Timelines mega-refactor / load more WIP

DB/Sources/DB/Content/ContentDatabase+Migration.swift

@@ -71,6 +71,13 @@ extension ContentDatabase {
                 t.column("profileCollection", .text)
             }
 
+            try db.create(table: "loadMore") { t in
+                t.column("timelineId").notNull().references("timelineRecord", onDelete: .cascade)
+                t.column("afterStatusId", .text).notNull()
+
+                t.primaryKey(["timelineId", "afterStatusId"], onConflict: .replace)
+            }
+
             try db.create(table: "timelineStatusJoin") { t in
                 t.column("timelineId", .text).indexed().notNull()
                     .references("timelineRecord", onDelete: .cascade)

DB/Sources/DB/Content/ContentDatabase.swift

@@ -165,39 +165,81 @@ public extension ContentDatabase {
             .eraseToAnyPublisher()
     }
 
-    func statusesObservation(timeline: Timeline) -> AnyPublisher<[[Status]], Error> {
+    // Awkward maps explained: https://github.com/groue/GRDB.swift#valueobservation-performance
-        ValueObservation.tracking { db -> [[StatusInfo]] in
+
-            let statuses = try TimelineRecord(timeline: timeline).statuses.fetchAll(db)
+    func observation(timeline: Timeline) -> AnyPublisher<[[Timeline.Item]], Error> {
+        ValueObservation.tracking { db -> ([StatusInfo], [StatusInfo]?, [LoadMore], [Filter]) in
+            let timelineRecord = TimelineRecord(timeline: timeline)
+            let statuses = try timelineRecord.statuses.fetchAll(db)
+            let loadMores = try timelineRecord.loadMores.fetchAll(db)
+            let filters = try Filter.active.fetchAll(db)
 
             if case let .profile(accountId, profileCollection) = timeline, profileCollection == .statuses {
                 let pinnedStatuses = try AccountRecord.filter(AccountRecord.Columns.id == accountId)
-                    .fetchOne(db)?.pinnedStatuses.fetchAll(db) ?? []
+                    .fetchOne(db)?.pinnedStatuses.fetchAll(db)
 
-                return [pinnedStatuses, statuses]
+                return (statuses, pinnedStatuses, loadMores, filters)
             } else {
-                return [statuses]
+                return (statuses, nil, loadMores, filters)
+            }
+        }
+        .map { statuses, pinnedStatuses, loadMores, filters -> [[Timeline.Item]] in
+            var timelineItems = statuses.filtered(filters: filters, context: timeline.filterContext)
+                .map { Timeline.Item.status(.init(status: .init(info: $0))) }
+
+            for loadMore in loadMores {
+                guard let index = timelineItems.firstIndex(where: {
+                    guard case let .status(configuration) = $0 else { return false }
+
+                    return loadMore.afterStatusId < configuration.status.id
+                }) else { continue }
+
+                timelineItems.insert(.loadMore(loadMore), at: index)
+            }
+
+            if let pinnedStatuses = pinnedStatuses {
+                return [pinnedStatuses.filtered(filters: filters, context: timeline.filterContext)
+                            .map { Timeline.Item.status(.init(status: .init(info: $0), pinned: true)) },
+                        timelineItems]
+            } else {
+                return [timelineItems]
             }
         }
         .removeDuplicates()
-        .map { $0.map { $0.map(Status.init(info:)) } }
         .publisher(in: databaseWriter)
         .eraseToAnyPublisher()
     }
 
-    func contextObservation(parentID: String) -> AnyPublisher<[[Status]], Error> {
+    func contextObservation(parentID: String) -> AnyPublisher<[[Timeline.Item]], Error> {
-        ValueObservation.tracking { db -> [[StatusInfo]] in
+        ValueObservation.tracking { db -> ([[StatusInfo]], [Filter]) in
             guard let parent = try StatusInfo.request(StatusRecord.filter(StatusRecord.Columns.id == parentID))
                     .fetchOne(db) else {
-                return []
+                return ([], [])
             }
 
             let ancestors = try parent.record.ancestors.fetchAll(db)
             let descendants = try parent.record.descendants.fetchAll(db)
 
-            return [ancestors, [parent], descendants]
+            return ([ancestors, [parent], descendants], try Filter.active.fetchAll(db))
+        }
+        .map { statusSections, filters in
+            statusSections.map { section in
+                section.filtered(filters: filters, context: .thread)
+                    .enumerated()
+                    .map { index, statusInfo in
+                        let isReplyInContext = index > 0
+                            && section[index - 1].record.id == statusInfo.record.inReplyToId
+                        let hasReplyFollowing = section.count > index + 1
+                            && section[index + 1].record.inReplyToId == statusInfo.record.id
+
+                        return Timeline.Item.status(
+                            .init(status: .init(info: statusInfo),
+                                  isReplyInContext: isReplyInContext,
+                                  hasReplyFollowing: hasReplyFollowing))
+                    }
+            }
         }
         .removeDuplicates()
-        .map { $0.map { $0.map(Status.init(info:)) } }
         .publisher(in: databaseWriter)
         .eraseToAnyPublisher()
     }
@@ -212,15 +254,10 @@ public extension ContentDatabase {
             .eraseToAnyPublisher()
     }
 
