Make the api explicit and efficient

Author: hadilq

feature-flags/public/src/main/java/com/hadilq/guidomia/featureflags/api/CommandExecutor.kt

@@ -33,11 +33,23 @@ fun <reified IN : Command, reified OUT : Command> CommandExecutor.exe(
   execute(input, IN::class, OUT::class)
 
 suspend inline
-fun <reified IN : Command, reified OUT : Command> CommandExecutor.available(
+fun <reified IN : Command, reified OUT : Command> CommandExecutor.featureFlag(
   input: IN,
   @Suppress("UNUSED_PARAMETER") output: KClass<OUT>,
-): OUT? =
+): FeatureFlag<OUT> =
   when (val commandResult: CommandResult<OUT> = exe(input)) {
-    is Available<*> -> commandResult.command as OUT
-    else -> null
+    is Available<*> -> FeatureFlag.On(commandResult.command as OUT)
+    else -> FeatureFlag.Off()
   }
+
+sealed class FeatureFlag<T> {
+  abstract fun <O> to(map: T.() -> O): FeatureFlag<O>
+
+  class On<T>(val value: T) : FeatureFlag<T>() {
+    override fun <O> to(map: T.() -> O): FeatureFlag<O> = On(value.map())
+  }
+
+  class Off<T> : FeatureFlag<T>() {
+    override fun <O> to(map: T.() -> O): FeatureFlag<O> = Off()
+  }
+}

guidomia/impl/src/main/java/com/hadilq/guidomia/guidomia/impl/data/datasource/CarDatabaseDataSource.kt

@@ -19,7 +19,8 @@ import com.hadilq.guidomia.database.api.CarDataEntityCommand
 import com.hadilq.guidomia.database.api.GetCarEntityCommand
 import com.hadilq.guidomia.database.api.GetCarEntityCommandResult
 import com.hadilq.guidomia.featureflags.api.CommandExecutor
-import com.hadilq.guidomia.featureflags.api.available
+import com.hadilq.guidomia.featureflags.api.FeatureFlag
+import com.hadilq.guidomia.featureflags.api.featureFlag
 import com.hadilq.guidomia.guidomia.impl.data.mapper.CarDatabaseMapper
 import com.hadilq.guidomia.guidomia.impl.domain.entity.CarEntity
 import javax.inject.Inject
@@ -29,22 +30,32 @@ class CarDatabaseDataSource @Inject constructor(
   private val mapper: CarDatabaseMapper,
 ) {
 
-  private var command: CarDataEntityCommand? = null
+  private var command: FeatureFlag<CarDataEntityCommand>? = null
 
-  suspend fun availableCommand(): Boolean =
-    if (command != null) {
-      true
-    } else {
-      command = executor.available(GetCarEntityCommand(), GetCarEntityCommandResult::class)?.result
-      command != null
-    }
+  suspend fun featureFlag(): Boolean = when (fetchFlag()) {
+    is FeatureFlag.On -> true
+    is FeatureFlag.Off -> false
+  }
 
-  suspend fun isEmpty(): Boolean = command?.isEmpty() ?: true
+  suspend fun isEmpty(): Boolean = when (val flag = fetchFlag()) {
+    is FeatureFlag.On -> flag.value.isEmpty()
+    is FeatureFlag.Off -> true
+  }
 
-  suspend fun fetchCars(): List<CarEntity> =
-    command?.getAll()?.map { mapper.map(it) } ?: emptyList()
+  suspend fun fetchCars(): List<CarEntity> = when (val flag = fetchFlag()) {
+    is FeatureFlag.On -> flag.value.getAll().map { mapper.map(it) }
+    is FeatureFlag.Off -> emptyList()
+  }
 
   suspend fun save(cars: List<CarEntity>) {
-    command?.insertAll(cars.map { mapper.map(it) })
+    when (val flag = fetchFlag()) {
+      is FeatureFlag.On -> flag.value.insertAll(cars.map { mapper.map(it) })
+    }
+  }
+
+  private suspend fun fetchFlag(): FeatureFlag<CarDataEntityCommand> = command ?: run {
+    executor.featureFlag(GetCarEntityCommand(), GetCarEntityCommandResult::class)
+      .to { result }
+      .also { command = it }
   }
 }

guidomia/impl/src/main/java/com/hadilq/guidomia/guidomia/impl/data/repository/CarsRepository.kt

