Blogging Prompts: Fix Core Data concurrency issues in scheduler

WordPress/Classes/Services/BloggingPromptsService.swift

@@ -179,17 +179,44 @@ class BloggingPromptsService {
 
     // MARK: - Init
 
+    /// Initializes a service for blogging prompts.
+    ///
+    /// - Parameters:
+    ///   - contextManager: The CoreDataStack instance.
+    ///   - remote: When supplied, the service will use the specified remote service.
+    ///     Otherwise, a remote service with the default account's credentials will be used.
+    ///   - blog: When supplied, the service will perform blogging prompts requests for this specified blog.
+    ///     Otherwise, this falls back to the default account's primary blog.
     required init?(contextManager: CoreDataStackSwift = ContextManager.shared,
                    remote: BloggingPromptsServiceRemote? = nil,
                    blog: Blog? = nil) {
-        guard let account = try? WPAccount.lookupDefaultWordPressComAccount(in: contextManager.mainContext),
-              let siteID = blog?.dotComID ?? account.primaryBlogID else {
+        let blogObjectID = blog?.objectID
+        let (siteID, remoteInstance) = contextManager.performQuery { mainContext in
+            // if a blog exists, then try to use the blog's ID.
+            var blogInContext: Blog? = nil
+            if let blogObjectID {
+                blogInContext = (try? mainContext.existingObject(with: blogObjectID)) as? Blog
+            }
+
+            // fetch the default account and fall back to default values as needed.
+            guard let account = try? WPAccount.lookupDefaultWordPressComAccount(in: mainContext) else {
+                return (blogInContext?.dotComID, remote)
+            }
+
+            return (
+                blogInContext?.dotComID ?? account.primaryBlogID,
+                remote ?? .init(wordPressComRestApi: account.wordPressComRestV2Api)
+            )
+        }
+
+        guard let siteID,
+              let remoteInstance else {
             return nil
         }
 
         self.contextManager = contextManager
         self.siteID = siteID
-        self.remote = remote ?? .init(wordPressComRestApi: account.wordPressComRestV2Api)
+        self.remote = remoteInstance
     }
 }
 

WordPress/Classes/Utility/Blogging Prompts/PromptRemindersScheduler.swift

@@ -43,9 +43,16 @@ class PromptRemindersScheduler {
     ///   - time: The user's preferred time to be notified.
     ///   - completion: Closure called after the process completes.
     func schedule(_ schedule: BloggingRemindersScheduler.Schedule, for blog: Blog, time: Date? = nil, completion: @escaping (Result<Void, Error>) -> Void) {
+        guard let context = blog.managedObjectContext else {
+            completion(.failure(Errors.unknown))
+            return
+        }
+
         guard schedule != .none else {
-            // If there's no schedule, then we don't need to request authorization
-            processSchedule(schedule, blog: blog, time: time, completion: completion)
+            context.performAndWait {
+                // If there's no schedule, then we don't need to request authorization
+                processSchedule(schedule, blog: blog, time: time, completion: completion)
+            }
             return
         }
 
@@ -59,7 +66,9 @@ class PromptRemindersScheduler {
                 return
             }
 
-            self.processSchedule(schedule, blog: blog, time: time, completion: completion)
+            context.performAndWait {
+                self.processSchedule(schedule, blog: blog, time: time, completion: completion)
+            }
         }
     }
 
@@ -149,6 +158,7 @@ private extension PromptRemindersScheduler {
             return
         }
 
+        let title = blog.title
         let reminderTime = Time(from: time) ?? Constants.defaultTime
         let currentDate = currentDateProvider.date()
         promptsService.fetchPrompts(from: currentDate, number: Constants.promptsToFetch) { [weak self] prompts in
@@ -177,7 +187,7 @@ private extension PromptRemindersScheduler {
             var lastScheduledPrompt: BloggingPrompt? = nil
             var notificationIds = [String]()
             promptsToSchedule.forEach { prompt in
-                guard let identifier = self.addLocalNotification(for: prompt, blog: blog, at: reminderTime) else {
+                guard let identifier = self.addLocalNotification(for: prompt, siteID: siteID, siteTitle: title, at: reminderTime) else {
                     return
                 }
                 notificationIds.append(identifier)
@@ -197,7 +207,10 @@ private extension PromptRemindersScheduler {
                 return lastReminderDate
             }()
 
