Notifications for new course content & Automated downloads (#895)

- All features are enabled by feature flippers or launch arguments
- Get notified when a new course section starts
- Download the content of the new course section via the notification
- Download the most recent automatically (app launch, background)

Common/Base.lproj/Localizable.strings

@@ -1,4 +1,40 @@
 
+/* Automated Downloads (Deletion options): Explanation for manual deletion */
+"automated-downloads.deletion-options.explanation.manual" = "Downloaded content will not be removed automatically.";
+
+/* Automated Downloads (Deletion options): Explanation for deletion with next section */
+"automated-downloads.deletion-options.explanation.next-section" = "With the start of a new course section, the downloaded content of previous course sections will be removed from this device.";
+
+/* Automated Downloads (Deletion options): Explanation for deletion with second next section */
+"automated-downloads.deletion-options.explanation.second-next-section" = "With the start of a new course section, the downloaded content of the penultimate course section (and older) will be removed from this device.";
+
+/* Automated Downloads (Deletion options): Title for manual deletion */
+"automated-downloads.deletion-options.title.manually" = "Manually";
+
+/* Automated Downloads (Deletion options): Title for deletion with next section */
+"automated-downloads.deletion-options.title.next-section" = "With the start of the next course section";
+
+/* Automated Downloads (Deletion options): Title for deletion with second next section */
+"automated-downloads.deletion-options.title.second-next-section" = "With the start of the second next course section";
+
+/* Automated Downloads (Notification only): Explanation of the feature */
+"automated-downloads.feature.explanation.notification" = "When a new course section becomes available, you will receive a notification. If you tap this notification, you can open the course directly. If you long press on the notification, you can download the content of the new section for offline use.";
+
+/* Automated Downloads (Notification + Background Downloads): Explanation of the feature (add.) */
+"automated-downloads.feature.explanation.notification-background-download" = "In addition, the app will try to download the new content for you automatically. This is only triggered when your device is connected to a WiFi network and it has the least impact on battery life.";
+
+/* Automated Downloads (Notification only): Title of the feature */
+"automated-downloads.feature.title.notification" = "Notifications for New Content";
+
+/* Automated Downloads (Notification + Background Downloads): Title of the feature */
+"automated-downloads.feature.title.notification-background-download" = "Notifications for New Content & Automated Downloads";
+
+/* Automated Downloads (File types): Explanation for considering only videos */
+"automated-downloads.files-type.explanation.videos" = "Only videos will be downloaded.";
+
+/* Automated Downloads (File types): Explanation for considering videos and slides */
+"automated-downloads.files-type.explanation.videos-slides" = "Videos and slides will be downloaded.";
+
 /* title for course start in a course date cell */
 "course-date-cell.course-start.title" = "Course start";
 

Common/Data/Helper/CoreDataHelper.swift

@@ -44,7 +44,11 @@ public class CoreDataHelper { // swiftlint:disable:this convenience_type
                 let coordinator = container.persistentStoreCoordinator
                 if let oldStore = coordinator.persistentStore(for: url) {
                     do {
-                        try coordinator.migratePersistentStore(oldStore, to: sharedStoreURL, options: nil, withType: NSSQLiteStoreType)
+                        let options = [
+                            NSMigratePersistentStoresAutomaticallyOption: true,
+                            NSInferMappingModelAutomaticallyOption: true,
+                        ]
+                        try coordinator.migratePersistentStore(oldStore, to: sharedStoreURL, options: options, withType: NSSQLiteStoreType)
                     } catch {
                         print(error.localizedDescription)
                     }

Common/Data/Helper/CourseHelper.swift

@@ -4,6 +4,7 @@
 //
 
 import BrightFutures
+import CoreData
 import Foundation
 import Stockpile
 
@@ -30,6 +31,41 @@ public enum CourseHelper {
         return XikoloSyncEngine().synchronize(withFetchRequest: Self.FetchRequest.course(withSlugOrId: slugOrId), withQuery: query)
     }
 
