import 'package:flutter/foundation.dart';

import 'parse.dart';

enum AlertSeverity { info, warning, critical }

/// One live diagnostic from the aircraft (`DJIDiagnostics`).
@immutable
class DiagnosticAlert {
  const DiagnosticAlert({
    required this.component,
    required this.code,
    this.subCode,
    this.componentIndex,
    required this.reason,
    this.solution,
    required this.severity,
    required this.firstSeen,
  });

  /// `FLIGHT_CONTROLLER`, `BATTERY`, `CAMERA`, `GIMBAL`, `VISION`, `REMOTE_CONTROLLER` …
  final String component;
  final int code;
  final int? subCode;
  final int? componentIndex;
  final String reason;
  final String? solution;
  final AlertSeverity severity;
  final DateTime firstSeen;

  /// What de-duplicates an alert: the same fault on the same component.
  String get key => '$component/$code/${componentIndex ?? 0}';
}

/// The aircraft's active diagnostics, graded and ordered for the tip marquee,
/// the error stack and the Aircraft Status sheet.
///
/// The bridge sends the *complete* current list on every change, so [apply]
/// replaces the set: what is no longer listed has cleared. An alert keeps its
/// [DiagnosticAlert.firstSeen] for as long as it stays listed, and one the pilot
/// [dismiss]ed stays hidden until it clears and comes back.
class AlertState extends ChangeNotifier {
  List<DiagnosticAlert> _all = const <DiagnosticAlert>[];
  final Set<String> _dismissed = <String>{};

  /// Keys that appeared in the last [apply] — what P3 buzzes and pops a card for.
  Set<String> lastAdded = const <String>{};

  DateTime? updatedAt;

  /// Every listed alert, most severe first, then oldest first.
  List<DiagnosticAlert> get all => _all;

  /// [all] minus what the pilot dismissed.
  List<DiagnosticAlert> get active => <DiagnosticAlert>[for (final DiagnosticAlert a in _all) if (!_dismissed.contains(a.key)) a];

  /// The marquee's message: the most severe alert, dismissed or not.
  DiagnosticAlert? get top => _all.isEmpty ? null : _all.first;

  AlertSeverity? get worst => top?.severity;

  void apply(List<Map<String, dynamic>> items, {DateTime? now}) {
    final DateTime t = now ?? DateTime.now();
    final Map<String, DiagnosticAlert> previous = <String, DiagnosticAlert>{for (final DiagnosticAlert a in _all) a.key: a};
    final Map<String, DiagnosticAlert> next = <String, DiagnosticAlert>{};
    for (final Map<String, dynamic> m in items) {
      final String component = asString(m['component']) ?? 'OTHER';
      final int code = asInt(m['code']) ?? 0;
      final String reason = (asString(m['reason']) ?? '').trim();
      final String? solution = asString(m['solution'])?.trim();
      final int? index = asInt(m['componentIndex']);
      final String key = '$component/$code/${index ?? 0}';
      if (next.containsKey(key)) continue;
      next[key] = DiagnosticAlert(
        component: component,
        code: code,
        subCode: asInt(m['subCode']),
        componentIndex: index,
        reason: reason.isEmpty ? '$component error $code' : reason,
        solution: (solution == null || solution.isEmpty) ? null : solution,
        severity: grade(component, reason, solution),
        firstSeen: previous[key]?.firstSeen ?? t,
      );
    }
    lastAdded = <String>{for (final String k in next.keys) if (!previous.containsKey(k)) k};
    // A cleared alert forgets its dismissal, so it pops up again if it returns.
    _dismissed.removeWhere((String k) => !next.containsKey(k));
    _all = next.values.toList()
      ..sort((DiagnosticAlert a, DiagnosticAlert b) {
        final int s = b.severity.index.compareTo(a.severity.index);
        return s != 0 ? s : a.firstSeen.compareTo(b.firstSeen);
      });
    updatedAt = t;
    notifyListeners();
  }

  void dismiss(String key) {
    if (_dismissed.add(key)) notifyListeners();
  }

  void clear() {
    _all = const <DiagnosticAlert>[];
    _dismissed.clear();
    lastAdded = const <String>{};
    updatedAt = null;
    notifyListeners();
  }

  static final RegExp _critical = RegExp(
    r'critical|serious|forced? landing|landing immediately|auto[- ]?land|motor|propeller|\besc\b|overheat|'
    r'imu (error|abnormal)|compass (error|abnormal)|obstacle|collision',
    caseSensitive: false,
  );
  static final RegExp _info = RegExp(r'calibrat(ing|ion in progress)|updating|initializ|preheat', caseSensitive: false);

  /// The SDK attaches no severity, so it is read off the message. A heuristic
  /// until runtime capture (plan R2) maps GO 4's own code → colour table.
  @visibleForTesting
  static AlertSeverity grade(String component, String reason, String? solution) {
    final String text = '$reason ${solution ?? ''}';
    if (_critical.hasMatch(text)) return AlertSeverity.critical;
    if (_info.hasMatch(text)) return AlertSeverity.info;
    return AlertSeverity.warning;
  }
}