SpotiFLAC-Mobile/lib/utils/audio_format_utils.dart

import 'package:spotiflac_android/utils/int_utils.dart';
import 'package:spotiflac_android/utils/string_utils.dart';

/// Audio format/quality helpers shared by the download queue and history
/// providers.
int? readPositiveBitrateKbps(dynamic value) {
  final parsed = readPositiveInt(value);
  if (parsed == null) return null;
  final kbps = parsed >= 10000 ? (parsed / 1000).round() : parsed;
  return kbps >= 16 ? kbps : null;
}

String? audioFormatForPath(String? filePath, {String? fileName}) {
  final candidates = <String>[?filePath, ?fileName];
  for (final candidate in candidates) {
    final lower = candidate.trim().toLowerCase();
    if (lower.endsWith('.opus') || lower.endsWith('.ogg')) return 'OPUS';
    if (lower.endsWith('.mp3')) return 'MP3';
    if (lower.endsWith('.aac')) return 'AAC';
    if (lower.endsWith('.m4a') || lower.endsWith('.mp4')) return 'M4A';
  }
  return null;
}

String? nonPlaceholderQuality(String? quality) {
  final normalized = normalizeOptionalString(quality);
  if (normalized == null || isPlaceholderQualityLabel(normalized)) {
    return null;
  }
  final bitrateMatch = RegExp(
    r'\b(\d+)\s*kbps\b',
    caseSensitive: false,
  ).firstMatch(normalized);
  if (bitrateMatch != null) {
    final bitrate = int.tryParse(bitrateMatch.group(1) ?? '');
    if (bitrate != null && bitrate < 16) return null;
  }
  final lower = normalized.toLowerCase().replaceAll(RegExp(r'[^a-z0-9]+'), '_');
  const requestedLosslessLabels = {
    'hi_res_lossless',
    'hires_lossless',
    'hi_res',
    'hires',
    'flac_best_available',
  };
  if (requestedLosslessLabels.contains(lower)) return null;
  return normalized;
}

String? normalizeAudioFormatValue(String? value) {
  final normalized = normalizeOptionalString(
    value,
  )?.toLowerCase().replaceAll('-', '_');
  return switch (normalized) {
    'flac' => 'flac',
    'alac' => 'alac',
    'wav' || 'wave' => 'wav',
    'aiff' || 'aif' || 'aifc' => 'aiff',
    'aac' || 'mp4a' => 'aac',
    'eac3' || 'ec_3' => 'eac3',
    'ac3' || 'ac_3' => 'ac3',
    'ac4' || 'ac_4' => 'ac4',
    'mp3' => 'mp3',
    'opus' || 'ogg' => 'opus',
    'm4a' || 'mp4' => 'm4a',
    _ => null,
  };
}

/// Resolves the actual audio codec reported by native metadata probing, while
/// falling back to the container format when the codec is absent or generic.
///
/// This distinction matters for MP4/M4A files: the same container may hold
/// AAC, ALAC, Dolby, or other codecs.
String? detectedAudioFormatFromMetadata(Map<String, dynamic> metadata) {
  final codec = normalizeAudioFormatValue(metadata['audio_codec']?.toString());
  if (codec != null) return codec;
  return normalizeAudioFormatValue(metadata['format']?.toString());
}

bool isLossyAudioFormat(String? value) {
  return const {
    'aac',
    'eac3',
    'ac3',
    'ac4',
    'mp3',
    'opus',
    'm4a',
  }.contains(normalizeAudioFormatValue(value));
}

/// Returns a provider-independent quality label suitable for a filename.
///
/// Requested labels such as LOSSLESS and HI_RES are intentionally ignored:
/// they describe provider intent, not the audio that was actually written.
String? buildQualityVariantFilenameLabel({
  String? detectedFormat,
  int? bitDepth,
  int? sampleRate,
  int? bitrateKbps,
  String? measuredQuality,
}) {
  if (isLossyAudioFormat(detectedFormat)) {
    final effectiveBitrate =
        bitrateKbps ?? _bitrateFromQuality(measuredQuality);
    return effectiveBitrate != null && effectiveBitrate >= 16
        ? '${effectiveBitrate}kbps'
        : null;
  }

  final measured = _losslessSpecsFromQuality(measuredQuality);
  final effectiveBitDepth = bitDepth ?? measured?.$1;
  final effectiveSampleRate = sampleRate ?? measured?.$2;
  if (effectiveBitDepth == null ||
      effectiveBitDepth <= 0 ||
      effectiveSampleRate == null ||
      effectiveSampleRate <= 0) {
    return null;
  }
  return '${effectiveBitDepth}bit-${formatSampleRateKHz(effectiveSampleRate)}';
}

int? _bitrateFromQuality(String? quality) {
  final match = RegExp(
    r'\b(\d+)\s*kbps\b',
    caseSensitive: false,
  ).firstMatch(quality ?? '');
  final value = int.tryParse(match?.group(1) ?? '');
  return value != null && value >= 16 ? value : null;
}

