Reset viewBing when new view is created (#3409)

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>

Corona-Warn-App/src/main/java/de/rki/coronawarnapp/util/ui/ViewBindingExtensions.kt

@@ -12,6 +12,7 @@ import androidx.viewbinding.ViewBinding
 import timber.log.Timber
 import kotlin.properties.ReadOnlyProperty
 import kotlin.reflect.KProperty
+import com.google.android.material.bottomnavigation.BottomNavigationView
 
 inline fun <reified BindingT : ViewBinding> Fragment.viewBinding() =
     viewBinding(
@@ -44,12 +45,13 @@ class ViewBindingProperty<ComponentT : LifecycleOwner, BindingT : ViewBinding>(
     private val onDestroyObserver = object : DefaultLifecycleObserver {
         // Called right before Fragment.onDestroyView
         override fun onDestroy(owner: LifecycleOwner) {
+            Timber.tag(TAG).v("onDestroy(%s)", owner)
             localRef?.lifecycle?.removeObserver(this) ?: return
 
             localRef = null
 
             uiHandler.post {
-                Timber.v("Resetting viewBinding")
+                Timber.tag(TAG).v("Resetting viewBinding owner=%s", owner)
                 viewBinding = null
             }
         }
@@ -58,15 +60,34 @@ class ViewBindingProperty<ComponentT : LifecycleOwner, BindingT : ViewBinding>(
     @MainThread
     override fun getValue(thisRef: ComponentT, property: KProperty<*>): BindingT {
         if (localRef == null && viewBinding != null) {
-            Timber.w("Fragment.onDestroyView() was called, but the handler didn't execute our delayed reset.")
+            Timber.tag(TAG).w(
+                "Fragment.onDestroyView(%s) was called, but the handler didn't execute our delayed reset.",
+                thisRef
+            )
             /**
-             * There is a fragment racecondition if you navigate to another fragment and quickly popBackStack().
+             * There is a fragment race condition if you navigate to another fragment and quickly popBackStack().
              * Our uiHandler.post { } will not have executed for some reason.
              * In that case we manually null the old viewBinding, to allow for clean recreation.
              */
             viewBinding = null
         }
 
+        /**
+         * This is a fix for an edge case where the fragment is created but was never visible to the user
+         * [DefaultLifecycleObserver.onDestroy] was never called despite that the [Fragment.onDestroyView] was called,
+         * therefore the ViewBinding will not be set to `null` and will hold the old view ,while Fragment will
+         * inflate a new [View] when navigating back to it. As result of that the screen ends being blank.
+         *
+         * This is very specific case when navigating by deeplink to one of the [BottomNavigationView] destinations,
+         * that is not the "home destination" of the graph.
+         */
+        (localRef as? Fragment)?.view?.let {
+            if (it != viewBinding?.root && localRef === thisRef) {
+                Timber.tag(TAG).w("Different view for the same fragment, resetting old viewBinding")
+                viewBinding = null
+            }
+        }
+
         viewBinding?.let {
             // Only accessible from within the same component
             require(localRef === thisRef)
@@ -76,9 +97,12 @@ class ViewBindingProperty<ComponentT : LifecycleOwner, BindingT : ViewBinding>(
         val lifecycle = lifecycleOwnerProvider(thisRef).lifecycle
 
         return bindingProvider(thisRef).also {
+            Timber.tag(TAG).d("bindingProvider(%s)", thisRef)
             viewBinding = it
             localRef = thisRef
             lifecycle.addObserver(onDestroyObserver)
         }
     }
 }
+
+private const val TAG = "ViewBindingExtension"