.totalUnreadCount().getOrDefault(0).toInt() })
         val currentUserAndNeighbors by remember {
             combine(
                 client.userProfile,

features/home/impl/src/test/kotlin/io/element/android/features/home/impl/HomePresenterTest.kt

@@ -6,6 +6,8 @@
  * Please see LICENSE files in the repository root for full details.
  */
 
+@file:OptIn(ExperimentalCoroutinesApi::class)
+
 package io.element.android.features.home.impl
 
 import com.google.common.truth.Truth.assertThat
@@ -39,6 +41,7 @@ import io.element.android.tests.testutils.WarmUpRule
 import io.element.android.tests.testutils.lambda.lambdaRecorder
 import io.element.android.tests.testutils.lambda.value
 import io.element.android.tests.testutils.test
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.test.advanceTimeBy
 import kotlinx.coroutines.test.runTest
@@ -124,7 +127,10 @@ class HomePresenterTest {
         var unreadCount = 0L
         val syncService = FakeSyncService()
         val presenter = createHomePresenter(
-            client = FakeMatrixClient(totalUnreadCountResult = { Result.success(unreadCount) }),
+            client = FakeMatrixClient(
+                syncService = syncService,
+                totalUnreadCountResult = { Result.success(unreadCount) },
+            ),
             syncService = syncService,
         )
         presenter.test {
@@ -140,7 +146,10 @@ class HomePresenterTest {
     fun `present - total unread count defaults to 0 when the SDK call fails`() = runTest {
         val syncService = FakeSyncService()
         val presenter = createHomePresenter(
-            client = FakeMatrixClient(totalUnreadCountResult = { Result.failure(AN_EXCEPTION) }),
+            client = FakeMatrixClient(
+                syncService = syncService,
+                totalUnreadCountResult = { Result.failure(AN_EXCEPTION) },
+            ),
             syncService = syncService,
         )
         presenter.test {

features/preferences/impl/src/main/kotlin/io/element/android/features/preferences/impl/root/PreferencesRootPresenter.kt

@@ -32,6 +32,7 @@ import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.matrix.api.MatrixClientProvider
 import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.totalUnreadCountFlow
 import io.element.android.libraries.matrix.api.user.toMatrixUser
 import io.element.android.libraries.preferences.api.store.AppPreferencesStore
 import io.element.android.libraries.sessionstorage.api.SessionStore
@@ -40,17 +41,12 @@ import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.debounce
-import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.launch
-import kotlin.time.Duration.Companion.milliseconds
 
 @OptIn(ExperimentalCoroutinesApi::class)
 @Inject
@@ -182,14 +178,8 @@ class PreferencesRootPresenter(
         )
     }
 
-    @OptIn(FlowPreview::class)
     private fun unreadCountFlow(sessionId: SessionId): Flow<Int> {
         val client = matrixClientProvider.getOrNull(sessionId) ?: return flowOf(0)
-        return client.syncService.heartBeat
-            // Delay the heartbeat so the SDK has time to update the unread count before we read it.
-            .debounce(100.milliseconds)
-            .onStart { emit(Unit) }
-            .map { client.totalUnreadCount().getOrDefault(0).toInt() }
-            .distinctUntilChanged()
+        return client.totalUnreadCountFlow()
     }
 }

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/MatrixClient.kt

@@ -51,9 +51,15 @@ import io.element.android.libraries.matrix.api.user.UserStatus
 import io.element.android.libraries.matrix.api.verification.SessionVerificationService
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onStart
 import java.util.Optional
+import kotlin.time.Duration.Companion.milliseconds
 
 /**
  * Entry point for everything scoped to a single logged in session: the sub-services, room access, and account level operations.
@@ -523,3 +529,18 @@ fun MatrixClient.roomAliasFromName(name: String): RoomAlias? {
         ?.takeIf { MatrixPatterns.isRoomAlias(it) }
         ?.let { tryOrNull { RoomAlias(it) } }
 }
+
+/**
+ * Returns a flow of the total number of unread notifications across all rooms.
+ * The first value is emitted immediately, then the value is refreshed on each sync heartbeat.
+ * In case of error, 0 is emitted.
+ */
+@OptIn(FlowPreview::class)
+fun MatrixClient.totalUnreadCountFlow(): Flow<Int> {
+    return syncService.heartBeat
+        // Delay the heartbeat so the SDK has time to update the unread count before we read it.
+        .debounce(100.milliseconds)
+        .onStart { emit(Unit) }
+        .map { totalUnreadCount().getOrDefault(0).toInt() }
+        .distinctUntilChanged()
+}