spotube/lib/provider/server/routes/playback.dart

import 'dart:io';
import 'dart:math';

import 'package:collection/collection.dart';
import 'package:dio/dio.dart' hide Response;
import 'package:dio/dio.dart' as dio_lib;
import 'package:flutter/foundation.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:metadata_god/metadata_god.dart';
import 'package:path/path.dart';
import 'package:shelf/shelf.dart';
import 'package:spotube/models/metadata/metadata.dart';
import 'package:spotube/models/parser/range_headers.dart';
import 'package:spotube/models/playback/track_sources.dart';
import 'package:spotube/provider/audio_player/audio_player.dart';
import 'package:spotube/provider/audio_player/state.dart';

import 'package:spotube/provider/server/active_track_sources.dart';
import 'package:spotube/provider/server/track_sources.dart';
import 'package:spotube/provider/user_preferences/user_preferences_provider.dart';
import 'package:spotube/services/audio_player/audio_player.dart';
import 'package:spotube/services/logger/logger.dart';
import 'package:spotube/services/sourced_track/enums.dart';
import 'package:spotube/services/sourced_track/sourced_track.dart';
import 'package:spotube/utils/service_utils.dart';
import 'package:youtube_explode_dart/youtube_explode_dart.dart';

final _deviceClients = Set.unmodifiable({
  YoutubeApiClient.ios,
  YoutubeApiClient.android,
  YoutubeApiClient.mweb,
  YoutubeApiClient.safari,
});

String? get _randomUserAgent => _deviceClients
    .elementAt(
      Random().nextInt(_deviceClients.length),
    )
    .payload["context"]["client"]["userAgent"];

class ServerPlaybackRoutes {
  final Ref ref;
  UserPreferences get userPreferences => ref.read(userPreferencesProvider);
  AudioPlayerState get playlist => ref.read(audioPlayerProvider);
  final Dio dio;

  ServerPlaybackRoutes(this.ref) : dio = Dio();

  Future<({dio_lib.Response<Uint8List> response, Uint8List? bytes})>
      streamTrack(
    Request request,
    SourcedTrack track,
    Map<String, dynamic> headers,
  ) async {
    final trackCacheFile = File(
      join(
        await UserPreferencesNotifier.getMusicCacheDir(),
        ServiceUtils.sanitizeFilename(
          '${track.query.title} - ${track.query.artists.join(",")} (${track.info.id}).${track.codec.name}',
        ),
      ),
    );

    if (await trackCacheFile.exists() && userPreferences.cacheMusic) {
      final bytes = await trackCacheFile.readAsBytes();
      final cachedFileLength = bytes.length;

      return (
        response: dio_lib.Response<Uint8List>(
          statusCode: 200,
          headers: Headers.fromMap({
            "content-type": ["audio/${track.codec.name}"],
            "content-length": ["$cachedFileLength"],
            "accept-ranges": ["bytes"],
            "content-range": ["bytes 0-$cachedFileLength/$cachedFileLength"],
          }),
          requestOptions: RequestOptions(path: request.requestedUri.toString()),
        ),
        bytes: bytes,
      );
    }

    final trackPartialCacheFile = File("${trackCacheFile.path}.part");

    String url = track.url ??
        await ref
            .read(trackSourcesProvider(track.query).notifier)
            .swapWithNextSibling()
            .then((track) => track.url!);

    var options = Options(
      headers: {
        ...headers,
        "user-agent": _randomUserAgent,
        "Cache-Control": "max-age=3600",
        "Connection": "keep-alive",
        "host": Uri.parse(url).host,
      },
      responseType: ResponseType.bytes,
      validateStatus: (status) => status! < 400,
    );

    final contentLengthRes = await Future<dio_lib.Response?>.value(
      dio.head(
        url,
        options: options,
      ),
    ).catchError((e, stack) async {
      AppLogger.reportError(e, stack);

      final sourcedTrack = await ref
          .read(trackSourcesProvider(track.query).notifier)
          .refreshStreamingUrl();

      url = sourcedTrack.url!;

      return dio.head(url, options: options);
    });

    // Redirect to m3u8 link directly as it handles range requests internally
    if (contentLengthRes?.headers.value("content-type") ==
        "application/vnd.apple.mpegurl") {
      return (
        response: dio_lib.Response<Uint8List>(
          statusCode: 301,
          statusMessage: "M3U8 Redirect",
          headers: Headers.fromMap({
            "location": [url],
            "content-type": ["application/vnd.apple.mpegurl"],
          }),
          requestOptions: RequestOptions(path: request.requestedUri.toString()),
          isRedirect: true,
        ),
        bytes: null,
      );
    }

    final contentLength = contentLengthRes?.headers.value("content-length");

