spotube/lib/provider/Downloader.dart

import 'dart:async';
import 'dart:io';

import 'package:flutter/widgets.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:queue/queue.dart';
import 'package:path/path.dart' as path;
import 'package:spotube/models/SpotubeTrack.dart';
import 'package:spotube/provider/UserPreferences.dart';
import 'package:spotube/provider/YouTube.dart';
import 'package:spotube/utils/platform.dart';
import 'package:youtube_explode_dart/youtube_explode_dart.dart';

Queue _queueInstance = Queue(delay: const Duration(seconds: 5));

class Downloader with ChangeNotifier {
  Queue _queue;
  YoutubeExplode yt;
  String downloadPath;
  FutureOr<bool> Function(SpotubeTrack track)? onFileExists;
  Downloader(
    this._queue, {
    required this.downloadPath,
    required this.yt,
    this.onFileExists,
  });

  int currentlyRunning = 0;
  Set<String> inQueue = {};

  void addToQueue(SpotubeTrack track) async {
    currentlyRunning++;
    inQueue.add(track.id!);
    notifyListeners();
    final filename = '${track.ytTrack.title}.mp3';
    if (kIsMobile) {
      final url =
          ((await yt.videos.streamsClient.getManifest(track.ytTrack.url)))
              .audioOnly
              .where((audio) => audio.codec.mimeType == "audio/mp4")
              .withHighestBitrate()
              .url;
      await FlutterDownloader.enqueue(
        savedDir: downloadPath,
        url: url.toString(),
        fileName: filename,
        openFileFromNotification: true,
        showNotification: true,
      );
    } else {
      if (inQueue.contains(track.id!)) return;
      _queue.add(() async {
        try {
          final file = File(path.join(downloadPath, filename));
          if (file.existsSync() && await onFileExists?.call(track) != true) {
            return;
          }
          file.createSync(recursive: true);
          StreamManifest manifest =
              await yt.videos.streamsClient.getManifest(track.ytTrack.url);
          final audioStream = yt.videos.streamsClient
              .get(
                manifest.audioOnly
                    .where((audio) => audio.codec.mimeType == "audio/mp4")
                    .withHighestBitrate(),
              )
              .asBroadcastStream();

          IOSink outputFileStream = file.openWrite();
          await audioStream.pipe(outputFileStream);
          await outputFileStream.flush();
        } finally {
          currentlyRunning--;
          inQueue.remove(track.id);
          notifyListeners();
        }
      });
    }
  }

  cancelAll() {
    if (kIsMobile) {
      FlutterDownloader.cancelAll();
    } else {
      _queue.cancel();
      _queueInstance = Queue();
      _queue = _queueInstance;
    }
  }
}

final downloaderProvider = ChangeNotifierProvider(
  (ref) {
    return Downloader(
      _queueInstance,
      yt: ref.watch(youtubeProvider),
      downloadPath: ref.watch(
        userPreferencesProvider.select(
          (s) => s.downloadLocation,
        ),
      ),
    );
  },
);