-    func activeFiltersObservation(date: Date, context: Filter.Context? = nil) -> AnyPublisher<[Filter], Error> {
+    func activeFiltersObservation(date: Date) -> AnyPublisher<[Filter], Error> {
         ValueObservation.tracking(
             Filter.filter(Filter.Columns.expiresAt == nil || Filter.Columns.expiresAt > date).fetchAll)
             .removeDuplicates()
-            .map {
-                guard let context = context else { return $0 }
-
-                return $0.filter { $0.context.contains(context) }
-            }
             .publisher(in: databaseWriter)
             .eraseToAnyPublisher()
     }

DB/Sources/DB/Content/StatusInfo.swift

@@ -21,4 +21,8 @@ extension StatusInfo {
     static func request(_ request: QueryInterfaceRequest<StatusRecord>) -> QueryInterfaceRequest<Self> {
         addingIncludes(request).asRequest(of: self)
     }
+
+    var filterableContent: String {
+        (record.filterableContent + (reblogRecord?.filterableContent ?? [])).joined(separator: " ")
+    }
 }

DB/Sources/DB/Content/StatusRecord.swift

@@ -117,6 +117,10 @@ extension StatusRecord {
         StatusInfo.request(request(for: Self.descendants))
     }
 
+    var filterableContent: [String] {
+        [content.attributed.string, spoilerText] + (poll?.options.map(\.title) ?? [])
+    }
+
     init(status: Status) {
         id = status.id
         uri = status.uri

DB/Sources/DB/Content/TimelineRecord.swift

@@ -39,11 +39,16 @@ extension TimelineRecord {
         through: statusJoins,
         using: TimelineStatusJoin.status)
         .order(StatusRecord.Columns.createdAt.desc)
+    static let loadMores = hasMany(LoadMore.self)
 
     var statuses: QueryInterfaceRequest<StatusInfo> {
         StatusInfo.request(request(for: Self.statuses))
     }
 
+    var loadMores: QueryInterfaceRequest<LoadMore> {
+        request(for: Self.loadMores)
+    }
+
     init(timeline: Timeline) {
         id = timeline.id
 

DB/Sources/DB/Entities/LoadMore.swift

@@ -0,0 +1,27 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Foundation
+import GRDB
+import Mastodon
+
+public struct LoadMore: Codable, Hashable {
+    public let timelineId: String
+    public let afterStatusId: String
+}
+
+extension LoadMore: FetchableRecord, PersistableRecord {
+    public static func databaseJSONDecoder(for column: String) -> JSONDecoder {
+        MastodonDecoder()
+    }
+
+    public static func databaseJSONEncoder(for column: String) -> JSONEncoder {
+        MastodonEncoder()
+    }
+}
+
+extension LoadMore {
+    enum Columns {
+        static let timelineId = Column(LoadMore.CodingKeys.timelineId)
+        static let belowStatusId = Column(LoadMore.CodingKeys.afterStatusId)
+    }
+}

DB/Sources/DB/Entities/Timeline.swift

@@ -15,6 +15,38 @@ public enum Timeline: Hashable {
 public extension Timeline {
     static let unauthenticatedDefaults: [Timeline] = [.local, .federated]
     static let authenticatedDefaults: [Timeline] = [.home, .local, .federated]
+
+    enum Item: Hashable {
+        case status(StatusConfiguration)
+        case loadMore(LoadMore)
+    }
+
+    var filterContext: Filter.Context {
+        switch self {
+        case .home, .list:
+            return .home
+        case .local, .federated, .tag:
+            return .public
+        case .profile:
+            return .account
+        }
+    }
+}
+
+public extension Timeline.Item {
+    struct StatusConfiguration: Hashable {
+        public let status: Status
+        public let pinned: Bool
+        public let isReplyInContext: Bool
+        public let hasReplyFollowing: Bool
+
+        init(status: Status, pinned: Bool = false, isReplyInContext: Bool = false, hasReplyFollowing: Bool = false) {
+            self.status = status
+            self.pinned = pinned
+            self.isReplyInContext = isReplyInContext
+            self.hasReplyFollowing = hasReplyFollowing
+        }
+    }
 }
 
 extension Timeline: Identifiable {

DB/Sources/DB/Extensions/Filter+Extensions.swift

@@ -5,6 +5,16 @@ import GRDB
 import Mastodon
 
 extension Filter: FetchableRecord, PersistableRecord {
+    public static func databaseJSONDecoder(for column: String) -> JSONDecoder {
+        MastodonDecoder()
+    }
+
+    public static func databaseJSONEncoder(for column: String) -> JSONEncoder {
+        MastodonEncoder()
+    }
+}
+
+extension Filter {
     enum Columns: String, ColumnExpression {
         case id
         case phrase
@@ -14,11 +24,15 @@ extension Filter: FetchableRecord, PersistableRecord {
         case wholeWord
     }
 
