Startup and syncing

2024-11-21 15:50:59 +00:00 · 2020-10-26 20:01:12 -07:00 · 2020-10-26 20:01:12 -07:00 · ed82cffd91
commit ed82cffd91
parent c7e4186749
24 changed files with 427 additions and 43 deletions
--- a/DB/Sources/DB/Content/ContentDatabase+Migration.swift
+++ b/DB/Sources/DB/Content/ContentDatabase+Migration.swift
@ -105,6 +105,11 @@ extension ContentDatabase {
                t.column("wholeWord", .boolean).notNull()
            }

+            try db.create(table: "lastReadIdRecord") { t in
+                t.column("markerTimeline", .text).primaryKey(onConflict: .replace)
+                t.column("id", .text).notNull()
+            }
+
            try db.create(table: "statusAncestorJoin") { t in
                t.column("parentId", .text).indexed().notNull()
                    .references("statusRecord", onDelete: .cascade)
--- a/DB/Sources/DB/Content/ContentDatabase.swift
+++ b/DB/Sources/DB/Content/ContentDatabase.swift
@ -7,12 +7,17 @@ import Keychain
 import Mastodon
 import Secrets

+// swiftlint:disable file_length
 public struct ContentDatabase {
    public let activeFiltersPublisher: AnyPublisher<[Filter], Error>

    private let databaseWriter: DatabaseWriter

-    public init(id: Identity.Id, inMemory: Bool, keychain: Keychain.Type) throws {
+    public init(id: Identity.Id,
+                useHomeTimelineLastReadId: Bool,
+                useNotificationsLastReadId: Bool,
+                inMemory: Bool,
+                keychain: Keychain.Type) throws {
        if inMemory {
            databaseWriter = DatabaseQueue()
        } else {
@ -27,7 +32,10 @@ public struct ContentDatabase {
        }

        try Self.migrator.migrate(databaseWriter)
-        try Self.clean(databaseWriter)
+        try Self.clean(
+            databaseWriter,
+            useHomeTimelineLastReadId: useHomeTimelineLastReadId,
+            useNotificationsLastReadId: useNotificationsLastReadId)

        activeFiltersPublisher = ValueObservation.tracking {
            try Filter.filter(Filter.Columns.expiresAt == nil || Filter.Columns.expiresAt > Date()).fetchAll($0)
@ -278,6 +286,12 @@ public extension ContentDatabase {
            .eraseToAnyPublisher()
    }

+    func setLastReadId(_ id: String, markerTimeline: Marker.Timeline) -> AnyPublisher<Never, Error> {
+        databaseWriter.writePublisher(updates: LastReadIdRecord(markerTimeline: markerTimeline, id: id).save)
+            .ignoreOutput()
+            .eraseToAnyPublisher()
+    }
+
    func timelinePublisher(_ timeline: Timeline) -> AnyPublisher<[[CollectionItem]], Error> {
        ValueObservation.tracking(
            TimelineItemsInfo.request(TimelineRecord.filter(TimelineRecord.Columns.id == timeline.id)).fetchOne)
@ -331,19 +345,64 @@ public extension ContentDatabase {
            .publisher(in: databaseWriter)
            .eraseToAnyPublisher()
    }
+
+    func lastReadId(_ markerTimeline: Marker.Timeline) -> String? {
+        try? databaseWriter.read {
+            try String.fetchOne(
+                $0,
+                LastReadIdRecord.filter(LastReadIdRecord.Columns.markerTimeline == markerTimeline.rawValue)
+                    .select(LastReadIdRecord.Columns.id))
+        }
+    }
 }

 private extension ContentDatabase {
+    static let cleanAfterLastReadIdCount = 40
    static func fileURL(id: Identity.Id) throws -> URL {
        try FileManager.default.databaseDirectoryURL(name: id.uuidString)
    }

