Refactor CaptioningRepository to take current UserHandle into account.

CaptioningRepository now uses `createContextAsUser` to get a
CaptioningManager for current user.

Flag: EXEMPT BUGFIX
Fixes: 361042246
Test: atest VolumePanelScreenshotTest
Test: atest CaptioningViewModelTest
Change-Id: I32cec55231db16bc3b7401716326b8b8f2a631d7

9 files changed, 183 insertions, 134 deletions

diff --git a/packages/SystemUI/multivalentTests/src/com/android/systemui/accessibility/data/repository/CaptioningRepositoryTest.kt b/packages/SystemUI/multivalentTests/src/com/android/systemui/accessibility/data/repository/CaptioningRepositoryTest.kt
index dd85d9bd2d7c..fc57757c9a8c 100644
--- a/packages/SystemUI/multivalentTests/src/com/android/systemui/accessibility/data/repository/CaptioningRepositoryTest.kt
+++ b/packages/SystemUI/multivalentTests/src/com/android/systemui/accessibility/data/repository/CaptioningRepositoryTest.kt
@@ -20,11 +20,15 @@ import android.view.accessibility.CaptioningManager
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.filters.SmallTest
 import com.android.systemui.SysuiTestCase
+import com.android.systemui.coroutines.collectValues
+import com.android.systemui.kosmos.applicationCoroutineScope
+import com.android.systemui.kosmos.testScope
+import com.android.systemui.testKosmos
+import com.android.systemui.user.data.repository.userRepository
+import com.android.systemui.user.utils.FakeUserScopedService
 import com.google.common.truth.Truth.assertThat
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.flow.filterNotNull
 import kotlinx.coroutines.test.runCurrent
 import kotlinx.coroutines.test.runTest
 import org.junit.Before
@@ -39,10 +43,11 @@ import org.mockito.MockitoAnnotations
 
 @OptIn(ExperimentalCoroutinesApi::class)
 @SmallTest
-@Suppress("UnspecifiedRegisterReceiverFlag")
 @RunWith(AndroidJUnit4::class)
 class CaptioningRepositoryTest : SysuiTestCase() {
 
+    private val kosmos = testKosmos()
+
     @Captor
     private lateinit var listenerCaptor: ArgumentCaptor<CaptioningManager.CaptioningChangeListener>
 
@@ -50,34 +55,33 @@ class CaptioningRepositoryTest : SysuiTestCase() {
 
     private lateinit var underTest: CaptioningRepository
 
-    private val testScope = TestScope()
-
     @Before
     fun setup() {
         MockitoAnnotations.initMocks(this)
 
         underTest =
-            CaptioningRepositoryImpl(
-                captioningManager,
-                testScope.testScheduler,
-                testScope.backgroundScope
-            )
+            with(kosmos) {
+                CaptioningRepositoryImpl(
+                    FakeUserScopedService(captioningManager),
+                    userRepository,
+                    testScope.testScheduler,
+                    applicationCoroutineScope,
+                )
+            }
     }
 
     @Test
     fun isSystemAudioCaptioningEnabled_change_repositoryEmits() {
-        testScope.runTest {
-            `when`(captioningManager.isEnabled).thenReturn(false)
-            val isSystemAudioCaptioningEnabled = mutableListOf<Boolean>()
-            underTest.isSystemAudioCaptioningEnabled
-                .onEach { isSystemAudioCaptioningEnabled.add(it) }
-                .launchIn(backgroundScope)
+        kosmos.testScope.runTest {
+            `when`(captioningManager.isSystemAudioCaptioningEnabled).thenReturn(false)
+            val models by collectValues(underTest.captioningModel.filterNotNull())
             runCurrent()
 
+            `when`(captioningManager.isSystemAudioCaptioningEnabled).thenReturn(true)
             triggerOnSystemAudioCaptioningChange()
             runCurrent()
 
-            assertThat(isSystemAudioCaptioningEnabled)
+            assertThat(models.map { it.isSystemAudioCaptioningEnabled })
                 .containsExactlyElementsIn(listOf(false, true))
                 .inOrder()
         }
@@ -85,18 +89,16 @@ class CaptioningRepositoryTest : SysuiTestCase() {
 
