wip: bg downloader module

modules/background-downloader/README.md

@@ -0,0 +1,235 @@
+# Background Downloader Module
+
+A native iOS module for downloading large files in the background using `NSURLSession` with background configuration.
+
+## Features
+
+- **Background Downloads**: Downloads continue even when the app is backgrounded or suspended
+- **Progress Tracking**: Real-time progress updates via events
+- **Multiple Downloads**: Support for concurrent downloads
+- **Cancellation**: Cancel individual or all downloads
+- **Custom Destination**: Optionally specify custom file paths
+- **Error Handling**: Comprehensive error reporting
+
+## Usage
+
+### Basic Example
+
+```typescript
+import { BackgroundDownloader } from '@/modules';
+
+// Start a download
+const taskId = await BackgroundDownloader.startDownload(
+  'https://example.com/largefile.mp4'
+);
+
+// Listen for progress updates
+const progressSub = BackgroundDownloader.addProgressListener((event) => {
+  console.log(`Progress: ${Math.floor(event.progress * 100)}%`);
+  console.log(`Downloaded: ${event.bytesWritten} / ${event.totalBytes}`);
+});
+
+// Listen for completion
+const completeSub = BackgroundDownloader.addCompleteListener((event) => {
+  console.log('Download complete!');
+  console.log('File saved to:', event.filePath);
+  console.log('Task ID:', event.taskId);
+});
+
+// Listen for errors
+const errorSub = BackgroundDownloader.addErrorListener((event) => {
+  console.error('Download failed:', event.error);
+});
+
+// Cancel a download
+BackgroundDownloader.cancelDownload(taskId);
+
+// Get all active downloads
+const activeDownloads = await BackgroundDownloader.getActiveDownloads();
+
+// Cleanup listeners when done
+progressSub.remove();
+completeSub.remove();
+errorSub.remove();
+```
+
+### Custom Destination Path
+
+```typescript
+import { BackgroundDownloader } from '@/modules';
+import * as FileSystem from 'expo-file-system';
+
+const destinationPath = `${FileSystem.documentDirectory}myfile.mp4`;
+const taskId = await BackgroundDownloader.startDownload(
+  'https://example.com/video.mp4',
+  destinationPath
+);
+```
+
+### Managing Multiple Downloads
+
+```typescript
+import { BackgroundDownloader } from '@/modules';
+
+const downloads = new Map();
+
+async function startMultipleDownloads(urls: string[]) {
+  for (const url of urls) {
+    const taskId = await BackgroundDownloader.startDownload(url);
+    downloads.set(taskId, { url, progress: 0 });
+  }
+}
+
+// Track progress for each download
+const progressSub = BackgroundDownloader.addProgressListener((event) => {
+  const download = downloads.get(event.taskId);
+  if (download) {
+    download.progress = event.progress;
+  }
+});
+
+// Cancel all downloads
+BackgroundDownloader.cancelAllDownloads();
+```
+
+## API Reference
+
+### Methods
+
+#### `startDownload(url: string, destinationPath?: string): Promise<number>`
+
+Starts a new background download.
+
+- **Parameters:**
+  - `url`: The URL of the file to download
+  - `destinationPath`: (Optional) Custom file path for the downloaded file
+- **Returns:** Promise that resolves to the task ID (number)
+
+#### `cancelDownload(taskId: number): void`
+
+Cancels a specific download by task ID.
+
+- **Parameters:**
+  - `taskId`: The task ID returned by `startDownload`
+
+#### `cancelAllDownloads(): void`
+
+Cancels all active downloads.
+
+#### `getActiveDownloads(): Promise<ActiveDownload[]>`
+
+Gets information about all active downloads.
+
+- **Returns:** Promise that resolves to an array of active downloads
+
+### Event Listeners
+
+#### `addProgressListener(listener: (event: DownloadProgressEvent) => void): Subscription`
+
+Listens for download progress updates.
+
+- **Event payload:**
+  - `taskId`: number
+  - `bytesWritten`: number
+  - `totalBytes`: number
+  - `progress`: number (0.0 to 1.0)
+
+#### `addCompleteListener(listener: (event: DownloadCompleteEvent) => void): Subscription`
+
+Listens for download completion.
+
+- **Event payload:**
+  - `taskId`: number
+  - `filePath`: string
+  - `url`: string
+
+#### `addErrorListener(listener: (event: DownloadErrorEvent) => void): Subscription`
+
+Listens for download errors.
+
+- **Event payload:**
+  - `taskId`: number
+  - `error`: string
+
+#### `addStartedListener(listener: (event: DownloadStartedEvent) => void): Subscription`
+
+Listens for download start confirmation.
+
+- **Event payload:**
+  - `taskId`: number
+  - `url`: string
+
+## Types
+
+```typescript
+interface DownloadProgressEvent {
+  taskId: number;
+  bytesWritten: number;
+  totalBytes: number;
+  progress: number;
+}
+
+interface DownloadCompleteEvent {
+  taskId: number;
+  filePath: string;
+  url: string;
+}
+
+interface DownloadErrorEvent {
+  taskId: number;
+  error: string;
+}
+
+interface DownloadStartedEvent {
+  taskId: number;
+  url: string;
+}
+
+interface ActiveDownload {
+  taskId: number;
+  url: string;
+  state: 'running' | 'suspended' | 'canceling' | 'completed' | 'unknown';
+}
+```
+
+## Implementation Details
+
+### iOS Background Downloads
+
+- Uses `NSURLSession` with background configuration
+- Session identifier: `com.fredrikburmester.streamyfin.backgrounddownloader`
+- Downloads continue when app is backgrounded or suspended
+- System may terminate downloads if app is force-quit
+
+### Background Modes
+
+The app's `Info.plist` already includes the required background mode:
+
+- `UIBackgroundModes`: `["audio", "fetch"]`
+
+### File Storage
+
+By default, downloaded files are saved to the app's Documents directory. You can specify a custom path using the `destinationPath` parameter.
+
+## Building
+
+After adding this module, rebuild the iOS app:
+
+```bash
+npx expo prebuild -p ios
+npx expo run:ios
+```
+
+Or install pods manually:
+
+```bash
+cd ios
+pod install
+cd ..
+```
+
+## Notes
+
+- Background downloads may be cancelled if the user force-quits the app
+- The OS manages download priority and may pause downloads to save battery
+- Downloads over cellular can be disabled in the module configuration if needed

