[BWA-59] Define feature flag manager (#177)

app/src/main/kotlin/com/bitwarden/authenticator/data/platform/manager/FeatureFlagManager.kt

@@ -0,0 +1,24 @@
+package com.bitwarden.authenticator.data.platform.manager
+
+import com.bitwarden.authenticator.data.platform.manager.model.FeatureFlag
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * Manages the available feature flags for the Bitwarden application.
+ */
+interface FeatureFlagManager {
+
+    /**
+     * Returns a flow emitting the value of flag [key] which is of generic type [T].
+     * If the value of the flag cannot be retrieved, the default value of [key] will be returned
+     */
+    fun <T : Any> getFeatureFlagFlow(key: FeatureFlag<T>): Flow<T>
+
+    /**
+     * Gets the value for feature flag with [key] and returns it as generic type [T].
+     * If no value is found the given [key] its [FeatureFlag.defaultValue] will be returned.
+     */
+    fun <T : Any> getFeatureFlag(
+        key: FeatureFlag<T>,
+    ): T
+}

app/src/main/kotlin/com/bitwarden/authenticator/data/platform/manager/FeatureFlagManagerImpl.kt

@@ -0,0 +1,52 @@
+package com.bitwarden.authenticator.data.platform.manager
+
+import com.bitwarden.authenticator.data.platform.datasource.disk.model.FeatureFlagsConfiguration
+import com.bitwarden.authenticator.data.platform.manager.model.FeatureFlag
+import com.bitwarden.authenticator.data.platform.repository.FeatureFlagRepository
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+
+/**
+ * Primary implementation of [FeatureFlagManager].
+ */
+class FeatureFlagManagerImpl(
+    private val featureFlagRepository: FeatureFlagRepository,
+) : FeatureFlagManager {
+
+    override fun <T : Any> getFeatureFlagFlow(key: FeatureFlag<T>): Flow<T> =
+        featureFlagRepository
+            .featureFlagConfigStateFlow
+            .map { serverConfig ->
+                serverConfig.getFlagValueOrDefault(key = key)
+            }
+
+    override fun <T : Any> getFeatureFlag(key: FeatureFlag<T>): T =
+        featureFlagRepository
+            .featureFlagConfigStateFlow
+            .value
+            .getFlagValueOrDefault(key = key)
+}
+
+private fun <T : Any> FeatureFlagsConfiguration?.getFlagValueOrDefault(key: FeatureFlag<T>): T {
+    val defaultValue = key.defaultValue
+    return this
+        ?.featureFlags
+        ?.get(key.name)
+        ?.let {
+            try {
+                // Suppressed since we are checking the type before doing the cast
+                @Suppress("UNCHECKED_CAST")
+                when (defaultValue::class) {
+                    Boolean::class -> it.content.toBoolean() as T
+                    String::class -> it.content as T
+                    Int::class -> it.content.toInt() as T
+                    else -> defaultValue
+                }
+            } catch (ex: ClassCastException) {
+                defaultValue
+            } catch (ex: NumberFormatException) {
+                defaultValue
+            }
+        }
+        ?: defaultValue
+}

app/src/main/kotlin/com/bitwarden/authenticator/data/platform/manager/di/PlatformManagerModule.kt

@@ -11,12 +11,15 @@ import com.bitwarden.authenticator.data.platform.manager.CrashLogsManager
 import com.bitwarden.authenticator.data.platform.manager.CrashLogsManagerImpl
 import com.bitwarden.authenticator.data.platform.manager.DispatcherManager
 import com.bitwarden.authenticator.data.platform.manager.DispatcherManagerImpl
+import com.bitwarden.authenticator.data.platform.manager.FeatureFlagManager
+import com.bitwarden.authenticator.data.platform.manager.FeatureFlagManagerImpl
 import com.bitwarden.authenticator.data.platform.manager.SdkClientManager
 import com.bitwarden.authenticator.data.platform.manager.SdkClientManagerImpl
 import com.bitwarden.authenticator.data.platform.manager.clipboard.BitwardenClipboardManager
 import com.bitwarden.authenticator.data.platform.manager.clipboard.BitwardenClipboardManagerImpl
 import com.bitwarden.authenticator.data.platform.manager.imports.ImportManager
 import com.bitwarden.authenticator.data.platform.manager.imports.ImportManagerImpl
+import com.bitwarden.authenticator.data.platform.repository.FeatureFlagRepository
 import com.bitwarden.authenticator.data.platform.repository.SettingsRepository
 import dagger.Module
 import dagger.Provides
@@ -73,4 +76,10 @@ object PlatformManagerModule {
     @Provides
     @Singleton
     fun provideEncodingManager(): BitwardenEncodingManager = BitwardenEncodingManagerImpl()
+
+    @Provides
+    @Singleton
+    fun provideFeatureFlagManager(
+        featureFlagRepository: FeatureFlagRepository,
+    ): FeatureFlagManager = FeatureFlagManagerImpl(featureFlagRepository)
 }

app/src/test/java/com/bitwarden/authenticator/data/platform/manager/FeatureFlagManagerTest.kt