+    @discardableResult public static func setAutomatedDownloadSetting(
+        forCourse course: Course,
+        to settings: AutomatedDownloadSettings?
+    ) -> Future<Void, XikoloError> {
+        let promise = Promise<Void, XikoloError>()
+
+        CoreDataHelper.persistentContainer.performBackgroundTask { context in
+            context.mergePolicy = NSMergePolicy.mergeByPropertyObjectTrump
+
+            guard let course = context.existingTypedObject(with: course.objectID) as? Course else {
+                promise.failure(.missingResource(ofType: Course.self))
+                return
+            }
+
+            if settings == nil { // delete settings
+                course.automatedDownloadSettings = settings
+                promise.complete(context.saveWithResult())
+            } else {
+                let center = UNUserNotificationCenter.current()
+                let options: UNAuthorizationOptions = [.alert]
+                center.requestAuthorization(options: options) { granted, error in
+                    if granted {
+                        course.automatedDownloadSettings = settings
+                        course.automatedDownloadsHaveBeenNoticed = true
+                        promise.complete(context.saveWithResult())
+                    } else {
+                        promise.failure(.permissionError(error))
+                    }
+                }
+            }
+        }
+
+        return promise.future
+    }
+
     public static func visit(_ course: Course) {
         let courseObjectId = course.objectID
         CoreDataHelper.persistentContainer.performBackgroundTask { context in

Common/Data/Helper/CourseItemHelper.swift

@@ -70,4 +70,17 @@ public enum CourseItemHelper {
         return promise.future
     }
 
+    @discardableResult public static func syncCourseItemsWithContent(
+        for course: Course,
+        withContentType type: String,
+        networker: SyncNetworker
+    ) -> Future<SyncMultipleResult, XikoloError> {
+        let fetchRequest = Self.FetchRequest.courseItems(forCourse: course)
+        var query = MultipleResourcesQuery(type: CourseItem.self)
+        query.addFilter(forKey: "course", withValue: course.id)
+        query.addFilter(forKey: "content_type", withValue: type)
+        query.include("content")
+        return XikoloSyncEngine(networker: networker).synchronize(withFetchRequest: fetchRequest, withQuery: query, deleteNotExistingResources: false)
+    }
+
 }

Common/Data/Helper/ExperimentAssignmentHelper.swift

@@ -8,9 +8,13 @@ import Stockpile
 
 public enum ExperimentAssignmentHelper {
 
+    public enum ExperimentIdentifier: String {
+        case newContentNotifications = "mobile.new_content_notification"
+    }
+
     @discardableResult
-    public static func assign(to experimentIdentifier: String, inCourse course: Course? = nil) -> Future<Void, XikoloError> {
-        let experimentAssignment = ExperimentAssignment(experimentIdentifier: experimentIdentifier, course: course)
+    public static func assign(to experimentIdentifier: ExperimentIdentifier, inCourse course: Course? = nil) -> Future<Void, XikoloError> {
+        let experimentAssignment = ExperimentAssignment(experimentIdentifier: experimentIdentifier.rawValue, course: course)
         return XikoloSyncEngine().createResource(experimentAssignment)
     }
 

Common/Data/Helper/FeatureHelper.swift

@@ -11,6 +11,10 @@ public enum FeatureHelper {
     public enum FeatureIdentifier: String {
         case quizRecap = "quiz_recap"
         case courseReactivation = "course_reactivation"
+
+        // Identifiers for content notification and automated downloads user test
+        case newContentNotification = "mobile.new_content.notification"
+        case newContentBackgroundDownload = "mobile.new_content.background_download"
     }
 
     @discardableResult
@@ -26,6 +30,14 @@ public enum FeatureHelper {
     }
 
     public static func hasFeature(_ featureIdentifier: FeatureIdentifier, for course: Course? = nil) -> Bool {
+        #if DEBUG
+        if featureIdentifier == .newContentNotification && CommandLine.arguments.contains("-new-content-notification") {
+            return true
+        } else if featureIdentifier == .newContentBackgroundDownload && CommandLine.arguments.contains("-new-content-background-download") {
+            return true
+        }
+        #endif
+
         let hasFeatureInGlobalScope: Bool = {
             let fetchRequest = Self.FetchRequest.globalFeatures
             guard let features = CoreDataHelper.viewContext.fetchSingle(fetchRequest).value else { return false }

Common/Data/Helper/FetchRequests/CourseHelper+FetchRequests.swift

@@ -167,6 +167,34 @@ extension CourseHelper {
             return request
         }
 