modules/background-downloader/example.ts

@@ -0,0 +1,98 @@
+import type {
+  DownloadCompleteEvent,
+  DownloadErrorEvent,
+  DownloadProgressEvent,
+} from "@/modules";
+import { BackgroundDownloader } from "@/modules";
+
+export class DownloadManager {
+  private progressSubscription: any;
+  private completeSubscription: any;
+  private errorSubscription: any;
+  private activeDownloads = new Map<
+    number,
+    { url: string; progress: number }
+  >();
+
+  constructor() {
+    this.setupListeners();
+  }
+
+  private setupListeners() {
+    this.progressSubscription = BackgroundDownloader.addProgressListener(
+      (event: DownloadProgressEvent) => {
+        const download = this.activeDownloads.get(event.taskId);
+        if (download) {
+          download.progress = event.progress;
+          console.log(
+            `Download ${event.taskId}: ${Math.floor(event.progress * 100)}%`,
+          );
+        }
+      },
+    );
+
+    this.completeSubscription = BackgroundDownloader.addCompleteListener(
+      (event: DownloadCompleteEvent) => {
+        console.log("Download complete:", event.filePath);
+        this.activeDownloads.delete(event.taskId);
+      },
+    );
+
+    this.errorSubscription = BackgroundDownloader.addErrorListener(
+      (event: DownloadErrorEvent) => {
+        console.error("Download error:", event.error);
+        this.activeDownloads.delete(event.taskId);
+      },
+    );
+  }
+
+  async startDownload(url: string, destinationPath?: string): Promise<number> {
+    const taskId = await BackgroundDownloader.startDownload(
+      url,
+      destinationPath,
+    );
+    this.activeDownloads.set(taskId, { url, progress: 0 });
+    return taskId;
+  }
+
+  cancelDownload(taskId: number): void {
+    BackgroundDownloader.cancelDownload(taskId);
+    this.activeDownloads.delete(taskId);
+  }
+
+  cancelAllDownloads(): void {
+    BackgroundDownloader.cancelAllDownloads();
+    this.activeDownloads.clear();
+  }
+
+  async getActiveDownloads() {
+    return await BackgroundDownloader.getActiveDownloads();
+  }
+
+  cleanup(): void {
+    this.progressSubscription?.remove();
+    this.completeSubscription?.remove();
+    this.errorSubscription?.remove();
+  }
+}
+
+const downloadManager = new DownloadManager();
+
+export async function downloadFile(
+  url: string,
+  destinationPath?: string,
+): Promise<number> {
+  return await downloadManager.startDownload(url, destinationPath);
+}
+
+export function cancelDownload(taskId: number): void {
+  downloadManager.cancelDownload(taskId);
+}
+
+export function cancelAllDownloads(): void {
+  downloadManager.cancelAllDownloads();
+}
+
+export async function getActiveDownloads() {
+  return await downloadManager.getActiveDownloads();
+}