@@ -0,0 +1,69 @@
+package com.bitwarden.authenticator.data.platform.manager
+
+import app.cash.turbine.test
+import com.bitwarden.authenticator.data.platform.datasource.disk.model.FeatureFlagsConfiguration
+import com.bitwarden.authenticator.data.platform.manager.model.LocalFeatureFlag
+import com.bitwarden.authenticator.data.platform.repository.util.FakeFeatureFlagRepository
+import kotlinx.coroutines.test.runTest
+import kotlinx.serialization.json.JsonPrimitive
+import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Assertions.assertTrue
+
+class FeatureFlagManagerTest {
+    private val fakeFeatureFlagRepository = FakeFeatureFlagRepository()
+
+    private val featureFlagManager = FeatureFlagManagerImpl(
+        featureFlagRepository = fakeFeatureFlagRepository,
+    )
+
+    @Test
+    fun `FeatureFlagRepository flow with value should trigger new flags`() = runTest {
+        fakeFeatureFlagRepository.featureFlagsConfiguration = null
+        assertNull(
+            fakeFeatureFlagRepository.featureFlagsConfiguration,
+        )
+
+        fakeFeatureFlagRepository.featureFlagsConfiguration = FEATURE_FLAGS_CONFIG
+
+        featureFlagManager
+            .getFeatureFlagFlow(LocalFeatureFlag.BitwardenAuthenticationEnabled)
+            .test {
+                assertNotNull(awaitItem())
+            }
+    }
+
+    @Test
+    fun `getFeatureFlag should return value if exists`() = runTest {
+        fakeFeatureFlagRepository.featureFlagsConfiguration = FEATURE_FLAGS_CONFIG
+
+        val flagValue = featureFlagManager.getFeatureFlag(
+            key = LocalFeatureFlag.BitwardenAuthenticationEnabled,
+        )
+
+        assertTrue(flagValue)
+    }
+
+    @Test
+    fun `getFeatureFlag should return default value if flag doesn't exist`() {
+        fakeFeatureFlagRepository.featureFlagsConfiguration = FEATURE_FLAGS_CONFIG.copy(
+            featureFlags = emptyMap()
+        )
+
+        val flagValue = featureFlagManager.getFeatureFlag(
+            LocalFeatureFlag.BitwardenAuthenticationEnabled,
+        )
+
+        assertFalse(flagValue)
+    }
+}
+
+private val FEATURE_FLAGS_CONFIG =
+    FeatureFlagsConfiguration(
+        mapOf(
+            LocalFeatureFlag.BitwardenAuthenticationEnabled.name to
+                JsonPrimitive(true),
+        )
+    )

app/src/test/java/com/bitwarden/authenticator/data/platform/repository/util/FakeFeatureFlagRepository.kt

@@ -0,0 +1,38 @@
+package com.bitwarden.authenticator.data.platform.repository.util
+
+import com.bitwarden.authenticator.data.platform.datasource.disk.model.FeatureFlagsConfiguration
+import com.bitwarden.authenticator.data.platform.manager.model.LocalFeatureFlag
+import com.bitwarden.authenticator.data.platform.repository.FeatureFlagRepository
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.serialization.json.JsonPrimitive
+
+/**
+ * Faked implementation of [FeatureFlagRepository] for testing.
+ */
+class FakeFeatureFlagRepository : FeatureFlagRepository {
+    var featureFlagsConfiguration: FeatureFlagsConfiguration?
+        get() = mutableFeatureFlagsConfiguration.value
+        set(value) {
+            mutableFeatureFlagsConfiguration.value = value
+        }
+
+    private val mutableFeatureFlagsConfiguration =
+        MutableStateFlow<FeatureFlagsConfiguration?>(FEATURE_FLAGS_CONFIG)
+
+    override val featureFlagConfigStateFlow: StateFlow<FeatureFlagsConfiguration?> =
+        mutableFeatureFlagsConfiguration
+
+    override suspend fun getFeatureFlagsConfiguration(): FeatureFlagsConfiguration {
+        return featureFlagsConfiguration
+            ?: FEATURE_FLAGS_CONFIG
+    }
+}
+
+private val FEATURE_FLAGS_CONFIG =
+    FeatureFlagsConfiguration(
+        featureFlags = mapOf(
+            LocalFeatureFlag.BitwardenAuthenticationEnabled.name to
+                JsonPrimitive(LocalFeatureFlag.BitwardenAuthenticationEnabled.defaultValue)
+        )
+    )