Coordinate DraftsManager reading writing between processes

Packages/ComposeUI/Sources/ComposeUI/API/PostService.swift

@@ -33,7 +33,7 @@ class PostService: ObservableObject {
         }
         
         // save before posting, so if a crash occurs during network request, the status won't be lost
-        DraftsManager.save()
+        DraftsManager.shared.save()
         
         let uploadedAttachments = try await uploadAttachments()
         
@@ -59,7 +59,7 @@ class PostService: ObservableObject {
             currentStep += 1
             
             DraftsManager.shared.remove(self.draft)
-            DraftsManager.save()
+            DraftsManager.shared.save()
         } catch let error as Client.Error {
             throw Error.posting(error)
         }

Packages/ComposeUI/Sources/ComposeUI/Controllers/ComposeController.swift

@@ -189,7 +189,7 @@ public final class ComposeController: ViewController {
         if !self.draft.hasContent {
             DraftsManager.shared.remove(self.draft)
         }
-        DraftsManager.save()
+        DraftsManager.shared.save()
         
         self.draft = draft
     }
@@ -198,7 +198,7 @@ public final class ComposeController: ViewController {
         if !draft.hasContent {
             DraftsManager.shared.remove(draft)
         }
-        DraftsManager.save()
+        DraftsManager.shared.save()
     }
     
     func toggleContentWarning() {

Packages/ComposeUI/Sources/ComposeUI/Controllers/DraftsController.swift

@@ -48,7 +48,7 @@ class DraftsController: ViewController {
     
     func closeDrafts() {
         isPresented = false
-        DraftsManager.save()
+        DraftsManager.shared.save()
     }
     
     struct DraftsRepresentable: UIViewControllerRepresentable {

Packages/ComposeUI/Sources/ComposeUI/Model/DraftsManager.swift

@@ -11,75 +11,86 @@ import Combine
 import OSLog
 
 private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "DraftsManager")
+private let encoder = PropertyListEncoder()
+private let decoder = PropertyListDecoder()
 
-public class DraftsManager: Codable, ObservableObject {
+public class DraftsManager: NSObject, ObservableObject, NSFilePresenter {
-
+    public private(set) static var shared: DraftsManager = {
-    public private(set) static var shared: DraftsManager = load()
+        let draftsManager = DraftsManager(url: DraftsManager.archiveURL)
+        draftsManager.load()
+        return draftsManager
+    }()
     
     private static var appGroupDirectory = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.space.vaccor.Tusker")!
     private static var archiveURL = appGroupDirectory.appendingPathComponent("drafts").appendingPathExtension("plist")
     
-    private static let saveQueue = DispatchQueue(label: "DraftsManager", qos: .utility)
+    private var url: URL
     
-    public static func save() {
+    @Published private var drafts: [UUID: Draft] = [:]
-        saveQueue.async {
+    
-            let encoder = PropertyListEncoder()
+    public init(url: URL) {
+        self.url = url
+        
+        super.init()
+    }
+    
+    private func merge(from container: DraftsContainer) {
+        for draft in container.drafts.values {
+            if let existing = self.drafts[draft.id] {
+                existing.merge(from: draft)
+            } else {
+                self.drafts[draft.id] = draft
+            }
+        }
+        for id in self.drafts.keys where !container.drafts.keys.contains(id) {
+            self.drafts.removeValue(forKey: id)
+        }
+    }
+    
+    public func load(completion: ((Error?) -> Void)? = nil) {
+        NSFileCoordinator(filePresenter: self).coordinate(readingItemAt: self.url, options: [], error: nil) { url in
             do {
-                let data = try encoder.encode(shared)
+                let data = try Data(contentsOf: url)
-                try data.write(to: archiveURL, options: .noFileProtection)
+                let container = try decoder.decode(DraftsContainer.self, from: data)
+                DispatchQueue.main.async {
+                    self.merge(from: container)
+                    completion?(nil)
+                }
             } catch {
-                logger.error("Save failed: \(String(describing: error))")
+                logger.error("Error loading: \(String(describing: error))")
+                completion?(error)
             }
         }
     }
     
-    static func load() -> DraftsManager {
+    public func migrate(from url: URL) -> Result<Void, any Error> {
-        let decoder = PropertyListDecoder()
         do {
-            let data = try Data(contentsOf: archiveURL)
+            let data = try Data(contentsOf: url)
-            let draftsManager = try decoder.decode(DraftsManager.self, from: data)
+            let container = try decoder.decode(DraftsContainer.self, from: data)
-            return draftsManager
+            self.merge(from: container)
-        } catch {
+            self.save()
-            logger.error("Load failed: \(String(describing: error))")
-            return DraftsManager()
-        }
-    }
-    
-    public static func migrate(from url: URL) -> Result<Void, any Error> {
-        do {
-            try? FileManager.default.removeItem(at: archiveURL)
-            try FileManager.default.moveItem(at: url, to: archiveURL)
         } catch {
+            logger.error("Error migrating: \(String(describing: error))")
             return .failure(error)
         }
-        shared = load()
         return .success(())
     }
     
