part of 'download_queue_provider.dart';

/// Result of [DownloadQueueNotifier._finalizeDecryption]. [failStage] is
/// only meaningful to the inline single-item pipeline, which surfaces a
/// distinct error message per stage; the native-worker pipeline uses one
/// generic message and ignores it.
class _DecryptOutcome {
  final String? path;
  final String? newFileName;
  final String? failStage;
  const _DecryptOutcome(this.path, {this.newFileName, this.failStage});
}

class _QualityVariantFileOutcome {
  final String filePath;
  final String? fileName;
  final Map<String, dynamic>? metadata;

  const _QualityVariantFileOutcome({
    required this.filePath,
    this.fileName,
    this.metadata,
  });
}

/// AC-4 repair only applies to MP4 containers; decrypt can also emit raw
/// FLAC, which the native MP4 box parser would reject as corrupt.
bool _isMp4Container(String path) {
  final lower = path.toLowerCase();
  return lower.endsWith('.m4a') || lower.endsWith('.mp4');
}

extension _DownloadQueueFinalization on DownloadQueueNotifier {
  /// Builds the [DownloadHistoryItem] shared by the native-worker and inline
  /// completion paths. Fields whose source/derivation legitimately differs
  /// between the two callers (SAF location, probed vs. raw audio metadata,
  /// genre/label/copyright fallback chain) are left as parameters.
  DownloadHistoryItem _historyItemFromResult({
    required DownloadItem item,
    required Track trackToDownload,
    required Map<String, dynamic> result,
    required String filePath,
    required String quality,
    required bool useSaf,
    String? downloadTreeUri,
    String? safRelativeDir,
    String? safFileName,
    int? bitDepth,
    int? sampleRate,
    int? bitrate,
    String? format,
    String? genre,
    String? label,
    String? copyright,
  }) {
    final backendTitle = result['title'] as String?;
    final backendArtist = result['artist'] as String?;
    final backendAlbum = result['album'] as String?;
    final backendYear = result['release_date'] as String?;
    final backendTrackNum = readPositiveInt(result['track_number']);
    final backendDiscNum = readPositiveInt(result['disc_number']);
    final backendTotalTracks = readPositiveInt(result['total_tracks']);
    final backendTotalDiscs = readPositiveInt(result['total_discs']);
    final backendISRC = result['isrc'] as String?;
    final backendComposer = result['composer'] as String?;

    final historyTotalTracks = _resolvePositiveMetadataInt(
      trackToDownload.totalTracks,
      backendTotalTracks,
    );
    final historyTotalDiscs = _resolvePositiveMetadataInt(
      trackToDownload.totalDiscs,
      backendTotalDiscs,
    );
    final historyTrackNumber = _resolveMetadataIndex(
      sourceValue: trackToDownload.trackNumber,
      backendValue: backendTrackNum,
      total: historyTotalTracks,
    );
    final historyDiscNumber = _resolveMetadataIndex(
      sourceValue: trackToDownload.discNumber,
      backendValue: backendDiscNum,
      total: historyTotalDiscs,
    );
    final historyTitle =
        _resolveMetadataText(trackToDownload.name, backendTitle) ??
        item.track.name;
    final historyArtist =
        _resolveMetadataText(trackToDownload.artistName, backendArtist) ??
        item.track.artistName;
    final historyAlbum =
        _resolveMetadataText(trackToDownload.albumName, backendAlbum) ??
        item.track.albumName;
    final historyIsrc = _resolveMetadataText(trackToDownload.isrc, backendISRC);
    final historyReleaseDate = _resolveMetadataText(
      trackToDownload.releaseDate,
      backendYear,
    );
    final historyComposer = _resolveMetadataText(
      trackToDownload.composer,
      backendComposer,
    );