+        public static var coursesForAutomatedDownloads: NSFetchRequest<Course> {
+            let request = self.visibleCoursesRequest
+            request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [
+                visiblePredicate,
+                enrolledPredicate,
+                NSPredicate(format: "endsAt >= %@", Date() as NSDate),
+                NSPredicate(format: "automatedDownloadSettings == nil"),
+            ])
+            request.sortDescriptors = [
+                NSSortDescriptor(keyPath: \Course.endsAt, ascending: true),
+            ]
+            return request
+        }
+
+        public static var coursesWithAutomatedDownloads: NSFetchRequest<Course> {
+            let request = self.visibleCoursesRequest
+            request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [
+                visiblePredicate,
+                enrolledPredicate,
+                NSPredicate(format: "endsAt >= %@", Date() as NSDate),
+                NSPredicate(format: "automatedDownloadSettings != nil"),
+            ])
+            request.sortDescriptors = [
+                NSSortDescriptor(keyPath: \Course.endsAt, ascending: true),
+            ]
+            return request
+        }
+
         public static func currentCourses(for channel: Channel) -> NSFetchRequest<Course> {
             let request = self.visibleCoursesRequest
             request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [

Common/Data/Helper/FetchRequests/CourseSectionHelper+FetchRequests.swift

@@ -36,6 +36,13 @@ extension CourseSectionHelper {
             return request
         }
 
+        public static func courseSection(withId id: String) -> NSFetchRequest<CourseSection> {
+            let request: NSFetchRequest<CourseSection> = CourseSection.fetchRequest()
+            request.predicate = NSPredicate(format: "id = %@", id)
+            request.fetchLimit = 1
+            return request
+        }
+
     }
 
 }

Common/Data/Helper/Sync/XikoloSyncEngine.swift

@@ -46,6 +46,55 @@ public struct XikoloNetworker: SyncNetworker {
 
 }
 
+public class XikoloBackgroundNetworker: NSObject, SyncNetworker, URLSessionDownloadDelegate {
+
+    public typealias CompletionHandler = (Data?, URLResponse?, Error?) -> Void
+
+    let sessionConfiguration: URLSessionConfiguration
+    var backgroundCompletionHandler: (() -> Void)
+    var completionHandlers: [URLSessionTask: CompletionHandler] = [:]
+
+    var session: URLSession!
+
+    public init(withIdentifier identifier: String, saveBattery: Bool = false, backgroundCompletionHandler: @escaping (() -> Void)) {
+        self.sessionConfiguration = URLSessionConfiguration.background(withIdentifier: identifier)
+
+        if saveBattery {
+            self.sessionConfiguration.waitsForConnectivity = true
+            if #available(iOS 13, *) {
+                self.sessionConfiguration.allowsConstrainedNetworkAccess = false
+                self.sessionConfiguration.allowsExpensiveNetworkAccess = false
+            }
+        }
+
+        self.backgroundCompletionHandler = backgroundCompletionHandler
+        super.init()
+        self.session = URLSession(configuration: sessionConfiguration, delegate: self, delegateQueue: nil)
+    }
+
+    public func perform(request: URLRequest, completionHandler: @escaping CompletionHandler) {
+        let task = self.session.downloadTask(with: request)
+        self.completionHandlers[task] = completionHandler
+        task.resume()
+    }
+
+    public func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
+        let completionHandler = self.completionHandlers.removeValue(forKey: task)
+        completionHandler?(nil, task.response, error)
+    }
+
+    public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
+        let completionHandler = self.completionHandlers.removeValue(forKey: downloadTask)
+        let data = try? Data(contentsOf: location)
+        completionHandler?(data, downloadTask.response, downloadTask.error)
+    }
+
+    public func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {
+        self.backgroundCompletionHandler()
+    }
+
+}
+
 public struct XikoloSyncEngine: SyncEngine {
 
     public static let persistentContainerQueue: OperationQueue = {
@@ -54,7 +103,7 @@ public struct XikoloSyncEngine: SyncEngine {
         return persistentContainerQueue
     }()
 
-    public let networker: XikoloNetworker
+    public let networker: SyncNetworker
 
     public let baseURL: URL = Routes.api
 
@@ -72,7 +121,7 @@ public struct XikoloSyncEngine: SyncEngine {
         return Self.persistentContainerQueue
     }()
 
-    public init(networker: XikoloNetworker = XikoloNetworker()) {
+    public init(networker: SyncNetworker = XikoloNetworker()) {
         self.networker = networker
     }
 

Common/Data/Helper/TrackingHelper.swift

@@ -45,6 +45,10 @@ public enum TrackingHelper {
 
         // social
         case shareCourse = "SHARE_COURSE"
+
+        // content notification
+        case contentNotificationsEnabled = "CONTENT_NOTIFICATIONS_ENABLED"
+        case contentNotificationsDisabled = "CONTENT_NOTIFICATIONS_DISABLED"
     }
 
     // swiftlint:disable redundant_string_enum_value