@@ -31,7 +31,7 @@ class CarsRepository @Inject constructor(
   fun getCars(): Flow<List<CarEntity>> =
     if (cacheDataSource.caching.isEmpty()) {
       flow {
-        if (!carDatabaseDataSource.availableCommand() || carDatabaseDataSource.isEmpty()) {
+        if (!carDatabaseDataSource.featureFlag() || carDatabaseDataSource.isEmpty()) {
           emitAll(carsDataSource.fetchCars()
             .onEach { carDatabaseDataSource.save(it) }
             .onEach { cacheDataSource.caching = it }

guidomia/impl/src/test/java/com/hadilq/guidomia/guidomia/impl/data/repository/CarRepositoryTest.kt

@@ -48,7 +48,7 @@ internal class CarRepositoryTest {
     val repository = CarsRepository(carsDataSource, cacheDataSource, carDatabaseDataSource)
     every { cacheDataSource.caching } returns listOf()
     coEvery { carDatabaseDataSource.isEmpty() } returns true
-    coEvery { carDatabaseDataSource.availableCommand() } returns true
+    coEvery { carDatabaseDataSource.featureFlag() } returns true
     every { carsDataSource.fetchCars() } returns flowOf()
 
     repository.getCars().collect()
@@ -63,7 +63,7 @@ internal class CarRepositoryTest {
     val repository = CarsRepository(carsDataSource, cacheDataSource, carDatabaseDataSource)
     every { cacheDataSource.caching } returns listOf()
     coEvery { carDatabaseDataSource.isEmpty() } returns true
-    coEvery { carDatabaseDataSource.availableCommand() } returns false
+    coEvery { carDatabaseDataSource.featureFlag() } returns false
     every { carsDataSource.fetchCars() } returns flowOf()
 
     repository.getCars().collect()
@@ -78,7 +78,7 @@ internal class CarRepositoryTest {
     val repository = CarsRepository(carsDataSource, cacheDataSource, carDatabaseDataSource)
     every { cacheDataSource.caching } returns listOf()
     coEvery { carDatabaseDataSource.isEmpty() } returns false
-    coEvery { carDatabaseDataSource.availableCommand() } returns true
+    coEvery { carDatabaseDataSource.featureFlag() } returns true
     coEvery { carDatabaseDataSource.fetchCars() } returns listOf()
 
     repository.getCars().collect()

single-activity/impl/src/main/java/com/hadilq/guidomia/singleactivity/impl/SingleActivity.kt

@@ -23,7 +23,8 @@ import com.hadilq.guidomia.core.api.viewBinding
 import com.hadilq.guidomia.di.api.SingleActivityScope
 import com.hadilq.guidomia.di.api.SingleIn
 import com.hadilq.guidomia.featureflags.api.CommandExecutor
-import com.hadilq.guidomia.featureflags.api.available
+import com.hadilq.guidomia.featureflags.api.FeatureFlag
+import com.hadilq.guidomia.featureflags.api.featureFlag
 import com.hadilq.guidomia.guidomia.api.GetGuidomiaNavigatorFactoryCommand
 import com.hadilq.guidomia.guidomia.api.GetGuidomiaNavigatorFactoryCommandResult
 import com.hadilq.guidomia.guidomia.api.GuidomiaNavigatorFactory
@@ -44,7 +45,7 @@ class SingleActivity : AppCompatActivity() {
   @Inject
   internal lateinit var executor: CommandExecutor
 
-  private var guidomiaNavigatorFactory: GuidomiaNavigatorFactory? = null
+  private var guidomiaNavigatorFactory: FeatureFlag<GuidomiaNavigatorFactory>? = null
 
   private val binding by viewBinding { ActivityMainBinding.inflate(layoutInflater) }
 
@@ -66,19 +67,18 @@ class SingleActivity : AppCompatActivity() {
   }
 
   private fun openFirstPossiblePage() = lifecycleScope.launchWhenCreated {
-    if (guidomiaNavigatorFactoryAvailable()) {
-      guidomiaNavigatorFactory?.create(this@SingleActivity)?.commit()
+    when (val flag = fetchFlag()) {
+      is FeatureFlag.On -> flag.value.create(this@SingleActivity).commit()
     }
   }
 
-  private suspend fun guidomiaNavigatorFactoryAvailable(): Boolean =
-    if (guidomiaNavigatorFactory != null) {
-      true
-    } else {
-      guidomiaNavigatorFactory = executor.available(
+  private suspend fun fetchFlag(): FeatureFlag<GuidomiaNavigatorFactory> =
+    guidomiaNavigatorFactory ?: run {
+      executor.featureFlag(
         GetGuidomiaNavigatorFactoryCommand(),
-        GetGuidomiaNavigatorFactoryCommandResult::class
-      )?.result
-      guidomiaNavigatorFactory != null
+        GetGuidomiaNavigatorFactoryCommandResult::class,
+      ).to { result }
+        .also { guidomiaNavigatorFactory = it }
     }
+
 }