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| 1 | +import Foundation |
| 2 | +import BackgroundTasks |
| 3 | +import Combine |
| 4 | +import WordPressShared |
| 5 | + |
| 6 | +// This protocol is used to hide the `@available(iOS 26.0, *)` check. |
| 7 | +protocol MediaUploadBackgroundTracker { |
| 8 | + |
| 9 | + func track(progress: Progress, media: TaggedManagedObjectID<Media>) async |
| 10 | + |
| 11 | +} |
| 12 | + |
| 13 | +func mediaUploadBackgroundTracker() -> MediaUploadBackgroundTracker? { |
| 14 | + if #available(iOS 26.0, *) { |
| 15 | + ConcreteMediaUploadBackgroundTracker.shared |
| 16 | + } else { |
| 17 | + nil |
| 18 | + } |
| 19 | +} |
| 20 | + |
| 21 | +@available(iOS 26.0, *) |
| 22 | +/// Utilize `BGContinuedProcessingTask` to show the uploading media activity. |
| 23 | +private actor ConcreteMediaUploadBackgroundTracker: MediaUploadBackgroundTracker { |
| 24 | + struct Item { |
| 25 | + var media: TaggedManagedObjectID<Media> |
| 26 | + var progress: Progress |
| 27 | + } |
| 28 | + |
| 29 | + enum BGTaskState { |
| 30 | + struct Accepted { |
| 31 | + let task: BGContinuedProcessingTask |
| 32 | + var items = [Item]() |
| 33 | + var observers: [AnyCancellable] = [] |
| 34 | + |
| 35 | + init(task: BGContinuedProcessingTask) { |
| 36 | + self.task = task |
| 37 | + } |
| 38 | + } |
| 39 | + |
| 40 | + // No uploading. No `BGContinuedProcessingTask`. |
| 41 | + case idle |
| 42 | + // Waiting for the OS to response to the creating `BGContinuedProcessingTask` request. |
| 43 | + case pending([Item]) |
| 44 | + // OS has created a `BGContinuedProcessingTask` instance. |
| 45 | + case accepted(Accepted) |
| 46 | + } |
| 47 | + |
| 48 | + // Since this type works with `BGTaskScheduler.shared`, it only makes sense for the type to also be a singleton. |
| 49 | + static let shared = ConcreteMediaUploadBackgroundTracker() |
| 50 | + |
| 51 | + // We only use one `BGContinuedProcessingTask` for all uploads. When adding new media during uploading, the new ones |
| 52 | + // will be added to the existing task. |
| 53 | + private let taskId: String |
| 54 | + |
| 55 | + // State transtion: idle -> pending -> accepted -> [accepted...] -> idle. |
| 56 | + private var state: BGTaskState = .idle |
| 57 | + |
| 58 | + private init?() { |
| 59 | + let taskId = (Bundle.main.infoDictionary?["BGTaskSchedulerPermittedIdentifiers"] as? [String])?.first { |
| 60 | + $0.hasSuffix(".mediaUpload") |
| 61 | + } |
| 62 | + guard let taskId else { |
| 63 | + wpAssertionFailure("media upload task id not found in the Info.plist") |
| 64 | + return nil |
| 65 | + } |
| 66 | + |
| 67 | + self.taskId = taskId |
| 68 | + BGTaskScheduler.shared.register(forTaskWithIdentifier: self.taskId, using: nil) { [weak self] task in |
| 69 | + guard let task = task as? BGContinuedProcessingTask else { |
| 70 | + wpAssertionFailure("Unexpected task instance") |
| 71 | + return |
| 72 | + } |
| 73 | + |
| 74 | + Task { |
| 75 | + await self?.taskCreated(task) |
| 76 | + } |
| 77 | + } |
| 78 | + } |
| 79 | + |
| 80 | + func track(progress: Progress, media: TaggedManagedObjectID<Media>) async { |
| 81 | + let item = Item(media: media, progress: progress) |
| 82 | + switch state { |
| 83 | + case .idle: |
| 84 | + state = .pending([item]) |
| 85 | + |
| 86 | + let request = BGContinuedProcessingTaskRequest(identifier: taskId, title: Strings.uploadingMediaTitle, subtitle: "") |
| 87 | + request.strategy = .queue |
| 88 | + do { |
| 89 | + try BGTaskScheduler.shared.submit(request) |
| 90 | + } catch { |
| 91 | + DDLogError("Failed to submit a background task: \(error)") |
| 92 | + } |
| 93 | + case var .pending(items): |
| 94 | + items.removeAll { |
| 95 | + $0.media == media |
| 96 | + } |
| 97 | + items.append(item) |
| 98 | + self.state = .pending(items) |
| 99 | + case var .accepted(accepted): |
| 100 | + observe(item, accepted: &accepted) |
| 101 | + self.state = .accepted(accepted) |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + private func taskCreated(_ task: BGContinuedProcessingTask) { |
| 106 | + task.progress.totalUnitCount = 100 |
| 107 | + task.expirationHandler = { [weak self] in |
| 108 | + Task { |
| 109 | + await self?.setTaskCompleted(success: false) |
| 110 | + } |
| 111 | + } |
| 112 | + |
| 113 | + var accepted = BGTaskState.Accepted(task: task) |
| 114 | + switch state { |
| 115 | + case .idle, .accepted: |
| 116 | + wpAssertionFailure("Unexpected background task state") |
| 117 | + case let .pending(items): |
| 118 | + for item in items { |
| 119 | + observe(item, accepted: &accepted) |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + self.state = .accepted(accepted) |
| 124 | + } |
| 125 | + |
| 126 | + private func observe(_ item: Item, accepted: inout BGTaskState.Accepted) { |
| 127 | + accepted.items.append(item) |
| 128 | + |
| 129 | + let progress = item.progress.publisher(for: \.fractionCompleted).sink { [weak self] _ in |
