Allow ViewModel injection from the MainActivity.

app/src/main/java/cash/z/ecc/android/di/viewmodel/ViewModelExt.kt

@@ -2,6 +2,7 @@ package cash.z.ecc.android.di.viewmodel
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
+import cash.z.ecc.android.ui.MainActivity
 import cash.z.ecc.android.ui.base.BaseFragment
 
 
@@ -35,4 +36,26 @@ inline fun <reified VM : ViewModel> BaseFragment<*>.activityViewModel(isSynchron
 inline fun <reified VM : ViewModel> BaseFragment<*>.scopedFactory(isSynchronizerScope: Boolean = true): ViewModelProvider.Factory {
     val factory = if (isSynchronizerScope) mainActivity?.synchronizerComponent?.viewModelFactory() else mainActivity?.component?.viewModelFactory()
     return factory ?: throw IllegalStateException("Error: mainActivity should not be null by the time the ${VM::class.java.simpleName} viewmodel is lazily accessed!")
+}
+
+/**
+ * Create a viewModel that is scoped to the lifecycle of the activity. This viewModel will be
+ * created from the `synchronizerComponent` rather than the `component`, meaning the synchronizer
+ * will be available but this also requires that this view model not be accessed before the
+ * synchronizerComponent is ready. Doing so will throw an exception.
+ */
+inline fun <reified VM : ViewModel> MainActivity.activityViewModel() = object : Lazy<VM> {
+    val cached: VM? = null
+    override fun isInitialized(): Boolean = cached != null
+    override val value: VM
+        get() {
+            return cached
+                ?: this@activityViewModel.run {
+                    if (isInitialized) {
+                        ViewModelProvider(this, synchronizerComponent.viewModelFactory())[VM::class.java]
+                    } else {
+                        throw IllegalStateException("Error: the SynchronizerComponent must be initialized before the ${VM::class.java.simpleName} viewmodel is lazily accessed!")
+                    }
+                }
+        }
 }