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https://github.com/venera-app/venera.git
synced 2025-09-27 15:57:25 +00:00
add archive download
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298
lib/network/file_downloader.dart
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298
lib/network/file_downloader.dart
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@@ -0,0 +1,298 @@
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import 'dart:async';
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import 'dart:io';
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import 'package:dio/io.dart';
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import 'package:venera/network/app_dio.dart';
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import 'package:venera/utils/ext.dart';
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class FileDownloader {
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final String url;
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final String savePath;
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final int maxConcurrent;
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FileDownloader(this.url, this.savePath, {this.maxConcurrent = 4});
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int _currentBytes = 0;
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int _lastBytes = 0;
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late int _fileSize;
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final _dio = Dio();
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RandomAccessFile? _file;
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bool _isWriting = false;
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int _kChunkSize = 16 * 1024 * 1024;
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bool _canceled = false;
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late List<_DownloadBlock> _blocks;
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Future<void> _writeStatus() async {
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var file = File("$savePath.download");
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await file.writeAsString(_blocks.map((e) => e.toString()).join("\n"));
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}
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Future<void> _readStatus() async {
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var file = File("$savePath.download");
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if (!await file.exists()) {
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return;
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}
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var lines = await file.readAsLines();
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_blocks = lines.map((e) => _DownloadBlock.fromString(e)).toList();
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}
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/// create file and write empty bytes
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Future<void> _prepareFile() async {
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var file = File(savePath);
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if (await file.exists()) {
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if (file.lengthSync() == _fileSize &&
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File("$savePath.download").existsSync()) {
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_file = await file.open(mode: FileMode.append);
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return;
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} else {
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await file.delete();
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}
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}
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await file.create(recursive: true);
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_file = await file.open(mode: FileMode.append);
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await _file!.truncate(_fileSize);
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}
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Future<void> _createTasks() async {
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var res = await _dio.head(url);
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var length = res.headers["content-length"]?.first;
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_fileSize = length == null ? 0 : int.parse(length);
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await _prepareFile();
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if (File("$savePath.download").existsSync()) {
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await _readStatus();
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_currentBytes = _blocks.fold<int>(0,
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(previousValue, element) => previousValue + element.downloadedBytes);
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} else {
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if (_fileSize > 1024 * 1024 * 1024) {
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_kChunkSize = 64 * 1024 * 1024;
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} else if (_fileSize > 512 * 1024 * 1024) {
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_kChunkSize = 32 * 1024 * 1024;
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}
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_blocks = [];
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for (var i = 0; i < _fileSize; i += _kChunkSize) {
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var end = i + _kChunkSize;
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if (end > _fileSize) {
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_blocks.add(_DownloadBlock(i, _fileSize, 0, false));
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} else {
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_blocks.add(_DownloadBlock(i, i + _kChunkSize, 0, false));
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}
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}
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}
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}
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Stream<DownloadingStatus> start() {
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var stream = StreamController<DownloadingStatus>();
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_download(stream);
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return stream.stream;
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}
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void _reportStatus(StreamController<DownloadingStatus> stream) {
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stream.add(DownloadingStatus(_currentBytes, _fileSize, 0));
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}
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void _download(StreamController<DownloadingStatus> resultStream) async {
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try {
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var proxy = await AppDio.getProxy();
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_dio.httpClientAdapter = IOHttpClientAdapter(
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createHttpClient: () {
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return HttpClient()
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..findProxy = (uri) => proxy == null ? "DIRECT" : "PROXY $proxy";
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},
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);
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// get file size
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await _createTasks();
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if (_canceled) return;
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// check if file is downloaded
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if (_currentBytes >= _fileSize) {
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await _file!.close();
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_file = null;
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_reportStatus(resultStream);
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resultStream.close();
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return;
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}
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_reportStatus(resultStream);
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Timer.periodic(const Duration(seconds: 1), (timer) {
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if (_canceled || _currentBytes >= _fileSize) {
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timer.cancel();
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return;
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}
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resultStream.add(DownloadingStatus(
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_currentBytes, _fileSize, _currentBytes - _lastBytes));
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_lastBytes = _currentBytes;
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});
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// start downloading
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await _scheduleDownload();
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if (_canceled) {
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resultStream.close();
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return;
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}
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await _file!.close();
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_file = null;
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await File("$savePath.download").delete();