-    public static func databaseJSONDecoder(for column: String) -> JSONDecoder {
+    static var active: QueryInterfaceRequest<Self> {
-        MastodonDecoder()
+        filter(Filter.Columns.expiresAt == nil || Filter.Columns.expiresAt > Date())
-    }
+    }
-
+}
-    public static func databaseJSONEncoder(for column: String) -> JSONEncoder {
+
-        MastodonEncoder()
+extension Array where Element == StatusInfo {
+    func filtered(filters: [Filter], context: Filter.Context) -> Self {
+        guard let regEx = filters.filter({ $0.context.contains(context) }).regularExpression() else { return self }
+
+        return filter { $0.filterableContent.range(of: regEx, options: [.regularExpression, .caseInsensitive]) == nil }
     }
 }

Extensions/CollectionItemKind+Extensions.swift

@@ -2,13 +2,15 @@
 
 import ViewModels
 
-extension CollectionItem.Kind {
+extension CollectionItemIdentifier.Kind {
     var cellClass: AnyClass {
         switch self {
         case .status:
             return StatusListCell.self
         case .account:
             return AccountListCell.self
+        case .loadMore:
+            return LoadMoreCell.self
         }
     }
 }

Mastodon/Sources/Mastodon/Entities/Status.swift

@@ -109,14 +109,6 @@ public extension Status {
     var displayStatus: Status {
         reblog ?? self
     }
-
-    var filterableContent: String {
-        [content.attributed.string,
-         spoilerText,
-         (poll?.options.map(\.title) ?? []).joined(separator: " "),
-         reblog?.filterableContent ?? ""]
-            .joined(separator: " ")
-    }
 }
 
 extension Status: Hashable {

Metatext.xcodeproj/project.pbxproj

@@ -21,6 +21,7 @@
 		D0B32F50250B373600311912 /* RegistrationView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0B32F4F250B373600311912 /* RegistrationView.swift */; };
 		D0B5FE9B251583DB00478838 /* ProfileCollection+Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0B5FE9A251583DB00478838 /* ProfileCollection+Extensions.swift */; };
 		D0B7434925100DBB00C13DB6 /* StatusView.xib in Resources */ = {isa = PBXBuildFile; fileRef = D0B7434825100DBB00C13DB6 /* StatusView.xib */; };
+		D0B8510C25259E56004E0744 /* LoadMoreCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0B8510B25259E56004E0744 /* LoadMoreCell.swift */; };
 		D0BEB1F324F8EE8C001B0F04 /* AttachmentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0BEB1F224F8EE8C001B0F04 /* AttachmentView.swift */; };
 		D0BEB1F724F9A84B001B0F04 /* LoadingTableFooterView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0BEB1F624F9A84B001B0F04 /* LoadingTableFooterView.swift */; };
 		D0BEB1FF24F9E5BB001B0F04 /* ListsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0BEB1FE24F9E5BB001B0F04 /* ListsView.swift */; };
@@ -112,6 +113,7 @@
 		D0B32F4F250B373600311912 /* RegistrationView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RegistrationView.swift; sourceTree = "<group>"; };
 		D0B5FE9A251583DB00478838 /* ProfileCollection+Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "ProfileCollection+Extensions.swift"; sourceTree = "<group>"; };
 		D0B7434825100DBB00C13DB6 /* StatusView.xib */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.xib; path = StatusView.xib; sourceTree = "<group>"; };
+		D0B8510B25259E56004E0744 /* LoadMoreCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LoadMoreCell.swift; sourceTree = "<group>"; };
 		D0BDF66524FD7A6400C7FA1C /* ServiceLayer */ = {isa = PBXFileReference; lastKnownFileType = folder; path = ServiceLayer; sourceTree = "<group>"; };
 		D0BEB1F224F8EE8C001B0F04 /* AttachmentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AttachmentView.swift; sourceTree = "<group>"; };
 		D0BEB1F624F9A84B001B0F04 /* LoadingTableFooterView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LoadingTableFooterView.swift; sourceTree = "<group>"; };
@@ -288,6 +290,7 @@
 				D0C7D42224F76169001EBDBB /* IdentitiesView.swift */,
 				D0BEB1FE24F9E5BB001B0F04 /* ListsView.swift */,
 				D0BEB1F624F9A84B001B0F04 /* LoadingTableFooterView.swift */,
+				D0B8510B25259E56004E0744 /* LoadMoreCell.swift */,
 				D0C7D42D24F76169001EBDBB /* NotificationTypesPreferencesView.swift */,
 				D0C7D42824F76169001EBDBB /* PostingReadingPreferencesView.swift */,
 				D0C7D42624F76169001EBDBB /* PreferencesView.swift */,
@@ -558,6 +561,7 @@
 				D01EF22425182B1F00650C6B /* AccountHeaderView.swift in Sources */,
 				D0EA59482522B8B600804347 /* ViewConstants.swift in Sources */,
 				D0C7D49824F7616A001EBDBB /* CustomEmojiText.swift in Sources */,
+				D0B8510C25259E56004E0744 /* LoadMoreCell.swift in Sources */,
 				D01F41E424F8889700D55A2D /* AttachmentsView.swift in Sources */,
 				D0BEB21124FA2A91001B0F04 /* EditFilterView.swift in Sources */,
 				D0030982250C6C8500EACB32 /* URL+Extensions.swift in Sources */,