    return DownloadHistoryItem(
      id: item.id,
      trackName: historyTitle,
      artistName: historyArtist,
      albumName: historyAlbum,
      albumArtist: normalizeOptionalString(trackToDownload.albumArtist),
      coverUrl: normalizeCoverReference(trackToDownload.coverUrl),
      filePath: filePath,
      storageMode: useSaf ? 'saf' : 'app',
      downloadTreeUri: useSaf ? downloadTreeUri : null,
      safRelativeDir: useSaf ? safRelativeDir : null,
      safFileName: useSaf ? safFileName : null,
      safRepaired: false,
      service: result['service'] as String? ?? item.service,
      downloadedAt: DateTime.now(),
      isrc: historyIsrc,
      spotifyId: trackToDownload.id,
      trackNumber: historyTrackNumber,
      totalTracks: historyTotalTracks,
      discNumber: historyDiscNumber,
      totalDiscs: historyTotalDiscs,
      duration: trackToDownload.duration,
      releaseDate: historyReleaseDate,
      quality: quality,
      bitDepth: bitDepth,
      sampleRate: sampleRate,
      bitrate: bitrate,
      format: format,
      genre: genre,
      composer: historyComposer,
      label: label,
      copyright: copyright,
    );
  }

  Future<String?> _copySafToTemp(String uri) async {
    try {
      return await PlatformBridge.copyContentUriToTemp(uri);
    } catch (e) {
      _log.w('Failed to copy SAF uri to temp: $e');
      return null;
    }
  }

  Future<String?> _writeTempToSaf({
    required String treeUri,
    required String relativeDir,
    required String fileName,
    required String mimeType,
    required String srcPath,
  }) async {
    try {
      return await PlatformBridge.createSafFileFromPath(
        treeUri: treeUri,
        relativeDir: relativeDir,
        fileName: fileName,
        mimeType: mimeType,
        srcPath: srcPath,
      );
    } catch (e) {
      _log.w('Failed to write temp file to SAF: $e');
      return null;
    }
  }

  Future<({String uri, String fileName})?> _writeTempToSafUnique({
    required String treeUri,
    required String relativeDir,
    required String fileName,
    required String mimeType,
    required String srcPath,
    String preservedSuffix = '',
  }) async {
    try {
      final result = await PlatformBridge.createUniqueSafFileFromPath(
        treeUri: treeUri,
        relativeDir: relativeDir,
        fileName: fileName,
        mimeType: mimeType,
        srcPath: srcPath,
        preservedSuffix: preservedSuffix,
      );
      final uri = (result['uri'] as String? ?? '').trim();
      final publishedName = (result['file_name'] as String? ?? '').trim();
      if (uri.isEmpty || publishedName.isEmpty) return null;
      return (uri: uri, fileName: publishedName);
    } catch (e) {
      _log.w('Failed to write unique temp file to SAF: $e');
      return null;
    }
  }

  Future<void> _writeLrcToSaf({
    required String treeUri,
    required String relativeDir,
    required String baseName,
    required String lrcContent,
  }) async {
    try {
      if (lrcContent.isEmpty) return;
      final tempDir = await getTemporaryDirectory();
      final tempPath = '${tempDir.path}/$baseName.lrc';
      await File(tempPath).writeAsString(lrcContent);
      final lrcName = '$baseName.lrc';
      final uri = await _writeTempToSaf(
        treeUri: treeUri,
        relativeDir: relativeDir,
        fileName: lrcName,
        mimeType: _mimeTypeForExt('.lrc'),
        srcPath: tempPath,
      );
      if (uri != null) {
        _log.d('External LRC saved to SAF: $lrcName');
      } else {
        _log.w('Failed to write external LRC to SAF');
      }
      try {
        await File(tempPath).delete();
      } catch (_) {}
    } catch (e) {
      _log.w('Failed to create external LRC in SAF: $e');
    }
  }

  Future<void> _deleteSafFile(String uri) async {
    try {
      await PlatformBridge.safDelete(uri);
    } catch (e) {
      _log.w('Failed to delete SAF file: $e');
    }
  }