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// check if download is finished
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if (_currentBytes < _fileSize) {
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resultStream
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.addError(Exception("Download failed: Expected $_fileSize bytes, "
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"but only $_currentBytes bytes downloaded."));
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resultStream.close();
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}
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resultStream.add(DownloadingStatus(_currentBytes, _fileSize, 0, true));
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resultStream.close();
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} catch (e, s) {
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await _file?.close();
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_file = null;
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resultStream.addError(e, s);
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resultStream.close();
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}
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}
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Future<void> _scheduleDownload() async {
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var tasks = <Future>[];
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while (true) {
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if (_canceled) return;
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if (tasks.length >= maxConcurrent) {
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await Future.any(tasks);
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}
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final block = _blocks.firstWhereOrNull((element) =>
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!element.downloading &&
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element.end - element.start > element.downloadedBytes);
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if (block == null) {
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break;
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}
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block.downloading = true;
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var task = _fetchBlock(block);
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task.then((value) => tasks.remove(task), onError: (e) {
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if(_canceled) return;
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throw e;
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});
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tasks.add(task);
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}
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await Future.wait(tasks);
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}
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Future<void> _fetchBlock(_DownloadBlock block) async {
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final start = block.start;
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final end = block.end;
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if (start > _fileSize) {
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return;
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}
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var options = Options(
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responseType: ResponseType.stream,
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headers: {
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"Range": "bytes=${start + block.downloadedBytes}-${end - 1}",
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"Accept": "*/*",
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"Accept-Encoding": "deflate, gzip",
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},
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preserveHeaderCase: true,
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);
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var res = await _dio.get<ResponseBody>(url, options: options);
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if (_canceled) return;
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if (res.data == null) {
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throw Exception("Failed to block $start-$end");
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}
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var buffer = <int>[];
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await for (var data in res.data!.stream) {
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if (_canceled) return;
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buffer.addAll(data);
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if (buffer.length > 16 * 1024) {
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if (_isWriting) continue;
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_currentBytes += buffer.length;
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_isWriting = true;
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await _file!.setPosition(start + block.downloadedBytes);
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await _file!.writeFrom(buffer);
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block.downloadedBytes += buffer.length;
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buffer.clear();
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await _writeStatus();
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_isWriting = false;
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}
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}
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if (buffer.isNotEmpty) {
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while (_isWriting) {
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await Future.delayed(const Duration(milliseconds: 10));
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}
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_isWriting = true;
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_currentBytes += buffer.length;
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await _file!.setPosition(start + block.downloadedBytes);
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await _file!.writeFrom(buffer);
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block.downloadedBytes += buffer.length;
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await _writeStatus();
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_isWriting = false;
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}
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block.downloading = false;
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}
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Future<void> stop() async {
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_canceled = true;
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await _file?.close();
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_file = null;
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}
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}
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class DownloadingStatus {
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/// The current downloaded bytes
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final int downloadedBytes;
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/// The total bytes of the file
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final int totalBytes;
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/// Whether the download is finished
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final bool isFinished;
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/// The download speed in bytes per second
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final int bytesPerSecond;
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const DownloadingStatus(
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this.downloadedBytes, this.totalBytes, this.bytesPerSecond,
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[this.isFinished = false]);
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@override
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String toString() {
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return "Downloaded: $downloadedBytes/$totalBytes ${isFinished ? "Finished" : ""}";
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}
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}
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class _DownloadBlock {
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final int start;
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final int end;
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int downloadedBytes;
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bool downloading;
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_DownloadBlock(this.start, this.end, this.downloadedBytes, this.downloading);
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@override
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String toString() {
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return "$start-$end-$downloadedBytes";
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}
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_DownloadBlock.fromString(String str)
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: start = int.parse(str.split("-")[0]),
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end = int.parse(str.split("-")[1]),
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downloadedBytes = int.parse(str.split("-")[2]),
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downloading = false;
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}
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