Move cache management to a dedicated class and in the setting module, for clarity.

appnav/src/main/kotlin/io/element/android/appnav/RootFlowNode.kt

@@ -44,6 +44,7 @@ import io.element.android.appnav.root.RootPresenter
 import io.element.android.appnav.root.RootView
 import io.element.android.features.login.api.oidc.OidcAction
 import io.element.android.features.login.api.oidc.OidcActionFlow
+import io.element.android.features.preferences.api.CacheService
 import io.element.android.features.rageshake.api.bugreport.BugReportEntryPoint
 import io.element.android.libraries.architecture.BackstackNode
 import io.element.android.libraries.architecture.animation.rememberDefaultTransitionHandler
@@ -67,6 +68,7 @@ class RootFlowNode @AssistedInject constructor(
     @Assisted val buildContext: BuildContext,
     @Assisted plugins: List<Plugin>,
     private val authenticationService: MatrixAuthenticationService,
+    private val cacheService: CacheService,
     private val matrixClientsHolder: MatrixClientsHolder,
     private val presenter: RootPresenter,
     private val bugReportEntryPoint: BugReportEntryPoint,
@@ -91,7 +93,7 @@ class RootFlowNode @AssistedInject constructor(
         authenticationService.isLoggedIn()
             .distinctUntilChanged()
             .combine(
-                authenticationService.cacheIndex().onEach {
+                cacheService.cacheIndex().onEach {
                     Timber.v("cacheIndex=$it")
                     matrixClientsHolder.removeAll()
                 }
@@ -245,7 +247,7 @@ class RootFlowNode @AssistedInject constructor(
     }
 
     private suspend fun attachSession(sessionId: SessionId): LoggedInFlowNode {
-        val cacheIndex = authenticationService.cacheIndex().first()
+        val cacheIndex = cacheService.cacheIndex().first()
         return attachChild {
             backstack.newRoot(NavTarget.LoggedInFlow(sessionId, cacheIndex))
         }

features/preferences/api/src/main/kotlin/io/element/android/features/preferences/api/CacheService.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * 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 io.element.android.features.preferences.api
+
+import kotlinx.coroutines.flow.Flow
+
+interface CacheService {
+    /**
+     * Returns a flow of the current cache index, can let the app to know when the
+     * cache has been cleared, for instance to restart the app.
+     * Will be a flow of Int, starting from 0, and incrementing each time the cache is cleared.
+     */
+    fun cacheIndex(): Flow<Int>
+}

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

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * 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 io.element.android.features.preferences.impl
+
+import com.squareup.anvil.annotations.ContributesBinding
+import io.element.android.features.preferences.api.CacheService
+import io.element.android.libraries.di.AppScope
+import io.element.android.libraries.di.SingleIn
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import javax.inject.Inject
+
+@SingleIn(AppScope::class)
+@ContributesBinding(AppScope::class)
+class DefaultCacheService @Inject constructor() : CacheService {
+    private val cacheIndexState = MutableStateFlow(0)
+
+    override fun cacheIndex(): Flow<Int> {
+        return cacheIndexState
+    }
+
+    fun incrementCacheIndex() {
+        cacheIndexState.value++
+    }
+}

features/preferences/impl/src/main/kotlin/io/element/android/features/preferences/impl/tasks/ClearCacheUseCase.kt

@@ -22,11 +22,11 @@ import android.content.Context
 import coil.Coil
 import coil.annotation.ExperimentalCoilApi
 import com.squareup.anvil.annotations.ContributesBinding
+import io.element.android.features.preferences.impl.DefaultCacheService
 import io.element.android.libraries.core.coroutine.CoroutineDispatchers
 import io.element.android.libraries.di.ApplicationContext
 import io.element.android.libraries.di.SessionScope
 import io.element.android.libraries.matrix.api.MatrixClient
-import io.element.android.libraries.matrix.api.auth.MatrixAuthenticationService
 import kotlinx.coroutines.withContext
 import okhttp3.OkHttpClient
 import javax.inject.Inject
@@ -41,7 +41,7 @@ class DefaultClearCacheUseCase @Inject constructor(
     @ApplicationContext private val context: Context,
     private val matrixClient: MatrixClient,
     private val coroutineDispatchers: CoroutineDispatchers,
-    private val authenticationService: MatrixAuthenticationService,
+    private val defaultCacheIndexProvider: DefaultCacheService,
     private val okHttpClient: Provider<OkHttpClient>,
 ) : ClearCacheUseCase {
     override suspend fun invoke() = withContext(coroutineDispatchers.io) {
@@ -57,6 +57,6 @@ class DefaultClearCacheUseCase @Inject constructor(
         // Clear app cache
         context.cacheDir.deleteRecursively()
         // Ensure the app is restarted
-        authenticationService.incrementCacheIndex()
+        defaultCacheIndexProvider.incrementCacheIndex()
     }
 }

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

@@ -29,13 +29,6 @@ interface MatrixAuthenticationService {
     suspend fun setHomeserver(homeserver: String): Result<Unit>
     suspend fun login(username: String, password: String): Result<SessionId>
 
-    /*
-     * Cache index
-     */
-
-    fun cacheIndex(): Flow<Int>
-    fun incrementCacheIndex()
-
     /*
      * OIDC part.
      */

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/auth/RustMatrixAuthenticationService.kt

@@ -58,8 +58,6 @@ class RustMatrixAuthenticationService @Inject constructor(
     private val clock: SystemClock,
 ) : MatrixAuthenticationService {
 
-    private val cacheIndexState = MutableStateFlow(0)
-
     private val authService: RustAuthenticationService = RustAuthenticationService(
         basePath = baseDirectory.absolutePath,
         passphrase = null,
@@ -73,14 +71,6 @@ class RustMatrixAuthenticationService @Inject constructor(
         return sessionStore.isLoggedIn()
     }
 
-    override fun incrementCacheIndex() {
-        cacheIndexState.value++
-    }
-
-    override fun cacheIndex(): Flow<Int> {
-        return cacheIndexState
-    }
-
     override suspend fun getLatestSessionId(): SessionId? = withContext(coroutineDispatchers.io) {
         sessionStore.getLatestSession()?.userId?.let { SessionId(it) }
     }

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/auth/FakeAuthenticationService.kt

@@ -65,16 +65,6 @@ class FakeAuthenticationService : MatrixAuthenticationService {
         loginError?.let { Result.failure(it) } ?: Result.success(A_USER_ID)
     }
 
-    private val cacheIndexFlow = MutableStateFlow(0)
-
-    override fun cacheIndex(): Flow<Int> {
-        return cacheIndexFlow
-    }
-
-    override fun incrementCacheIndex() {
-        cacheIndexFlow.value++
-    }
-
     override suspend fun getOidcUrl(): Result<OidcDetails> = simulateLongTask {
         oidcError?.let { Result.failure(it) } ?: Result.success(A_OIDC_DATA)
     }