Fixes 1864 - Message forwarding room list filtering and pagination problems (#1867)

* Fixes 1864 - Message forwarding room list filtering and pagination problems

* Fix SwiftFormat redundant closures body error

* Prevent crashes when writing to the localization bundle cache from different threads

* Fix unit tests

* Fix unit tests

* Address PR comments

ElementX/Sources/Screens/MessageForwardingScreen/MessageForwardingScreenModels.swift

@@ -24,15 +24,6 @@ enum MessageForwardingScreenViewModelAction {
 struct MessageForwardingScreenViewState: BindableState {
     var rooms: [MessageForwardingRoom] = []
     var selectedRoomID: String?
-    
-    var visibleRooms: [MessageForwardingRoom] {
-        if bindings.searchQuery.isEmpty {
-            return rooms
-        }
-        
-        return rooms.filter { $0.name.localizedStandardContains(bindings.searchQuery) }
-    }
-    
     var bindings = MessageForwardingScreenViewStateBindings()
 }
 
@@ -44,6 +35,8 @@ enum MessageForwardingScreenViewAction {
     case cancel
     case send
     case selectRoom(roomID: String)
+    case reachedTop
+    case reachedBottom
 }
 
 struct MessageForwardingRoom: Identifiable, Equatable {

ElementX/Sources/Screens/MessageForwardingScreen/MessageForwardingScreenViewModel.swift

@@ -43,6 +43,15 @@ class MessageForwardingScreenViewModel: MessageForwardingScreenViewModelType, Me
             }
             .store(in: &cancellables)
         
+        context.$viewState
+            .map(\.bindings.searchQuery)
+            .removeDuplicates()
+            .sink { [weak self] searchQuery in
+                guard let self else { return }
+                self.roomSummaryProvider?.setFilter(.normalizedMatchRoomName(searchQuery))
+            }
+            .store(in: &cancellables)
+        
         updateRooms()
     }
     
@@ -58,6 +67,10 @@ class MessageForwardingScreenViewModel: MessageForwardingScreenViewModelType, Me
             actionsSubject.send(.send(roomID: roomID))
         case .selectRoom(let roomID):
             state.selectedRoomID = roomID
+        case .reachedTop:
+            updateVisibleRange(edge: .top)
+        case .reachedBottom:
+            updateVisibleRange(edge: .bottom)
         }
     }
     
@@ -91,4 +104,26 @@ class MessageForwardingScreenViewModel: MessageForwardingScreenViewModelType, Me
         
         MXLog.verbose("Finished updating rooms")
     }
+    
+    /// The actual range values don't matter as long as they contain the lower
+    /// or upper bounds. updateVisibleRange is a hybrid API that powers both
+    /// sliding sync visible range update and list paginations
+    /// For lists other than the home screen one we don't care about visible ranges,
+    /// we just need the respective bounds to be there to trigger a next page load or
+    /// a reset to just one page
+    private func updateVisibleRange(edge: UIRectEdge) {
+        guard let roomSummaryProvider else {
+            return
+        }
+        
+        switch edge {
+        case .top:
+            roomSummaryProvider.updateVisibleRange(0..<0)
+        case .bottom:
+            let roomCount = roomSummaryProvider.roomListPublisher.value.count
+            roomSummaryProvider.updateVisibleRange(roomCount..<roomCount)
+        default:
+            break
+        }
+    }
 }

ElementX/Sources/Screens/MessageForwardingScreen/View/MessageForwardingScreen.swift

@@ -22,10 +22,19 @@ struct MessageForwardingScreen: View {
     var body: some View {
         Form {
             Section {
-                ForEach(context.viewState.visibleRooms) { room in
+                ForEach(context.viewState.rooms) { room in
                     MessageForwardingRoomCell(room: room, context: context)
                         .buttonStyle(FormButtonStyle(accessory: .singleSelection(isSelected: context.viewState.selectedRoomID == room.id)))
                 }
+                // Replace these with ScrollView's `scrollPosition` when dropping iOS 16.
+            } header: {
+                Rectangle().hidden().onAppear {
+                    context.send(viewAction: .reachedTop)
+                }
+            } footer: {
+                Rectangle().hidden().onAppear {
+                    context.send(viewAction: .reachedBottom)
+                }
             }
             .compoundFormSection()
         }