ServiceLayer/Sources/ServiceLayer/Entities/LoadMore.swift

@@ -0,0 +1,5 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import DB
+
+public typealias LoadMore = DB.LoadMore

ServiceLayer/Sources/ServiceLayer/Services/StatusListService.swift

@@ -7,7 +7,7 @@ import Mastodon
 import MastodonAPI
 
 public struct StatusListService {
-    public let statusSections: AnyPublisher<[[Status]], Error>
+    public let sections: AnyPublisher<[[Timeline.Item]], Error>
     public let nextPageMaxIDs: AnyPublisher<String?, Never>
     public let contextParentID: String?
     public let title: String?
@@ -29,7 +29,7 @@ extension StatusListService {
 
         let nextPageMaxIDsSubject = PassthroughSubject<String?, Never>()
 
-        self.init(statusSections: contentDatabase.statusesObservation(timeline: timeline),
+        self.init(sections: contentDatabase.observation(timeline: timeline),
                   nextPageMaxIDs: nextPageMaxIDsSubject.eraseToAnyPublisher(),
                   contextParentID: nil,
                   title: title,
@@ -48,7 +48,7 @@ extension StatusListService {
     }
 
     init(statusID: String, mastodonAPIClient: MastodonAPIClient, contentDatabase: ContentDatabase) {
-        self.init(statusSections: contentDatabase.contextObservation(parentID: statusID),
+        self.init(sections: contentDatabase.contextObservation(parentID: statusID),
                   nextPageMaxIDs: Empty().eraseToAnyPublisher(),
                   contextParentID: statusID,
                   title: nil,
@@ -75,10 +75,6 @@ public extension StatusListService {
     func request(maxID: String?, minID: String?) -> AnyPublisher<Never, Error> {
         requestClosure(maxID, minID)
     }
-
-    var filters: AnyPublisher<[Filter], Error> {
-        contentDatabase.activeFiltersObservation(date: Date(), context: filterContext)
-    }
 }
 
 private extension Timeline {
@@ -117,15 +113,4 @@ private extension Timeline {
                 pinned: false)
         }
     }
-
-    var filterContext: Filter.Context {
-        switch self {
-        case .home, .list:
-            return .home
-        case .local, .federated, .tag:
-            return .public
-        case .profile:
-            return .account
-        }
-    }
 }

View Controllers/TableViewController.swift

@@ -10,11 +10,11 @@ class TableViewController: UITableViewController {
     private let loadingTableFooterView = LoadingTableFooterView()
     private let webfingerIndicatorView = WebfingerIndicatorView()
     private var cancellables = Set<AnyCancellable>()
-    private var cellHeightCaches = [CGFloat: [CollectionItem: CGFloat]]()
+    private var cellHeightCaches = [CGFloat: [CollectionItemIdentifier: CGFloat]]()
     private let dataSourceQueue =
         DispatchQueue(label: "com.metabolist.metatext.collection.data-source-queue")
 
-    private lazy var dataSource: UITableViewDiffableDataSource<Int, CollectionItem> = {
+    private lazy var dataSource: UITableViewDiffableDataSource<Int, CollectionItemIdentifier> = {
         UITableViewDiffableDataSource(tableView: tableView) { [weak self] tableView, indexPath, item in
             guard let self = self, let cellViewModel = self.viewModel.viewModel(item: item) else { return nil }
 
@@ -49,7 +49,7 @@ class TableViewController: UITableViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
 
