/// Video transcode quality presets modeled on Plex Web's custom-quality table.
///
/// When a non-[original] preset is selected, playback asks the active backend
/// for a capped transcode stream. [original] bypasses transcoding entirely and
/// uses the direct-play URL.
enum TranscodeQualityPreset {
  original(null, null, null),
  p240_320(320, '420x240', 30),
  p320_720(720, '576x320', 40),
  p480_1_5mbps(1500, '720x480', 60),
  p720_2mbps(2000, '1280x720', 60),
  p720_3mbps(3000, '1280x720', 75),
  p720_4mbps(4000, '1280x720', 100),
  p1080_8mbps(8000, '1920x1080', 60),
  p1080_10mbps(10000, '1920x1080', 75),
  p1080_12mbps(12000, '1920x1080', 90),
  p1080_20mbps(20000, '1920x1080', 100);

  const TranscodeQualityPreset(this.videoBitrateKbps, this.videoResolution, this.videoQuality);

  final int? videoBitrateKbps;
  final String? videoResolution;
  final int? videoQuality;

  bool get isOriginal => this == TranscodeQualityPreset.original;

  /// Resolution height (e.g. 720, 1080) parsed from [videoResolution]. Null for original.
  int? get resolutionHeight {
    final r = videoResolution;
    if (r == null) return null;
    final parts = r.split('x');
    if (parts.length != 2) return null;
    return int.tryParse(parts[1]);
  }

  /// Whether a source of [bitrateKbps] and [heightPx] already fits inside this
  /// preset's ceiling, so re-encoding it could not improve on the file.
  ///
  /// Height counts as well as bitrate, because the label promises a resolution
  /// too and a device that asked for 1080p may not decode the 4K source a
  /// bitrate-only comparison would pass. An unreported bitrate or height
  /// answers false, as does [original], which has no ceiling.
  bool coversSource({required int? bitrateKbps, required int? heightPx}) {
    final capKbps = videoBitrateKbps;
    final capHeight = resolutionHeight;
    if (capKbps == null || capHeight == null) return false;
    if (bitrateKbps == null || bitrateKbps <= 0 || heightPx == null || heightPx <= 0) return false;
    return bitrateKbps <= capKbps && heightPx <= capHeight;
  }

  /// Order shared by every picker surface so they can't drift apart:
  /// [original] pinned first, then transcode presets highest-bitrate first.
  static final List<TranscodeQualityPreset> displayOrder = List.unmodifiable([
    original,
    ...values.where((p) => !p.isOriginal).toList().reversed,
  ]);

  /// The saved default playback starts at, for callers without an explicit
  /// per-play pick (those apply their own preset directly).
  ///
  /// Backends that cannot transcode start at [original] regardless of any
  /// saved default. Otherwise the cellular default applies on a cellular-only
  /// connection when set, else the general default.
  static TranscodeQualityPreset resolveStartupDefault({
    required bool serverSupportsTranscoding,
    required bool onCellularOnly,
    required TranscodeQualityPreset? cellularDefault,
    required TranscodeQualityPreset generalDefault,
  }) {
    if (!serverSupportsTranscoding) return original;
    if (onCellularOnly && cellularDefault != null) return cellularDefault;
    return generalDefault;
  }
}

/// Outcome of a transcode decision call.
enum TranscodeDecisionOutcome {
  /// Decision indicates transcode is available (`transcodeDecisionCode == 1001`).
  transcodeOk,

  /// Decision indicates only direct play is available (`transcodeDecisionCode == 1000`).
  /// Caller should fall back to the direct-play URL.
  directPlayOnly,

  /// Decision failed (HTTP error, code >= 2000, or parse error).
  failed,
}