Test code to add merge detection on Settings Registry keys

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

Code/Framework/AzToolsFramework/AzToolsFramework/Editor/Settings/EditorSettingsOriginTracker.cpp

@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AzToolsFramework/Editor/Settings/EditorSettingsOriginTracker.h>
+
+#include <AzCore/IO/Path/Path.h>
+#include <AzCore/Utils/Utils.h>
+
+namespace AzToolsFramework
+{
+    EditorPreferencesSettingsOriginTracker::SettingsNotificationHandler::SettingsNotificationHandler(
+        AZ::SettingsRegistryInterface& registry)
+        : m_settingsRegistry(registry)
+    {
+        AZ::JsonApplyPatchSettings applyPatchSettings;
+        m_settingsRegistry.GetApplyPatchSettings(applyPatchSettings);
+        // Wrap any existing callbacks into the reporting callback, so that both this struct
+        // reporting callbacks and the existing callbacks can be invoked
+        m_prevReportingCallback = applyPatchSettings.m_reporting;
+        applyPatchSettings.m_reporting = [this](
+            AZStd::string_view message, AZ::JsonSerializationResult::ResultCode result,
+            AZStd::string_view path) -> AZ::JsonSerializationResult::ResultCode
+        {
+            m_prevReportingCallback(message, result, path);
+            (*this)(message, result, path);
+            return result;
+        };
+        m_settingsRegistry.SetApplyPatchSettings(applyPatchSettings);
+    }
+
+    EditorPreferencesSettingsOriginTracker::SettingsNotificationHandler::~SettingsNotificationHandler()
+    {
+        // Restore previous reporting callback
+        AZ::JsonApplyPatchSettings applyPatchSettings;
+        m_settingsRegistry.GetApplyPatchSettings(applyPatchSettings);
+        applyPatchSettings.m_reporting = m_prevReportingCallback;
+        m_settingsRegistry.SetApplyPatchSettings(applyPatchSettings);
+    }
+
+    // Use the Json Serialization Issue Callback system
+    // to determine when a merge option modifies a value
+    AZ::JsonSerializationResult::ResultCode EditorPreferencesSettingsOriginTracker::SettingsNotificationHandler::operator()(
+        AZStd::string_view /*message*/, AZ::JsonSerializationResult::ResultCode result, AZStd::string_view path)
+    {
+        using FixedValueString = AZ::SettingsRegistryInterface::FixedValueString;
+
+        AZ::IO::PathView preferencesRootKey{ "/Amazon/Preferences", AZ::IO::PosixPathSeparator };
+        AZ::IO::PathView inputKey{ path, AZ::IO::PosixPathSeparator };
+
+        // Delegate to the Notifier Handler callable below
+        if (result.GetTask() == AZ::JsonSerializationResult::Tasks::Merge &&
+            result.GetProcessing() == AZ::JsonSerializationResult::Processing::Completed && inputKey.IsRelativeTo(preferencesRootKey))
+        {
+            if (auto type = m_settingsRegistry.GetType(path); type != AZ::SettingsRegistryInterface::Type::NoType)
+            {
+                operator()(path, type);
+            }
+        }
+
+        return result;
+    }
+
+    void EditorPreferencesSettingsOriginTracker::SettingsNotificationHandler::operator()(
+        AZStd::string_view path, AZ::SettingsRegistryInterface::Type /*type*/)
+    {
+        constexpr AZ::IO::PathView preferencesRootKey{ "/Amazon/Preferences", AZ::IO::PosixPathSeparator };
+        AZ::IO::PathView inputKey{ path, AZ::IO::PosixPathSeparator };
+        if (inputKey.IsRelativeTo(preferencesRootKey))
+        {
+            // Do stuff with key
+        }
+    }
+
+    EditorPreferencesSettingsOriginTracker::EditorPreferencesSettingsOriginTracker(AZ::SettingsRegistryInterface& registry)
+        : m_settingsRegistry(registry)
+    {
+        auto PreMergeEvent = [this](AZStd::string_view filePath, AZStd::string_view /*rootKey*/)
+        {
+            AZ::IO::FixedMaxPath editorPreferencesPath = AZ::Utils::GetProjectPath();
+            editorPreferencesPath = editorPreferencesPath / "user" / "Registry" / "editorpreferences.setreg";
+
+            if (AZ::IO::PathView(filePath) == editorPreferencesPath)
+            {
+                m_notifyHandler = m_settingsRegistry.RegisterNotifier(SettingsNotificationHandler(m_settingsRegistry));
+            }
+        };
+
+        auto PostMergeEvent = [this](AZStd::string_view /*filePath*/, AZStd::string_view /*rootKey*/)
+        {
+            // Clear the notification handler so that it goes out of scope
+            // and this tracker instance no handles settings updates
+            m_notifyHandler = {};
+        };
+
+        m_preMergeEventHandler = m_settingsRegistry.RegisterPreMergeEvent(PreMergeEvent);
+        m_postMergeEventHandler = m_settingsRegistry.RegisterPostMergeEvent(PostMergeEvent);
+    }
+}

Code/Framework/AzToolsFramework/AzToolsFramework/Editor/Settings/EditorSettingsOriginTracker.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) Contributors to the Open 3D Engine Project.
+ * For complete copyright and license terms please see the LICENSE at the root of this distribution.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ *
+ */
+
+#include <AzCore/Serialization/Json/JsonSerializationSettings.h>
+#include <AzCore/Settings/SettingsRegistry.h>
+#include <AzCore/Settings/SettingsRegistryMergeUtils.h>
+
+namespace AzToolsFramework
+{
+    struct EditorPreferencesSettingsOriginTracker
+    {
+        explicit EditorPreferencesSettingsOriginTracker(AZ::SettingsRegistryInterface& registry);
+
+        struct SettingsNotificationHandler
+        {
+            SettingsNotificationHandler(AZ::SettingsRegistryInterface& registry);
+            ~SettingsNotificationHandler();
+
+            AZ::JsonSerializationResult::ResultCode operator()(
+                AZStd::string_view message, AZ::JsonSerializationResult::ResultCode result, AZStd::string_view path);
+            void operator()(AZStd::string_view path, AZ::SettingsRegistryInterface::Type type);
+
+        private:
+            AZ::SettingsRegistryInterface& m_settingsRegistry;
+            AZ::JsonSerializationResult::JsonIssueCallback m_prevReportingCallback;
+        };
+
+    private:
+        AZ::SettingsRegistryInterface& m_settingsRegistry;
+        AZ::SettingsRegistryInterface::PreMergeEventHandler m_preMergeEventHandler;
+        AZ::SettingsRegistryInterface::PostMergeEventHandler m_postMergeEventHandler;
+        AZ::SettingsRegistryInterface::NotifyEventHandler m_notifyHandler;
+    };
+} // namespace AZ

Code/Framework/AzToolsFramework/AzToolsFramework/aztoolsframework_files.cmake

@@ -113,6 +113,8 @@ set(FILES
     Component/EditorLevelComponentAPIComponent.h
     Editor/EditorContextMenuBus.h
     Editor/EditorSettingsAPIBus.h
+    Editor/Settings/EditorSettingsOriginTracker.cpp
+    Editor/Settings/EditorSettingsOriginTracker.h
     Entity/EditorEntityStartStatus.h
     Entity/EditorEntityAPIBus.h
     Entity/EditorEntityContextComponent.cpp