(int, int)? _losslessSpecsFromQuality(String? quality) {
  final match = RegExp(
    r'\b(\d+)\s*(?:-|\s)?bit\s*[/_-]\s*(\d+(?:\.\d+)?)\s*k?hz\b',
    caseSensitive: false,
  ).firstMatch(quality ?? '');
  final bitDepth = int.tryParse(match?.group(1) ?? '');
  final rate = double.tryParse(match?.group(2) ?? '');
  if (bitDepth == null || bitDepth <= 0 || rate == null || rate <= 0) {
    return null;
  }
  final sampleRate = rate < 1000 ? (rate * 1000).round() : rate.round();
  return (bitDepth, sampleRate);
}

String qualityVariantStagingLabel(String itemId) {
  var hash = 0x811c9dc5;
  for (final byte in itemId.codeUnits) {
    hash ^= byte;
    hash = (hash * 0x01000193) & 0xffffffff;
  }
  return 'qv_${hash.toRadixString(16).padLeft(8, '0')}';
}

String applyQualityVariantFilenameLabel({
  required String fileName,
  required String stagingLabel,
  required String qualityLabel,
}) {
  if (stagingLabel.isNotEmpty && fileName.contains(stagingLabel)) {
    return fileName.replaceAll(stagingLabel, qualityLabel);
  }
  if (fileName.contains(qualityLabel)) {
    return fileName;
  }
  final dotIndex = fileName.lastIndexOf('.');
  final hasExtension = dotIndex > 0;
  final stem = hasExtension ? fileName.substring(0, dotIndex) : fileName;
  final extension = hasExtension ? fileName.substring(dotIndex) : '';
  return '$stem - $qualityLabel$extension';
}

String lossyFormatForSetting(String value) {
  final normalized = value.trim().toLowerCase();
  if (normalized.startsWith('opus')) return 'opus';
  if (normalized.startsWith('aac') || normalized.startsWith('m4a')) {
    return 'aac';
  }
  return 'mp3';
}

String lossyExtensionForFormat(String format) {
  return switch (format) {
    'opus' => '.opus',
    'aac' => '.m4a',
    _ => '.mp3',
  };
}

String metadataFormatForLossyFormat(String format) {
  return format == 'aac' ? 'm4a' : format;
}

String displayFormatForLossyFormat(String format) {
  return format == 'aac' ? 'AAC' : format.toUpperCase();
}

String? resolveDisplayQuality({
  required String? filePath,
  String? fileName,
  String? detectedFormat,
  int? bitDepth,
  int? sampleRate,
  int? bitrateKbps,
  String? storedQuality,
}) {
  final format =
      displayFormatForCodec(detectedFormat) ??
      audioFormatForPath(filePath, fileName: fileName);
  if (format == 'OPUS' ||
      format == 'MP3' ||
      format == 'AAC' ||
      format == 'EAC3' ||
      format == 'AC3' ||
      format == 'AC4' ||
      (format == 'M4A' && (bitDepth == null || bitDepth <= 0))) {
    return buildDisplayAudioQuality(bitrateKbps: bitrateKbps, format: format) ??
        nonPlaceholderQuality(storedQuality) ??
        format;
  }
  return buildDisplayAudioQuality(
    bitDepth: bitDepth,
    sampleRate: sampleRate,
    storedQuality: nonPlaceholderQuality(storedQuality) ?? storedQuality,
  );
}

String? displayFormatForCodec(String? value) {
  final normalized = normalizeOptionalString(
    value,
  )?.toLowerCase().replaceAll('-', '_');
  return switch (normalized) {
    'flac' => 'FLAC',
    'alac' => 'ALAC',
    'aac' || 'mp4a' => 'AAC',
    'eac3' || 'ec_3' => 'EAC3',
    'ac3' || 'ac_3' => 'AC3',
    'ac4' || 'ac_4' => 'AC4',
    'mp3' => 'MP3',
    'opus' => 'OPUS',
    _ => null,
  };
}