-    static func clean(_ databaseWriter: DatabaseWriter) throws {
+    static func clean(_ databaseWriter: DatabaseWriter,
+                      useHomeTimelineLastReadId: Bool,
+                      useNotificationsLastReadId: Bool) throws {
        try databaseWriter.write {
-            try TimelineRecord.deleteAll($0)
-            try StatusRecord.deleteAll($0)
-            try AccountRecord.deleteAll($0)
+            if useHomeTimelineLastReadId {
+                try TimelineRecord.filter(TimelineRecord.Columns.id != Timeline.home.id).deleteAll($0)
+                var statusIds = try Status.Id.fetchAll(
+                    $0,
+                    TimelineStatusJoin.select(TimelineStatusJoin.Columns.statusId)
+                        .order(TimelineStatusJoin.Columns.statusId.desc))
+
+                if let lastReadId = try Status.Id.fetchOne(
+                    $0,
+                    LastReadIdRecord.filter(LastReadIdRecord.Columns.markerTimeline == Marker.Timeline.home.rawValue)
+                        .select(LastReadIdRecord.Columns.id))
+                    ?? statusIds.first,
+                   let index = statusIds.firstIndex(of: lastReadId) {
+                    statusIds = Array(statusIds.prefix(index + Self.cleanAfterLastReadIdCount))
+                }
+
+                statusIds += try Status.Id.fetchAll(
+                    $0,
+                    StatusRecord.filter(statusIds.contains(StatusRecord.Columns.id)
+                                            && StatusRecord.Columns.reblogId != nil)
+                        .select(StatusRecord.Columns.reblogId))
+                try StatusRecord.filter(!statusIds.contains(StatusRecord.Columns.id) ).deleteAll($0)
+                var accountIds = try Account.Id.fetchAll($0, StatusRecord.select(StatusRecord.Columns.accountId))
+                accountIds += try Account.Id.fetchAll(
+                    $0,
+                    AccountRecord.filter(accountIds.contains(AccountRecord.Columns.id)
+                                            && AccountRecord.Columns.movedId != nil)
+                        .select(AccountRecord.Columns.movedId))
+                try AccountRecord.filter(!accountIds.contains(AccountRecord.Columns.id)).deleteAll($0)
+            } else {
+                try TimelineRecord.deleteAll($0)
+                try StatusRecord.deleteAll($0)
+                try AccountRecord.deleteAll($0)
+            }
+
            try AccountList.deleteAll($0)
        }
    }
 }
+// swiftlint:enable file_length
--- a/DB/Sources/DB/Content/LastReadIdRecord.swift
+++ b/DB/Sources/DB/Content/LastReadIdRecord.swift
@ -0,0 +1,17 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Foundation
+import GRDB
+import Mastodon
+
+struct LastReadIdRecord: ContentDatabaseRecord, Hashable {
+    let markerTimeline: Marker.Timeline
+    let id: String
+}
+
+extension LastReadIdRecord {
+    enum Columns {
+        static let markerTimeline = Column(LastReadIdRecord.CodingKeys.markerTimeline)
+        static let id = Column(LastReadIdRecord.CodingKeys.id)
+    }
+}
--- a/HTTP/Sources/HTTP/Target.swift
+++ b/HTTP/Sources/HTTP/Target.swift
@ -6,7 +6,7 @@ public protocol Target {
    var baseURL: URL { get }
    var pathComponents: [String] { get }
    var method: HTTPMethod { get }
-    var queryParameters: [String: String]? { get }
+    var queryParameters: [URLQueryItem] { get }
    var jsonBody: [String: Any]? { get }
    var headers: [String: String]? { get }
 }
@ -19,9 +19,8 @@ public extension Target {
            url.appendPathComponent(pathComponent)
        }

-        if var components = URLComponents(url: url, resolvingAgainstBaseURL: true),
-           let queryItems = queryParameters?.map(URLQueryItem.init(name:value:)) {
-            components.queryItems = queryItems
+        if var components = URLComponents(url: url, resolvingAgainstBaseURL: true), !queryParameters.isEmpty {
+            components.queryItems = queryParameters

            if let queryComponentURL = components.url {
                url = queryComponentURL
--- a/Localizations/Localizable.strings
+++ b/Localizations/Localizable.strings
@ -67,6 +67,13 @@
 "preferences.notification-types.reblog" = "Reblog";
 "preferences.notification-types.mention" = "Mention";
 "preferences.notification-types.poll" = "Poll";
+"preferences.startup-and-syncing" = "Startup and Syncing";
+"preferences.startup-and-syncing.home-timeline" = "Home timeline";
+"preferences.startup-and-syncing.notifications-tab" = "Notifications tab";
+"preferences.startup-and-syncing.position-on-startup" = "Position on startup";
+"preferences.startup-and-syncing.remember-position" = "Remember position";
+"preferences.startup-and-syncing.sync-position" = "Sync position with web and other devices";
+"preferences.startup-and-syncing.newest" = "Load newest";
 "filters.active" = "Active";
 "filters.expired" = "Expired";
 "filter.add-new" = "Add New Filter";
--- a/Mastodon/Sources/Mastodon/Entities/Marker.swift
+++ b/Mastodon/Sources/Mastodon/Entities/Marker.swift
@ -0,0 +1,16 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Foundation
+
+public struct Marker: Codable, Hashable {
+    public let lastReadId: String
+    public let updatedAt: Date
+    public let version: Int
+}
+
+public extension Marker {
+    enum Timeline: String, Codable {
+        case home
+        case notifications
+    }
+}
--- a/MastodonAPI/Sources/MastodonAPI/Endpoint.swift
+++ b/MastodonAPI/Sources/MastodonAPI/Endpoint.swift
@ -9,7 +9,7 @@ public protocol Endpoint {
    var context: [String] { get }
    var pathComponentsInContext: [String] { get }
    var method: HTTPMethod { get }
-    var queryParameters: [String: String]? { get }
+    var queryParameters: [URLQueryItem] { get }
    var jsonBody: [String: Any]? { get }
    var headers: [String: String]? { get }
 }
@ -29,7 +29,7 @@ public extension Endpoint {
        context + pathComponentsInContext
    }

