Timeline jump to present

Pachyderm/Sources/Pachyderm/Request/RequestRange.swift

@@ -11,7 +11,9 @@ import Foundation
 public enum RequestRange {
     case `default`
     case count(Int)
+    /// Chronologically immediately before the given ID
     case before(id: String, count: Int?)
+    /// Chronologically immediately after the given ID
     case after(id: String, count: Int?)
 }
 

Tusker/Screens/Explore/TrendingStatusesViewController.swift

@@ -97,7 +97,7 @@ class TrendingStatusesViewController: UIViewController {
         do {
             statuses = try await mastodonController.run(Client.getTrendingStatuses()).0
         } catch {
-            var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
+            let snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
             await dataSource.apply(snapshot)
             let config = ToastConfiguration(from: error, with: "Loading Trending Posts", in: self) { toast in
                 toast.dismissToast(animated: true)

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -25,8 +25,8 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
     private var older: RequestRange?
     private var cancellables = Set<AnyCancellable>()
     
-    var collectionView: UICollectionView {
+    var collectionView: UICollectionView! {
-        view as! UICollectionView
+        view as? UICollectionView
     }
     private(set) var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
     private(set) var headerCell: ProfileHeaderCollectionViewCell?
@@ -157,7 +157,7 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
         }
         
         Task {
-            if case .notLoadedInitial = await controller.state {
+            if case .notLoadedInitial = controller.state {
                 await load()
             }
         }

Tusker/Screens/Timeline/TimelineGapCollectionViewCell.swift

@@ -10,7 +10,7 @@ import UIKit
 
 class TimelineGapCollectionViewCell: UICollectionViewCell {
     
-    var fillGap: ((TimelineLikeController<TimelineViewController.TimelineItem>.GapDirection) -> Void)?
+    var fillGap: ((TimelineGapDirection) -> Void)?
     
     override init(frame: CGRect) {
         super.init(frame: frame)

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -16,14 +16,10 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     
     private(set) var controller: TimelineLikeController<TimelineItem>!
     let confirmLoadMore = PassthroughSubject<Void, Never>()
-    private var newer: RequestRange?
-    private var older: RequestRange?
     // stored separately because i don't want to query the snapshot every time the user scrolls
     private var isShowingTimelineDescription = false
     
-    var collectionView: UICollectionView {
+    private(set) var collectionView: UICollectionView!
-        view as! UICollectionView
-    }
     private(set) var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
     
     init(for timeline: Timeline, mastodonController: MastodonController!) {
@@ -42,7 +38,9 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         fatalError("init(coder:) has not been implemented")
     }
     
-    override func loadView() {
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
         var config = UICollectionLayoutListConfiguration(appearance: .plain)
         config.leadingSwipeActionsConfigurationProvider = { [unowned self] in
             (collectionView.cellForItem(at: $0) as? TimelineStatusCollectionViewCell)?.leadingSwipeActions()
@@ -66,9 +64,17 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             return config
         }
         let layout = UICollectionViewCompositionalLayout.list(using: config)
-        view = UICollectionView(frame: .zero, collectionViewLayout: layout)
+        collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
         collectionView.delegate = self
         collectionView.dragDelegate = self
+        collectionView.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(collectionView)
+        NSLayoutConstraint.activate([
+            collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            collectionView.topAnchor.constraint(equalTo: view.topAnchor),
+            collectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+        ])
         
         registerTimelineLikeCells()
         collectionView.register(PublicTimelineDescriptionCollectionViewCell.self, forCellWithReuseIdentifier: "publicTimelineDescription")
@@ -79,23 +85,31 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         collectionView.refreshControl = UIRefreshControl()
         collectionView.refreshControl!.addTarget(self, action: #selector(refresh), for: .valueChanged)
 #endif
-    }
-    
-    override func viewDidLoad() {
-        super.viewDidLoad()
         
