/// Immutable record of a single fluid-intake log.
///
/// Pure Dart (no framework imports) so the entity can be shared by the
/// nutrition use cases, the drift-backed repository, and the Riverpod
/// presentation layer without leaking infrastructure concerns into the
/// domain.
class HydrationLogEntry {
  const HydrationLogEntry({
    this.id,
    required this.timestamp,
    required this.volumeOz,
  });

  /// Database primary key; `null` until the entry has been persisted.
  final int? id;

  /// When the fluid was consumed.
  final DateTime timestamp;

  /// Consumed volume in fluid ounces (US fl oz).
  final double volumeOz;

  /// Copy helper preserving the database identifier.
  HydrationLogEntry copyWith({int? id, DateTime? timestamp, double? volumeOz}) =>
      HydrationLogEntry(
        id: id ?? this.id,
        timestamp: timestamp ?? this.timestamp,
        volumeOz: volumeOz ?? this.volumeOz,
      );
}