Convert ProfileStatusesViewController to DiffableTimelineLike

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -9,7 +9,7 @@
 import UIKit
 import Pachyderm
 
-class ProfileStatusesViewController: TimelineLikeTableViewController<TimelineEntry> {
+class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<ProfileStatusesViewController.Section, ProfileStatusesViewController.Item> {
     
     weak var mastodonController: MastodonController!
     
@@ -43,106 +43,128 @@ class ProfileStatusesViewController: TimelineLikeTableViewController<TimelineEnt
     }
     
     func updateUI(account: AccountMO) {
-        loadInitial()
+        if isViewLoaded {
+            reloadInitial()
+        }
     }
     
     override class func refreshCommandTitle() -> String {
         return NSLocalizedString("Refresh Statuses", comment: "refresh statuses command discoverability title")
     }
     
-    override func headerSectionsCount() -> Int {
-        return 1
+    override func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ item: Item) -> UITableViewCell? {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "statusCell", for: indexPath) as! TimelineStatusTableViewCell
+        
+        cell.delegate = self
+        // todo: dataSource.sectionIdentifier is only available on iOS 15
+        cell.showPinned = dataSource.snapshot().indexOfSection(.pinned) == indexPath.section
+        cell.updateUI(statusID: item.id, state: item.state)
+        
+        return cell
     }
     
-    override func loadInitial() {
+    override func loadInitialItems(completion: @escaping (LoadResult) -> Void) {
         guard accountID != nil else {
+            completion(.failure(.noClient))
             return
         }
         
-        if !loaded {
-            loadPinnedStatuses()
-        }
-        
-        super.loadInitial()
-    }
-    
-    private func loadPinnedStatuses() {
-        guard kind == .statuses else {
-            return
-        }
-        getPinnedStatuses { (response) in
-            guard case let .success(statuses, _) = response,
-                  !statuses.isEmpty else {
-                // todo: error message
-                return
-            }
-            
-            self.mastodonController.persistentContainer.addAll(statuses: statuses) {
-                let items = statuses.map { ($0.id, StatusState.unknown) }
-                DispatchQueue.main.async {
-                    UIView.performWithoutAnimation {
-                        if self.sections.count < 1 {
-                            self.sections.append(items)
-                            self.tableView.insertSections(IndexSet(integer: 0), with: .none)
-                        } else {
-                            self.sections[0] = items
-                            self.tableView.reloadSections(IndexSet(integer: 0), with: .none)
-                        }
-                    }
-                }
-            }
-        }
-    }
-    
-    override func loadInitialItems(completion: @escaping ([TimelineEntry]) -> Void) {
         getStatuses { (response) in
-            guard case let .success(statuses, pagination) = response,
-                  !statuses.isEmpty else {
-                // todo: error message
-                completion([])
-                return
-            }
+            switch response {
+            case let .failure(error):
+                completion(.failure(.client(error)))
                 
+            case let .success(statuses, pagination):
                 self.older = pagination?.older
                 self.newer = pagination?.newer
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
-                completion(statuses.map { ($0.id, .unknown) })
+                    DispatchQueue.main.async {
+                        var snapshot = self.dataSource.snapshot()
+                        snapshot.appendSections([.statuses])
+                        snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown) }, toSection: .statuses)
+                        if self.kind == .statuses {
+                            self.loadPinnedStatuses(snapshot: { snapshot }, completion: completion)
+                        } else {
+                            completion(.success(snapshot))
+                        }
+                    }
+                }
             }
         }
     }
     
-    override func loadOlder(completion: @escaping ([TimelineEntry]) -> Void) {
+    private func loadPinnedStatuses(snapshot: @escaping () -> Snapshot, completion: @escaping (LoadResult) -> Void) {
+        guard kind == .statuses else {
+            completion(.success(snapshot()))
+            return
+        }
+        getPinnedStatuses { (response) in
+            switch response {
+            case let .failure(error):
+                completion(.failure(.client(error)))
+                
+            case let .success(statuses, _):
+                self.mastodonController.persistentContainer.addAll(statuses: statuses) {
+                    DispatchQueue.main.async {
+                        var snapshot = snapshot()
+                        if snapshot.indexOfSection(.pinned) != nil {
+                            snapshot.deleteSections([.pinned])
+                        }
+                        snapshot.insertSections([.pinned], beforeSection: .statuses)
+                        snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown) }, toSection: .pinned)
+                        completion(.success(snapshot))
+                    }
+                }
+            }
+        }
+    }
+    
+    override func loadOlderItems(currentSnapshot: @escaping () -> Snapshot, completion: @escaping (LoadResult) -> Void) {
         guard let older = older else {
-            completion([])
+            completion(.failure(.noOlder))
             return
         }
         
         getStatuses(for: older) { (response) in
-            guard case let .success(statuses, pagination) = response else {
-                // todo: error message
-                completion([])
+            switch response {
+            case let .failure(error):
+                completion(.failure(.client(error)))
+                
+            case let .success(statuses, pagination):
+                guard !statuses.isEmpty else {
+                    completion(.failure(.noOlder))
                     return
                 }
                 
-            self.older = pagination?.older
+                if let older = pagination?.older {
+                    self.older = older
+                }
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
-                completion(statuses.map { ($0.id, .unknown) })
+                    var snapshot = currentSnapshot()
+                    snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown) }, toSection: .statuses)
+                    completion(.success(snapshot))
+                }
             }
         }
     }
    
