Fix back pagination (#432)

* Use pagination and start items for view state. isBackPaginating and canBackPaginate are updated each time the timeline is rebuilt * Update some timeline snapshots The top section has gone, which has altered the layout slightly.
2023-01-11 09:11:36 +00:00
parent 5672fef5a5
commit 19e0052fc4
24 changed files with 54 additions and 72 deletions
--- a/ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift
+++ b/ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift
@@ -49,6 +49,7 @@ struct RoomScreenViewState: BindableState {
    var roomTitle = ""
    var roomAvatar: UIImage?
    var items: [RoomTimelineViewProvider] = []
+    var canBackPaginate = true
    var isBackPaginating = false
    var showLoading = false
    var bindings: RoomScreenViewStateBindings
--- a/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift
+++ b/ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift
@@ -61,10 +61,14 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
                    }
                    
                    self.state.items[viewIndex] = timelineViewFactory.buildTimelineViewFor(timelineItem: timelineItem)
-                case .startedBackPaginating:
-                    self.state.isBackPaginating = true
-                case .finishedBackPaginating:
-                    self.state.isBackPaginating = false
+                case .canBackPaginate(let canBackPaginate):
+                    if self.state.canBackPaginate != canBackPaginate {
+                        self.state.canBackPaginate = canBackPaginate
+                    }
+                case .isBackPaginating(let isBackPaginating):
+                    if self.state.isBackPaginating != isBackPaginating {
+                        self.state.isBackPaginating = isBackPaginating
+                    }
                }
            }
            .store(in: &cancellables)
--- a/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift
+++ b/ElementX/Sources/Screens/RoomScreen/View/TimelineTableViewController.swift
@@ -61,6 +61,9 @@ class TimelineTableViewController: UIViewController {
        }
    }
    
+    /// Whether or not the timeline has more messages to back paginate.
+    var canBackPaginate = true
+    
    /// Whether or not the timeline is waiting for more messages to be added to the top.
    var isBackPaginating = false {
        didSet {
@@ -334,7 +337,8 @@ class TimelineTableViewController: UIViewController {
    ///
    /// Prefer not to call this directly, instead using ``paginateBackwardsPublisher`` to throttle requests.
    private func paginateBackwardsIfNeeded() {
-        guard !isBackPaginating,
+        guard canBackPaginate,
+              !isBackPaginating,
              !hasPendingUpdates,
              tableView.contentOffset.y < tableView.visibleSize.height * 2.0
        else { return }
--- a/ElementX/Sources/Screens/RoomScreen/View/TimelineView.swift
+++ b/ElementX/Sources/Screens/RoomScreen/View/TimelineView.swift
@@ -59,6 +59,9 @@ struct TimelineView: UIViewControllerRepresentable {
            if tableViewController.timelineItems != context.viewState.items {
                tableViewController.timelineItems = context.viewState.items
            }
+            if tableViewController.canBackPaginate != context.viewState.canBackPaginate {
+                tableViewController.canBackPaginate = context.viewState.canBackPaginate
+            }
            if tableViewController.isBackPaginating != context.viewState.isBackPaginating {
                tableViewController.isBackPaginating = context.viewState.isBackPaginating
            }
--- a/ElementX/Sources/Services/Timeline/MockRoomTimelineProvider.swift
+++ b/ElementX/Sources/Services/Timeline/MockRoomTimelineProvider.swift
@@ -19,8 +19,6 @@ import Combine
 struct MockRoomTimelineProvider: RoomTimelineProviderProtocol {
    var itemsPublisher = CurrentValueSubject<[TimelineItemProxy], Never>([])
    
-    var backPaginationPublisher = CurrentValueSubject<Bool, Never>(false)
-    
    private var itemProxies = [TimelineItemProxy]()
    
    func paginateBackwards(requestSize: UInt, untilNumberOfItems: UInt) async -> Result<Void, RoomTimelineProviderError> {
--- a/ElementX/Sources/Services/Timeline/RoomTimelineProvider.swift
+++ b/ElementX/Sources/Services/Timeline/RoomTimelineProvider.swift
@@ -32,15 +32,10 @@ class RoomTimelineProvider: RoomTimelineProviderProtocol {
    private var cancellables = Set<AnyCancellable>()
    
    let itemsPublisher = CurrentValueSubject<[TimelineItemProxy], Never>([])
-    let backPaginationPublisher = CurrentValueSubject<Bool, Never>(false)
    
    private var itemProxies: [TimelineItemProxy] {
        didSet {
            itemsPublisher.send(itemProxies)
-            
-            if backPaginationPublisher.value == true {
-                backPaginationPublisher.send(false)
-            }
        }
    }
    