-    var queryParameters: [String: String]? { nil }
+    var queryParameters: [URLQueryItem] { [] }

    var jsonBody: [String: Any]? { nil }

--- a/MastodonAPI/Sources/MastodonAPI/Endpoints/MarkersEndpoint.swift
+++ b/MastodonAPI/Sources/MastodonAPI/Endpoints/MarkersEndpoint.swift
@ -0,0 +1,45 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Foundation
+import HTTP
+import Mastodon
+
+public enum MarkersEndpoint {
+    case get(Set<Marker.Timeline>)
+    case post([Marker.Timeline: String])
+}
+
+extension MarkersEndpoint: Endpoint {
+    public typealias ResultType = [String: Marker]
+
+    public var pathComponentsInContext: [String] {
+        ["markers"]
+    }
+
+    public var queryParameters: [URLQueryItem] {
+        switch self {
+        case let .get(timelines):
+            return Array(timelines).map { URLQueryItem(name: "timeline[]", value: $0.rawValue) }
+        case .post:
+            return []
+        }
+    }
+
+    public var jsonBody: [String: Any]? {
+        switch self {
+        case .get:
+            return nil
+        case let .post(lastReadIds):
+            return Dictionary(uniqueKeysWithValues: lastReadIds.map { ($0.rawValue, ["last_read_id": $1]) })
+        }
+    }
+
+    public var method: HTTPMethod {
+        switch self {
+        case .get:
+            return .get
+        case .post:
+            return .post
+        }
+    }
+}
--- a/MastodonAPI/Sources/MastodonAPI/Endpoints/Paged.swift
+++ b/MastodonAPI/Sources/MastodonAPI/Endpoints/Paged.swift
@ -31,15 +31,23 @@ extension Paged: Endpoint {

    public var method: HTTPMethod { endpoint.method }

-    public var queryParameters: [String: String]? {
-        var queryParameters = endpoint.queryParameters ?? [String: String]()
+    public var queryParameters: [URLQueryItem] {
+        var queryParameters = endpoint.queryParameters

-        queryParameters["max_id"] = maxId
-        queryParameters["min_id"] = minId
-        queryParameters["since_id"] = sinceId
+        if let maxId = maxId {
+            queryParameters.append(.init(name: "max_id", value: maxId))
+        }
+
+        if let minId = minId {
+            queryParameters.append(.init(name: "min_id", value: minId))
+        }
+
+        if let sinceId = sinceId {
+            queryParameters.append(.init(name: "since_id", value: sinceId))
+        }

        if let limit = limit {
-            queryParameters["limit"] = String(limit)
+            queryParameters.append(.init(name: "limit", value: String(limit)))
        }

        return queryParameters
--- a/MastodonAPI/Sources/MastodonAPI/Endpoints/ResultsEndpoint.swift
+++ b/MastodonAPI/Sources/MastodonAPI/Endpoints/ResultsEndpoint.swift
@ -32,13 +32,13 @@ extension ResultsEndpoint: Endpoint {
        }
    }

-    public var queryParameters: [String: String]? {
+    public var queryParameters: [URLQueryItem] {
        switch self {
        case let .search(query, resolve):
-            var params = ["q": query]
+            var params = [URLQueryItem(name: "q", value: query)]

            if resolve {
-                params["resolve"] = String(true)
+                params.append(.init(name: "resolve", value: "true"))
            }

            return params
--- a/MastodonAPI/Sources/MastodonAPI/Endpoints/StatusesEndpoint.swift
+++ b/MastodonAPI/Sources/MastodonAPI/Endpoints/StatusesEndpoint.swift
@ -39,16 +39,16 @@ extension StatusesEndpoint: Endpoint {
        }
    }

