Merge branch 'bugfix/CXTDT-579050' into 'develop'

Digital PCT265 defect CXTDT-579049: Fix indexing safety to mocules to add....

### Summary
A new attempt at synchronizing data + UI updates.

### JIRA Ticket
https://onejira.verizon.com/browse/CXTDT-579050

Co-authored-by: Hedden, Kyle Matthew <kyle.hedden@verizonwireless.com>

See merge request https://gitlab.verizon.com/BPHV_MIPS/mvm_core_ui/-/merge_requests/1142

MVMCoreUI/Atomic/Organisms/Carousel/Carousel.swift

@@ -43,6 +43,9 @@ open class Carousel: View {
     /// The models for the molecules.
     public var molecules: [MoleculeModelProtocol & CarouselItemModelProtocol]?
     
+    /// A list of currently registered cells.
+    public var registeredMoleculeIds: [String]?
+    
     /// The horizontal alignment of the cell in the collection view. Only noticeable if the itemWidthPercent is less than 100%.
     public var itemAlignment = UICollectionView.ScrollPosition.left
     
@@ -174,9 +177,7 @@ open class Carousel: View {
         MVMCoreLoggingHandler.shared()?.handleDebugMessage("[\(Self.self)] [\(ObjectIdentifier(self).hashValue)]\noriginal model: \(originalModel?.debugDescription ?? "none")\nnew model: \(model)")
         
         if #available(iOS 15.0, *) {
-            if let originalModel, carouselModel.isDeeplyVisuallyEquivalent(to: originalModel),
+            if hasSameCellRegistration(with: carouselModel, delegateObject: delegateObject) {
-               originalModel.visibleMolecules.isVisuallyEquivalent(to: molecules ?? []) // Since the carousel model's children are in place replaced and we do not have a deep copy of this model tree, add in this hack to check if the prior captured carousel items match the newly visible ones.
-            {
                 // Prevents a carousel reset while still updating the cell backing data through reconfigureItems.
                 MVMCoreLoggingHandler.shared()?.handleDebugMessage("[\(Self.self)] Model is visually equivalent. Skipping rebuild...")
                 prepareMolecules(with: carouselModel)
@@ -284,12 +285,29 @@ open class Carousel: View {
     
     /// Registers the cells with the collection view
     func registerCells(with carouselModel: CarouselModel, delegateObject: MVMCoreUIDelegateObject?) {
-        
+        var registeredIds = [String]()
         for molecule in carouselModel.molecules {
             if let info = getMoleculeInfo(with: molecule, delegateObject: delegateObject) {
                 collectionView.register(info.class, forCellWithReuseIdentifier: info.identifier)
+                registeredIds.append(info.identifier)
+            } else {
+                registeredIds.append(molecule.moleculeName)
             }
         }
+        registeredMoleculeIds = registeredIds
+    }
+    
+    func hasSameCellRegistration(with carouselModel: CarouselModel, delegateObject: MVMCoreUIDelegateObject?) -> Bool {
+        guard let registeredMoleculeIds else { return false }
+        
+        let incomingIds = carouselModel.molecules.map { molecule in
+            if let info = getMoleculeInfo(with: molecule, delegateObject: delegateObject) {
+                return info.identifier
+            } else {
+                return molecule.moleculeName
+            }
+        }
+        return incomingIds == registeredMoleculeIds
     }
     
     //--------------------------------------------------

MVMCoreUI/BaseControllers/ViewController.swift

@@ -8,6 +8,7 @@
 
 import UIKit
 import MVMCore
+import Combine
 
 @objc open class ViewController: UIViewController, MVMCoreViewControllerProtocol, MVMCoreViewManagerViewControllerProtocol, MoleculeDelegateProtocol, FormHolderProtocol, MVMCoreActionDelegateProtocol, ActionDelegateProtocol, MVMCoreLoadDelegateProtocol, UITextFieldDelegate, UITextViewDelegate, ObservingTextFieldDelegate, MVMCoreUIDetailViewProtocol, PageProtocol, PageBehaviorHandlerProtocol {
     
@@ -38,7 +39,7 @@ import MVMCore
     public var behaviors: [PageBehaviorProtocol]?
     
     public var needsUpdateUI = false
-    private var observingForResponses: NSObjectProtocol?
+    private var observingForResponses: AnyCancellable?
     private var initialLoadFinished = false
     public var isFirstRender = true
     public var previousScreenSize = CGSize.zero
@@ -66,9 +67,28 @@ import MVMCore
               (pagesToListenFor()?.count ?? 0 > 0 || modulesToListenFor()?.count ?? 0 > 0)
         else { return }
         
-        observingForResponses = NotificationCenter.default.addObserver(forName: NSNotification.Name(rawValue: NotificationResponseLoaded), object: nil, queue: pageUpdateQueue) { [weak self] notification in
+        observingForResponses = NotificationCenter.default.publisher(for: NSNotification.Name(rawValue: NotificationResponseLoaded))
-            self?.responseJSONUpdated(notification: notification)
+            .receive(on: self.pageUpdateQueue) // Background serial queue.
-        }
+            .compactMap { [weak self] notification in
+                self?.pullUpdates(from: notification) ?? nil
+            }
+            // Merge all page and module updates into one update event.
+            .scan((nil, nil, nil)) { accumulator, next in
+                // Always take the latest page and the latest modules with same key.
+                return (next.0 ?? accumulator.0, next.1 ?? accumulator.1, next.2?.mergingRight(accumulator.2 ?? [:]))
+            }
+            // Delay allowing the previous model update to settle before triggering a re-render.
+            .throttle(for: .seconds(0.05), scheduler: RunLoop.main, latest: true)
+            .sink { [weak self] (pageUpdates: [String : Any]?, pageModel: PageModelProtocol?, moduleUpdates: [String : Any]?) in
+                guard let self = self else { return }
+                if let pageUpdates, pageModel != nil {
+                    self.loadObject?.pageJSON = pageUpdates
+                }
+                let mergedModuleUpdates = (loadObject?.modulesJSON ?? [:]).mergingLeft(moduleUpdates ?? [:])
+                self.loadObject?.modulesJSON = mergedModuleUpdates
+                self.debugLog("Applying async update page model \(pageModel.debugDescription) and modules \(mergedModuleUpdates.keys) to page.")
+                self.handleNewData(pageModel)
+            }
     }
     
     open func stopObservingForResponseJSONUpdates() {
@@ -77,6 +97,31 @@ import MVMCore
         self.observingForResponses = nil
     }
     