-    override func loadNewer(completion: @escaping ([TimelineEntry]) -> Void) {
+    
+    override func loadNewerItems(currentSnapshot: @escaping () -> Snapshot, completion: @escaping (LoadResult) -> Void) {
         guard let newer = newer else {
-            completion([])
+            completion(.failure(.noNewer))
             return
         }
 
         getStatuses(for: newer) { (response) in
-            guard case let .success(statuses, pagination) = response else {
-                // todo: error message
-                completion([])
+            switch response {
+            case let .failure(error):
+                completion(.failure(.client(error)))
+                
+            case let .success(statuses, pagination):
+                guard !statuses.isEmpty else {
+                    completion(.failure(.noNewer))
                     return
                 }
                 
@@ -151,7 +173,15 @@ class ProfileStatusesViewController: TimelineLikeTableViewController<TimelineEnt
                 }
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
-                completion(statuses.map { ($0.id, .unknown) })
+                    var snapshot = currentSnapshot()
+                    let items = statuses.map { Item(id: $0.id, state: .unknown) }
+                    if let first = snapshot.itemIdentifiers(inSection: .statuses).first {
+                        snapshot.insertItems(items, beforeItem: first)
+                    } else {
+                        snapshot.appendItems(items, toSection: .statuses)
+                    }
+                    completion(.success(snapshot))
+                }
             }
         }
     }
@@ -178,52 +208,19 @@ class ProfileStatusesViewController: TimelineLikeTableViewController<TimelineEnt
         super.refresh()
         
         if kind == .statuses {
-            getPinnedStatuses { (response) in
-                guard case let .success(newPinnedStatues, _) = response else {
-                    // todo: error message
-                    return
-                }
+            loadPinnedStatuses(snapshot: dataSource.snapshot) { (result) in
+                switch result {
+                case .failure(_):
+                    break
                     
-                self.mastodonController.persistentContainer.addAll(statuses: newPinnedStatues) {
-                    // if the user refreshes before the initial pinned statuses request completes, self.sections will be empty
-                    let oldPinnedStatuses = self.sections.isEmpty ? [] : self.sections[0]
-                    let pinnedStatues = newPinnedStatues.map { (status) -> TimelineEntry in
-                        let state: StatusState
-                        if let (_, oldState) = oldPinnedStatuses.first(where: { $0.id == status.id }) {
-                            state = oldState
-                        } else {
-                            state = .unknown
-                        }
-                        return (status.id, state)
-                    }
+                case let .success(snapshot):
                     DispatchQueue.main.async {
-                        UIView.performWithoutAnimation {
-                            if self.sections.count < 1 {
-                                self.sections.append(pinnedStatues)
-                                self.tableView.insertSections(IndexSet(integer: 0), with: .none)
-                            } else {
-                                self.sections[0] = pinnedStatues
-                                self.tableView.reloadSections(IndexSet(integer: 0), with: .none)
+                        self.dataSource.apply(snapshot)
                     }
                 }
             }
         }
     }
-        }
-    }
-    
-    // MARK: - UITableViewDatasource
-    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
-        let cell = tableView.dequeueReusableCell(withIdentifier: "statusCell", for: indexPath) as! TimelineStatusTableViewCell
-        
-        cell.delegate = self
-        cell.showPinned = indexPath.section == 0
-        
-        let (id, state) = item(for: indexPath)
-        cell.updateUI(statusID: id, state: state)
-        
-        return cell
-    }
     
 }
 
@@ -233,6 +230,17 @@ extension ProfileStatusesViewController {
     }
 }
 
+extension ProfileStatusesViewController {
+    enum Section: CaseIterable {
+        case pinned
+        case statuses
+    }
+    struct Item: Hashable {
+        let id: String
+        let state: StatusState
+    }
+}
+
 extension ProfileStatusesViewController: TuskerNavigationDelegate {
     var apiController: MastodonController { mastodonController }
 }
@@ -245,18 +253,12 @@ extension ProfileStatusesViewController: StatusTableViewCellDelegate {
 
 extension ProfileStatusesViewController: UITableViewDataSourcePrefetching, StatusTablePrefetching {
     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
-        let ids = indexPaths.map { item(for: $0).id }
+        let ids = indexPaths.compactMap { dataSource.itemIdentifier(for: $0)?.id }
         prefetchStatuses(with: ids)
     }
     
     func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
-        let ids: [String] = indexPaths.compactMap {
-            guard $0.section < sections.count,
-                  $0.row < sections[$0.section].count else {
-                return nil
-            }
-            return item(for: $0).id
-        }
+        let ids = indexPaths.compactMap { dataSource.itemIdentifier(for: $0)?.id }
         cancelPrefetchingStatuses(with: ids)
     }
 }

Tusker/Screens/Profile/ProfileViewController.swift

@@ -211,9 +211,8 @@ class ProfileViewController: UIPageViewController {
                 // Layout and update the table view, otherwise the content jumps around when first scrolling it,
                 // if old was not scrolled all the way to the top
                 new.tableView.layoutIfNeeded()
-                UIView.performWithoutAnimation {
-                    new.tableView.performBatchUpdates(nil, completion: nil)
-                }
+                let snapshot = new.dataSource.snapshot()
+                new.dataSource.apply(snapshot, animatingDifferences: false)
                 
                 completion?(finished)
             }

Tusker/Screens/Utilities/DiffableTimelineLikeTableViewController.swift

@@ -88,7 +88,10 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
             let sectionsToRemove = contentSections[lastVisibleContentSectionIndex...]
             snapshot.deleteSections(Array(sectionsToRemove))
             
-            willRemoveItems(sectionsToRemove.flatMap(snapshot.itemIdentifiers(inSection:)))
+            let itemsToRemove = sectionsToRemove.filter {
+                snapshot.indexOfSection($0) != nil
+            }.flatMap(snapshot.itemIdentifiers(inSection:))
+            willRemoveItems(itemsToRemove)
         } else if lastVisibleContentSectionIndex == contentSections.count - 1 {
             let items = snapshot.itemIdentifiers(inSection: lastVisibleRowSection)