Fiddle with how the timeline markers API is organized

Packages/Pachyderm/Sources/Pachyderm/Model/TimelineMarkers.swift

@@ -7,34 +7,83 @@
 
 import Foundation
 
-public struct TimelineMarkers: Decodable, Sendable {
-    public let home: Marker?
-    public let notifications: Marker?
+public struct TimelineMarkers {
+    private init() {}
     
-    public static func request(timelines: [Timeline]) -> Request<TimelineMarkers> {
-        return Request(method: .get, path: "/api/v1/markers", queryParameters: "timeline[]" => timelines.map(\.rawValue))
+    public static func request<T: TimelineMarkerType>(timeline: T) -> Request<TimelineMarker<T.Payload>> {
+        Request(method: .get, path: "/api/v1/markers", queryParameters: ["timeline[]" => T.name])
     }
     
-    public static func update(timeline: Timeline, lastReadID: String) -> Request<Empty> {
-        return Request(method: .post, path: "/api/v1/markers", body: ParametersBody([
-            "\(timeline.rawValue)[last_read_id]" => lastReadID,
+    public static func update<T: TimelineMarkerType>(timeline: T, lastReadID: String) -> Request<Empty> {
+        Request(method: .post, path: "/api/v1/markers", body: ParametersBody([
+            "\(T.name)[last_read_id]" => lastReadID
         ]))
     }
+}
 
-    public enum Timeline: String {
-        case home
-        case notifications
+public struct TimelineMarker<Payload: TimelineMarkerTypePayload>: Decodable, Sendable {
+    let payload: Payload
+    
+    public var lastReadID: String {
+        payload.payload.lastReadID
+    }
+    public var version: Int {
+        payload.payload.version
+    }
+    public var updatedAt: Date {
+        payload.payload.updatedAt
     }
 
-    public struct Marker: Decodable, Sendable {
-        public let lastReadID: String
-        public let version: Int
-        public let updatedAt: Date
-        
-        enum CodingKeys: String, CodingKey {
-            case lastReadID = "last_read_id"
-            case version
-            case updatedAt = "updated_at"
-        }
+    public init(from decoder: any Decoder) throws {
+        self.payload = try Payload(from: decoder)
     }
 }
+
+public protocol TimelineMarkerTypePayload: Decodable, Sendable {
+    var payload: MarkerPayload { get }
+}
+
+public struct HomeMarkerPayload: TimelineMarkerTypePayload {
+    public var home: MarkerPayload
+    public var payload: MarkerPayload { home }
+}
+
+public struct NotificationsMarkerPayload: TimelineMarkerTypePayload {
+    public var notifications: MarkerPayload
+    public var payload: MarkerPayload { notifications }
+}
+
+public struct MarkerPayload: Decodable, Sendable {
+    public let lastReadID: String
+    public let version: Int
+    public let updatedAt: Date
+    
+    enum CodingKeys: String, CodingKey {
+        case lastReadID = "last_read_id"
+        case version
+        case updatedAt = "updated_at"
+    }
+}
+
+public protocol TimelineMarkerType {
+    static var name: String { get }
+    associatedtype Payload: TimelineMarkerTypePayload
+}
+
+extension TimelineMarkerType where Self == HomeMarker {
+    public static var home: Self { .init() }
+}
+
+extension TimelineMarkerType where Self == NotificationsMarker {
+    public static var notifications: Self { .init() }
+}
+
+public struct HomeMarker: TimelineMarkerType {
+    public typealias Payload = HomeMarkerPayload
+    public static var name: String { "home" }
+}
+
+public struct NotificationsMarker: TimelineMarkerType {
+    public typealias Payload = NotificationsMarkerPayload
+    public static var name: String { "notifications" }
+}

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -573,12 +573,9 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     @MainActor
     private func restoreStatusesFromMarkerPosition() async -> Bool {
         do {
-            let (marker, _) = try await mastodonController.run(TimelineMarkers.request(timelines: [.home]))
-            guard let home = marker.home else {
-                return false
-            }
-            async let status = try await mastodonController.run(Client.getStatus(id: home.lastReadID)).0
-            async let olderStatuses = try await mastodonController.run(Client.getStatuses(timeline: .home, range: .before(id: home.lastReadID, count: Self.pageSize))).0
+            let (marker, _) = try await mastodonController.run(TimelineMarkers.request(timeline: .home))
+            async let status = try await mastodonController.run(Client.getStatus(id: marker.lastReadID)).0
+            async let olderStatuses = try await mastodonController.run(Client.getStatuses(timeline: .home, range: .before(id: marker.lastReadID, count: Self.pageSize))).0
             
             let allStatuses = try await [status] + olderStatuses
             await mastodonController.persistentContainer.addAll(statuses: allStatuses)
@@ -590,7 +587,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             await apply(snapshot, animatingDifferences: false)
             collectionView.contentOffset = CGPoint(x: 0, y: -collectionView.adjustedContentInset.top)
             
-            stateRestorationLogger.debug("TimelineViewController: restored from timeline marker with last read ID: \(home.lastReadID)")
+            stateRestorationLogger.debug("TimelineViewController: restored from timeline marker with last read ID: \(marker.lastReadID)")
             
             return true
         } catch {