| 130 | + Task { |
| 131 | + await self?.handleProgressUpdates() |
| 132 | + } |
| 133 | + } |
| 134 | + accepted.observers.append(progress) |
| 135 | + |
| 136 | + Task { @MainActor in |
| 137 | + guard let media = try? ContextManager.shared.mainContext.existingObject(with: item.media) else { return } |
| 138 | + |
| 139 | + let completion = media.publisher(for: \.remoteStatusNumber).sink { [weak self] _ in |
| 140 | + Task { |
| 141 | + await self?.handleStatusUpdates() |
| 142 | + } |
| 143 | + } |
| 144 | + await self.addObserver(completion) |
| 145 | + } |
| 146 | + } |
| 147 | + |
| 148 | + private func addObserver(_ cancellable: AnyCancellable) { |
| 149 | + guard case var .accepted(accepted) = state else { return } |
| 150 | + accepted.observers.append(cancellable) |
| 151 | + self.state = .accepted(accepted) |
| 152 | + } |
| 153 | + |
| 154 | + private func handleProgressUpdates() { |
| 155 | + guard case let .accepted(accepted) = state else { return } |
| 156 | + |
| 157 | + let fractionCompleted = accepted.items.map(\.progress.fractionCompleted).reduce(0, +) / Double(accepted.items.count) |
| 158 | + accepted.task.progress.completedUnitCount = Int64(fractionCompleted * Double(accepted.task.progress.totalUnitCount)) |
| 159 | + } |
| 160 | + |
| 161 | + private func handleStatusUpdates() async { |
| 162 | + await updateMessaging() |
| 163 | + await updateResult() |
| 164 | + } |
| 165 | + |
| 166 | + @MainActor |
| 167 | + private func updateMessaging() async { |
| 168 | + guard case let .accepted(accepted) = await self.state else { return } |
| 169 | + |
| 170 | + let context = ContextManager.shared.mainContext |
| 171 | + let mediaItems = accepted.items.compactMap { try? context.existingObject(with: $0.media) } |
| 172 | + |
| 173 | + let failed = mediaItems.count { $0.remoteStatus == .failed } |
| 174 | + let success = mediaItems.count { $0.remoteStatus == .sync } |
| 175 | + let total = mediaItems.count |
| 176 | + |
| 177 | + var subtitle = [String]() |
| 178 | + if total - success - failed > 0 { |
| 179 | + subtitle.append(String.localizedStringWithFormat(Strings.uploadingStatus, total - success - failed)) |
| 180 | + } |
| 181 | + if success > 0 { |
| 182 | + subtitle.append(String.localizedStringWithFormat(Strings.successStatus, success)) |
| 183 | + } |
| 184 | + if failed > 0 { |
| 185 | + subtitle.append(String.localizedStringWithFormat(Strings.failedStatus, failed)) |
| 186 | + } |
| 187 | + |
| 188 | + accepted.task.updateTitle(Strings.uploadingMediaTitle, subtitle: ListFormatter.localizedString(byJoining: subtitle)) |
| 189 | + } |
| 190 | + |
| 191 | + @MainActor |
| 192 | + private func updateResult() async { |
| 193 | + guard case let .accepted(accepted) = await self.state else { return } |
| 194 | + |
| 195 | + let context = ContextManager.shared.mainContext |
| 196 | + let mediaItems = accepted.items.compactMap { try? context.existingObject(with: $0.media) } |
| 197 | + |
| 198 | + let completed = mediaItems.allSatisfy { $0.remoteStatus == .sync || $0.remoteStatus == .failed } |
| 199 | + guard completed else { |
| 200 | + return |
| 201 | + } |
| 202 | + |
| 203 | + let success = mediaItems.allSatisfy { $0.remoteStatus == .sync } |
| 204 | + await setTaskCompleted(success: success) |
| 205 | + } |
| 206 | + |
| 207 | + private func setTaskCompleted(success: Bool) { |
| 208 | + guard case let .accepted(accepted) = self.state else { return } |
| 209 | + DDLogInfo("BGTask completed with success? \(success)") |
| 210 | + |
| 211 | + accepted.task.setTaskCompleted(success: success) |
| 212 | + self.state = .idle |
| 213 | + } |
| 214 | +} |
| 215 | + |
| 216 | +private enum Strings { |
| 217 | + static let uploadingMediaTitle = NSLocalizedString( |
| 218 | + "BGTask.mediaUpload.title", |
| 219 | + value: "Uploading media", |
| 220 | + comment: "Title shown in background task when uploading media files" |
| 221 | + ) |
| 222 | + |
| 223 | + static let uploadingStatus = NSLocalizedString( |
| 224 | + "BGTask.mediaUpload.uploading", |
| 225 | + value: "%1$d uploading", |
| 226 | + comment: "Status message showing number of files currently uploading. %1$d is the count of uploading files." |
| 227 | + ) |
| 228 | + |
| 229 | + static let successStatus = NSLocalizedString( |
| 230 | + "BGTask.mediaUpload.successful", |
| 231 | + value: "%1$d successful", |
| 232 | + comment: "Status message showing number of files uploaded successfully. %1$d is the count of successful uploads." |
| 233 | + ) |
| 234 | + |
| 235 | + static let failedStatus = NSLocalizedString( |
| 236 | + "BGTask.mediaUpload.failed", |
| 237 | + value: "%1$d failed", |
| 238 | + comment: "Status message showing number of files that failed to upload. %1$d is the count of failed uploads." |
| 239 | + ) |
| 240 | +} |
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