     @Test
     fun isSystemAudioCaptioningUiEnabled_change_repositoryEmits() {
-        testScope.runTest {
-            `when`(captioningManager.isSystemAudioCaptioningUiEnabled).thenReturn(false)
-            val isSystemAudioCaptioningUiEnabled = mutableListOf<Boolean>()
-            underTest.isSystemAudioCaptioningUiEnabled
-                .onEach { isSystemAudioCaptioningUiEnabled.add(it) }
-                .launchIn(backgroundScope)
+        kosmos.testScope.runTest {
+            `when`(captioningManager.isEnabled).thenReturn(false)
+            val models by collectValues(underTest.captioningModel.filterNotNull())
             runCurrent()
 
+            `when`(captioningManager.isSystemAudioCaptioningUiEnabled).thenReturn(true)
             triggerSystemAudioCaptioningUiChange()
             runCurrent()
 
-            assertThat(isSystemAudioCaptioningUiEnabled)
+            assertThat(models.map { it.isSystemAudioCaptioningUiEnabled })
                 .containsExactlyElementsIn(listOf(false, true))
                 .inOrder()
         }
diff --git a/packages/SystemUI/src/com/android/systemui/accessibility/data/model/CaptioningModel.kt b/packages/SystemUI/src/com/android/systemui/accessibility/data/model/CaptioningModel.kt
new file mode 100644
index 000000000000..4eb2274cf129
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/accessibility/data/model/CaptioningModel.kt
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.accessibility.data.model
+
+data class CaptioningModel(
+    val isSystemAudioCaptioningUiEnabled: Boolean,
+    val isSystemAudioCaptioningEnabled: Boolean,
+)
diff --git a/packages/SystemUI/src/com/android/systemui/accessibility/data/repository/CaptioningRepository.kt b/packages/SystemUI/src/com/android/systemui/accessibility/data/repository/CaptioningRepository.kt
index bf749d4cfc35..5414b623ff97 100644
--- a/packages/SystemUI/src/com/android/systemui/accessibility/data/repository/CaptioningRepository.kt
+++ b/packages/SystemUI/src/com/android/systemui/accessibility/data/repository/CaptioningRepository.kt
@@ -16,98 +16,90 @@
 
 package com.android.systemui.accessibility.data.repository
 
+import android.annotation.SuppressLint
 import android.view.accessibility.CaptioningManager
+import com.android.systemui.accessibility.data.model.CaptioningModel
+import com.android.systemui.dagger.qualifiers.Application
+import com.android.systemui.dagger.qualifiers.Background
+import com.android.systemui.user.data.repository.UserRepository
+import com.android.systemui.user.utils.UserScopedService
+import com.android.systemui.utils.coroutines.flow.conflatedCallbackFlow
+import javax.inject.Inject
 import kotlin.coroutines.CoroutineContext
 import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.channels.ProducerScope
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.channels.awaitClose
-import kotlinx.coroutines.flow.SharedFlow
+import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.callbackFlow
-import kotlinx.coroutines.flow.filterIsInstance
+import kotlinx.coroutines.flow.filterNotNull
+import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.flowOn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onStart
-import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.flow.stateIn
-import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 interface CaptioningRepository {
 
-    /** The system audio caption enabled state. */
-    val isSystemAudioCaptioningEnabled: StateFlow<Boolean>
+    /** Current state of Live Captions. */
+    val captioningModel: StateFlow<CaptioningModel?>
 
-    /** The system audio caption UI enabled state. */
-    val isSystemAudioCaptioningUiEnabled: StateFlow<Boolean>
-
-    /** Sets [isSystemAudioCaptioningEnabled]. */
+    /** Sets [CaptioningModel.isSystemAudioCaptioningEnabled]. */
     suspend fun setIsSystemAudioCaptioningEnabled(isEnabled: Boolean)
 }
 
-class CaptioningRepositoryImpl(
-    private val captioningManager: CaptioningManager,
-    private val backgroundCoroutineContext: CoroutineContext,
-    coroutineScope: CoroutineScope,
+@OptIn(ExperimentalCoroutinesApi::class)
+class CaptioningRepositoryImpl
+@Inject
+constructor(
+    private val userScopedCaptioningManagerProvider: UserScopedService<CaptioningManager>,
+    userRepository: UserRepository,
+    @Background private val backgroundCoroutineContext: CoroutineContext,
+    @Application coroutineScope: CoroutineScope,
 ) : CaptioningRepository {
 