-    public var queryParameters: [String: String]? {
+    public var queryParameters: [URLQueryItem] {
        switch self {
        case let .timelinesPublic(local):
-            return ["local": String(local)]
+            return [URLQueryItem(name: "local", value: String(local))]
        case let .accountsStatuses(_, excludeReplies, onlyMedia, pinned):
-            return ["exclude_replies": String(excludeReplies),
-                    "only_media": String(onlyMedia),
-                    "pinned": String(pinned)]
+            return [URLQueryItem(name: "exclude_replies", value: String(excludeReplies)),
+                    URLQueryItem(name: "only_media", value: String(onlyMedia)),
+                    URLQueryItem(name: "pinned", value: String(pinned))]
        default:
-            return nil
+            return []
        }
    }

--- a/MastodonAPI/Sources/MastodonAPI/MastodonAPITarget.swift
+++ b/MastodonAPI/Sources/MastodonAPI/MastodonAPITarget.swift
@ -22,7 +22,7 @@ extension MastodonAPITarget: DecodableTarget {

    public var method: HTTPMethod { endpoint.method }

-    public var queryParameters: [String: String]? { endpoint.queryParameters }
+    public var queryParameters: [URLQueryItem] { endpoint.queryParameters }

    public var jsonBody: [String: Any]? { endpoint.jsonBody }

--- a/Metatext.xcodeproj/project.pbxproj
+++ b/Metatext.xcodeproj/project.pbxproj
@ -15,6 +15,7 @@
 		D01F41E424F8889700D55A2D /* StatusAttachmentsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D01F41E224F8889700D55A2D /* StatusAttachmentsView.swift */; };
 		D02E1F95250B13210071AD56 /* SafariView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D02E1F94250B13210071AD56 /* SafariView.swift */; };
 		D03B1B2A253818F3008F964B /* MediaPreferencesView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D03B1B29253818F3008F964B /* MediaPreferencesView.swift */; };
+		D04226FD2546AC0B000980A3 /* StartupAndSyncingPreferencesView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04226FC2546AC0B000980A3 /* StartupAndSyncingPreferencesView.swift */; };
 		D0625E59250F092900502611 /* StatusListCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0625E58250F092900502611 /* StatusListCell.swift */; };
 		D0625E5D250F0B5C00502611 /* StatusContentConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0625E5C250F0B5C00502611 /* StatusContentConfiguration.swift */; };
 		D06B492324D4611300642749 /* KingfisherSwiftUI in Frameworks */ = {isa = PBXBuildFile; productRef = D06B492224D4611300642749 /* KingfisherSwiftUI */; };
@ -118,6 +119,7 @@
 		D01F41E224F8889700D55A2D /* StatusAttachmentsView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = StatusAttachmentsView.swift; sourceTree = "<group>"; };
 		D02E1F94250B13210071AD56 /* SafariView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SafariView.swift; sourceTree = "<group>"; };
 		D03B1B29253818F3008F964B /* MediaPreferencesView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MediaPreferencesView.swift; sourceTree = "<group>"; };
+		D04226FC2546AC0B000980A3 /* StartupAndSyncingPreferencesView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StartupAndSyncingPreferencesView.swift; sourceTree = "<group>"; };
 		D047FA8C24C3E21200AF17C5 /* Metatext.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Metatext.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		D0625E58250F092900502611 /* StatusListCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusListCell.swift; sourceTree = "<group>"; };
 		D0625E5C250F0B5C00502611 /* StatusContentConfiguration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusContentConfiguration.swift; sourceTree = "<group>"; };
@ -348,6 +350,7 @@
 				D0C7D42724F76169001EBDBB /* RootView.swift */,
 				D02E1F94250B13210071AD56 /* SafariView.swift */,
 				D0C7D42924F76169001EBDBB /* SecondaryNavigationView.swift */,
+				D04226FC2546AC0B000980A3 /* StartupAndSyncingPreferencesView.swift */,
 				D0625E55250F086B00502611 /* Status */,
 				D0C7D42524F76169001EBDBB /* TableView.swift */,
 				D0C7D42E24F76169001EBDBB /* TabNavigationView.swift */,
@ -632,6 +635,7 @@
 				D0C7D49724F7616A001EBDBB /* IdentitiesView.swift in Sources */,
 				D01EF22425182B1F00650C6B /* AccountHeaderView.swift in Sources */,
 				D0EA59482522B8B600804347 /* ViewConstants.swift in Sources */,
+				D04226FD2546AC0B000980A3 /* StartupAndSyncingPreferencesView.swift in Sources */,
 				D0C7D49824F7616A001EBDBB /* CustomEmojiText.swift in Sources */,
 				D08B8D3D253F929E00B1EBEF /* ImageViewController.swift in Sources */,
 				D0B8510C25259E56004E0744 /* LoadMoreCell.swift in Sources */,
--- a/ServiceLayer/Sources/ServiceLayer/Services/CollectionService.swift
+++ b/ServiceLayer/Sources/ServiceLayer/Services/CollectionService.swift
@ -8,6 +8,7 @@ public protocol CollectionService {
    var nextPageMaxId: AnyPublisher<String, Never> { get }
    var title: AnyPublisher<String, Never> { get }
    var navigationService: NavigationService { get }
+    var markerTimeline: Marker.Timeline? { get }
    func request(maxId: String?, minId: String?) -> AnyPublisher<Never, Error>
 }

