freezer/lib/api/download_manager/download_manager.dart

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

import 'package:flutter/widgets.dart';
import 'package:flutter_background_service/flutter_background_service.dart';
import 'package:freezer/api/deezer.dart';
import 'package:freezer/api/definitions.dart' as d;
import 'package:freezer/api/download_manager/database.dart';
import 'package:freezer/api/download_manager/download_service.dart';
import 'package:freezer/api/download_manager/service_interface.dart';
import 'package:freezer/api/paths.dart';
import 'package:freezer/main.dart';
import 'package:freezer/settings.dart';
import 'package:freezer/translations.i18n.dart';
import 'package:isar/isar.dart';
import '../download.dart' as dl;

class DownloadManager {
  //implements dl.DownloadManager {

  late Isar _isar;

  Isolate? _isolate;
  ServiceInterface? _service;

  bool _started = false;

  Future<void> startDebug() async {
    if (_started) return;
    _started = true;

    await configure();
    await startService();
    await Future.delayed(const Duration(milliseconds: 500));
  }

  Future<bool> configure() async {
    _isar = await Isar.open(
      [
        // collections
        TrackSchema,
        AlbumSchema,
        ArtistSchema,
        PlaylistSchema,
      ],
      directory: await Paths.dataDirectory(),
      name: 'offline',
    );
    if (Platform.isAndroid || Platform.isIOS) {
      return FlutterBackgroundService().configure(
          iosConfiguration: IosConfiguration(), // fuck ios
          androidConfiguration: AndroidConfiguration(
            onStart: _startNative,
            isForegroundMode: false,
            autoStart: false,
            autoStartOnBoot: false,
            foregroundServiceNotificationId: DownloadService.NOTIFICATION_ID,
            notificationChannelId: DownloadService.NOTIFICATION_CHANNEL_ID,
            initialNotificationTitle: 'Freezer'.i18n,
            initialNotificationContent: 'Starting download service...'.i18n,
          ));
    }

    // will run in foreground instead, in a separate isolate
    return Future.value(true);
  }

  Future<bool> startService() async {
    if (Platform.isAndroid) {
      final didStart = await FlutterBackgroundService().startService();

      if (!didStart) return false;
    } else {
      // UI -> Service communication
      final receivePort = ReceivePort();
      _isolate = await Isolate.spawn(_startIsolate, receivePort.sendPort);
      _service = ServiceInterface(receivePort: receivePort);
      _service!.on('sendPort', (args) {
        _service!.sendPort = args!['s'];
        _service!.no('sendPort');
      });
    }

    final completer = Completer<void>();
    on('ready', (args) => completer.complete());
    await completer.future;
    invoke('updateSettings', {
      'downloadFilename': settings.downloadFilename,
      'deezerLanguage': settings.deezerLanguage,
      'deezerCountry': settings.deezerCountry,
    });

    return true;
  }

  void kill() {
    _isolate?.kill();
  }

  void invoke(String method, [Map<String, dynamic>? args]) {
    if (_service != null) {
      _service!.send(method, args);
      return;
    }

    FlutterBackgroundService().invoke(method, args);
  }

  void on(String method, ListenerCallback listener) {
    if (_service != null) {
      _service!.on(method, listener);
      return;
    }

    FlutterBackgroundService().on(method).listen(listener);
  }

  Future<bool> checkOffline(String trackId) async {
    final c =
        await _isar.tracks.where().isarIdEqualTo(int.parse(trackId)).count();
    return c > 0;
  }

  Future<bool> addOfflineTrack(d.Track track, AudioQuality downloadQuality,
      {bool private = true}) async {
    //Permission
    if (!private && !(await dl.DownloadManager.checkCanDownload())) {
      return false;
    }

    if (downloadQuality == AudioQuality.ASK) {
      throw Exception('Invalid quality.');
    }
    if (private) {
      if (track.artists == null ||
          track.artists!.isEmpty ||
          track.album == null) {
        track = await DeezerAPI.instance.track(track.id);
      }

      // cache album art
      cacheManager.getSingleFile(track.albumArt!.thumb);
      cacheManager.getSingleFile(track.albumArt!.full);

      await _isar.writeTxn(() async {
        await _isar.tracks.put(Track.from(track));
        if (track.album != null) {
          await _isar.albums.put(Album.from(track.album!));
        }

        if (track.artists != null) {
          await _isar.artists
              .putAll(track.artists!.map(Artist.from).toList(growable: false));
        }
      });
    }

    // logic for downloading the track
    invoke(
        'addDownloads',
        DownloadInfo(
          trackId: track.id,
          path: private ? null : settings.downloadPath,
        ).toJson());

    return true;
  }

  static void _startNative(ServiceInstance service) =>
      _startService(ServiceInterface(service: service));

  static void _startIsolate(SendPort sendPort) async {
    final receivePort = ReceivePort();
    final service = ServiceInterface(receivePort: receivePort)
      ..sendPort = sendPort;
    service.send('sendPort', {'s': receivePort.sendPort});
    return _startService(service);
  }

  static void _startService(ServiceInterface service) =>
      DownloadService(service).run();
}