modules/background-downloader/expo-module.config.json

@@ -0,0 +1,8 @@
+{
+  "name": "background-downloader",
+  "version": "1.0.0",
+  "platforms": ["ios"],
+  "ios": {
+    "appDelegateSubscribers": ["BackgroundDownloaderAppDelegate"]
+  }
+}

modules/background-downloader/index.ts

@@ -0,0 +1,84 @@
+import { EventEmitter, type Subscription } from "expo-modules-core";
+import type {
+  ActiveDownload,
+  DownloadCompleteEvent,
+  DownloadErrorEvent,
+  DownloadProgressEvent,
+  DownloadStartedEvent,
+} from "./src/BackgroundDownloader.types";
+import BackgroundDownloaderModule from "./src/BackgroundDownloaderModule";
+
+const emitter = new EventEmitter(BackgroundDownloaderModule);
+
+export interface BackgroundDownloader {
+  startDownload(url: string, destinationPath?: string): Promise<number>;
+  cancelDownload(taskId: number): void;
+  cancelAllDownloads(): void;
+  getActiveDownloads(): Promise<ActiveDownload[]>;
+
+  addProgressListener(
+    listener: (event: DownloadProgressEvent) => void,
+  ): Subscription;
+
+  addCompleteListener(
+    listener: (event: DownloadCompleteEvent) => void,
+  ): Subscription;
+
+  addErrorListener(listener: (event: DownloadErrorEvent) => void): Subscription;
+
+  addStartedListener(
+    listener: (event: DownloadStartedEvent) => void,
+  ): Subscription;
+}
+
+const BackgroundDownloader: BackgroundDownloader = {
+  async startDownload(url: string, destinationPath?: string): Promise<number> {
+    return await BackgroundDownloaderModule.startDownload(url, destinationPath);
+  },
+
+  cancelDownload(taskId: number): void {
+    BackgroundDownloaderModule.cancelDownload(taskId);
+  },
+
+  cancelAllDownloads(): void {
+    BackgroundDownloaderModule.cancelAllDownloads();
+  },
+
+  async getActiveDownloads(): Promise<ActiveDownload[]> {
+    return await BackgroundDownloaderModule.getActiveDownloads();
+  },
+
+  addProgressListener(
+    listener: (event: DownloadProgressEvent) => void,
+  ): Subscription {
+    return emitter.addListener("onDownloadProgress", listener);
+  },
+
+  addCompleteListener(
+    listener: (event: DownloadCompleteEvent) => void,
+  ): Subscription {
+    return emitter.addListener("onDownloadComplete", listener);
+  },
+
+  addErrorListener(
+    listener: (event: DownloadErrorEvent) => void,
+  ): Subscription {
+    return emitter.addListener("onDownloadError", listener);
+  },
+
+  addStartedListener(
+    listener: (event: DownloadStartedEvent) => void,
+  ): Subscription {
+    return emitter.addListener("onDownloadStarted", listener);
+  },
+};
+
+export default BackgroundDownloader;
+
+export type {
+  DownloadProgressEvent,
+  DownloadCompleteEvent,
+  DownloadErrorEvent,
+  DownloadStartedEvent,
+  ActiveDownload,
+};