-        for kind in CollectionItem.Kind.allCases {
+        for kind in CollectionItemIdentifier.Kind.allCases {
             tableView.register(kind.cellClass, forCellReuseIdentifier: String(describing: kind.cellClass))
         }
 
@@ -80,7 +80,7 @@ class TableViewController: UITableViewController {
                             forRowAt indexPath: IndexPath) {
         guard let item = dataSource.itemIdentifier(for: indexPath) else { return }
 
-        var heightCache = cellHeightCaches[tableView.frame.width] ?? [CollectionItem: CGFloat]()
+        var heightCache = cellHeightCaches[tableView.frame.width] ?? [CollectionItemIdentifier: CGFloat]()
 
         heightCache[item] = cell.frame.height
         cellHeightCaches[tableView.frame.width] = heightCache
@@ -192,7 +192,7 @@ private extension TableViewController {
         .store(in: &cancellables)
     }
 
-    func update(items: [[CollectionItem]]) {
+    func update(items: [[CollectionItemIdentifier]]) {
         var offsetFromNavigationBar: CGFloat?
 
         if

ViewModels/Sources/ViewModels/AccountListViewModel.swift

@@ -6,7 +6,7 @@ import Mastodon
 import ServiceLayer
 
 public final class AccountListViewModel: ObservableObject {
-    @Published public private(set) var items = [[CollectionItem]]()
+    @Published public private(set) var items = [[CollectionItemIdentifier]]()
     @Published public var alertItem: AlertItem?
     public let navigationEvents: AnyPublisher<NavigationEvent, Never>
     public private(set) var nextPageMaxID: String?
@@ -27,7 +27,7 @@ public final class AccountListViewModel: ObservableObject {
                 self?.cleanViewModelCache(newAccountSections: $0)
                 self?.accounts = Dictionary(uniqueKeysWithValues: Set($0.reduce([], +)).map { ($0.id, $0) })
             })
-            .map { $0.map { $0.map { CollectionItem(id: $0.id, kind: .account) } } }
+            .map { $0.map { $0.map(CollectionItemIdentifier.init(account:)) } }
             .receive(on: DispatchQueue.main)
             .assignErrorsToAlertItem(to: \.alertItem, on: self)
             .assign(to: &$items)
@@ -39,7 +39,7 @@ public final class AccountListViewModel: ObservableObject {
 }
 
 extension AccountListViewModel: CollectionViewModel {
-    public var collectionItems: AnyPublisher<[[CollectionItem]], Never> { $items.eraseToAnyPublisher() }
+    public var collectionItems: AnyPublisher<[[CollectionItemIdentifier]], Never> { $items.eraseToAnyPublisher() }
 
     public var title: AnyPublisher<String?, Never> { Just(nil).eraseToAnyPublisher() }
 
@@ -47,7 +47,7 @@ extension AccountListViewModel: CollectionViewModel {
 
     public var loading: AnyPublisher<Bool, Never> { loadingSubject.eraseToAnyPublisher() }
 
-    public var maintainScrollPositionOfItem: CollectionItem? {
+    public var maintainScrollPositionOfItem: CollectionItemIdentifier? {
         nil
     }
 
@@ -62,7 +62,7 @@ extension AccountListViewModel: CollectionViewModel {
             .store(in: &cancellables)
     }
 
-    public func itemSelected(_ item: CollectionItem) {
+    public func itemSelected(_ item: CollectionItemIdentifier) {
         switch item.kind {
         case .account:
             let navigationService = accountListService.navigationService
@@ -80,11 +80,11 @@ extension AccountListViewModel: CollectionViewModel {
         }
     }
 
-    public func canSelect(item: CollectionItem) -> Bool {
+    public func canSelect(item: CollectionItemIdentifier) -> Bool {
         true
     }
 
-    public func viewModel(item: CollectionItem) -> Any? {
+    public func viewModel(item: CollectionItemIdentifier) -> Any? {
         switch item.kind {
         case .account:
             return accountViewModel(id: item.id)

ViewModels/Sources/ViewModels/CollectionViewModel.swift

@@ -4,15 +4,15 @@ import Combine
 import Foundation
 
 public protocol CollectionViewModel {
-    var collectionItems: AnyPublisher<[[CollectionItem]], Never> { get }
+    var collectionItems: AnyPublisher<[[CollectionItemIdentifier]], Never> { get }
     var title: AnyPublisher<String?, Never> { get }
     var alertItems: AnyPublisher<AlertItem, Never> { get }
     var loading: AnyPublisher<Bool, Never> { get }
     var navigationEvents: AnyPublisher<NavigationEvent, Never> { get }
     var nextPageMaxID: String? { get }
-    var maintainScrollPositionOfItem: CollectionItem? { get }
+    var maintainScrollPositionOfItem: CollectionItemIdentifier? { get }
     func request(maxID: String?, minID: String?)
-    func itemSelected(_ item: CollectionItem)
+    func itemSelected(_ item: CollectionItemIdentifier)
-    func canSelect(item: CollectionItem) -> Bool
+    func canSelect(item: CollectionItemIdentifier) -> Bool
-    func viewModel(item: CollectionItem) -> Any?
+    func viewModel(item: CollectionItemIdentifier) -> Any?
 }