  /// Shared "SAF roundtrip" used by every finalize step that needs to
  /// transform a SAF file: copies [uri] to a local temp file, lets [op]
  /// transform it (returning the local path to publish plus the file name
  /// to publish it under, or null to abort), writes that file back into the
  /// SAF tree, deletes the original SAF file if its URI changed, and always
  /// cleans up the local temp file(s). Returns the new content:// URI, or
  /// null if the temp copy, [op], or the SAF write failed.
  Future<String?> _replaceSafFileVia({
    required String uri,
    required String treeUri,
    required String relativeDir,
    required Future<(String path, String fileName)?> Function(
      String tempPath,
      void Function(String path) addCleanup,
    )
    op,
    bool avoidOverwrite = false,
    String preservedSuffix = '',
    void Function(String fileName)? onPublishedFileName,
  }) async {
    final tempPath = await _copySafToTemp(uri);
    if (tempPath == null) return null;
    // Files op produces are registered here the moment they exist, so they
    // are cleaned up even if op throws before returning.
    final producedTemps = <String>{};
    String? outPath;
    try {
      final produced = await op(tempPath, producedTemps.add);
      if (produced == null) return null;
      outPath = produced.$1;
      final fileName = produced.$2;
      final dotIndex = fileName.lastIndexOf('.');
      final ext = dotIndex >= 0 ? fileName.substring(dotIndex) : '';
      String? newUri;
      if (avoidOverwrite) {
        final published = await _writeTempToSafUnique(
          treeUri: treeUri,
          relativeDir: relativeDir,
          fileName: fileName,
          mimeType: _mimeTypeForExt(ext),
          srcPath: outPath,
          preservedSuffix: preservedSuffix,
        );
        newUri = published?.uri;
        if (published != null) {
          onPublishedFileName?.call(published.fileName);
        }
      } else {
        newUri = await _writeTempToSaf(
          treeUri: treeUri,
          relativeDir: relativeDir,
          fileName: fileName,
          mimeType: _mimeTypeForExt(ext),
          srcPath: outPath,
        );
        if (newUri != null) {
          onPublishedFileName?.call(fileName);
        }
      }
      if (newUri == null) return null;
      if (newUri != uri) {
        await _deleteSafFile(uri);
      }
      return newUri;
    } finally {
      try {
        await File(tempPath).delete();
      } catch (_) {}
      if (outPath != null) {
        producedTemps.add(outPath);
      }
      for (final path in producedTemps) {
        if (path == tempPath) continue;
        try {
          await File(path).delete();
        } catch (_) {}
      }
    }
  }

  Future<_QualityVariantFileOutcome> _finalizeQualityVariantFilename({
    required DownloadItem item,
    required Map<String, dynamic> result,
    required String filePath,
    required String storageMode,
    String? downloadTreeUri,
    String? safRelativeDir,
    String? fileName,
  }) async {
    if (!item.preserveQualityVariant || result['already_exists'] == true) {
      return _QualityVariantFileOutcome(filePath: filePath, fileName: fileName);
    }

    Map<String, dynamic>? metadata;
    try {
      metadata = await PlatformBridge.readFileMetadata(filePath);
      if (metadata['error'] != null) metadata = null;
    } catch (e) {
      _log.d('Quality variant metadata probe failed for $filePath: $e');
    }

    final bitDepth = readPositiveInt(
      metadata?['bit_depth'] ?? result['actual_bit_depth'],
    );
    final sampleRate = readPositiveInt(
      metadata?['sample_rate'] ?? result['actual_sample_rate'],
    );
    final detectedFormat =
        normalizeAudioFormatValue(
          metadata?['audio_codec']?.toString() ??
              metadata?['codec']?.toString() ??
              metadata?['format']?.toString(),
        ) ??
        normalizeAudioFormatValue(
          result['audio_codec']?.toString() ?? result['format']?.toString(),
        ) ??
        normalizeAudioFormatValue(
          audioFormatForPath(filePath, fileName: fileName),
        );
    final bitrateKbps = readPositiveBitrateKbps(
      metadata?['bitrate'] ??
          metadata?['bit_rate'] ??
          result['bitrate'] ??
          result['actual_bitrate'],
    );
    final qualityLabel = buildQualityVariantFilenameLabel(
      detectedFormat: detectedFormat,
      bitDepth: bitDepth,
      sampleRate: sampleRate,
      bitrateKbps: bitrateKbps,
      measuredQuality:
          result['_native_actual_quality']?.toString() ??
          result['quality']?.toString(),
    );
    if (qualityLabel == null) {
      _log.w(
        'Keeping collision-safe temporary quality label because the final '
        'audio specification could not be measured: $filePath',
      );
      return _QualityVariantFileOutcome(
        filePath: filePath,
        fileName: fileName,
        metadata: metadata,
      );
    }

