Add support for Hilt AssistedInject (#271)

* Add support for Hilt AssistedInject

* Review changes

Co-authored-by: Natan Vieira <natanvnascimento@gmail.com>

* Fix lint erors

* Annotate function with`@ExperimentalVoyagerApi`

---------

Co-authored-by: Natan Vieira <natanvnascimento@gmail.com>

Author: ghostbear

gradle/libs.versions.toml

@@ -10,7 +10,7 @@ kotlin = "1.9.21"
 kodein = "7.20.2"
 koin = "3.4.3"
 koin-compose = "1.0.4"
-hilt = "2.47"
+hilt = "2.49"
 leakCanary = "2.9.1"
 appCompat = "1.6.1"
 lifecycle = "2.6.1"

samples/android/src/main/java/cafe/adriel/voyager/sample/hiltIntegration/HiltDetailsScreen.kt

@@ -20,9 +20,7 @@ data class HiltDetailsScreen(
 
         // Uncomment version below if you want keep using ViewModel instead of to convert it to ScreenModel
         // ViewModelProvider.Factory is not required. Until now Hilt has no support to Assisted Injection by default
-        /*val viewModel: HiltDetailsViewModel = getViewModel(
-            viewModelProviderFactory = HiltDetailsViewModel.provideFactory(index)
-        )*/
+        // val viewModel: HiltDetailsViewModel = getViewModel<HiltDetailsViewModel, HiltDetailsViewModel.Factory> { factory -> factory.create(index) }
 
         // This version include more boilerplate because we are simulating support
         // to Assisted Injection using ScreenModel. See [HiltListScreen] for a simple version

samples/android/src/main/java/cafe/adriel/voyager/sample/hiltIntegration/HiltDetailsViewModel.kt

@@ -1,18 +1,18 @@
 package cafe.adriel.voyager.sample.hiltIntegration
 
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import dagger.hilt.android.lifecycle.HiltViewModel
 
-// Until now, there is no support to assisted injection.
-// Follow the thread here: https://github.com/google/dagger/issues/2287
-class HiltDetailsViewModel(
-    val index: Int
+@HiltViewModel(assistedFactory = HiltDetailsViewModel.Factory::class)
+class HiltDetailsViewModel @AssistedInject constructor(
+    @Assisted val index: Int
 ) : ViewModel() {
-    companion object {
-        fun provideFactory(
-            index: Int
-        ): ViewModelProvider.Factory = object : ViewModelProvider.Factory {
-            override fun <T : ViewModel> create(modelClass: Class<T>): T = HiltDetailsViewModel(index) as T
-        }
+
+    @AssistedFactory
+    interface Factory {
+        fun create(index: Int): HiltDetailsViewModel
     }
 }

voyager-hilt/src/main/java/cafe/adriel/voyager/hilt/ViewModel.kt

@@ -9,8 +9,10 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.ViewModelStore
 import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner
+import cafe.adriel.voyager.core.annotation.ExperimentalVoyagerApi
 import cafe.adriel.voyager.core.screen.Screen
 import cafe.adriel.voyager.hilt.internal.componentActivity
+import dagger.hilt.android.lifecycle.withCreationCallback
 
 /**
  * A function to provide a [dagger.hilt.android.lifecycle.HiltViewModel] managed by voyager ViewModelLifecycleOwner
@@ -50,3 +52,51 @@ public inline fun <reified T : ViewModel> Screen.getViewModel(
         provider[T::class.java]
     }
 }
+
+/**
+ * A function to provide a [dagger.hilt.android.lifecycle.HiltViewModel] managed by Voyager ViewModelLifecycleOwner
+ * instead of using Activity ViewModelLifecycleOwner.
+ * There is compatibility with Activity ViewModelLifecycleOwner too but it must be avoided because your ViewModels
+ * will be cleared when activity is totally destroyed only.
+ *
+ * @param viewModelProviderFactory A custom factory commonly used with Assisted Injection
+ * @param viewModelFactory A custom factory to assist with creation of ViewModels
+ * @return A new instance of [ViewModel] or the existent instance in the [ViewModelStore]
+ */
+@Composable
+@ExperimentalVoyagerApi
+public inline fun <reified VM : ViewModel, F> Screen.getViewModel(
+    viewModelProviderFactory: ViewModelProvider.Factory? = null,
+    noinline viewModelFactory: (F) -> VM
+): VM {
+    val context = LocalContext.current
+    val lifecycleOwner = LocalLifecycleOwner.current
+    val viewModelStoreOwner = checkNotNull(LocalViewModelStoreOwner.current) {
+        "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner"
+    }
+    return remember(key1 = VM::class) {
+        val hasDefaultViewModelProviderFactory = requireNotNull(lifecycleOwner as? HasDefaultViewModelProviderFactory) {
+            "$lifecycleOwner is not a androidx.lifecycle.HasDefaultViewModelProviderFactory"
+        }
+        val viewModelStore = requireNotNull(viewModelStoreOwner?.viewModelStore) {
+            "$viewModelStoreOwner is null or have a null viewModelStore"
+        }
+
+        val creationExtras = hasDefaultViewModelProviderFactory.defaultViewModelCreationExtras
+            .withCreationCallback(viewModelFactory)
+
+        val factory = VoyagerHiltViewModelFactories.getVoyagerFactory(
+            activity = context.componentActivity,
+            delegateFactory = viewModelProviderFactory
+                ?: hasDefaultViewModelProviderFactory.defaultViewModelProviderFactory
+        )
+
+        val provider = ViewModelProvider(
+            store = viewModelStore,
+            factory = factory,
+            defaultCreationExtras = creationExtras
+        )
+
+        provider[VM::class.java]
+    }
+}