@ -15,4 +16,6 @@ extension CollectionService {
    public var nextPageMaxId: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }

    public var title: AnyPublisher<String, Never> { Empty().eraseToAnyPublisher() }
+
+    public var markerTimeline: Marker.Timeline? { nil }
 }
--- a/ServiceLayer/Sources/ServiceLayer/Services/IdentityService.swift
+++ b/ServiceLayer/Sources/ServiceLayer/Services/IdentityService.swift
@ -27,9 +27,14 @@ public struct IdentityService {
                                              instanceURL: try secrets.getInstanceURL())
        mastodonAPIClient.accessToken = try? secrets.getAccessToken()

-        contentDatabase = try ContentDatabase(id: id,
-                                              inMemory: environment.inMemoryContent,
-                                              keychain: environment.keychain)
+        let appPreferences = AppPreferences(environment: environment)
+
+        contentDatabase = try ContentDatabase(
+            id: id,
+            useHomeTimelineLastReadId: appPreferences.homeTimelineBehavior == .rememberPosition,
+            useNotificationsLastReadId: appPreferences.notificationsTabBehavior == .rememberPosition,
+            inMemory: environment.inMemoryContent,
+            keychain: environment.keychain)
    }
 }

@ -87,6 +92,29 @@ public extension IdentityService {
            .eraseToAnyPublisher()
    }

+    func getMarker(_ markerTimeline: Marker.Timeline) -> AnyPublisher<Marker, Error> {
+        mastodonAPIClient.request(MarkersEndpoint.get([markerTimeline]))
+            .compactMap { $0[markerTimeline.rawValue] }
+            .eraseToAnyPublisher()
+    }
+
+    func getLocalLastReadId(_ markerTimeline: Marker.Timeline) -> String? {
+        contentDatabase.lastReadId(markerTimeline)
+    }
+
+    func setLastReadId(_ id: String, forMarker markerTimeline: Marker.Timeline) -> AnyPublisher<Never, Error> {
+        switch AppPreferences(environment: environment).positionBehavior(markerTimeline: markerTimeline) {
+        case .rememberPosition:
+            return contentDatabase.setLastReadId(id, markerTimeline: markerTimeline)
+        case .syncPosition:
+            return mastodonAPIClient.request(MarkersEndpoint.post([markerTimeline: id]))
+                .ignoreOutput()
+                .eraseToAnyPublisher()
+        case .newest:
+            return Empty().eraseToAnyPublisher()
+        }
+    }
+
    func identityPublisher(immediate: Bool) -> AnyPublisher<Identity, Error> {
        identityDatabase.identityPublisher(id: id, immediate: immediate)
    }
--- a/ServiceLayer/Sources/ServiceLayer/Services/InstanceURLService.swift
+++ b/ServiceLayer/Sources/ServiceLayer/Services/InstanceURLService.swift
@ -73,7 +73,7 @@ private struct UpdatedFilterTarget: DecodableTarget {
    let baseURL = URL(string: "https://filter.metabolist.com")!
    let pathComponents = ["filter"]
    let method = HTTPMethod.get
-    let queryParameters: [String: String]? = nil
+    let queryParameters: [URLQueryItem] = []
    let jsonBody: [String: Any]? = nil
    let headers: [String: String]? = nil
 }
--- a/ServiceLayer/Sources/ServiceLayer/Services/TimelineService.swift
+++ b/ServiceLayer/Sources/ServiceLayer/Services/TimelineService.swift
@ -15,15 +15,27 @@ public struct TimelineService {
    private let timeline: Timeline
    private let mastodonAPIClient: MastodonAPIClient
    private let contentDatabase: ContentDatabase
-    private let nextPageMaxIdSubject = PassthroughSubject<String, Never>()
+    private let nextPageMaxIdSubject: CurrentValueSubject<String, Never>