modules/background-downloader/ios/BackgroundDownloader.podspec

@@ -0,0 +1,21 @@
+Pod::Spec.new do |s|
+  s.name           = 'BackgroundDownloader'
+  s.version        = '1.0.0'
+  s.summary        = 'Background file downloader for iOS'
+  s.description    = 'Native iOS module for downloading large files in the background using NSURLSession'
+  s.author         = ''
+  s.homepage       = 'https://docs.expo.dev/modules/'
+  s.platforms      = { :ios => '15.6', :tvos => '15.0' }
+  s.source         = { git: '' }
+  s.static_framework = true
+
+  s.dependency 'ExpoModulesCore'
+
+  s.pod_target_xcconfig = {
+    'DEFINES_MODULE' => 'YES',
+    'SWIFT_COMPILATION_MODE' => 'wholemodule'
+  }
+
+  s.source_files = "**/*.{h,m,mm,swift,hpp,cpp}"
+end
+

modules/background-downloader/ios/BackgroundDownloaderAppDelegate.swift

@@ -0,0 +1,15 @@
+import ExpoModulesCore
+import UIKit
+
+public class BackgroundDownloaderAppDelegate: ExpoAppDelegateSubscriber {
+  public func application(
+    _ application: UIApplication,
+    handleEventsForBackgroundURLSession identifier: String,
+    completionHandler: @escaping () -> Void
+  ) {
+    if identifier == "com.fredrikburmester.streamyfin.backgrounddownloader" {
+      BackgroundDownloaderModule.setBackgroundCompletionHandler(completionHandler)
+    }
+  }
+}
+

