import 'dart:async';

import 'package:clide/kernel/src/events/message_bus.dart';
import 'package:clide/kernel/src/toast.dart';
import 'package:flutter/foundation.dart';

enum NotificationLevel { info, warning, error, success }

@immutable
class ClideNotification {
  ClideNotification({required this.id, required this.level, required this.message, this.title, this.duration = const Duration(seconds: 4)})
    : createdAt = DateTime.now().toUtc();

  final String id;
  final NotificationLevel level;
  final String? title;
  final String message;
  final DateTime createdAt;
  final Duration duration;
}

class Notifications extends ChangeNotifier {
  Notifications({MessageBus? messages}) : _messages = messages;

  /// When wired (the facade passes the kernel bus), every notification is
  /// also published to the toast channel so it actually renders — the
  /// in-memory list had zero widget consumers and messages vanished
  /// silently (T-382).
  final MessageBus? _messages;

  final List<ClideNotification> _active = [];
  final Map<String, Timer> _timers = {};
  int _seq = 0;

  List<ClideNotification> get active => List.unmodifiable(_active);

  void info(String message, {String? title, Duration? duration}) => _push(NotificationLevel.info, message, title: title, duration: duration);
  void warn(String message, {String? title, Duration? duration}) => _push(NotificationLevel.warning, message, title: title, duration: duration);
  void error(String message, {String? title, Duration? duration}) => _push(NotificationLevel.error, message, title: title, duration: duration);
  void success(String message, {String? title, Duration? duration}) => _push(NotificationLevel.success, message, title: title, duration: duration);

  void dismiss(String id) {
    _timers.remove(id)?.cancel();
    final before = _active.length;
    _active.removeWhere((n) => n.id == id);
    if (_active.length != before) notifyListeners();
  }

  void _push(NotificationLevel level, String message, {String? title, Duration? duration}) {
    final id = 'n${_seq++}';
    final n = ClideNotification(id: id, level: level, message: message, title: title, duration: duration ?? const Duration(seconds: 4));
    _active.add(n);
    _timers[id] = Timer(n.duration, () => dismiss(id));
    final bus = _messages;
    if (bus != null) {
      publishToast(
        bus,
        'kernel.notify',
        title == null ? message : '$title — $message',
        severity: switch (level) {
          NotificationLevel.info => ToastSeverity.info,
          NotificationLevel.warning => ToastSeverity.warning,
          NotificationLevel.error => ToastSeverity.error,
          NotificationLevel.success => ToastSeverity.success,
        },
        duration: duration,
      );
    }
    notifyListeners();
  }

  @override
  void dispose() {
    for (final t in _timers.values) {
      t.cancel();
    }
    _timers.clear();
    super.dispose();
  }
}