    init(timeline: Timeline, mastodonAPIClient: MastodonAPIClient, contentDatabase: ContentDatabase) {
        self.timeline = timeline
        self.mastodonAPIClient = mastodonAPIClient
        self.contentDatabase = contentDatabase
+
+        let nextPageMaxIdSubject = CurrentValueSubject<String, Never>(String(Int.max))
+
+        self.nextPageMaxIdSubject = nextPageMaxIdSubject
        sections = contentDatabase.timelinePublisher(timeline)
+            .handleEvents(receiveOutput: {
+                guard case let .status(status, _) = $0.last?.last,
+                      status.id < nextPageMaxIdSubject.value
+                else { return }
+
+                nextPageMaxIdSubject.send(status.id)
+            })
+            .eraseToAnyPublisher()
        navigationService = NavigationService(mastodonAPIClient: mastodonAPIClient, contentDatabase: contentDatabase)
-        nextPageMaxId = nextPageMaxIdSubject.eraseToAnyPublisher()
+        nextPageMaxId = nextPageMaxIdSubject.dropFirst().eraseToAnyPublisher()

        if case let .tag(tag) = timeline {
            title = Just("#".appending(tag)).eraseToAnyPublisher()
@ -34,10 +46,19 @@ public struct TimelineService {
 }

 extension TimelineService: CollectionService {
+    public var markerTimeline: Marker.Timeline? {
+        switch timeline {
+        case .home:
+            return .home
+        default:
+            return nil
+        }
+    }
+
    public func request(maxId: String?, minId: String?) -> AnyPublisher<Never, Error> {
        mastodonAPIClient.pagedRequest(timeline.endpoint, maxId: maxId, minId: minId)
            .handleEvents(receiveOutput: {
-                guard let maxId = $0.info.maxId else { return }
+                guard let maxId = $0.info.maxId, maxId < nextPageMaxIdSubject.value else { return }

                nextPageMaxIdSubject.send(maxId)
            })
--- a/ServiceLayer/Sources/ServiceLayer/Utilities/AppPreferences.swift
+++ b/ServiceLayer/Sources/ServiceLayer/Utilities/AppPreferences.swift
@ -2,6 +2,7 @@

 import CodableBloomFilter
 import Foundation
+import Mastodon

 public struct AppPreferences {
    private let userDefaults: UserDefaults
@ -30,6 +31,14 @@ public extension AppPreferences {
        public var id: String { rawValue }
    }

+    enum PositionBehavior: String, CaseIterable, Identifiable {
+        case rememberPosition
+        case syncPosition
+        case newest
+
+        public var id: String { rawValue }
+    }
+
    var useSystemReduceMotionForMedia: Bool {
        get { self[.useSystemReduceMotionForMedia] ?? true }
        set { self[.useSystemReduceMotionForMedia] = newValue }
@ -76,9 +85,42 @@ public extension AppPreferences {
        set { self[.autoplayVideos] = newValue.rawValue }
    }

+    var homeTimelineBehavior: PositionBehavior {
+        get {
+            if let rawValue = self[.homeTimelineBehavior] as String?,
+               let value = PositionBehavior(rawValue: rawValue) {
+                return value
+            }
+
+            return .rememberPosition
+        }
+        set { self[.homeTimelineBehavior] = newValue.rawValue }
+    }
+
+    var notificationsTabBehavior: PositionBehavior {
+        get {
+            if let rawValue = self[.notificationsTabBehavior] as String?,
+               let value = PositionBehavior(rawValue: rawValue) {
+                return value
+            }
+
+            return .newest
+        }
+        set { self[.notificationsTabBehavior] = newValue.rawValue }
+    }
+
    var shouldReduceMotion: Bool {
        systemReduceMotion() && useSystemReduceMotionForMedia
    }
+
+    func positionBehavior(markerTimeline: Marker.Timeline) -> PositionBehavior {
+        switch markerTimeline {
+        case .home:
+            return homeTimelineBehavior
+        case .notifications:
+            return notificationsTabBehavior
+        }
+    }
 }

 extension AppPreferences {
@ -103,6 +145,8 @@ private extension AppPreferences {
        case animateHeaders
        case autoplayGIFs
        case autoplayVideos
+        case homeTimelineBehavior
+        case notificationsTabBehavior
    }

    subscript<T>(index: Item) -> T? {
--- a/Controllers/TableViewController.swift
+++ b/Controllers/TableViewController.swift
@ -6,6 +6,7 @@ import SafariServices
 import SwiftUI
 import ViewModels

+// swiftlint:disable file_length
 class TableViewController: UITableViewController {
    var transitionViewTag = -1