-    private val captioningChanges: SharedFlow<CaptioningChange> =
-        callbackFlow {
-                val listener = CaptioningChangeProducingListener(this)
-                captioningManager.addCaptioningChangeListener(listener)
-                awaitClose { captioningManager.removeCaptioningChangeListener(listener) }
-            }
-            .shareIn(coroutineScope, SharingStarted.WhileSubscribed(), replay = 0)
-
-    override val isSystemAudioCaptioningEnabled: StateFlow<Boolean> =
-        captioningChanges
-            .filterIsInstance(CaptioningChange.IsSystemAudioCaptioningEnabled::class)
-            .map { it.isEnabled }
-            .onStart { emit(captioningManager.isSystemAudioCaptioningEnabled) }
-            .stateIn(
-                coroutineScope,
-                SharingStarted.WhileSubscribed(),
-                captioningManager.isSystemAudioCaptioningEnabled,
-            )
+    @SuppressLint("NonInjectedService") // this uses user-aware context
+    private val captioningManager: StateFlow<CaptioningManager?> =
+        userRepository.selectedUser
+            .map { userScopedCaptioningManagerProvider.forUser(it.userInfo.userHandle) }
+            .stateIn(coroutineScope, SharingStarted.WhileSubscribed(), null)
 
-    override val isSystemAudioCaptioningUiEnabled: StateFlow<Boolean> =
-        captioningChanges
-            .filterIsInstance(CaptioningChange.IsSystemUICaptioningEnabled::class)
-            .map { it.isEnabled }
-            .onStart { emit(captioningManager.isSystemAudioCaptioningUiEnabled) }
-            .stateIn(
-                coroutineScope,
-                SharingStarted.WhileSubscribed(),
-                captioningManager.isSystemAudioCaptioningUiEnabled,
-            )
+    override val captioningModel: StateFlow<CaptioningModel?> =
+        captioningManager
+            .filterNotNull()
+            .flatMapLatest { it.captioningModel() }
+            .stateIn(coroutineScope, SharingStarted.WhileSubscribed(), null)
 
     override suspend fun setIsSystemAudioCaptioningEnabled(isEnabled: Boolean) {
         withContext(backgroundCoroutineContext) {
-            captioningManager.isSystemAudioCaptioningEnabled = isEnabled
+            captioningManager.value?.isSystemAudioCaptioningEnabled = isEnabled
         }
     }
 
-    private sealed interface CaptioningChange {
-
-        data class IsSystemAudioCaptioningEnabled(val isEnabled: Boolean) : CaptioningChange
-
-        data class IsSystemUICaptioningEnabled(val isEnabled: Boolean) : CaptioningChange
-    }
-
-    private class CaptioningChangeProducingListener(
-        private val scope: ProducerScope<CaptioningChange>
-    ) : CaptioningManager.CaptioningChangeListener() {
-
-        override fun onSystemAudioCaptioningChanged(enabled: Boolean) {
-            emitChange(CaptioningChange.IsSystemAudioCaptioningEnabled(enabled))
-        }
-
-        override fun onSystemAudioCaptioningUiChanged(enabled: Boolean) {
-            emitChange(CaptioningChange.IsSystemUICaptioningEnabled(enabled))
-        }
-
-        private fun emitChange(change: CaptioningChange) {
-            scope.launch { scope.send(change) }
-        }
+    private fun CaptioningManager.captioningModel(): Flow<CaptioningModel> {
+        return conflatedCallbackFlow {
+                val listener =
+                    object : CaptioningManager.CaptioningChangeListener() {
+
+                        override fun onSystemAudioCaptioningChanged(enabled: Boolean) {
+                            trySend(Unit)
+                        }
+
+                        override fun onSystemAudioCaptioningUiChanged(enabled: Boolean) {
+                            trySend(Unit)
+                        }
+                    }
+                addCaptioningChangeListener(listener)
+                awaitClose { removeCaptioningChangeListener(listener) }
+            }
+            .onStart { emit(Unit) }
+            .map {
+                CaptioningModel(
+                    isSystemAudioCaptioningEnabled = isSystemAudioCaptioningEnabled,
+                    isSystemAudioCaptioningUiEnabled = isSystemAudioCaptioningUiEnabled,
+                )
+            }
+            .flowOn(backgroundCoroutineContext)
     }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/accessibility/domain/interactor/CaptioningInteractor.kt b/packages/SystemUI/src/com/android/systemui/accessibility/domain/interactor/CaptioningInteractor.kt
index 1d493c697652..840edf44ecf5 100644
--- a/packages/SystemUI/src/com/android/systemui/accessibility/domain/interactor/CaptioningInteractor.kt
+++ b/packages/SystemUI/src/com/android/systemui/accessibility/domain/interactor/CaptioningInteractor.kt
@@ -17,16 +17,22 @@
 package com.android.systemui.accessibility.domain.interactor
 
 import com.android.systemui.accessibility.data.repository.CaptioningRepository
-import kotlinx.coroutines.flow.StateFlow
+import com.android.systemui.dagger.SysUISingleton
+import javax.inject.Inject
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.filterNotNull
+import kotlinx.coroutines.flow.map
 