         #if DEBUG
-        navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "square.split.1x2.fill"), primaryAction: UIAction(handler: { [unowned self] _ in
+//        navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "square.split.1x2.fill"), primaryAction: UIAction(handler: { [unowned self] _ in
+//            var snapshot = self.dataSource.snapshot()
+//            let statuses = snapshot.itemIdentifiers(inSection: .statuses)
+//            if statuses.count > 20 {
+//                let toRemove = Array(Array(statuses.dropFirst(10)).dropLast(10))
+//                if !toRemove.isEmpty {
+//                    print("REMOVING MIDDLE \(toRemove.count) STATUSES")
+//                    snapshot.insertItems([.gap], beforeItem: toRemove.first!)
+//                    snapshot.deleteItems(toRemove)
+//                    self.dataSource.apply(snapshot)
+//                }
+//            }
+//        }))
+        navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(systemName: "clock.arrow.circlepath"), primaryAction: UIAction(handler: { [unowned self] _ in
             var snapshot = self.dataSource.snapshot()
             let statuses = snapshot.itemIdentifiers(inSection: .statuses)
             if statuses.count > 20 {
-                let toRemove = Array(Array(statuses.dropFirst(10)).dropLast(10))
+                let toRemove = Array(statuses.dropLast(20))
-                if !toRemove.isEmpty {
-                    print("REMOVING MIDDLE \(toRemove.count) STATUSES")
-                    snapshot.insertItems([.gap], beforeItem: toRemove.first!)
                 snapshot.deleteItems(toRemove)
                 self.dataSource.apply(snapshot)
-                }
+//                if case .status(id: let id, state: _) = snapshot.itemIdentifiers(inSection: .statuses).first {
+//                    self.controller.dataSource.state.newer = .after(id: id, count: nil)
+//                }
             }
         }))
         #else
@@ -167,7 +181,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         }
         
         Task {
-            if case .notLoadedInitial = await controller.state {
+            if case .notLoadedInitial = controller.state {
                 await controller.loadInitial()
             }
         }
@@ -224,10 +238,53 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     
     @objc func refresh() {
         Task {
-            if case .notLoadedInitial = await controller.state {
+            if case .notLoadedInitial = controller.state {
                 await controller.loadInitial()
             } else {
-                await controller.loadNewer()
+                // I'm not sure whether this should move into TimelineLikeController/TimelineLikeCollectionViewController
+                let (_, presentItems) = await (controller.loadNewer(), try? loadInitial())
+                if let presentItems,
+                   case .status(id: let id, state: _) = dataSource.snapshot().itemIdentifiers(inSection: .statuses).first {
+                    // if there's no overlap between presentItems and the existing items in the data source, prompt the user to scroll to present
+                    if !presentItems.contains(id) {
+                        var snapshot = self.dataSource.snapshot()
+                        let currentItems = snapshot.itemIdentifiers(inSection: .statuses)
+                        guard let item = currentItems.first,
+                              case .status(id: id, state: _) = item else {
+                            return
+                        }
+
+                        // remove any existing gap if there is one
+                        if let index = currentItems.lastIndex(of: .gap) {
+                            snapshot.deleteItems(Array(currentItems[index...]))
+                        }
+                        snapshot.insertItems([.gap], beforeItem: item)
+                        snapshot.insertItems(presentItems.map { .status(id: $0, state: .unknown) }, beforeItem: .gap)
+                        
+                        // use a snapshot of the collection view to hide the flicker as the content offset changes and then changes back
+                        let snapshotView = collectionView.snapshotView(afterScreenUpdates: false)!
+                        snapshotView.layer.zPosition = 1000
+                        snapshotView.frame = view.bounds
+                        view.addSubview(snapshotView)
+                        
+                        let bottomOffset = collectionView.contentSize.height - collectionView.contentOffset.y
+                        self.dataSource.apply(snapshot, animatingDifferences: false) {
+                            self.collectionView.contentOffset = CGPoint(x: 0, y: self.collectionView.contentSize.height - bottomOffset)
+                            snapshotView.removeFromSuperview()
+                        }
+                        
+                        var config = ToastConfiguration(title: "Jump to present")
+                        config.edge = .top
+                        config.systemImageName = "arrow.up"
+                        config.dismissAutomaticallyAfter = 2
+                        config.action = { [unowned self] toast in
+                            toast.dismissToast(animated: true)
+
+                            self.collectionView.scrollToTop()
+                        }
+                        self.showToast(configuration: config, animated: true)
+                    }
+                }
             }
             #if !targetEnvironment(macCatalyst)
             collectionView.refreshControl?.endRefreshing()
@@ -318,50 +375,48 @@ extension TimelineViewController {
     func loadInitial() async throws -> [TimelineItem] {
         try await Task.sleep(nanoseconds: 1 * NSEC_PER_SEC)
         
