Initial commit

lib/features/downloader/domain/entities/download_exceptions.dart

@@ -0,0 +1,24 @@
+sealed class DownloadException implements Exception {
+  final String message;
+
+  const DownloadException(this.message);
+
+  @override
+  String toString() => '$runtimeType: $message';
+}
+
+final class NetworkException extends DownloadException {
+  const NetworkException(super.message);
+}
+
+final class RemoteException extends DownloadException {
+  const RemoteException(super.message);
+}
+
+final class IoException extends DownloadException {
+  const IoException(super.message);
+}
+
+final class CancelledException extends DownloadException {
+  const CancelledException() : super('Cancelled');
+}

lib/features/downloader/domain/entities/download_progress.dart

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+/// Represents the state of a download.
+final class DownloadProgress {
+  /// Download speed in bytes per second.
+  final int speed;
+
+  /// Total bytes downloaded so far.
+  final int downloaded;
+
+  /// Total bytes to download.
+  final int total;
+
+  /// Estimated time of arrival (ETA) for the download to complete.
+  final Duration eta;
+
+  const DownloadProgress({
+    required this.speed,
+    required this.downloaded,
+    required this.total,
+    required this.eta,
+  });
+
+  const DownloadProgress.initial()
+    : speed = 0,
+      downloaded = 0,
+      total = 0,
+      eta = Duration.zero;
+}

lib/features/downloader/domain/entities/download_request.dart

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+/// Represents a request to download an object from a storage bucket.
+class DownloadRequest {
+  /// Local file path to save the downloaded object
+  final String destinationPath;
+
+  const DownloadRequest({required this.destinationPath});
+}

lib/features/downloader/domain/entities/download_result.dart

@@ -0,0 +1,17 @@
+/// Represents the result of a download operation.
+class DownloadResult {
+  /// Local file path where the downloaded object is stored.
+  final String path;
+
+  /// Number of bytes downloaded.
+  final int bytes;
+
+  /// Entity tag (ETag) of the downloaded object.
+  final String eTag;
+
+  const DownloadResult({
+    required this.path,
+    required this.bytes,
+    required this.eTag,
+  });
+}

lib/features/downloader/domain/entities/remote_object_meta.dart

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+/// Represents metadata for a remote object in a storage bucket.
+class RemoteObjectMeta {
+  /// Size of the object in bytes.
+  final int size;
+
+  /// Entity tag (ETag) of the object.
+  final String eTag;
+
+  const RemoteObjectMeta({required this.size, required this.eTag});
+}

lib/features/downloader/domain/repositories/file_system.dart

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+import 'dart:async';
+
+/// Interface for interacting with the file system.
+abstract interface class FileSystem {
+  /// Ensures that the parent directory of the given path exists.
+  Future<void> ensureParentExists(String path);
+
+  /// Checks if a file or directory exists at the given path.
+  Future<bool> exists(String path);
+
+  /// Returns the size of the file at the given path.
+  Future<int> sizeOf(String path);
+
+  /// Truncates the file at the given path to zero length.
+  Future<void> truncate(String path);
+
+  /// Creates an empty file at the given path.
+  Future<void> createEmpty(String path);
+
+  /// Opens a stream sink for appending data to the file at the given path.
+  Future<StreamSink<List<int>>> openAppend(String path);
+
+  /// Verifies the integrity of a file at the given path.
+  Future<bool> verifyFile(
+    String path, {
+    required String expected,
+    required String algo,
+  });
+}

lib/features/downloader/domain/repositories/storage_reader.dart

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+import 'package:moonwell_launcher/features/downloader/domain/entities/remote_object_meta.dart';
+
+/// Interface for reading data from storage.
+abstract interface class StorageReader {
+  /// Retrieves metadata about a remote object.
+  Future<RemoteObjectMeta> stat({required String bucket, required String key});
+
+  /// Reads data from a remote object starting at the specified offset.
+  Future<Stream<List<int>>> readFromOffset({
+    required String bucket,
+    required String key,
+    required int startOffset,
+  });
+}