/// Muscle groups tracked by the resistance-training log.
///
/// Pure Dart (no framework imports) so the enum can be shared by the domain
/// entity, the future drift-backed repository (persisted via
/// [persistenceKey]), and the presentation layer.
enum MuscleGroup {
  chest,
  back,
  shoulders,
  legs,
  arms,
  core;

  /// Stable string persisted in the database; never changes across renames.
  String get persistenceKey => name;

  /// Human-readable label for dialogs and log grouping headers.
  String get displayName {
    switch (this) {
      case MuscleGroup.chest:
        return 'Chest';
      case MuscleGroup.back:
        return 'Back';
      case MuscleGroup.shoulders:
        return 'Shoulders';
      case MuscleGroup.legs:
        return 'Legs';
      case MuscleGroup.arms:
        return 'Arms';
      case MuscleGroup.core:
        return 'Core';
    }
  }

  /// Parses a persisted key; returns `null` for unknown/legacy values.
  static MuscleGroup? tryParse(String? raw) {
    if (raw == null) return null;
    for (final group in values) {
      if (group.persistenceKey == raw) return group;
    }
    return null;
  }
}