-    private init() {}
+    public func save(completion: ((Error?) -> Void)? = nil) {
-    
+        NSFileCoordinator(filePresenter: self).coordinate(writingItemAt: Self.archiveURL, options: .forReplacing, error: nil) { url in
-    public required init(from decoder: Decoder) throws {
+            do {
-        let container = try decoder.container(keyedBy: CodingKeys.self)
+                let data = try encoder.encode(DraftsContainer(drafts: self.drafts))
-        
+                try data.write(to: url, options: .atomic)
-        if let dict = try? container.decode([UUID: SafeDraft].self, forKey: .drafts) {
+                completion?(nil)
-            self.drafts = dict.compactMapValues { $0.draft }
+            } catch {
-        } else if let array = try? container.decode([SafeDraft].self, forKey: .drafts) {
+                logger.error("Error saving: \(String(describing: error))")
-            self.drafts = array.reduce(into: [:], { partialResult, safeDraft in
+                completion?(error)
-                if let draft = safeDraft.draft {
-                    partialResult[draft.id] = draft
             }
-            })
-        } else {
-            throw DecodingError.dataCorruptedError(forKey: .drafts, in: container, debugDescription: "expected drafts to be a dict or array of drafts")
         }
     }
     
-    public func encode(to encoder: Encoder) throws {
+    // MARK: Drafts API
-        var container = encoder.container(keyedBy: CodingKeys.self)
-        try container.encode(drafts, forKey: .drafts)
-    }
     
-    @Published private var drafts: [UUID: Draft] = [:]
     var sorted: [Draft] {
         return drafts.values.sorted(by: { $0.lastModified > $1.lastModified })
     }
@@ -96,9 +107,40 @@ public class DraftsManager: Codable, ObservableObject {
         return drafts[id]
     }
 
-    enum CodingKeys: String, CodingKey {
+    // MARK: NSFilePresenter
+    
+    public var presentedItemURL: URL? {
+        url
+    }
+    
+    public let presentedItemOperationQueue = OperationQueue()
+    
+    public func presentedItemDidMove(to newURL: URL) {
+        self.url = newURL
+    }
+    
+    public func presentedItemDidChange() {
+        self.load()
+    }
+    
+    // MARK: Supporting Types
+    
+    struct DraftsContainer: Codable {
+        let drafts: [UUID: Draft]
+        
+        init(drafts: [UUID: Draft]) {
+            self.drafts = drafts
+        }
+        
+        init(from decoder: Decoder) throws {
+            let container = try decoder.container(keyedBy: CodingKeys.self)
+            self.drafts = try container.decode([UUID: SafeDraft].self, forKey: .drafts).compactMapValues(\.draft)
+        }
+        
+        enum CodingKeys: CodingKey {
             case drafts
         }
+    }
     
     // a container that always succeeds at decoding
     // so if a single draft can't be decoded, we don't lose all drafts
@@ -110,5 +152,22 @@ public class DraftsManager: Codable, ObservableObject {
             self.draft = try? container.decode(Draft.self)
         }
     }
-    
+}
+
+private extension Draft {
+    func merge(from other: Draft) {
+        self.lastModified = other.lastModified
+        
+        self.accountID = other.accountID
+        self.text = other.text
+        self.contentWarningEnabled = other.contentWarningEnabled
+        self.contentWarning = other.contentWarning
+        self.attachments = other.attachments
+        self.inReplyToID = other.inReplyToID
+        self.visibility = other.visibility
+        self.poll = other.poll
+        self.localOnly = other.localOnly
+        
+        self.initialText = other.initialText
+    }
 }