ViewModels/Sources/ViewModels/Entities/CollectionItem.swift

@@ -1,24 +0,0 @@
-// Copyright © 2020 Metabolist. All rights reserved.
-
-public struct CollectionItem: Hashable {
-    public let id: String
-    public let kind: Kind
-    public let info: [InfoKey: AnyHashable]
-
-    init(id: String, kind: Kind, info: [InfoKey: AnyHashable]? = nil) {
-        self.id = id
-        self.kind = kind
-        self.info = info ?? [InfoKey: AnyHashable]()
-    }
-}
-
-public extension CollectionItem {
-    enum Kind: Hashable, CaseIterable {
-        case status
-        case account
-    }
-
-    enum InfoKey {
-        case pinned
-    }
-}

ViewModels/Sources/ViewModels/Entities/CollectionItemIdentifier.swift

@@ -0,0 +1,42 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Mastodon
+
+public struct CollectionItemIdentifier: Hashable {
+    public let id: String
+    public let kind: Kind
+    public let info: [InfoKey: AnyHashable]
+}
+
+public extension CollectionItemIdentifier {
+    enum Kind: Hashable, CaseIterable {
+        case status
+        case loadMore
+        case account
+    }
+
+    enum InfoKey {
+        case pinned
+    }
+}
+
+extension CollectionItemIdentifier {
+    init(timelineItem: Timeline.Item) {
+        switch timelineItem {
+        case let .status(configuration):
+            id = configuration.status.id
+            kind = .status
+            info = configuration.pinned ? [.pinned: true] : [:]
+        case let .loadMore(loadMore):
+            id = loadMore.afterStatusId
+            kind = .loadMore
+            info = [:]
+        }
+    }
+
+    init(account: Account) {
+        id = account.id
+        kind = .account
+        info = [:]
+    }
+}

ViewModels/Sources/ViewModels/ProfileViewModel.swift

@@ -39,18 +39,8 @@ final public class ProfileViewModel {
 }
 
 extension ProfileViewModel: CollectionViewModel {
-    public var collectionItems: AnyPublisher<[[CollectionItem]], Never> {
+    public var collectionItems: AnyPublisher<[[CollectionItemIdentifier]], Never> {
-        collectionViewModel.flatMap(\.collectionItems).map {
+        collectionViewModel.flatMap(\.collectionItems).eraseToAnyPublisher()
-            $0.enumerated().map { [weak self] in
-                if let self = self, self.collection == .statuses, $0 == 0 {
-                    // The pinned key is added to the info of collection items in the first section
-                    // so a diffable data source can potentially render it in both sections
-                    return $1.map { .init(id: $0.id, kind: $0.kind, info: [.pinned: true]) }
-                } else {
-                    return $1
-                }
-            }
-        }.eraseToAnyPublisher()
     }
 
     public var title: AnyPublisher<String?, Never> {
@@ -80,7 +70,7 @@ extension ProfileViewModel: CollectionViewModel {
         collectionViewModel.value.nextPageMaxID
     }
 
-    public var maintainScrollPositionOfItem: CollectionItem? {
+    public var maintainScrollPositionOfItem: CollectionItemIdentifier? {
         collectionViewModel.value.maintainScrollPositionOfItem
     }
 
@@ -95,15 +85,15 @@ extension ProfileViewModel: CollectionViewModel {
         collectionViewModel.value.request(maxID: maxID, minID: minID)
     }
 
-    public func itemSelected(_ item: CollectionItem) {
+    public func itemSelected(_ item: CollectionItemIdentifier) {
         collectionViewModel.value.itemSelected(item)
     }
 
-    public func canSelect(item: CollectionItem) -> Bool {
+    public func canSelect(item: CollectionItemIdentifier) -> Bool {
         collectionViewModel.value.canSelect(item: item)
     }
 
-    public func viewModel(item: CollectionItem) -> Any? {
+    public func viewModel(item: CollectionItemIdentifier) -> Any? {
         collectionViewModel.value.viewModel(item: item)
     }
 }

ViewModels/Sources/ViewModels/StatusListViewModel.swift

@@ -6,15 +6,15 @@ import Mastodon
 import ServiceLayer
 
 final public class StatusListViewModel: ObservableObject {
-    @Published public private(set) var items = [[CollectionItem]]()
+    @Published public private(set) var items = [[CollectionItemIdentifier]]()
     @Published public var alertItem: AlertItem?
     public private(set) var nextPageMaxID: String?
-    public private(set) var maintainScrollPositionOfItem: CollectionItem?
+    public private(set) var maintainScrollPositionOfItem: CollectionItemIdentifier?
 