    if (bitDepth != null) result['actual_bit_depth'] = bitDepth;
    if (sampleRate != null) result['actual_sample_rate'] = sampleRate;
    if (detectedFormat != null) result['audio_codec'] = detectedFormat;
    if (bitrateKbps != null && isLossyAudioFormat(detectedFormat)) {
      result['bitrate'] = bitrateKbps;
    }

    final stagingLabel = qualityVariantStagingLabel(item.id);
    final localPathSegments = File(filePath).uri.pathSegments;
    final currentFileName = storageMode == 'saf' && isContentUri(filePath)
        ? (fileName ?? result['file_name']?.toString() ?? '')
        : (localPathSegments.isEmpty ? '' : localPathSegments.last);
    final preferredFileName = applyQualityVariantFilenameLabel(
      fileName: currentFileName,
      stagingLabel: stagingLabel,
      qualityLabel: qualityLabel,
    );
    if (preferredFileName == currentFileName) {
      return _QualityVariantFileOutcome(
        filePath: filePath,
        fileName: fileName,
        metadata: metadata,
      );
    }

    if (storageMode == 'saf' && isContentUri(filePath)) {
      if (downloadTreeUri == null || downloadTreeUri.isEmpty) {
        return _QualityVariantFileOutcome(
          filePath: filePath,
          fileName: fileName,
          metadata: metadata,
        );
      }
      String? publishedFileName;
      final renamedUri = await _replaceSafFileVia(
        uri: filePath,
        treeUri: downloadTreeUri,
        relativeDir: safRelativeDir ?? '',
        avoidOverwrite: true,
        preservedSuffix: qualityLabel,
        onPublishedFileName: (name) => publishedFileName = name,
        op: (tempPath, addCleanup) async => (tempPath, preferredFileName),
      );
      if (renamedUri == null) {
        return _QualityVariantFileOutcome(
          filePath: filePath,
          fileName: fileName,
          metadata: metadata,
        );
      }
      final finalName = publishedFileName ?? preferredFileName;
      result['file_path'] = renamedUri;
      result['file_name'] = finalName;
      return _QualityVariantFileOutcome(
        filePath: renamedUri,
        fileName: finalName,
        metadata: metadata,
      );
    }

    final source = File(filePath);
    final parent = source.parent;
    var target = File(
      '${parent.path}${Platform.pathSeparator}$preferredFileName',
    );
    var counter = 2;
    while (await target.exists() && target.path != source.path) {
      final dotIndex = preferredFileName.lastIndexOf('.');
      final hasExtension = dotIndex > 0;
      final stem = hasExtension
          ? preferredFileName.substring(0, dotIndex)
          : preferredFileName;
      final extension = hasExtension
          ? preferredFileName.substring(dotIndex)
          : '';
      target = File(
        '${parent.path}${Platform.pathSeparator}$stem ($counter)$extension',
      );
      counter++;
    }
    try {
      final renamed = await source.rename(target.path);
      result['file_path'] = renamed.path;
      final renamedSegments = renamed.uri.pathSegments;
      result['file_name'] = renamedSegments.isEmpty
          ? null
          : renamedSegments.last;
      return _QualityVariantFileOutcome(
        filePath: renamed.path,
        fileName: result['file_name'] as String?,
        metadata: metadata,
      );
    } catch (e) {
      _log.w('Failed to apply measured quality filename: $e');
      return _QualityVariantFileOutcome(
        filePath: filePath,
        fileName: fileName,
        metadata: metadata,
      );
    }
  }