@ -272,13 +273,16 @@ private extension TableViewController {
            if
                let item = update.maintainScrollPosition,
                let indexPath = self.dataSource.indexPath(for: item) {
-                self.tableView.contentInset.bottom = max(
-                    0,
-                    self.tableView.frame.height
-                        - self.tableView.contentSize.height
-                        - self.tableView.safeAreaInsets.top
-                        - self.tableView.safeAreaInsets.bottom)
-                    + self.tableView.rectForRow(at: indexPath).minY
+                if self.viewModel.shouldAdjustContentInset {
+                    self.tableView.contentInset.bottom = max(
+                        0,
+                        self.tableView.frame.height
+                            - self.tableView.contentSize.height
+                            - self.tableView.safeAreaInsets.top
+                            - self.tableView.safeAreaInsets.bottom)
+                        + self.tableView.rectForRow(at: indexPath).minY
+                }
+
                self.tableView.scrollToRow(at: indexPath, at: .top, animated: false)

                if let offsetFromNavigationBar = offsetFromNavigationBar {
@ -399,3 +403,4 @@ private extension TableViewController {
        }
    }
 }
+// swiftlint:enable file_length
--- a/ViewModels/Sources/ViewModels/CollectionItemsViewModel.swift
+++ b/ViewModels/Sources/ViewModels/CollectionItemsViewModel.swift
@ -18,7 +18,10 @@ final public class CollectionItemsViewModel: ObservableObject {
    private let expandAllSubject: CurrentValueSubject<ExpandAllState, Never>
    private var maintainScrollPosition: CollectionItem?
    private var topVisibleIndexPath = IndexPath(item: 0, section: 0)
+    private let lastReadId = CurrentValueSubject<String?, Never>(nil)
    private var lastSelectedLoadMore: LoadMore?
+    private var hasRequestedUsingMarker = false
+    private var hasRememberedPosition = false
    private var cancellables = Set<AnyCancellable>()

    public init(collectionService: CollectionService, identification: Identification) {
@ -38,6 +41,15 @@ final public class CollectionItemsViewModel: ObservableObject {
        collectionService.nextPageMaxId
            .sink { [weak self] in self?.nextPageMaxId = $0 }
            .store(in: &cancellables)
+
+        if let markerTimeline = collectionService.markerTimeline {
+            lastReadId.compactMap { $0 }
+                .removeDuplicates()
+                .debounce(for: 0.5, scheduler: DispatchQueue.global())
+                .flatMap { identification.service.setLastReadId($0, forMarker: markerTimeline) }
+                .sink { _ in } receiveValue: { _ in }
+                .store(in: &cancellables)
+        }
    }
 }

@ -62,8 +74,32 @@ extension CollectionItemsViewModel: CollectionViewModel {

    public var events: AnyPublisher<CollectionItemEvent, Never> { eventsSubject.eraseToAnyPublisher() }

+    public var shouldAdjustContentInset: Bool { collectionService is ContextService }
+
    public func request(maxId: String? = nil, minId: String? = nil) {
-        collectionService.request(maxId: maxId, minId: minId)
+        let publisher: AnyPublisher<Never, Error>
+
+        if let markerTimeline = collectionService.markerTimeline,
+           identification.appPreferences.positionBehavior(markerTimeline: markerTimeline) == .syncPosition,
+           !hasRequestedUsingMarker {
+            publisher = identification.service.getMarker(markerTimeline)
+                .flatMap { [weak self] in
+                    self?.collectionService.request(maxId: $0.lastReadId, minId: nil) ?? Empty().eraseToAnyPublisher()
+                }
+                .catch { [weak self] _ in
+                    self?.collectionService.request(maxId: nil, minId: nil) ?? Empty().eraseToAnyPublisher()
+                }
+                .collect()
+                .flatMap { [weak self] _ in
+                    self?.collectionService.request(maxId: nil, minId: nil) ?? Empty().eraseToAnyPublisher()
+                }
+                .eraseToAnyPublisher()
+            self.hasRequestedUsingMarker = true
+        } else {
+            publisher = collectionService.request(maxId: maxId, minId: minId)
+        }
+
+        publisher
            .receive(on: DispatchQueue.main)
            .assignErrorsToAlertItem(to: \.alertItem, on: self)
            .handleEvents(
@ -95,6 +131,15 @@ extension CollectionItemsViewModel: CollectionViewModel {

    public func viewedAtTop(indexPath: IndexPath) {
        topVisibleIndexPath = indexPath
+
+        if items.value.count > indexPath.section, items.value[indexPath.section].count > indexPath.item {
+            switch items.value[indexPath.section][indexPath.item] {
+            case let .status(status, _):
+                lastReadId.send(status.id)
+            default:
+                break
+            }
+        }
    }

    public func canSelect(indexPath: IndexPath) -> Bool {
@ -196,9 +241,27 @@ private extension CollectionItemsViewModel {
        viewModelCache = viewModelCache.filter { itemsSet.contains($0.key) }
    }