-            if let staticNotificationIds = self.addStaticNotifications(after: lastReminderDate, with: schedule, time: reminderTime, blog: blog) {
+            if let staticNotificationIds = self.addStaticNotifications(after: lastReminderDate,
+                                                                       with: schedule,
+                                                                       time: reminderTime,
+                                                                       siteID: siteID) {
                 notificationIds.append(contentsOf: staticNotificationIds)
             }
 
@@ -224,17 +237,13 @@ private extension PromptRemindersScheduler {
     ///   - blog: The user's blog.
     ///   - time: The preferred reminder time for the notification.
     /// - Returns: String representing the notification identifier.
-    func addLocalNotification(for prompt: BloggingPrompt, blog: Blog, at time: Time) -> String? {
-        guard blog.dotComID != nil else {
-            return nil
-        }
-
+    func addLocalNotification(for prompt: BloggingPrompt, siteID: Int, siteTitle: String? = nil, at time: Time) -> String? {
         let content = UNMutableNotificationContent()
         content.title = Constants.notificationTitle
-        content.subtitle = blog.title ?? String()
+        content.subtitle = siteTitle ?? String()
         content.body = prompt.text
         content.categoryIdentifier = InteractiveNotificationsManager.NoteCategoryDefinition.bloggingPrompt.rawValue
-        content.userInfo = notificationPayload(for: blog, prompt: prompt)
+        content.userInfo = notificationPayload(for: siteID, prompt: prompt)
 
         guard let reminderDateComponents = reminderDateComponents(for: prompt, at: time) else {
             return nil
@@ -282,12 +291,11 @@ private extension PromptRemindersScheduler {
     func addStaticNotifications(after afterDate: Date,
                                 with schedule: Schedule,
                                 time: Time,
-                                blog: Blog,
+                                siteID: Int,
                                 maxDays: Int = Constants.staticNotificationMaxDays) -> [String]? {
         guard case .weekdays(let weekdays) = schedule,
               maxDays > 0,
-              let maxDate = Calendar.current.date(byAdding: .day, value: maxDays, to: afterDate),
-              blog.dotComID != nil else {
+              let maxDate = Calendar.current.date(byAdding: .day, value: maxDays, to: afterDate) else {
             return nil
         }
 
@@ -297,7 +305,7 @@ private extension PromptRemindersScheduler {
         content.title = Constants.notificationTitle
         content.body = Constants.staticNotificationContent
         content.categoryIdentifier = InteractiveNotificationsManager.NoteCategoryDefinition.bloggingPrompt.rawValue
-        content.userInfo = notificationPayload(for: blog)
+        content.userInfo = notificationPayload(for: siteID)
 
         var date = afterDate
         var identifiers = [String]()
@@ -358,11 +366,7 @@ private extension PromptRemindersScheduler {
         return identifier
     }
 
-    func notificationPayload(for blog: Blog, prompt: BloggingPrompt? = nil) -> [AnyHashable: Any] {
-        guard let siteID = blog.dotComID?.intValue else {
-            return [:]
-        }
-
+    func notificationPayload(for siteID: Int, prompt: BloggingPrompt? = nil) -> [AnyHashable: Any] {
         var userInfo: [AnyHashable: Any] = [BloggingPrompt.NotificationKeys.siteID: siteID]
 
         if let prompt = prompt {

WordPress/Classes/ViewRelated/Blog/Blogging Prompts/BloggingPromptCoordinator.swift

@@ -112,6 +112,7 @@ private extension BloggingPromptCoordinator {
         guard let service = promptsServiceFactory.makeService(for: blog),
               let settings = service.localSettings,
               let reminderDays = settings.reminderDays,
+              let context = settings.managedObjectContext,
               settings.promptRemindersEnabled else {
             completion()
             return
@@ -125,10 +126,12 @@ private extension BloggingPromptCoordinator {
                 return
             }
 
-            // Reschedule the prompt reminders.
-            let schedule = BloggingRemindersScheduler.Schedule.weekdays(reminderDays.getActiveWeekdays())
-            self.scheduler.schedule(schedule, for: blog, time: settings.reminderTimeDate()) { result in
-                completion()
+            context.performAndWait {
+                // Reschedule the prompt reminders.
+                let schedule = BloggingRemindersScheduler.Schedule.weekdays(reminderDays.getActiveWeekdays())
+                self.scheduler.schedule(schedule, for: blog, time: settings.reminderTimeDate()) { result in
+                    completion()
+                }
             }
         }
     }