  /// Shared decrypt finalize used by both the inline single-item pipeline
  /// and the native-worker pipeline. Divergences captured as parameters:
  /// [repairAc4] (inline repairs AC-4 containers using the still-encrypted
  /// source; native-worker does not) and [onStart] (inline logs its own
  /// "detected" message; native-worker logs a differently worded one).
  Future<_DecryptOutcome> _finalizeDecryption({
    required Map<String, dynamic> result,
    required String filePath,
    required String storageMode,
    String? downloadTreeUri,
    required String safRelativeDir,
    required String baseName,
    required String extFallback,
    required bool repairAc4,
    void Function(String strategy)? onStart,
  }) async {
    if (result['already_exists'] == true) {
      return _DecryptOutcome(filePath);
    }

    final descriptor = DownloadDecryptionDescriptor.fromDownloadResult(result);
    if (descriptor == null) {
      return _DecryptOutcome(filePath);
    }
    onStart?.call(descriptor.normalizedStrategy);

    if (storageMode == 'saf' && isContentUri(filePath)) {
      if (downloadTreeUri == null || downloadTreeUri.isEmpty) {
        return const _DecryptOutcome(
          null,
          failStage: DownloadQueueNotifier._decryptStageSafAccess,
        );
      }
      String? failStage;
      var opStarted = false;
      String? producedFileName;
      final newUri = await _replaceSafFileVia(
        uri: filePath,
        treeUri: downloadTreeUri,
        relativeDir: safRelativeDir,
        op: (tempPath, addCleanup) async {
          opStarted = true;
          final decryptedTempPath = await FFmpegService.decryptWithDescriptor(
            inputPath: tempPath,
            descriptor: descriptor,
            deleteOriginal: false,
          );
          if (decryptedTempPath == null) {
            failStage = DownloadQueueNotifier._decryptStageDecrypt;
            return null;
          }
          addCleanup(decryptedTempPath);
          if (repairAc4 && _isMp4Container(decryptedTempPath)) {
            try {
              await PlatformBridge.ensureAC4Config(decryptedTempPath, tempPath);
            } catch (e) {
              _log.w('AC-4 container repair skipped: $e');
            }
          }
          final dotIndex = decryptedTempPath.lastIndexOf('.');
          final decryptedExt = dotIndex >= 0
              ? decryptedTempPath.substring(dotIndex).toLowerCase()
              : extFallback;
          const allowedExt = <String>{'.flac', '.m4a', '.mp4', '.mp3', '.opus'};
          final finalExt = allowedExt.contains(decryptedExt)
              ? decryptedExt
              : extFallback;
          final newFileName = '$baseName$finalExt';
          producedFileName = newFileName;
          return (decryptedTempPath, newFileName);
        },
      );
      if (newUri == null) {
        return _DecryptOutcome(
          null,
          failStage:
              failStage ??
              (opStarted
                  ? DownloadQueueNotifier._decryptStageSafWrite
                  : DownloadQueueNotifier._decryptStageSafAccess),
        );
      }
      return _DecryptOutcome(newUri, newFileName: producedFileName);
    }

    if (repairAc4) {
      final decryptedPath = await FFmpegService.decryptWithDescriptor(
        inputPath: filePath,
        descriptor: descriptor,
        deleteOriginal: false,
      );
      if (decryptedPath == null) {
        try {
          await deleteFile(filePath);
        } catch (_) {}
        return const _DecryptOutcome(
          null,
          failStage: DownloadQueueNotifier._decryptStageDecrypt,
        );
      }
      if (_isMp4Container(decryptedPath)) {
        try {
          await PlatformBridge.ensureAC4Config(decryptedPath, filePath);
        } catch (e) {
          _log.w('AC-4 container repair skipped: $e');
        }
      }
      try {
        await deleteFile(filePath);
      } catch (_) {}
      return _DecryptOutcome(decryptedPath);
    }

    final decryptedPath = await FFmpegService.decryptWithDescriptor(
      inputPath: filePath,
      descriptor: descriptor,
      deleteOriginal: true,
    );
    return _DecryptOutcome(
      decryptedPath,
      failStage: decryptedPath == null
          ? DownloadQueueNotifier._decryptStageDecrypt
          : null,
    );
  }