-        guard let mastodonController else {
-            throw Error.noClient
-        }
-        
         let request = Client.getStatuses(timeline: timeline)
         let (statuses, _) = try await mastodonController.run(request)
         
-        if !statuses.isEmpty {
+        await withCheckedContinuation { continuation in
-            newer = .after(id: statuses.first!.id, count: nil)
+            mastodonController.persistentContainer.addAll(statuses: statuses) {
-            older = .before(id: statuses.last!.id, count: nil)
+                continuation.resume()
+            }
         }
         
-        return await withCheckedContinuation { continuation in
+        return statuses.map(\.id)
-            mastodonController.persistentContainer.addAll(statuses: statuses) {
-                continuation.resume(returning: statuses.map(\.id))
-            }
-        }
     }
     
     func loadNewer() async throws -> [TimelineItem] {
-        guard let newer else {
+        let statusesSection = dataSource.snapshot().indexOfSection(.statuses)!
+        guard case .status(id: let id, state: _) = dataSource.itemIdentifier(for: IndexPath(row: 0, section: statusesSection)) else {
             throw Error.noNewer
         }
+        let newer = RequestRange.after(id: id, count: nil)
         
         let request = Client.getStatuses(timeline: timeline, range: newer)
         let (statuses, _) = try await mastodonController.run(request)
         
         guard !statuses.isEmpty else {
-            throw Error.allCaughtUp
+            throw TimelineViewController.Error.allCaughtUp
         }
         
-        self.newer = .after(id: statuses.first!.id, count: nil)
+        await withCheckedContinuation { continuation in
-        
-        return await withCheckedContinuation { continuation in
             mastodonController.persistentContainer.addAll(statuses: statuses) {
-                continuation.resume(returning: statuses.map(\.id))
+                continuation.resume()
             }
         }
+        
+        return statuses.map(\.id)
     }
     
     func loadOlder() async throws -> [TimelineItem] {
-        guard let older else {
+        let snapshot = dataSource.snapshot()
-            throw Error.noOlder
+        let statusesSection = snapshot.indexOfSection(.statuses)!
+        guard case .status(id: let id, state: _) = dataSource.itemIdentifier(for: IndexPath(row: snapshot.numberOfItems(inSection: .statuses) - 1, section: statusesSection)) else {
+            throw Error.noNewer
         }
+        let older = RequestRange.before(id: id, count: nil)
         
         let request = Client.getStatuses(timeline: timeline, range: older)
         let (statuses, _) = try await mastodonController.run(request)
@@ -370,16 +425,16 @@ extension TimelineViewController {
             return []
         }
         
-        self.older = .before(id: statuses.last!.id, count: nil)
+        await withCheckedContinuation { continuation in
-        
-        return await withCheckedContinuation { continuation in
             mastodonController.persistentContainer.addAll(statuses: statuses) {
-                continuation.resume(returning: statuses.map(\.id))
+                continuation.resume()
-            }
             }
         }
         
-    func loadGap(in direction: TimelineLikeController<TimelineItem>.GapDirection) async throws -> [TimelineItem] {
+        return statuses.map(\.id)
+    }
+    
+    func loadGap(in direction: TimelineGapDirection) async throws -> [TimelineItem] {
         guard let gapIndexPath = dataSource.indexPath(for: .gap) else {
             throw Error.noGap
         }
@@ -410,14 +465,16 @@ extension TimelineViewController {
         
         // NOTE: closing the gap (if necessary) happens in handleFillGap
         
-        return await withCheckedContinuation { continuation in
+        await withCheckedContinuation { continuation in
             mastodonController.persistentContainer.addAll(statuses: statuses) {
-                continuation.resume(returning: statuses.map(\.id))
+                continuation.resume()
-            }
             }
         }
         
