From e0e2d26b4b6521500d7ee4bf31bafb973050c6d2 Mon Sep 17 00:00:00 2001
From: Stefan Ceriu <stefanc@matrix.org>
Date: Mon, 19 Dec 2022 16:25:41 +0200
Subject: [PATCH] Fixes #351 - Replace Syncing toast indicator with an
 in-timeline loading activity indicator (#378)

---
 .../RoomScreen/RoomScreenViewModel.swift      | 12 +---
 .../View/TimelineTableViewController.swift    | 70 +++++++++++--------
 .../RoomTimelineViewProvider.swift            |  7 ++
 3 files changed, 48 insertions(+), 41 deletions(-)

diff --git a/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift b/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift
index 41c1f8b8c..41f403db0 100644
--- a/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift
+++ b/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift
@@ -22,7 +22,6 @@ typealias RoomScreenViewModelType = StateStoreViewModel<RoomScreenViewState, Roo
 class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol {
     private enum Constants {
         static let backPaginationPageSize: UInt = 20
-        static let backPaginationIndicatorID = "RoomBackPagination"
     }
 
     private let timelineController: RoomTimelineControllerProtocol
@@ -30,11 +29,7 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
     private let mediaProvider: MediaProviderProtocol
 
     // MARK: - Setup
-    
-    deinit {
-        ServiceLocator.shared.userNotificationController.retractNotificationWithId(Constants.backPaginationIndicatorID)
-    }
-    
+        
     init(timelineController: RoomTimelineControllerProtocol,
          timelineViewFactory: RoomTimelineViewFactoryProtocol,
          mediaProvider: MediaProviderProtocol,
@@ -66,13 +61,8 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
                     self.state.items[viewIndex] = timelineViewFactory.buildTimelineViewFor(timelineItem: timelineItem)
                 case .startedBackPaginating:
                     self.state.isBackPaginating = true
-                    ServiceLocator.shared.userNotificationController.submitNotification(UserNotification(id: Constants.backPaginationIndicatorID,
-                                                                                                         type: .toast,
-                                                                                                         title: ElementL10n.roomTimelineSyncing,
-                                                                                                         persistent: true))
                 case .finishedBackPaginating:
                     self.state.isBackPaginating = false
-                    ServiceLocator.shared.userNotificationController.retractNotificationWithId(Constants.backPaginationIndicatorID)
                 }
             }
             .store(in: &cancellables)
diff --git a/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift b/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift
index 81e86e526..dc3602754 100644
--- a/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift
+++ b/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift
@@ -66,6 +66,7 @@ class TimelineTableViewController: UIViewController {
         didSet {
             // Paginate again if the threshold hasn't been satisfied.
             paginateBackwardsPublisher.send(())
+            applySnapshot()
         }
     }
     
@@ -197,37 +198,41 @@ class TimelineTableViewController: UIViewController {
             
             cell.item = timelineItem
             cell.contentConfiguration = UIHostingConfiguration {
-                VStack {
-                    if displayReactionsMenuForItemId == timelineItem.id {
-                        TimelineItemReactionsMenuView { emoji in
-                            coordinator.send(viewAction: .emojiTapped(emoji: emoji, itemId: timelineItem.id))
-                        } onDisplayEmojiPicker: {
-                            coordinator.send(viewAction: .displayEmojiPicker(itemId: timelineItem.id))
-                        }
-                    }
-                    
+                if case .backPaginationIndicator = timelineItem {
                     timelineItem
-                        .frame(maxWidth: .infinity, alignment: .leading)
-                        .opacity(opacity)
-                        .contextMenu {
-                            contextMenuBuilder?(timelineItem.id)
-                        }
-                        .onAppear {
-                            coordinator.send(viewAction: .itemAppeared(id: timelineItem.id))
-                        }
-                        .onDisappear {
-                            coordinator.send(viewAction: .itemDisappeared(id: timelineItem.id))
-                        }
-                        .environment(\.openURL, OpenURLAction { url in
-                            coordinator.send(viewAction: .linkClicked(url: url))
-                            return .systemAction
-                        })
-                        .onTapGesture(count: 2) {
-                            coordinator.send(viewAction: .displayReactionsMenuForItemId(itemId: timelineItem.id))
-                        }
-                        .onTapGesture {
-                            coordinator.send(viewAction: .itemTapped(id: timelineItem.id))
+                } else {
+                    VStack {
+                        if displayReactionsMenuForItemId == timelineItem.id {
+                            TimelineItemReactionsMenuView { emoji in
+                                coordinator.send(viewAction: .emojiTapped(emoji: emoji, itemId: timelineItem.id))
+                            } onDisplayEmojiPicker: {
+                                coordinator.send(viewAction: .displayEmojiPicker(itemId: timelineItem.id))
+                            }
                         }
+                        
+                        timelineItem
+                            .frame(maxWidth: .infinity, alignment: .leading)
+                            .opacity(opacity)
+                            .contextMenu {
+                                contextMenuBuilder?(timelineItem.id)
+                            }
+                            .onAppear {
+                                coordinator.send(viewAction: .itemAppeared(id: timelineItem.id))
+                            }
+                            .onDisappear {
+                                coordinator.send(viewAction: .itemDisappeared(id: timelineItem.id))
+                            }
+                            .environment(\.openURL, OpenURLAction { url in
+                                coordinator.send(viewAction: .linkClicked(url: url))
+                                return .systemAction
+                            })
+                            .onTapGesture(count: 2) {
+                                coordinator.send(viewAction: .displayReactionsMenuForItemId(itemId: timelineItem.id))
+                            }
+                            .onTapGesture {
+                                coordinator.send(viewAction: .itemTapped(id: timelineItem.id))
+                            }
+                    }
                 }
             }
             .margins(.all, self.timelineStyle.rowInsets)
@@ -248,6 +253,8 @@ class TimelineTableViewController: UIViewController {
         let previousLayout = layout()
         
         var snapshot = NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>()
+        snapshot.appendSections([.loadingIndicator])
+        snapshot.appendItems([.backPaginationIndicator(isBackPaginating)])
         snapshot.appendSections([.main])
         snapshot.appendItems(timelineItems)
         dataSource.apply(snapshot, animatingDifferences: false)
@@ -409,7 +416,10 @@ extension TimelineTableViewController: UITableViewDelegate {
 
 extension TimelineTableViewController {
     /// The sections of the table view used in the diffable data source.
-    enum TimelineSection { case main }
+    enum TimelineSection {
+        case loadingIndicator
+        case main
+    }
     
     /// A description of the timeline's layout.
     struct LayoutDescriptor {
diff --git a/ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift b/ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift
index 011a23d9d..aac1cee6a 100644
--- a/ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift
+++ b/ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift
@@ -27,6 +27,7 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
     case notice(NoticeRoomTimelineItem)
     case redacted(RedactedRoomTimelineItem)
     case encrypted(EncryptedRoomTimelineItem)
+    case backPaginationIndicator(Bool)
     
     var id: String {
         switch self {
@@ -48,6 +49,8 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
             return item.id
         case .encrypted(let item):
             return item.id
+        case .backPaginationIndicator:
+            return "BackpaginationLoadingIndicator"
         }
     }
 }
@@ -73,6 +76,10 @@ extension RoomTimelineViewProvider: View {
             RedactedRoomTimelineView(timelineItem: item)
         case .encrypted(let item):
             EncryptedRoomTimelineView(timelineItem: item)
+        case .backPaginationIndicator(let isBackPaginating):
+            ProgressView()
+                .frame(maxWidth: .infinity)
+                .opacity(isBackPaginating ? 1.0 : 0.0)
         }
     }
 }