  Future<String?> _finalizeNativeWorkerHighConversion({
    required _NativeWorkerRequestContext context,
    required Map<String, dynamic> result,
    required AppSettings settings,
    required Track track,
    required String filePath,
  }) async {
    if (context.quality != 'HIGH') {
      return filePath;
    }

    final lowerPath = filePath.toLowerCase();
    final resultFileName = (result['file_name'] as String?)?.toLowerCase();
    final looksLikeM4a =
        lowerPath.endsWith('.m4a') ||
        lowerPath.endsWith('.mp4') ||
        (resultFileName != null &&
            (resultFileName.endsWith('.m4a') ||
                resultFileName.endsWith('.mp4')));
    if (!looksLikeM4a) {
      return filePath;
    }

    final tidalHighFormat = settings.tidalHighFormat;
    final format = lossyFormatForSetting(tidalHighFormat);
    final newExt = lossyExtensionForFormat(format);
    final displayFormat = displayFormatForLossyFormat(format);
    final bitrateDisplay = tidalHighFormat.contains('_')
        ? '${tidalHighFormat.split('_').last}kbps'
        : '320kbps';

    Future<void> embedConvertedMetadata(String convertedPath) async {
      if (!settings.embedMetadata) return;
      await _embedMetadataToFile(
        convertedPath,
        track,
        format: metadataFormatForLossyFormat(format),
        genre: result['genre'] as String?,
        label: result['label'] as String?,
        copyright: result['copyright'] as String?,
        downloadService: context.item.service,
      );
    }

    if (context.storageMode == 'saf' && isContentUri(filePath)) {
      final treeUri = context.downloadTreeUri;
      if (treeUri == null || treeUri.isEmpty) {
        return null;
      }
      final rawFileName =
          (result['file_name'] as String?) ?? context.safFileName ?? 'track';
      final baseName = rawFileName.replaceFirst(RegExp(r'\.[^.]+$'), '');
      final newFileName = '$baseName$newExt';
      final newUri = await _replaceSafFileVia(
        uri: filePath,
        treeUri: treeUri,
        relativeDir: context.safRelativeDir ?? '',
        op: (tempPath, addCleanup) async {
          final convertedPath = await FFmpegService.convertM4aToLossy(
            tempPath,
            format: format,
            bitrate: tidalHighFormat,
            deleteOriginal: false,
          );
          if (convertedPath == null) return null;
          addCleanup(convertedPath);
          await embedConvertedMetadata(convertedPath);
          return (convertedPath, newFileName);
        },
      );
      if (newUri == null) {
        return null;
      }
      result['file_name'] = newFileName;
      result['_native_actual_quality'] = '$displayFormat $bitrateDisplay';
      return newUri;
    }

    final convertedPath = await FFmpegService.convertM4aToLossy(
      filePath,
      format: format,
      bitrate: tidalHighFormat,
      deleteOriginal: true,
    );
    if (convertedPath == null) {
      return null;
    }
    await embedConvertedMetadata(convertedPath);
    result['_native_actual_quality'] = '$displayFormat $bitrateDisplay';
    return convertedPath;
  }