-    private var statuses = [String: Status]()
+    private var timelineItems = [CollectionItemIdentifier: Timeline.Item]()
     private var flatStatusIDs = [String]()
     private let statusListService: StatusListService
-    private var statusViewModelCache = [Status: (StatusViewModel, AnyCancellable)]()
+    private var viewModelCache = [Timeline.Item: (Any, AnyCancellable)]()
     private let navigationEventsSubject = PassthroughSubject<NavigationEvent, Never>()
     private let loadingSubject = PassthroughSubject<Bool, Never>()
     private var cancellables = Set<AnyCancellable>()
@@ -22,18 +22,11 @@ final public class StatusListViewModel: ObservableObject {
     init(statusListService: StatusListService) {
         self.statusListService = statusListService
 
-        statusListService.statusSections
+        statusListService.sections
-            .combineLatest(statusListService.filters.map { $0.regularExpression() })
+            .handleEvents(receiveOutput: { [weak self] in self?.process(sections: $0) })
-            .map(Self.filter(statusSections:regularExpression:))
+            .map { $0.map { $0.map(CollectionItemIdentifier.init(timelineItem:)) } }
-            .handleEvents(receiveOutput: { [weak self] in
-                self?.determineIfScrollPositionShouldBeMaintained(newStatusSections: $0)
-                self?.cleanViewModelCache(newStatusSections: $0)
-                self?.statuses = Dictionary(uniqueKeysWithValues: Set($0.reduce([], +)).map { ($0.id, $0) })
-                self?.flatStatusIDs = $0.reduce([], +).map(\.id)
-            })
             .receive(on: DispatchQueue.main)
             .assignErrorsToAlertItem(to: \.alertItem, on: self)
-            .map { $0.map { $0.map { CollectionItem(id: $0.id, kind: .status) } } }
             .assign(to: &$items)
 
         statusListService.nextPageMaxIDs
@@ -43,7 +36,7 @@ final public class StatusListViewModel: ObservableObject {
 }
 
 extension StatusListViewModel: CollectionViewModel {
-    public var collectionItems: AnyPublisher<[[CollectionItem]], Never> { $items.eraseToAnyPublisher() }
+    public var collectionItems: AnyPublisher<[[CollectionItemIdentifier]], Never> { $items.eraseToAnyPublisher() }
 
     public var title: AnyPublisher<String?, Never> { Just(statusListService.title).eraseToAnyPublisher() }
 
@@ -64,23 +57,23 @@ extension StatusListViewModel: CollectionViewModel {
             .store(in: &cancellables)
     }
 
-    public func itemSelected(_ item: CollectionItem) {
+    public func itemSelected(_ item: CollectionItemIdentifier) {
-        switch item.kind {
+        guard let timelineItem = timelineItems[item] else { return }
-        case .status:
-            let displayStatusID = statuses[item.id]?.displayStatus.id ?? item.id
 
+        switch timelineItem {
+        case let .status(configuration):
             navigationEventsSubject.send(
                 .collectionNavigation(
                     StatusListViewModel(
                         statusListService: statusListService
                             .navigationService
-                            .contextStatusListService(id: displayStatusID))))
+                            .contextStatusListService(id: configuration.status.displayStatus.id))))
         default:
             break
         }
     }
 
-    public func canSelect(item: CollectionItem) -> Bool {
+    public func canSelect(item: CollectionItemIdentifier) -> Bool {
         if case .status = item.kind, item.id == statusListService.contextParentID {
             return false
         }
@@ -88,7 +81,7 @@ extension StatusListViewModel: CollectionViewModel {
         return true
     }
 
-    public func viewModel(item: CollectionItem) -> Any? {
+    public func viewModel(item: CollectionItemIdentifier) -> Any? {
         switch item.kind {
         case .status:
             return statusViewModel(item: item)
@@ -99,83 +92,59 @@ extension StatusListViewModel: CollectionViewModel {
 }
 
 private extension StatusListViewModel {
-    static func filter(statusSections: [[Status]], regularExpression: String?) -> [[Status]] {
+    func statusViewModel(item: CollectionItemIdentifier) -> StatusViewModel? {
-        guard let regEx = regularExpression else { return statusSections }
+        guard let timelineItem = timelineItems[item],
-
+              case let .status(configuration) = timelineItem
-        return statusSections.map {
+        else { return nil }
-            $0.filter { $0.filterableContent.range(of: regEx, options: [.regularExpression, .caseInsensitive]) == nil }
-        }
-    }
-
-    var contextParentID: String? { statusListService.contextParentID }
-
-    func statusViewModel(item: CollectionItem) -> StatusViewModel? {
-        guard let status = statuses[item.id] else { return nil }
 