ShareExtension/ShareViewController.swift

@@ -11,14 +11,16 @@ import UserAccounts
 import ComposeUI
 import UniformTypeIdentifiers
 import TuskerPreferences
+import Combine
 
 class ShareViewController: UIViewController {
     
     private var state: State = .loading
     
+    private var draftsPresenterCancellable: AnyCancellable?
+    
     required init?(coder: NSCoder) {
         super.init(coder: coder)
-        
     }
     
     override func viewDidLoad() {
@@ -27,6 +29,11 @@ class ShareViewController: UIViewController {
         view.tintColor = Preferences.shared.accentColor.color
         
         if let account = UserAccountsManager.shared.getMostRecentAccount() {
+            NSFileCoordinator.addFilePresenter(DraftsManager.shared)
+            draftsPresenterCancellable = AnyCancellable({
+                NSFileCoordinator.removeFilePresenter(DraftsManager.shared)
+            })
+            
             Task { @MainActor in
                 let draft = await createDraft(account: account)
                 state = .ok
@@ -51,6 +58,11 @@ class ShareViewController: UIViewController {
     }
     
     private func createDraft(account: UserAccountInfo) async -> Draft {
+        await withCheckedContinuation({ continuation in
+            DraftsManager.shared.load { _ in
+                continuation.resume()
+            }
+        })
         let (text, attachments) = await getDraftConfigurationFromExtensionContext()
         let draft = Draft(
             accountID: account.id,

Tusker/AppDelegate.swift

@@ -22,6 +22,7 @@ private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category:
 @UIApplicationMain
 class AppDelegate: UIResponder, UIApplicationDelegate {
     
+    private var draftsFileCoordinatorManager: DraftsManagerFileCoordinatorManager!
 
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         configureSentry()
@@ -64,10 +65,12 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
         DispatchQueue.global(qos: .userInitiated).async {
             let oldDraftsFile = documentsDirectory.appendingPathComponent("drafts").appendingPathExtension("plist")
             if FileManager.default.fileExists(atPath: oldDraftsFile.path) {
-                if case .failure(let error) = DraftsManager.migrate(from: oldDraftsFile) {
+                if case .failure(let error) = DraftsManager.shared.migrate(from: oldDraftsFile) {
                     SentrySDK.capture(error: error)
                 }
             }
+            
+            self.draftsFileCoordinatorManager = DraftsManagerFileCoordinatorManager()
         }
         
         return true
@@ -211,3 +214,25 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     }
 
 }
+
+private class DraftsManagerFileCoordinatorManager {
+    init() {
+        NSFileCoordinator.addFilePresenter(DraftsManager.shared)
+        
+        NotificationCenter.default.addObserver(self, selector: #selector(didEnterBackground), name: UIApplication.didEnterBackgroundNotification, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(willEnterForeground), name: UIApplication.willEnterForegroundNotification, object: nil)
+    }
+    
+    deinit {
+        NSFileCoordinator.removeFilePresenter(DraftsManager.shared)
+    }
+    
+    @objc private func didEnterBackground() {
+        NSFileCoordinator.removeFilePresenter(DraftsManager.shared)
+    }
+    
+    @objc private func willEnterForeground() {
+        NSFileCoordinator.addFilePresenter(DraftsManager.shared)
+        DraftsManager.shared.load()
+    }
+}

Tusker/Scenes/ComposeSceneDelegate.swift

@@ -77,7 +77,7 @@ class ComposeSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDeleg
     }
     
     func sceneWillResignActive(_ scene: UIScene) {
-        DraftsManager.save()
+        DraftsManager.shared.save()
         
         if let window = window,
            let nav = window.rootViewController as? UINavigationController,

Tusker/Scenes/MainSceneDelegate.swift

@@ -88,7 +88,7 @@ class MainSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDelegate
         // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
         
         Preferences.save()
-        DraftsManager.save()
+        DraftsManager.shared.save()
     }
     
     func sceneDidBecomeActive(_ scene: UIScene) {
@@ -101,7 +101,7 @@ class MainSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDelegate
         // This may occur due to temporary interruptions (ex. an incoming phone call).
         
         Preferences.save()
-        DraftsManager.save()
+        DraftsManager.shared.save()
     }
     
     func stateRestorationActivity(for scene: UIScene) -> NSUserActivity? {

Tusker/Screens/Compose/ComposeHostingController.swift

@@ -6,6 +6,7 @@
 //  Copyright © 2023 Shadowfacts. All rights reserved.
 //
 
+import UIKit
 import SwiftUI
 import ComposeUI
 import Combine
@@ -27,12 +28,17 @@ class ComposeHostingController: UIHostingController<ComposeHostingController.Vie
     let controller: ComposeController
     let mastodonController: MastodonController
     
+    
     private var assetPickerCompletion: (@MainActor ([PHPickerResult]) -> Void)?
     private var drawingCompletion: ((PKDrawing) -> Void)?
     
     init(draft: Draft?, mastodonController: MastodonController) {
+//        self.draftsFileCoordinatorManager = DraftsManagerFileCoordinatorManager()
+        
         let draft = draft ?? mastodonController.createDraft()
+        DraftsManager.shared.load() { _ in
             DraftsManager.shared.add(draft)
+        }
         
         self.controller = ComposeController(
             draft: draft,