@@ -69,9 +64,6 @@ class RoomTimelineProvider: RoomTimelineProviderProtocol {
    }
    
    func paginateBackwards(requestSize: UInt, untilNumberOfItems: UInt) async -> Result<Void, RoomTimelineProviderError> {
-        // Set this back to false after actually updating the items or if failed
-        backPaginationPublisher.send(true)
-        
        MXLog.info("Started back pagination request")
        switch await roomProxy.paginateBackwards(requestSize: requestSize, untilNumberOfItems: untilNumberOfItems) {
        case .success:
@@ -79,7 +71,6 @@ class RoomTimelineProvider: RoomTimelineProviderProtocol {
            return .success(())
        case .failure(let error):
            MXLog.error("Failed back pagination request with error: \(error)")
-            backPaginationPublisher.send(false)
            
            if error == .noMoreMessagesToBackPaginate {
                return .failure(.noMoreMessagesToBackPaginate)
--- a/ElementX/Sources/Services/Timeline/RoomTimelineProviderProtocol.swift
+++ b/ElementX/Sources/Services/Timeline/RoomTimelineProviderProtocol.swift
@@ -29,8 +29,6 @@ enum RoomTimelineProviderError: Error {
 protocol RoomTimelineProviderProtocol {
    var itemsPublisher: CurrentValueSubject<[TimelineItemProxy], Never> { get }
    
-    var backPaginationPublisher: CurrentValueSubject<Bool, Never> { get }
-    
    func paginateBackwards(requestSize: UInt, untilNumberOfItems: UInt) async -> Result<Void, RoomTimelineProviderError>
    
    func sendMessage(_ message: String, inReplyToItemId: String?) async -> Result<Void, RoomTimelineProviderError>
--- a/ElementX/Sources/Services/Timeline/TimelineController/MockRoomTimelineController.swift
+++ b/ElementX/Sources/Services/Timeline/TimelineController/MockRoomTimelineController.swift
@@ -42,20 +42,7 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
    }
    
    func paginateBackwards(requestSize: UInt, untilNumberOfItems: UInt) async -> Result<Void, RoomTimelineControllerError> {
-        callbacks.send(.startedBackPaginating)
-        
-        guard !backPaginationResponses.isEmpty else {
-            callbacks.send(.finishedBackPaginating)
-            return .failure(.generic)
-        }
-        
-        let newItems = backPaginationResponses.removeFirst()
-        
-        try? await Task.sleep(for: backPaginationDelay)
-        timelineItems.insert(contentsOf: newItems, at: 0)
-        callbacks.send(.updatedTimelineItems)
-        callbacks.send(.finishedBackPaginating)
-        
+        callbacks.send(.canBackPaginate(false))
        return .success(())
    }
    
@@ -125,11 +112,12 @@ class MockRoomTimelineController: RoomTimelineControllerProtocol {
    /// Prepends the next chunk of items to the `timelineItems` array.
    private func simulateBackPagination() async throws {
        guard !backPaginationResponses.isEmpty else { return }
+        callbacks.send(.isBackPaginating(true))
        
        let newItems = backPaginationResponses.removeFirst()
        timelineItems.insert(contentsOf: newItems, at: 0)
        callbacks.send(.updatedTimelineItems)
-        callbacks.send(.finishedBackPaginating)
+        callbacks.send(.isBackPaginating(false))
        
        try? await connection?.send(.success)
    }
--- a/ElementX/Sources/Services/Timeline/TimelineController/RoomTimelineController.swift
+++ b/ElementX/Sources/Services/Timeline/TimelineController/RoomTimelineController.swift
@@ -61,18 +61,6 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
            }
            .store(in: &cancellables)
        
-        self.timelineProvider
-            .backPaginationPublisher
-            .receive(on: DispatchQueue.main)
-            .sink { [weak self] value in
-                if value {
-                    self?.callbacks.send(.startedBackPaginating)
-                } else {
-                    self?.callbacks.send(.finishedBackPaginating)
-                }
-            }
-            .store(in: &cancellables)
-        
        updateTimelineItems()
        
