Refactoring

DB/Sources/DB/Content/ContextItemsInfo.swift

@@ -34,6 +34,7 @@ extension ContextItemsInfo {
                         && section[index + 1].record.inReplyToId == statusInfo.record.id
 
                     return .status(.init(status: .init(info: statusInfo),
+                                         isContextParent: statusInfo.record.id == parent.record.id,
                                          isReplyInContext: isReplyInContext,
                                          hasReplyFollowing: hasReplyFollowing))
                 }

DB/Sources/DB/Content/TimelineItemsInfo.swift

@@ -51,7 +51,7 @@ extension TimelineItemsInfo {
 
         if let pinnedStatusInfos = pinnedStatusesInfo?.pinnedStatusInfos {
             return [pinnedStatusInfos.filtered(regularExpression: filterRegularExpression)
-                        .map { CollectionItem.status(.init(status: .init(info: $0), pinned: true)) },
+                        .map { CollectionItem.status(.init(status: .init(info: $0), isPinned: true)) },
                     timelineItems]
         } else {
             return [timelineItems]

DB/Sources/DB/Entities/CollectionItem.swift

@@ -11,13 +11,19 @@ public enum CollectionItem: Hashable {
 public extension CollectionItem {
     struct StatusConfiguration: Hashable {
         public let status: Status
-        public let pinned: Bool
+        public let isContextParent: Bool
+        public let isPinned: Bool
         public let isReplyInContext: Bool
         public let hasReplyFollowing: Bool
 
-        init(status: Status, pinned: Bool = false, isReplyInContext: Bool = false, hasReplyFollowing: Bool = false) {
+        init(status: Status,
+             isContextParent: Bool = false,
+             isPinned: Bool = false,
+             isReplyInContext: Bool = false,
+             hasReplyFollowing: Bool = false) {
             self.status = status
-            self.pinned = pinned
+            self.isContextParent = isContextParent
+            self.isPinned = isPinned
             self.isReplyInContext = isReplyInContext
             self.hasReplyFollowing = hasReplyFollowing
         }

ServiceLayer/Sources/ServiceLayer/Services/CollectionService.swift

@@ -7,7 +7,6 @@ public protocol CollectionService {
     var nextPageMaxId: AnyPublisher<String, Never> { get }
     var title: AnyPublisher<String, Never> { get }
     var navigationService: NavigationService { get }
-    var contextParentId: String? { get }
     func request(maxId: String?, minId: String?) -> AnyPublisher<Never, Error>
 }
 
@@ -15,6 +14,4 @@ extension CollectionService {
     public var nextPageMaxId: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }
 
     public var title: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }
-
-    public var contextParentId: String? { nil }
 }

ServiceLayer/Sources/ServiceLayer/Services/ContextService.swift

@@ -9,7 +9,6 @@ import MastodonAPI
 public struct ContextService {
     public let sections: AnyPublisher<[[CollectionItem]], Error>
     public let navigationService: NavigationService
-    public var contextParentId: String? { id }
 
     private let id: Status.Id
     private let mastodonAPIClient: MastodonAPIClient

ViewModels/Sources/ViewModels/CollectionItemsViewModel.swift

@@ -81,7 +81,7 @@ extension CollectionItemsViewModel: CollectionViewModel {
     public func canSelect(indexPath: IndexPath) -> Bool {
         switch items.value[indexPath.section][indexPath.item] {
         case let .status(configuration):
-            return configuration.status.id != collectionService.contextParentId
+            return !configuration.isContextParent
         case .loadMore:
             return !((viewModel(indexPath: indexPath) as? LoadMoreViewModel)?.loading ?? false)
         default:
@@ -104,8 +104,8 @@ extension CollectionItemsViewModel: CollectionViewModel {
                 cache(viewModel: viewModel, forItem: item)
             }
 
-            viewModel.isContextParent = configuration.status.id == collectionService.contextParentId
-            viewModel.isPinned = configuration.pinned
+            viewModel.isContextParent = configuration.isContextParent
+            viewModel.isPinned = configuration.isPinned
             viewModel.isReplyInContext = configuration.isReplyInContext
             viewModel.hasReplyFollowing = configuration.hasReplyFollowing
 
@@ -156,14 +156,14 @@ private extension CollectionItemsViewModel {
         maintainScrollPositionOfItem = nil // clear old value
 
         // Maintain scroll position of parent after initial load of context
-        if let contextParentId = collectionService.contextParentId {
-            let contextParentIdentifier = CollectionItemIdentifier(id: contextParentId, kind: .status, info: [:])
-            let onlyContextParentId = [[], [contextParentIdentifier], []]
+        if collectionService is ContextService,
+           items.value.isEmpty || items.value.map(\.count) == [0, 1, 0],
+           let contextParent = newItems.reduce([], +).first(where: {
+            guard case let .status(configuration) = $0 else { return false }
 
-            if items.value.isEmpty
-                || items.value.map({ $0.map(CollectionItemIdentifier.init(item:)) }) == onlyContextParentId {
-                maintainScrollPositionOfItem = contextParentIdentifier
-            }
+            return configuration.isContextParent
+           }) {
+            maintainScrollPositionOfItem = .init(item: contextParent)
         }
     }
 }

ViewModels/Sources/ViewModels/Entities/CollectionItemIdentifier.swift

@@ -27,7 +27,7 @@ extension CollectionItemIdentifier {
         case let .status(configuration):
             id = configuration.status.id
             kind = .status
-            info = configuration.pinned ? [.pinned: true] : [:]
+            info = configuration.isPinned ? [.pinned: true] : [:]
         case let .loadMore(loadMore):
             id = loadMore.afterStatusId
             kind = .loadMore