+    func pullUpdates(from notification: Notification) -> (pageUpdates: [String : Any]?, pageModel: PageModelProtocol?, moduleUpdates: [String : Any]?)? {
+       // Get the page data.
+       let pageUpdates = extractInterestedPageType(from: notification.userInfo?.optionalDictionaryForKey(KeyPageMap) ?? [:])
+       // Convert the page data into a new model.
+       var pageModel: PageModelProtocol? = nil
+       if let pageUpdates {
+           do {
+               // TODO: Rewiring to parse from plain JSON rather than this protocol indirection.
+               pageModel = try (self as? any TemplateProtocol & PageBehaviorHandlerProtocol & MVMCoreViewControllerProtocol)?.parseTemplate(pageJSON: pageUpdates)
+           } catch {
+               if let coreError = MVMCoreErrorObject.createErrorObject(for: error, location: "updateJSON for pageType: \(String(describing: self.pageType))") {
+                   MVMCoreLoggingHandler.shared()?.addError(toLog: coreError)
+               }
+           }
+       }
+       // Get the module data.
+       let moduleUpdates = extractInterestedModules(from: notification.userInfo?.optionalDictionaryForKey(KeyModuleMap) ?? [:])
+       debugLog("Receiving page \(pageModel?.pageType ?? "none") & \(moduleUpdates?.keys.description ?? "none") modules from  \((notification.userInfo?["MVMCoreLoadObject"] as? MVMCoreLoadObject)?.requestParameters?.url?.absoluteString ?? "")")
+        
+       guard (pageUpdates != nil && pageModel != nil) || (moduleUpdates != nil && moduleUpdates!.count > 0) else { return nil }
+        
+       // Bundle the transformations.
+       return (pageUpdates, pageModel, moduleUpdates)
+    }
+    
     open func pagesToListenFor() -> [String]? {
         guard let pageType = loadObject?.pageType else { return nil }
         return [pageType]
@@ -88,51 +133,22 @@ import MVMCore
         return requestModules + behaviorModules
     }
     
-    @objc open func responseJSONUpdated(notification: Notification) {
+    private func extractInterestedPageType(from pageMap: [String: Any]) -> [String: Any]? {
-        // Checks for a page we are listening for.
+        guard let pageType = pagesToListenFor()?.first(where: { pageTypeListened -> Bool in
-        var hasDataUpdate = false
+            guard let page = pageMap.optionalDictionaryForKey(pageTypeListened),
-        var pageModel: PageModelProtocol? = nil
-        if let pagesLoaded = notification.userInfo?.optionalDictionaryForKey(KeyPageMap),
-           let loadObject,
-           let pageType = pagesToListenFor()?.first(where: { (pageTypeListened) -> Bool in
-            guard let page = pagesLoaded.optionalDictionaryForKey(pageTypeListened),
                   let pageType = page.optionalStringForKey(KeyPageType),
                   pageType == pageTypeListened
             else { return false }
-            
             return true
-           }) {
+        }) else { return nil }
-            hasDataUpdate = true
+        return pageMap.optionalDictionaryForKey(pageType)
-            loadObject.pageJSON = pagesLoaded.optionalDictionaryForKey(pageType)
+    }
-            
+    
-            // Separate page updates from the module updates to avoid unecessary resets to behaviors and full re-renders.
+    private func extractInterestedModules(from moduleMap: [String: Any]) -> [String: Any]? {
-            do {
+        guard let modulesListened = modulesToListenFor() else { return nil }
-                pageModel = try parsePageJSON(loadObject: loadObject)
+        return moduleMap.filter { (key: String, value: Any) in
-            } catch {
+            modulesListened.contains { $0 == key }
-                if let coreError = MVMCoreErrorObject.createErrorObject(for: error, location: "updateJSON for pageType: \(String(describing: pageType))") {
-                    MVMCoreLoggingHandler.shared()?.addError(toLog: coreError)
-                }
-            }
         }
-        
-        // Checks for modules we are listening for.
-        if let modulesLoaded = notification.userInfo?.optionalDictionaryForKey(KeyModuleMap),
-           let modulesListened = modulesToListenFor() {
-            for moduleName in modulesListened {
-                if let module = modulesLoaded.optionalDictionaryForKey(moduleName) {
-                    hasDataUpdate = true
-                    var currentModules = loadObject?.modulesJSON ?? [:]
-                    currentModules.updateValue(module, forKey: moduleName)
-                    loadObject?.modulesJSON = currentModules
-                }
-            }
-        }
-        
-        guard hasDataUpdate else { return }
-        
-        MVMCoreDispatchUtility.performBlock(onMainThread: {
-            self.handleNewData(pageModel)
-        })
     }
     
     open func shouldFinishProcessingLoad(_ loadObject: MVMCoreLoadObject, error: AutoreleasingUnsafeMutablePointer<MVMCoreErrorObject?>) -> Bool {