-    func handleLoadGapError(_ error: Swift.Error, direction: TimelineLikeController<String>.GapDirection) async {
+        return statuses.map(\.id)
+    }
+    
+    func handleLoadGapError(_ error: Swift.Error, direction: TimelineGapDirection) async {
         // TODO: better title, involving direction?
         let config = ToastConfiguration(from: error, with: "Error Loading", in: self) { [weak self] toast in
             toast.dismissToast(animated: true)
@@ -428,7 +485,7 @@ extension TimelineViewController {
         self.showToast(configuration: config, animated: true)
     }
     
-    func handleFillGap(_ timelineItems: [String], direction: TimelineLikeController<String>.GapDirection) async {
+    func handleFillGap(_ timelineItems: [String], direction: TimelineGapDirection) async {
         var snapshot = dataSource.snapshot()
         let addedItems: Bool
         
@@ -496,14 +553,14 @@ extension TimelineViewController {
             }
         }
         
-        // if we didn't add any items, that implies the gap was removed, and we want to animate that to make clear what's happening
+        // if we didn't add any items, that implies the gap was removed, and we want to to make clear what's happening
         if !addedItems {
-            await apply(snapshot, animatingDifferences: true)
+            var config = ToastConfiguration(title: "There's nothing in between!")
-            let config = ToastConfiguration(title: "There's nothing in between!")
+            config.dismissAutomaticallyAfter = 2
             showToast(configuration: config, animated: true)
-        } else {
-            await apply(snapshot, animatingDifferences: false)
         }
+        
+        await apply(snapshot, animatingDifferences: true)
     }
     
     enum Error: TimelineLikeCollectionViewError {

Tusker/Screens/Utilities/TimelineLikeCollectionViewController.swift

@@ -19,7 +19,7 @@ protocol TimelineLikeCollectionViewController: UIViewController, TimelineLikeCon
     var controller: TimelineLikeController<TimelineItem>! { get }
     var confirmLoadMore: PassthroughSubject<Void, Never> { get }
     
-    var collectionView: UICollectionView { get }
+    var collectionView: UICollectionView! { get }
     var dataSource: UICollectionViewDiffableDataSource<Section, Item>! { get }
 }
 
@@ -64,7 +64,7 @@ extension TimelineLikeCollectionViewController {
     }
     
     func handleAddLoadingIndicator() async {
-        if case .loadingInitial(_, _) = await controller.state,
+        if case .loadingInitial(_, _) = controller.state,
            let refreshControl = collectionView.refreshControl,
            refreshControl.isRefreshing {
             refreshControl.beginRefreshing()
@@ -85,7 +85,7 @@ extension TimelineLikeCollectionViewController {
     }
     
     func handleRemoveLoadingIndicator() async {
-        if case .loadingInitial(_, _) = await controller.state,
+        if case .loadingInitial(_, _) = controller.state,
            let refreshControl = collectionView.refreshControl,
            refreshControl.isRefreshing {
             refreshControl.endRefreshing()
@@ -180,14 +180,14 @@ extension TimelineLikeCollectionViewController {
         await apply(snapshot, animatingDifferences: false)
     }
     
-    func loadGap(in direction: TimelineLikeController<TimelineItem>.GapDirection) async throws -> [TimelineItem] {
+    func loadGap(in direction: TimelineGapDirection) async throws -> [TimelineItem] {
         fatalError("not supported by \(String(describing: type(of: self)))")
     }
     
-    func handleLoadGapError(_ error: Swift.Error, direction: TimelineLikeController<TimelineItem>.GapDirection) async {
+    func handleLoadGapError(_ error: Swift.Error, direction: TimelineGapDirection) async {
     }
     
