import 'package:flutter/foundation.dart';

import 'parse.dart';

/// Settings as a component reported them, overlaid with the HUD's optimistic
/// writes (plan P4, reused by the gimbal in P5).
///
/// A pending value stands until the component reports that setting changed,
/// the write fails, or the writer gives up waiting ([dropPending]) — so a
/// value the component silently refused snaps back.
mixin SettingsOverlay on ChangeNotifier {
  Map<String, dynamic> _reported = const <String, dynamic>{};
  final Map<String, Object?> _pending = <String, Object?>{};

  /// What the component reported, overlaid with pending writes.
  Map<String, dynamic> get settings => _pending.isEmpty ? _reported : <String, dynamic>{..._reported, ..._pending};

  /// Only what the component itself reported.
  Map<String, dynamic> get reportedSettings => _reported;

  bool isPending(String id) => _pending.containsKey(id);

  Object? setting(String id) => settings[id];

  /// Shows [values] ahead of the component's read-back.
  void setPending(Map<String, Object?> values) {
    _pending.addAll(values);
    notifyListeners();
  }

  /// Rolls [ids] back to what the component last reported.
  void dropPending(Iterable<String> ids) {
    bool changed = false;
    for (final String id in ids) {
      changed = _pending.remove(id) != null || changed;
    }
    if (changed) notifyListeners();
  }

  /// Takes a new report; a pending write is answered once its setting moves.
  /// Does not notify — the caller does, with its other fields.
  @protected
  void replaceReported(Map<String, dynamic> reported) {
    _pending.removeWhere((String id, _) => !deepEquals(_reported[id], reported[id]));
    _reported = reported;
  }

  @protected
  void clearSettings() {
    _reported = const <String, dynamic>{};
    _pending.clear();
  }
}