  Future<String?> _finalizeNativeWorkerContainerConversion({
    required _NativeWorkerRequestContext context,
    required Map<String, dynamic> result,
    required AppSettings settings,
    required Track track,
    required String filePath,
  }) async {
    if (context.quality == 'HIGH' || context.outputExt != '.flac') {
      return filePath;
    }
    final resultAudioFormat = normalizeAudioFormatValue(
      result['audio_codec']?.toString() ??
          result['actual_audio_codec']?.toString(),
    );
    if (isLossyAudioFormat(resultAudioFormat)) {
      _log.d(
        'Native-worker output is $resultAudioFormat; preserving native container.',
      );
      return filePath;
    }
    final requiresContainerConversion =
        result['requires_container_conversion'] == true ||
        result['requiresContainerConversion'] == true;
    final resultOutputExt = _downloadResultOutputExt(
      result,
      filePath: filePath,
    );
    final lowerPath = filePath.toLowerCase();
    final resultFileName = (result['file_name'] as String?)?.toLowerCase();
    final mayNeedContainerConversion =
        requiresContainerConversion ||
        lowerPath.endsWith('.m4a') ||
        lowerPath.endsWith('.mp4') ||
        resultOutputExt == '.m4a' ||
        resultOutputExt == '.mp4' ||
        isContentUri(filePath);
    if (!mayNeedContainerConversion) {
      return filePath;
    }
    final requestedDecryptionExt =
        DownloadDecryptionDescriptor.fromDownloadResult(
          result,
        )?.normalizedOutputExtension;
    if (!requiresContainerConversion &&
        requestedDecryptionExt != null &&
        requestedDecryptionExt != '.flac') {
      _log.d(
        'Native-worker decrypted output requested $requestedDecryptionExt; preserving native container.',
      );
      return filePath;
    }
    final looksLikeM4a =
        lowerPath.endsWith('.m4a') ||
        lowerPath.endsWith('.mp4') ||
        resultOutputExt == '.m4a' ||
        resultOutputExt == '.mp4' ||
        (resultFileName != null &&
            (resultFileName.endsWith('.m4a') ||
                resultFileName.endsWith('.mp4')));
    if (!requiresContainerConversion &&
        !looksLikeM4a &&
        !isContentUri(filePath)) {
      return filePath;
    }

    Future<void> embedFlacMetadata(String flacPath) async {
      if (!settings.embedMetadata) return;
      await _embedMetadataToFile(
        flacPath,
        track,
        format: 'flac',
        genre: result['genre'] as String?,
        label: result['label'] as String?,
        copyright: result['copyright'] as String?,
        downloadService: context.item.service,
        writeExternalLrc: context.storageMode != 'saf',
      );
    }

    if (context.storageMode == 'saf' && isContentUri(filePath)) {
      final treeUri = context.downloadTreeUri;
      if (treeUri == null || treeUri.isEmpty) {
        return null;
      }
      var preserve = false;
      String? producedFileName;
      final newUri = await _replaceSafFileVia(
        uri: filePath,
        treeUri: treeUri,
        relativeDir: context.safRelativeDir ?? '',
        op: (tempPath, addCleanup) async {
          final codec = await FFmpegService.probePrimaryAudioCodec(tempPath);
          final isAlreadyNativeFlac =
              codec == 'flac' && await FFmpegService.isNativeFlacFile(tempPath);
          if (!FFmpegService.isLosslessAudioCodec(codec)) {
            _log.d(
              'Preserving native container; audio codec is ${codec ?? 'unknown'}, '
              'no FLAC container conversion needed.',
            );
            preserve = true;
            return null;
          }
          if (isAlreadyNativeFlac) {
            _log.d(
              'Native FLAC payload detected in temporary container; publishing '
              'as FLAC and embedding metadata.',
            );
            await embedFlacMetadata(tempPath);
            final rawFileName =
                (result['file_name'] as String?) ??
                context.safFileName ??
                'track';
            final baseName = rawFileName.replaceFirst(RegExp(r'\.[^.]+$'), '');
            final newFileName = '$baseName.flac';
            producedFileName = newFileName;
            return (tempPath, newFileName);
          }
          final flacPath = await FFmpegService.convertM4aToFlac(tempPath);
          if (flacPath == null) {
            return null;
          }
          addCleanup(flacPath);
          await embedFlacMetadata(flacPath);
          final rawFileName =
              (result['file_name'] as String?) ??
              context.safFileName ??
              'track';
          final baseName = rawFileName.replaceFirst(RegExp(r'\.[^.]+$'), '');
          final newFileName = '$baseName.flac';
          producedFileName = newFileName;
          return (flacPath, newFileName);
        },
      );
      if (preserve) {
        return filePath;
      }
      if (newUri == null) {
        return null;
      }
      result['file_name'] = producedFileName;
      return newUri;
    }