modules/background-downloader/ios/BackgroundDownloaderModule.swift

@@ -0,0 +1,247 @@
+import ExpoModulesCore
+import Foundation
+
+enum DownloadError: Error {
+  case invalidURL
+  case fileOperationFailed
+  case downloadFailed
+}
+
+public class BackgroundDownloaderModule: Module, URLSessionDownloadDelegate {
+  private var session: URLSession?
+  private static var backgroundCompletionHandler: (() -> Void)?
+  private var downloadTasks: [Int: DownloadTaskInfo] = [:]
+  
+  struct DownloadTaskInfo {
+    let url: String
+    let destinationPath: String?
+  }
+  
+  public func definition() -> ModuleDefinition {
+    Name("BackgroundDownloader")
+    
+    Events(
+      "onDownloadProgress",
+      "onDownloadComplete",
+      "onDownloadError",
+      "onDownloadStarted"
+    )
+    
+    OnCreate {
+      self.initializeSession()
+    }
+    
+    AsyncFunction("startDownload") { (urlString: String, destinationPath: String?) -> Int in
+      guard let url = URL(string: urlString) else {
+        throw DownloadError.invalidURL
+      }
+      
+      if self.session == nil {
+        self.initializeSession()
+      }
+      
+      guard let session = self.session else {
+        throw DownloadError.downloadFailed
+      }
+      
+      let task = session.downloadTask(with: url)
+      let taskId = task.taskIdentifier
+      
+      self.downloadTasks[taskId] = DownloadTaskInfo(
+        url: urlString,
+        destinationPath: destinationPath
+      )
+      
+      task.resume()
+      
+      self.sendEvent("onDownloadStarted", [
+        "taskId": taskId,
+        "url": urlString
+      ])
+      
+      return taskId
+    }
+    
+    Function("cancelDownload") { (taskId: Int) in
+      self.session?.getAllTasks { tasks in
+        for task in tasks where task.taskIdentifier == taskId {
+          task.cancel()
+          self.downloadTasks.removeValue(forKey: taskId)
+        }
+      }
+    }
+    
+    Function("cancelAllDownloads") {
+      self.session?.getAllTasks { tasks in
+        for task in tasks {
+          task.cancel()
+        }
+        self.downloadTasks.removeAll()
+      }
+    }
+    
+    AsyncFunction("getActiveDownloads") { () -> [[String: Any]] in
+      return try await withCheckedThrowingContinuation { continuation in
+        self.session?.getAllTasks { tasks in
+          let activeDownloads = tasks.compactMap { task -> [String: Any]? in
+            guard let downloadTask = task as? URLSessionDownloadTask,
+                  let info = self.downloadTasks[task.taskIdentifier] else {
+              return nil
+            }
+            
+            return [
+              "taskId": task.taskIdentifier,
+              "url": info.url,
+              "state": self.taskStateString(task.state)
+            ]
+          }
+          continuation.resume(returning: activeDownloads)
+        }
+      }
+    }
+  }
+  
+  private func initializeSession() {
+    let config = URLSessionConfiguration.background(
+      withIdentifier: "com.fredrikburmester.streamyfin.backgrounddownloader"
+    )
+    config.allowsCellularAccess = true
+    config.sessionSendsLaunchEvents = true
+    config.isDiscretionary = false
+    
+    self.session = URLSession(
+      configuration: config,
+      delegate: self,
+      delegateQueue: nil
+    )
+  }
+  
+  private func taskStateString(_ state: URLSessionTask.State) -> String {
+    switch state {
+    case .running:
+      return "running"
+    case .suspended:
+      return "suspended"
+    case .canceling:
+      return "canceling"
+    case .completed:
+      return "completed"
+    @unknown default:
+      return "unknown"
+    }
+  }
+  
+  public func urlSession(
+    _ session: URLSession,
+    downloadTask: URLSessionDownloadTask,
+    didWriteData bytesWritten: Int64,
+    totalBytesWritten: Int64,
+    totalBytesExpectedToWrite: Int64
+  ) {
+    let progress = totalBytesExpectedToWrite > 0
+      ? Double(totalBytesWritten) / Double(totalBytesExpectedToWrite)
+      : 0.0
+    
+    self.sendEvent("onDownloadProgress", [
+      "taskId": downloadTask.taskIdentifier,
+      "bytesWritten": totalBytesWritten,
+      "totalBytes": totalBytesExpectedToWrite,
+      "progress": progress
+    ])
+  }
+  
+  public func urlSession(
+    _ session: URLSession,
+    downloadTask: URLSessionDownloadTask,
+    didFinishDownloadingTo location: URL
+  ) {
+    let taskId = downloadTask.taskIdentifier
+    guard let taskInfo = downloadTasks[taskId] else {
+      self.sendEvent("onDownloadError", [
+        "taskId": taskId,
+        "error": "Download task info not found"
+      ])
+      return
+    }
+    
+    let fileManager = FileManager.default
+    
+    do {
+      let destinationURL: URL
+      
+      if let customPath = taskInfo.destinationPath {
+        destinationURL = URL(fileURLWithPath: customPath)
+      } else {
+        let documentsDir = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first!
+        let filename = downloadTask.response?.suggestedFilename
+          ?? downloadTask.originalRequest?.url?.lastPathComponent
+          ?? "download_\(taskId)"
+        destinationURL = documentsDir.appendingPathComponent(filename)
+      }
+      
+      if fileManager.fileExists(atPath: destinationURL.path) {
+        try fileManager.removeItem(at: destinationURL)
+      }
+      
+      let destinationDirectory = destinationURL.deletingLastPathComponent()
+      if !fileManager.fileExists(atPath: destinationDirectory.path) {
+        try fileManager.createDirectory(
+          at: destinationDirectory,
+          withIntermediateDirectories: true,
+          attributes: nil
+        )
+      }
+      
+      try fileManager.moveItem(at: location, to: destinationURL)
+      
+      self.sendEvent("onDownloadComplete", [
+        "taskId": taskId,
+        "filePath": destinationURL.path,
+        "url": taskInfo.url
+      ])
+      
+      downloadTasks.removeValue(forKey: taskId)
+      
+    } catch {
+      self.sendEvent("onDownloadError", [
+        "taskId": taskId,
+        "error": "File operation failed: \(error.localizedDescription)"
+      ])
+    }
+  }
+  
+  public func urlSession(
+    _ session: URLSession,
+    task: URLSessionTask,
+    didCompleteWithError error: Error?
+  ) {
+    if let error = error {
+      let taskId = task.taskIdentifier
+      
+      let isCancelled = (error as NSError).code == NSURLErrorCancelled
+      
+      if !isCancelled {
+        self.sendEvent("onDownloadError", [
+          "taskId": taskId,
+          "error": error.localizedDescription
+        ])
+      }
+      
+      downloadTasks.removeValue(forKey: taskId)
+    }
+  }
+  
+  public func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {
+    DispatchQueue.main.async {
+      if let completion = BackgroundDownloaderModule.backgroundCompletionHandler {
+        completion()
+        BackgroundDownloaderModule.backgroundCompletionHandler = nil
+      }
+    }
+  }
+  
+  static func setBackgroundCompletionHandler(_ handler: @escaping () -> Void) {
+    BackgroundDownloaderModule.backgroundCompletionHandler = handler
+  }
+}
+

