Fix pagination issues

ServiceLayer/Sources/ServiceLayer/Services/CollectionService.swift

@@ -6,6 +6,7 @@ import Mastodon
 public protocol CollectionService {
     var sections: AnyPublisher<[[CollectionItem]], Error> { get }
     var nextPageMaxId: AnyPublisher<String, Never> { get }
+    var preferLastPresentIdOverNextPageMaxId: Bool { get }
     var title: AnyPublisher<String, Never> { get }
     var titleLocalizationComponents: AnyPublisher<[String], Never> { get }
     var navigationService: NavigationService { get }
@@ -16,6 +17,8 @@ public protocol CollectionService {
 extension CollectionService {
     public var nextPageMaxId: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }
 
+    public var preferLastPresentIdOverNextPageMaxId: Bool { false }
+
     public var title: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }
 
     public var titleLocalizationComponents: AnyPublisher<[String], Never> { Empty().eraseToAnyPublisher() }

ServiceLayer/Sources/ServiceLayer/Services/TimelineService.swift

@@ -10,6 +10,7 @@ public struct TimelineService {
     public let sections: AnyPublisher<[[CollectionItem]], Error>
     public let navigationService: NavigationService
     public let nextPageMaxId: AnyPublisher<String, Never>
+    public let preferLastPresentIdOverNextPageMaxId = true
     public let title: AnyPublisher<String, Never>
 
     private let timeline: Timeline

View Controllers/TableViewController.swift

@@ -16,6 +16,7 @@ class TableViewController: UITableViewController {
     private let identification: Identification
     private let loadingTableFooterView = LoadingTableFooterView()
     private let webfingerIndicatorView = WebfingerIndicatorView()
+    @Published private var loading = false
     private var cancellables = Set<AnyCancellable>()
     private var cellHeightCaches = [CGFloat: [CollectionItem: CGFloat]]()
     private var shouldKeepPlayingVideoAfterDismissal = false
@@ -234,7 +235,9 @@ private extension TableViewController {
             .sink { [weak self] in self?.set(expandAllState: $0) }
             .store(in: &cancellables)
 
-        viewModel.loading.receive(on: RunLoop.main).sink { [weak self] in
+        viewModel.loading.receive(on: DispatchQueue.main).assign(to: &$loading)
+
+        $loading.sink { [weak self] in
             guard let self = self else { return }
 
             self.tableView.tableFooterView = $0 ? self.loadingTableFooterView : UIView()
@@ -244,7 +247,6 @@ private extension TableViewController {
 
         viewModel.alertItems
             .compactMap { $0 }
-            .handleEvents(receiveOutput: { print($0.error) })
             .sink { [weak self] in self?.present(alertItem: $0) }
             .store(in: &cancellables)
 
@@ -433,11 +435,13 @@ private extension TableViewController {
     }
 
     func paginateIfLastIndexPathPresent(indexPaths: [IndexPath]) {
-        guard
-            let maxId = viewModel.nextPageMaxId,
+        guard !loading,
               let indexPath = indexPaths.last,
               indexPath.section == dataSource.numberOfSections(in: tableView) - 1,
-            indexPath.row == dataSource.tableView(tableView, numberOfRowsInSection: indexPath.section) - 1
+              indexPath.row == dataSource.tableView(tableView, numberOfRowsInSection: indexPath.section) - 1,
+              let maxId = viewModel.preferLastPresentIdOverNextPageMaxId
+                ? dataSource.itemIdentifier(for: indexPath)?.itemId
+                : viewModel.nextPageMaxId
         else { return }
 
         viewModel.request(maxId: maxId, minId: nil)

ViewModels/Sources/ViewModels/CollectionItemsViewModel.swift

@@ -82,6 +82,8 @@ extension CollectionItemsViewModel: CollectionViewModel {
 
     public var shouldAdjustContentInset: Bool { collectionService is ContextService }
 
+    public var preferLastPresentIdOverNextPageMaxId: Bool { collectionService.preferLastPresentIdOverNextPageMaxId }
+
     public func request(maxId: String? = nil, minId: String? = nil) {
         let publisher: AnyPublisher<Never, Error>
 

ViewModels/Sources/ViewModels/CollectionViewModel.swift

@@ -13,6 +13,7 @@ public protocol CollectionViewModel {
     var events: AnyPublisher<CollectionItemEvent, Never> { get }
     var shouldAdjustContentInset: Bool { get }
     var nextPageMaxId: String? { get }
+    var preferLastPresentIdOverNextPageMaxId: Bool { get }
     func request(maxId: String?, minId: String?)
     func viewedAtTop(indexPath: IndexPath)
     func select(indexPath: IndexPath)

ViewModels/Sources/ViewModels/ProfileViewModel.swift

@@ -103,6 +103,10 @@ extension ProfileViewModel: CollectionViewModel {
         collectionViewModel.value.nextPageMaxId
     }
 
+    public var preferLastPresentIdOverNextPageMaxId: Bool {
+        collectionViewModel.value.preferLastPresentIdOverNextPageMaxId
+    }
+
     public func request(maxId: String?, minId: String?) {
         if case .statuses = collection, maxId == nil {
             profileService.fetchPinnedStatuses()