-    func handleFillGap(_ timelineItems: [TimelineItem], direction: TimelineLikeController<TimelineItem>.GapDirection) async {
+    func handleFillGap(_ timelineItems: [TimelineItem], direction: TimelineGapDirection) async {
         fatalError("not supported by \(String(describing: type(of: self)))")
     }
 }
@@ -217,7 +217,7 @@ extension TimelineLikeCollectionViewController {
         let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "confirmLoadMore", for: indexPath) as! ConfirmLoadMoreCollectionViewCell
         cell.confirmLoadMore = self.confirmLoadMore
         Task {
-            if case .loadingOlder(_, _) = await controller.state {
+            if case .loadingOlder(_, _) = controller.state {
                 cell.isLoading = true
             } else {
                 cell.isLoading = false

Tusker/TimelineLikeController.swift

@@ -16,11 +16,11 @@ protocol TimelineLikeControllerDelegate<TimelineItem>: AnyObject {
     
     func loadNewer() async throws -> [TimelineItem]
     
-    func loadOlder() async throws -> [TimelineItem]
-    
     func canLoadOlder() async -> Bool
     
-    func loadGap(in direction: TimelineLikeController<TimelineItem>.GapDirection) async throws -> [TimelineItem]
+    func loadOlder() async throws -> [TimelineItem]
+    
+    func loadGap(in direction: TimelineGapDirection) async throws -> [TimelineItem]
     
     func handleAddLoadingIndicator() async
     func handleRemoveLoadingIndicator() async
@@ -30,15 +30,16 @@ protocol TimelineLikeControllerDelegate<TimelineItem>: AnyObject {
     func handlePrependItems(_ timelineItems: [TimelineItem]) async
     func handleLoadOlderError(_ error: Swift.Error) async
     func handleAppendItems(_ timelineItems: [TimelineItem]) async
-    func handleLoadGapError(_ error: Swift.Error, direction: TimelineLikeController<TimelineItem>.GapDirection) async
+    func handleLoadGapError(_ error: Swift.Error, direction: TimelineGapDirection) async
-    func handleFillGap(_ timelineItems: [TimelineItem], direction: TimelineLikeController<TimelineItem>.GapDirection) async
+    func handleFillGap(_ timelineItems: [TimelineItem], direction: TimelineGapDirection) async
 }
 
 private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "TimelineLikeController")
 
-actor TimelineLikeController<Item> {
+@MainActor
+class TimelineLikeController<Item> {
     
-    unowned var delegate: any TimelineLikeControllerDelegate<Item>
+    private unowned var delegate: any TimelineLikeControllerDelegate<Item>
     
     private(set) var state = State.notLoadedInitial {
         willSet {
@@ -130,7 +131,7 @@ actor TimelineLikeController<Item> {
         }
     }
     
-    func fillGap(in direction: GapDirection) async {
+    func fillGap(in direction: TimelineGapDirection) async {
         guard state == .idle else {
             return
         }
@@ -190,7 +191,7 @@ actor TimelineLikeController<Item> {
         case loadingInitial(LoadAttemptToken, hasAddedLoadingIndicator: Bool)
         case loadingNewer(LoadAttemptToken)
         case loadingOlder(LoadAttemptToken, hasAddedLoadingIndicator: Bool)
-        case loadingGap(LoadAttemptToken, GapDirection)
+        case loadingGap(LoadAttemptToken, TimelineGapDirection)
         
         var debugDescription: String {
             switch self {
@@ -293,8 +294,8 @@ actor TimelineLikeController<Item> {
         case prependItems([Item], LoadAttemptToken)
         case loadOlderError(Error, LoadAttemptToken)
         case appendItems([Item], LoadAttemptToken)
-        case loadGapError(Error, GapDirection, LoadAttemptToken)
+        case loadGapError(Error, TimelineGapDirection, LoadAttemptToken)
-        case fillGap([Item], GapDirection, LoadAttemptToken)
+        case fillGap([Item], TimelineGapDirection, LoadAttemptToken)
         
         var debugDescription: String {
             switch self {
@@ -356,11 +357,11 @@ actor TimelineLikeController<Item> {
         }
     }
     
-    enum GapDirection {
+}
+
+enum TimelineGapDirection {
     /// Fill in below the gap. I.e., statuses that are immediately newer than the status below the gap.
     case below
     /// Fill in above the gap. I.e., statuses that are immediately older than the status above the gap.
     case above
 }
-    
-}