// One signal's current state as a display needs it: value, and whether to draw it dim
// (missing, stale or known-without-value; app guideline 2).

import 'boundary.dart';

/// One signal's current state, as the dash needs it.
class Reading {
  const Reading(this.value, {this.dim = false});

  /// The value, or null when missing or known-without-value.
  final Object? value;

  /// Missing or stale: drawn in subdued.
  final bool dim;

  static Reading of(Boundary b, String name) {
    final e = b.signals[name];
    if (e is! Map) return const Reading(null, dim: true);
    final q = e['quality'] as String? ?? 'ok';
    return Reading(e['value'], dim: q != 'ok' || e['value'] == null);
  }

  double? get number => value is num ? (value as num).toDouble() : null;
  bool get on => value == true;

  String fixed([int decimals = 0]) =>
      number == null ? '—' : number!.toStringAsFixed(decimals);
}