    /// Forcing partial content range as mpv sometimes greedily wants
    /// everything at one go. Slows down overall streaming.
    final range = RangeHeader.parse(headers["range"] ?? "");
    final contentPartialLength = int.tryParse(contentLength ?? "");
    if ((range.end == null) &&
        contentPartialLength != null &&
        range.start == 0) {
      options = options.copyWith(
        headers: {
          ...?options.headers,
          "range": "$range${(contentPartialLength * 0.3).ceil()}",
        },
      );
    }

    final res = await dio.get<Uint8List>(url, options: options);

    final bytes = res.data;

    if (bytes == null || !userPreferences.cacheMusic) {
      return (response: res, bytes: bytes);
    }

    final contentRange =
        ContentRangeHeader.parse(res.headers.value("content-range") ?? "");

    if (!await trackPartialCacheFile.exists()) {
      await trackPartialCacheFile.create(recursive: true);
    }

    // Write the stream to the file based on the range
    final partialCacheFile =
        await trackPartialCacheFile.open(mode: FileMode.writeOnlyAppend);
    int fileLength = 0;
    try {
      await partialCacheFile.setPosition(contentRange.start);
      await partialCacheFile.writeFrom(bytes);
      fileLength = await partialCacheFile.length();
    } finally {
      await partialCacheFile.close();
    }

    if (fileLength == contentRange.total) {
      await trackPartialCacheFile.rename(trackCacheFile.path);
    }

    if (contentRange.total == fileLength && track.codec != SourceCodecs.weba) {
      final playlistTrack = playlist.tracks.firstWhereOrNull(
        (element) => element.id == track.query.id,
      );
      if (playlistTrack == null) {
        AppLogger.log.e(
          "Track ${track.query.id} not found in playlist, cannot write metadata.",
        );
        return (response: res, bytes: bytes);
      }

      final imageBytes = await ServiceUtils.downloadImage(
        (playlistTrack.album.images).asUrlString(
          placeholder: ImagePlaceholder.albumArt,
          index: 1,
        ),
      );

      await MetadataGod.writeMetadata(
        file: trackCacheFile.path,
        metadata: (playlistTrack as SpotubeFullTrackObject).toMetadata(
          imageBytes: imageBytes,
          fileLength: fileLength,
        ),
      );
    }

    return (bytes: bytes, response: res);
  }

  /// @get('/stream/<trackId>')
  Future<Response> getStreamTrackId(Request request, String trackId) async {
    try {
      final track =
          playlist.tracks.firstWhere((element) => element.id == trackId);

      final activeSourcedTrack =
          await ref.read(activeTrackSourcesProvider.future);
      final sourcedTrack = activeSourcedTrack?.track.id == track.id
          ? activeSourcedTrack?.source
          : await ref.read(
              trackSourcesProvider(
                //! Use [Request.requestedUri] as it contains full https url.
                //! [Request.url] will exclude and starts relatively. (streams/<trackId>... basically)
                TrackSourceQuery.parseUri(request.requestedUri.toString()),
              ).future,
            );

      final (bytes: audioBytes, response: res) = await streamTrack(
        request,
        sourcedTrack!,
        request.headers,
      );

      return Response(
        res.statusCode!,
        body: audioBytes,
        headers: res.headers.map,
      );
    } catch (e, stack) {
      AppLogger.reportError(e, stack);
      return Response.internalServerError();
    }
  }

  /// @get('/playback/toggle-playback')
  Future<Response> togglePlayback(Request request) async {
    audioPlayer.isPlaying
        ? await audioPlayer.pause()
        : await audioPlayer.resume();

    return Response.ok("Playback toggled");
  }

  /// @get('/playback/previous')
  Future<Response> previousTrack(Request request) async {
    await audioPlayer.skipToPrevious();
    return Response.ok("Previous track");
  }

  /// @get('/playback/next')
  Future<Response> nextTrack(Request request) async {
    await audioPlayer.skipToNext();
    return Response.ok("Next track");
  }
}

final serverPlaybackRoutesProvider =
    Provider((ref) => ServerPlaybackRoutes(ref));