+    // swiftlint:disable:next cyclomatic_complexity function_body_length
    func itemForScrollPositionMaintenance(newItems: [[CollectionItem]]) -> CollectionItem? {
        let flatNewItems = newItems.reduce([], +)

+        if let markerTimeline = collectionService.markerTimeline,
+           identification.appPreferences.positionBehavior(markerTimeline: markerTimeline) == .rememberPosition,
+           let localLastReadId = identification.service.getLocalLastReadId(markerTimeline),
+           !hasRememberedPosition,
+           let lastReadItem = flatNewItems.first(where: {
+            switch $0 {
+            case let .status(status, _):
+                return status.id == localLastReadId
+            default:
+                return false
+            }
+           }) {
+            hasRememberedPosition = true
+
+            return lastReadItem
+        }
+
        if collectionService is ContextService,
           items.value.isEmpty || items.value.map(\.count) == [0, 1, 0],
           let contextParent = flatNewItems.first(where: {
--- a/ViewModels/Sources/ViewModels/CollectionViewModel.swift
+++ b/ViewModels/Sources/ViewModels/CollectionViewModel.swift
@ -10,6 +10,7 @@ public protocol CollectionViewModel {
    var alertItems: AnyPublisher<AlertItem, Never> { get }
    var loading: AnyPublisher<Bool, Never> { get }
    var events: AnyPublisher<CollectionItemEvent, Never> { get }
+    var shouldAdjustContentInset: Bool { get }
    var nextPageMaxId: String? { get }
    func request(maxId: String?, minId: String?)
    func viewedAtTop(indexPath: IndexPath)
--- a/ViewModels/Sources/ViewModels/ProfileViewModel.swift
+++ b/ViewModels/Sources/ViewModels/ProfileViewModel.swift
@ -81,6 +81,10 @@ extension ProfileViewModel: CollectionViewModel {
            .eraseToAnyPublisher()
    }

+    public var shouldAdjustContentInset: Bool {
+        collectionViewModel.value.shouldAdjustContentInset
+    }
+
    public var nextPageMaxId: String? {
        collectionViewModel.value.nextPageMaxId
    }
--- a/Views/PreferencesView.swift
+++ b/Views/PreferencesView.swift
@ -26,6 +26,8 @@ struct PreferencesView: View {
                NavigationLink("preferences.media",
                               destination: MediaPreferencesView(
                                viewModel: .init(identification: identification)))
+                NavigationLink("preferences.startup-and-syncing",
+                               destination: StartupAndSyncingPreferencesView())
            }
        }
        .navigationTitle("preferences")
--- a/Views/StartupAndSyncingPreferencesView.swift
+++ b/Views/StartupAndSyncingPreferencesView.swift
@ -0,0 +1,53 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import SwiftUI
+import ViewModels
+
+struct StartupAndSyncingPreferencesView: View {
+    @EnvironmentObject var identification: Identification
+
+    var body: some View {
+        Form {
+            Section(header: Text("preferences.startup-and-syncing.home-timeline")) {
+                Picker("preferences.startup-and-syncing.position-on-startup",
+                       selection: $identification.appPreferences.homeTimelineBehavior) {
+                    ForEach(AppPreferences.PositionBehavior.allCases) { option in
+                        Text(option.localizedStringKey).tag(option)
+                    }
+                }
+            }
+            Section(header: Text("preferences.startup-and-syncing.notifications-tab")) {
+                Picker("preferences.startup-and-syncing.position-on-startup",
+                       selection: $identification.appPreferences.notificationsTabBehavior) {
+                    ForEach(AppPreferences.PositionBehavior.allCases) { option in
+                        Text(option.localizedStringKey).tag(option)
+                    }
+                }
+            }
+        }
+    }
+}
+
+extension AppPreferences.PositionBehavior {
+    var localizedStringKey: LocalizedStringKey {
+        switch self {
+        case .rememberPosition:
+            return "preferences.startup-and-syncing.remember-position"
+        case .syncPosition:
+            return "preferences.startup-and-syncing.sync-position"
+        case .newest:
+            return "preferences.startup-and-syncing.newest"
+        }
+    }
+}
+
+#if DEBUG
+import PreviewViewModels
+
+struct StartupAndSyncingPreferencesView_Previews: PreviewProvider {
+    static var previews: some View {
+        StartupAndSyncingPreferencesView()
+            .environmentObject(Identification.preview)
+    }
+}
+#endif