Changed FocusOnOwningPrefab to return Outcome. Added comments and error checking.

Signed-off-by: Danilo Aimini <82231674+AMZN-daimini@users.noreply.github.com>

Code/Framework/AzToolsFramework/AzToolsFramework/FocusMode/FocusModeSystemComponent.cpp

@@ -10,6 +10,7 @@
 
 #include <AzCore/Component/TransformBus.h>
 
+#include <AzToolsFramework/API/ViewportEditorModeTrackerInterface.h>
 #include <AzToolsFramework/FocusMode/FocusModeSystemComponent.h>
 
 namespace AzToolsFramework::FocusModeFramework
@@ -53,8 +54,7 @@ namespace AzToolsFramework::FocusModeFramework
     {
         m_focusRoot = entityId;
 
-        // TODO - If m_focusRoot != AZ::EntityId(), register focus mode
-        //        Else, unregister focus mode
+        // TODO - If m_focusRoot != AZ::EntityId(), activate focus mode via ViewportEditorModeTrackerInterface; else, deactivate focus mode
     }
 
     AZ::EntityId FocusModeSystemComponent::GetFocusRoot()

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabFocusHandler.cpp

@@ -49,7 +49,7 @@ namespace AzToolsFramework::Prefab
         AZ::Interface<PrefabFocusInterface>::Register(this);
     }
 
-    void PrefabFocusHandler::FocusOnOwningPrefab(AZ::EntityId entityId)
+    PrefabFocusOperationResult PrefabFocusHandler::FocusOnOwningPrefab(AZ::EntityId entityId)
     {
         InstanceOptionalReference focusedInstance;
 
@@ -64,12 +64,15 @@ namespace AzToolsFramework::Prefab
 
         if (!focusedInstance.has_value())
         {
-            // TODO - ERROR
+            return AZ::Failure(AZStd::string(
+                "Prefab Focus Handler: Couldn't find owning instance of entityId provided."));
         }
 
         m_focusedInstance = focusedInstance;
         m_focusedTemplateId = focusedInstance->get().GetTemplateId();
         s_focusModeInterface->SetFocusRoot(focusedInstance->get().GetContainerEntityId());
+
+        return AZ::Success();
     }
     
     TemplateId PrefabFocusHandler::GetFocusedPrefabTemplateId()
@@ -86,16 +89,12 @@ namespace AzToolsFramework::Prefab
     {
         if (entityId == AZ::EntityId())
         {
-            // TODO - Warn?
             return false;
         }
 
         InstanceOptionalReference instance = s_instanceEntityMapperInterface->FindOwningInstance(entityId);
 
-        if (!instance.has_value())
-        {
-            // TODO - ERROR
-        }
+        AZ_Assert(instance.has_value(), "PrefabFocusHandler::IsOwningPrefabBeingFocused - Could not find owning Instance of queried entity.");
 
         return (&instance->get() == &m_focusedInstance->get());
     }

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabFocusHandler.h

@@ -39,7 +39,7 @@ namespace AzToolsFramework::Prefab
         void Initialize();
 
         // PrefabFocusInterface...
-        void FocusOnOwningPrefab(AZ::EntityId entityId) override;
+        PrefabFocusOperationResult FocusOnOwningPrefab(AZ::EntityId entityId) override;
         TemplateId GetFocusedPrefabTemplateId() override;
         InstanceOptionalReference GetFocusedPrefabInstance() override;
         bool IsOwningPrefabBeingFocused(AZ::EntityId entityId) override;

Code/Framework/AzToolsFramework/AzToolsFramework/Prefab/PrefabFocusInterface.h

@@ -16,6 +16,8 @@
 
 namespace AzToolsFramework::Prefab
 {
+    typedef AZ::Outcome<void, AZStd::string> PrefabFocusOperationResult;
+
     /*!
      * PrefabFocusInterface
      */
@@ -24,16 +26,19 @@ namespace AzToolsFramework::Prefab
     public:
         AZ_RTTI(PrefabFocusInterface, "{F3CFA37B-5FD8-436A-9C30-60EB54E350E1}");
 
-        // TODO - Add comment
-        virtual void FocusOnOwningPrefab(AZ::EntityId entityId) = 0;
+        //! Set the focused prefab instance to the owning instance of the entityId provided
+        //! @param entityId The entityId of the entity whose owning instance we want the prefab system to focus on.
+        virtual PrefabFocusOperationResult FocusOnOwningPrefab(AZ::EntityId entityId) = 0;
 
-        // TODO - Add comment
+        //! Returns the template id of the instance the prefab system is focusing on.
         virtual TemplateId GetFocusedPrefabTemplateId() = 0;
 
-        // TODO - Add comment
+        //! Returns a reference to the instance the prefab system is focusing on.
         virtual InstanceOptionalReference GetFocusedPrefabInstance() = 0;
 
-        // TODO - Add comment
+        //! Returns whether the entity belongs to the instance that is being focused on, or one of its descendants.
+        //! @param entityId The entityId of the queried entity.
+        //! @return true if the entity belongs to the focused instance or one of its descendants, false otherwise.
         virtual bool IsOwningPrefabBeingFocused(AZ::EntityId entityId) = 0;
     };