modules/background-downloader/src/BackgroundDownloader.types.ts

@@ -0,0 +1,35 @@
+export interface DownloadProgressEvent {
+  taskId: number;
+  bytesWritten: number;
+  totalBytes: number;
+  progress: number;
+}
+
+export interface DownloadCompleteEvent {
+  taskId: number;
+  filePath: string;
+  url: string;
+}
+
+export interface DownloadErrorEvent {
+  taskId: number;
+  error: string;
+}
+
+export interface DownloadStartedEvent {
+  taskId: number;
+  url: string;
+}
+
+export interface ActiveDownload {
+  taskId: number;
+  url: string;
+  state: "running" | "suspended" | "canceling" | "completed" | "unknown";
+}
+
+export interface BackgroundDownloaderModuleType {
+  startDownload(url: string, destinationPath?: string): Promise<number>;
+  cancelDownload(taskId: number): void;
+  cancelAllDownloads(): void;
+  getActiveDownloads(): Promise<ActiveDownload[]>;
+}

modules/background-downloader/src/BackgroundDownloaderModule.ts

@@ -0,0 +1,7 @@
+import { requireNativeModule } from "expo-modules-core";
+import type { BackgroundDownloaderModuleType } from "./BackgroundDownloader.types";
+
+const BackgroundDownloaderModule: BackgroundDownloaderModuleType =
+  requireNativeModule("BackgroundDownloader");
+
+export default BackgroundDownloaderModule;

modules/index.ts

@@ -1,3 +1,11 @@
+import type {
+  ActiveDownload,
+  DownloadCompleteEvent,
+  DownloadErrorEvent,
+  DownloadProgressEvent,
+  DownloadStartedEvent,
+} from "./background-downloader";
+import BackgroundDownloader from "./background-downloader";
 import {
   ChapterInfo,
   PlaybackStatePayload,
@@ -12,8 +20,8 @@ import {
 } from "./VlcPlayer.types";
 import VlcPlayerView from "./VlcPlayerView";
 
-export {
+export { VlcPlayerView, BackgroundDownloader };
-  VlcPlayerView,
+export type {
   VlcPlayerViewProps,
   VlcPlayerViewRef,
   PlaybackStatePayload,
@@ -24,4 +32,9 @@ export {
   VlcPlayerSource,
   TrackInfo,
   ChapterInfo,
+  DownloadProgressEvent,
+  DownloadCompleteEvent,
+  DownloadErrorEvent,
+  DownloadStartedEvent,
+  ActiveDownload,
 };