-class CaptioningInteractor(private val repository: CaptioningRepository) {
+@SysUISingleton
+class CaptioningInteractor @Inject constructor(private val repository: CaptioningRepository) {
 
-    val isSystemAudioCaptioningEnabled: StateFlow<Boolean>
-        get() = repository.isSystemAudioCaptioningEnabled
+    val isSystemAudioCaptioningEnabled: Flow<Boolean> =
+        repository.captioningModel.filterNotNull().map { it.isSystemAudioCaptioningEnabled }
 
-    val isSystemAudioCaptioningUiEnabled: StateFlow<Boolean>
-        get() = repository.isSystemAudioCaptioningUiEnabled
+    val isSystemAudioCaptioningUiEnabled: Flow<Boolean> =
+        repository.captioningModel.filterNotNull().map { it.isSystemAudioCaptioningUiEnabled }
 
-    suspend fun setIsSystemAudioCaptioningEnabled(enabled: Boolean) =
+    suspend fun setIsSystemAudioCaptioningEnabled(enabled: Boolean) {
         repository.setIsSystemAudioCaptioningEnabled(enabled)
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/dagger/FrameworkServicesModule.java b/packages/SystemUI/src/com/android/systemui/dagger/FrameworkServicesModule.java
index 21a704df074e..8818c3af4916 100644
--- a/packages/SystemUI/src/com/android/systemui/dagger/FrameworkServicesModule.java
+++ b/packages/SystemUI/src/com/android/systemui/dagger/FrameworkServicesModule.java
@@ -202,6 +202,13 @@ public class FrameworkServicesModule {
         return context.getSystemService(CaptioningManager.class);
     }
 
+    @Provides
+    @Singleton
+    static UserScopedService<CaptioningManager> provideUserScopedCaptioningManager(
+            Context context) {
+        return new UserScopedServiceImpl<>(context, CaptioningManager.class);
+    }
+
     /** */
     @Provides
     @Singleton
diff --git a/packages/SystemUI/src/com/android/systemui/volume/dagger/CaptioningModule.kt b/packages/SystemUI/src/com/android/systemui/volume/dagger/CaptioningModule.kt
index 9715772f089f..28a43df2bfb3 100644
--- a/packages/SystemUI/src/com/android/systemui/volume/dagger/CaptioningModule.kt
+++ b/packages/SystemUI/src/com/android/systemui/volume/dagger/CaptioningModule.kt
@@ -16,35 +16,16 @@
 
 package com.android.systemui.volume.dagger
 
-import android.view.accessibility.CaptioningManager
 import com.android.systemui.accessibility.data.repository.CaptioningRepository
 import com.android.systemui.accessibility.data.repository.CaptioningRepositoryImpl
-import com.android.systemui.accessibility.domain.interactor.CaptioningInteractor
 import com.android.systemui.dagger.SysUISingleton
-import com.android.systemui.dagger.qualifiers.Application
-import com.android.systemui.dagger.qualifiers.Background
+import dagger.Binds
 import dagger.Module
-import dagger.Provides
-import kotlin.coroutines.CoroutineContext
-import kotlinx.coroutines.CoroutineScope
 
 @Module
 interface CaptioningModule {
 
-    companion object {
-
-        @Provides
-        @SysUISingleton
-        fun provideCaptioningRepository(
-            captioningManager: CaptioningManager,
-            @Background coroutineContext: CoroutineContext,
-            @Application coroutineScope: CoroutineScope,
-        ): CaptioningRepository =
-            CaptioningRepositoryImpl(captioningManager, coroutineContext, coroutineScope)
-
-        @Provides
-        @SysUISingleton
-        fun provideCaptioningInteractor(repository: CaptioningRepository): CaptioningInteractor =
-            CaptioningInteractor(repository)
-    }
+    @Binds
+    @SysUISingleton
+    fun bindCaptioningRepository(impl: CaptioningRepositoryImpl): CaptioningRepository
 }
diff --git a/packages/SystemUI/src/com/android/systemui/volume/panel/component/captioning/domain/CaptioningAvailabilityCriteria.kt b/packages/SystemUI/src/com/android/systemui/volume/panel/component/captioning/domain/CaptioningAvailabilityCriteria.kt
index 52f2ce63ba21..2e5e389eba9c 100644
--- a/packages/SystemUI/src/com/android/systemui/volume/panel/component/captioning/domain/CaptioningAvailabilityCriteria.kt
+++ b/packages/SystemUI/src/com/android/systemui/volume/panel/component/captioning/domain/CaptioningAvailabilityCriteria.kt
@@ -26,7 +26,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.flow.shareIn
+import kotlinx.coroutines.flow.stateIn
 