    final codec = await FFmpegService.probePrimaryAudioCodec(filePath);
    final isAlreadyNativeFlac =
        codec == 'flac' && await FFmpegService.isNativeFlacFile(filePath);
    if (!FFmpegService.isLosslessAudioCodec(codec)) {
      _log.d(
        'Preserving native container; audio codec is ${codec ?? 'unknown'}, '
        'no FLAC container conversion needed.',
      );
      return filePath;
    }
    if (isAlreadyNativeFlac) {
      var flacPath = filePath;
      if (!filePath.toLowerCase().endsWith('.flac')) {
        final renamedPath = filePath.replaceAll(RegExp(r'\.[^.]+$'), '.flac');
        final targetPath = renamedPath == filePath
            ? '$filePath.flac'
            : renamedPath;
        await File(filePath).rename(targetPath);
        flacPath = targetPath;
      }
      await embedFlacMetadata(flacPath);
      return flacPath;
    }
    final flacPath = await FFmpegService.convertM4aToFlac(filePath);
    if (flacPath == null) {
      return null;
    }
    await embedFlacMetadata(flacPath);
    return flacPath;
  }

  /// Shared external-LRC finalize used by both the inline single-item
  /// pipeline (SAF only; the local-file case is already handled during
  /// metadata embedding) and the native-worker pipeline (both storage
  /// modes). [resolveBaseName] and [onFetchError] are each caller's own
  /// base-name fallback chain and fetch-failure log line, evaluated lazily
  /// to match the original call sites exactly.
  Future<void> _saveExternalLrc({
    required Map<String, dynamic> result,
    required AppSettings settings,
    required ExtensionState extensionState,
    required Track track,
    required String service,
    required String filePath,
    required String storageMode,
    String? downloadTreeUri,
    required String safRelativeDir,
    required Future<String> Function() resolveBaseName,
    required void Function(Object e) onFetchError,
  }) async {
    final lyricsMode = settings.lyricsMode;
    final shouldSaveExternalLrc =
        settings.embedMetadata &&
        settings.embedLyrics &&
        !_shouldSkipLyrics(extensionState, track.source, service) &&
        (lyricsMode == 'external' || lyricsMode == 'both');
    if (!shouldSaveExternalLrc) {
      return;
    }

    String? lrcContent = result['lyrics_lrc'] as String?;
    if (lrcContent == null || lrcContent.isEmpty) {
      try {
        lrcContent = await PlatformBridge.getLyricsLRC(
          track.id,
          track.name,
          track.artistName,
          durationMs: track.duration * 1000,
        );
      } catch (e) {
        onFetchError(e);
      }
    }
    if (lrcContent == null || lrcContent.isEmpty) {
      return;
    }

    if (storageMode == 'saf' && isContentUri(filePath)) {
      if (downloadTreeUri == null || downloadTreeUri.isEmpty) {
        return;
      }
      final baseName = await resolveBaseName();
      await _writeLrcToSaf(
        treeUri: downloadTreeUri,
        relativeDir: safRelativeDir,
        baseName: baseName,
        lrcContent: lrcContent,
      );
      return;
    }

    try {
      final lrcPath = filePath.replaceAll(RegExp(r'\.[^.]+$'), '.lrc');
      final safeLrcPath = lrcPath == filePath ? '$filePath.lrc' : lrcPath;
      await File(safeLrcPath).writeAsString(lrcContent);
      _log.d('Native-worker external LRC saved: $safeLrcPath');
    } catch (e) {
      _log.w('Failed to save native-worker external LRC: $e');
    }
  }
}