        NotificationCenter.default.addObserver(self, selector: #selector(contentSizeCategoryDidChange), name: UIContentSizeCategory.didChangeNotification, object: nil)
@@ -230,6 +218,8 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
    // swiftlint:disable:next cyclomatic_complexity
    private func asyncUpdateTimelineItems() async {
        var newTimelineItems = [RoomTimelineItemProtocol]()
+        var canBackPaginate = true
+        var isBackPaginating = false

        for (index, itemProxy) in timelineProvider.itemsPublisher.value.enumerated() {
            if Task.isCancelled {
@@ -262,8 +252,10 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
                    }
                case .loadingIndicator:
                    newTimelineItems.append(PaginationIndicatorRoomTimelineItem())
+                    isBackPaginating = true
                case .timelineStart:
                    newTimelineItems.append(TimelineStartRoomTimelineItem(name: roomProxy.displayName ?? roomProxy.name))
+                    canBackPaginate = false
                }
            default:
                break
@@ -277,6 +269,8 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
        timelineItems = newTimelineItems
        
        callbacks.send(.updatedTimelineItems)
+        callbacks.send(.canBackPaginate(canBackPaginate))
+        callbacks.send(.isBackPaginating(isBackPaginating))
    }
    
    private func computeGroupState(for itemProxy: TimelineItemProxy,
--- a/ElementX/Sources/Services/Timeline/TimelineController/RoomTimelineControllerProtocol.swift
+++ b/ElementX/Sources/Services/Timeline/TimelineController/RoomTimelineControllerProtocol.swift
@@ -21,8 +21,8 @@ import UIKit
 enum RoomTimelineControllerCallback {
    case updatedTimelineItems
    case updatedTimelineItem(_ itemId: String)
-    case startedBackPaginating
-    case finishedBackPaginating
+    case canBackPaginate(Bool)
+    case isBackPaginating(Bool)
 }

 enum RoomTimelineControllerAction {
--- a/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutMiddle-0.png
+++ b/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutMiddle-0.png
@@ -1,3 +1,3 @@
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+size 314028
--- a/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutMiddle-1.png
+++ b/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutMiddle-1.png
@@ -1,3 +1,3 @@
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--- a/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutTop.png
+++ b/UITests/Sources/Snapshots/Application/de-DE-iPad-9th-generation.roomLayoutTop.png
@@ -1,3 +1,3 @@
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--- a/UITests/Sources/Snapshots/Application/de-DE-iPhone-14.roomLayoutMiddle-0.png
+++ b/UITests/Sources/Snapshots/Application/de-DE-iPhone-14.roomLayoutMiddle-0.png
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--- a/UITests/Sources/Snapshots/Application/de-DE-iPhone-14.roomLayoutMiddle-1.png
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--- a/UITests/Sources/Snapshots/Application/de-DE-iPhone-14.roomLayoutTop.png
+++ b/UITests/Sources/Snapshots/Application/de-DE-iPhone-14.roomLayoutTop.png
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--- a/UITests/Sources/Snapshots/Application/en-GB-iPad-9th-generation.roomLayoutMiddle-1.png
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--- a/UITests/Sources/Snapshots/Application/en-GB-iPhone-14.roomLayoutMiddle-1.png
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--- a/UITests/SupportingFiles/target.yml
+++ b/UITests/SupportingFiles/target.yml
@@ -58,7 +58,7 @@ targets:
    - path: ../SupportingFiles
    - path: ../../Tools/Scripts/Templates/SimpleScreenExample/Tests/UI
    - path: ../../ElementX/Sources/UITests/UITestScreenIdentifier.swift
-    - path: ../../ElementX/Sources/UITests/UITestSignalling.swift
+    - path: ../../ElementX/Sources/UITests/UITestsSignalling.swift
    - path: ../../ElementX/Sources/Generated/Strings.swift
    - path: ../../ElementX/Sources/Generated/Strings+Untranslated.swift
    - path: ../../ElementX/Resources
--- a/changelog.d/pr-432.bugfix
+++ b/changelog.d/pr-432.bugfix
@@ -0,0 +1 @@
+Use pagination indicators and start of room timeline items to update the view's pagination state.
				`@@ -0,0 +1 @@`
				`Use pagination indicators and start of room timeline items to update the view's pagination state.`