 @VolumePanelScope
 class CaptioningAvailabilityCriteria
@@ -45,7 +45,7 @@ constructor(
                     else VolumePanelUiEvent.VOLUME_PANEL_LIVE_CAPTION_TOGGLE_GONE
                 )
             }
-            .shareIn(scope, SharingStarted.WhileSubscribed(), replay = 1)
+            .stateIn(scope, SharingStarted.WhileSubscribed(), false)
 
     override fun isAvailable(): Flow<Boolean> = availability
 }
diff --git a/packages/SystemUI/tests/utils/src/com/android/systemui/accessibility/data/repository/FakeCaptioningRepository.kt b/packages/SystemUI/tests/utils/src/com/android/systemui/accessibility/data/repository/FakeCaptioningRepository.kt
index 2a0e764279d6..a6394631d236 100644
--- a/packages/SystemUI/tests/utils/src/com/android/systemui/accessibility/data/repository/FakeCaptioningRepository.kt
+++ b/packages/SystemUI/tests/utils/src/com/android/systemui/accessibility/data/repository/FakeCaptioningRepository.kt
@@ -16,25 +16,31 @@
 
 package com.android.systemui.accessibility.data.repository
 
+import com.android.systemui.accessibility.data.model.CaptioningModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 
 class FakeCaptioningRepository : CaptioningRepository {
 
-    private val mutableIsSystemAudioCaptioningEnabled = MutableStateFlow(false)
-    override val isSystemAudioCaptioningEnabled: StateFlow<Boolean>
-        get() = mutableIsSystemAudioCaptioningEnabled.asStateFlow()
-
-    private val mutableIsSystemAudioCaptioningUiEnabled = MutableStateFlow(false)
-    override val isSystemAudioCaptioningUiEnabled: StateFlow<Boolean>
-        get() = mutableIsSystemAudioCaptioningUiEnabled.asStateFlow()
+    private val mutableCaptioningModel = MutableStateFlow<CaptioningModel?>(null)
+    override val captioningModel: StateFlow<CaptioningModel?> = mutableCaptioningModel.asStateFlow()
 
     override suspend fun setIsSystemAudioCaptioningEnabled(isEnabled: Boolean) {
-        mutableIsSystemAudioCaptioningEnabled.value = isEnabled
+        mutableCaptioningModel.value =
+            CaptioningModel(
+                isSystemAudioCaptioningEnabled = isEnabled,
+                isSystemAudioCaptioningUiEnabled =
+                    mutableCaptioningModel.value?.isSystemAudioCaptioningUiEnabled == true,
+            )
     }
 
-    fun setIsSystemAudioCaptioningUiEnabled(isSystemAudioCaptioningUiEnabled: Boolean) {
-        mutableIsSystemAudioCaptioningUiEnabled.value = isSystemAudioCaptioningUiEnabled
+    fun setIsSystemAudioCaptioningUiEnabled(isEnabled: Boolean) {
+        mutableCaptioningModel.value =
+            CaptioningModel(
+                isSystemAudioCaptioningEnabled =
+                    mutableCaptioningModel.value?.isSystemAudioCaptioningEnabled == true,
+                isSystemAudioCaptioningUiEnabled = isEnabled,
+            )
     }
 }
diff --git a/packages/SystemUI/tests/utils/src/com/android/systemui/user/utils/FakeUserScopedService.kt b/packages/SystemUI/tests/utils/src/com/android/systemui/user/utils/FakeUserScopedService.kt
new file mode 100644
index 000000000000..78763f97adc3
--- /dev/null
+++ b/packages/SystemUI/tests/utils/src/com/android/systemui/user/utils/FakeUserScopedService.kt
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.systemui.user.utils
+
+import android.os.UserHandle
+
+class FakeUserScopedService<T>(private val defaultImplementation: T) : UserScopedService<T> {
+
+    private val implementations = mutableMapOf<UserHandle, T>()
+
+    fun addImplementation(user: UserHandle, implementation: T) {
+        implementations[user] = implementation
+    }
+
+    fun removeImplementation(user: UserHandle): T? = implementations.remove(user)
+
+    override fun forUser(user: UserHandle): T =
+        implementations.getOrDefault(user, defaultImplementation)
+}