         var statusViewModel: StatusViewModel
 
-        if let cachedViewModel = statusViewModelCache[status]?.0 {
+        if let cachedViewModel = viewModelCache[timelineItem]?.0 as? StatusViewModel {
             statusViewModel = cachedViewModel
         } else {
             statusViewModel = StatusViewModel(
-                statusService: statusListService.navigationService.statusService(status: status))
+                statusService: statusListService.navigationService.statusService(status: configuration.status))
-            statusViewModelCache[status] = (statusViewModel,
+            viewModelCache[timelineItem] = (statusViewModel,
-                                            statusViewModel.events
+                                      statusViewModel.events
-                                                .flatMap { $0 }
+                                        .flatMap { $0 }
-                                                .assignErrorsToAlertItem(to: \.alertItem, on: self)
+                                        .assignErrorsToAlertItem(to: \.alertItem, on: self)
-                                                .sink { [weak self] in
+                                        .sink { [weak self] in
-                                                    guard
+                                            guard
-                                                        let self = self,
+                                                let self = self,
-                                                        let event = NavigationEvent($0)
+                                                let event = NavigationEvent($0)
-                                                    else { return }
+                                            else { return }
 
-                                                    self.navigationEventsSubject.send(event)
+                                            self.navigationEventsSubject.send(event)
-                                                })
+                                        })
         }
 
-        statusViewModel.isContextParent = status.id == statusListService.contextParentID
+        statusViewModel.isContextParent = configuration.status.id == statusListService.contextParentID
-        statusViewModel.isPinned = item.info[.pinned] != nil
+        statusViewModel.isPinned = configuration.pinned
-        statusViewModel.isReplyInContext = isReplyInContext(status: status)
+        statusViewModel.isReplyInContext = configuration.isReplyInContext
-        statusViewModel.hasReplyFollowing = hasReplyFollowing(status: status)
+        statusViewModel.hasReplyFollowing = configuration.hasReplyFollowing
 
         return statusViewModel
     }
 
-    func determineIfScrollPositionShouldBeMaintained(newStatusSections: [[Status]]) {
+    func process(sections: [[Timeline.Item]]) {
+        determineIfScrollPositionShouldBeMaintained(newSections: sections)
+
+        let timelineItemKeys = Set(sections.reduce([], +))
+
+        timelineItems = Dictionary(uniqueKeysWithValues: timelineItemKeys.map { (.init(timelineItem: $0), $0) })
+        viewModelCache = viewModelCache.filter { timelineItemKeys.contains($0.key) }
+    }
+
+    func determineIfScrollPositionShouldBeMaintained(newSections: [[Timeline.Item]]) {
         maintainScrollPositionOfItem = nil // clear old value
 
         // Maintain scroll position of parent after initial load of context
-        if let contextParentID = contextParentID, flatStatusIDs == [contextParentID] || flatStatusIDs == [] {
+        if let contextParentID = statusListService.contextParentID {
-            maintainScrollPositionOfItem = CollectionItem(id: contextParentID, kind: .status)
+            let contextParentIdentifier = CollectionItemIdentifier(id: contextParentID, kind: .status, info: [:])
+
+            if items == [[], [contextParentIdentifier], []] || items.isEmpty {
+                maintainScrollPositionOfItem = contextParentIdentifier
+            }
         }
     }
-
-    func cleanViewModelCache(newStatusSections: [[Status]]) {
-        let newStatuses = Set(newStatusSections.reduce([], +))
-
-        statusViewModelCache = statusViewModelCache.filter { newStatuses.contains($0.key) }
-    }
-
-    func isReplyInContext(status: Status) -> Bool {
-        guard
-            let contextParentID = contextParentID,
-            let index = flatStatusIDs.firstIndex(where: { $0 == status.id }),
-            index > 0
-        else { return false }
-
-        let previousStatusID = flatStatusIDs[index - 1]
-
-        return previousStatusID != contextParentID && status.inReplyToId == previousStatusID
-    }
-
-    func hasReplyFollowing(status: Status) -> Bool {
-        guard
-            let contextParentID = contextParentID,
-            let index = flatStatusIDs.firstIndex(where: { $0 == status.id }),
-            flatStatusIDs.count > index + 1,
-            let nextStatus = statuses[flatStatusIDs[index + 1]]
-        else { return false }
-
-        return status.id != contextParentID && nextStatus.inReplyToId == status.id
-    }
 }

Views/LoadMoreCell.swift

@@ -0,0 +1,7 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import UIKit
+
+class LoadMoreCell: UITableViewCell {
+
+}