import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:firebase_messaging/firebase_messaging.dart';

import '../models/notification_item.dart';
import '../providers/notifications_provider.dart';
import '../providers/realtime_controller.dart';

/// Wraps the app and installs both a Supabase realtime listener and the
/// FCM handlers described in the frontend design.
///
/// The navigator key is required so that snackbars and navigation can be
/// triggered from outside the widget tree (e.g. from realtime callbacks).
class NotificationBridge extends ConsumerStatefulWidget {
  const NotificationBridge({
    required this.navigatorKey,
    required this.child,
    super.key,
  });

  final GlobalKey<NavigatorState> navigatorKey;
  final Widget child;

  @override
  ConsumerState<NotificationBridge> createState() => _NotificationBridgeState();
}

class _NotificationBridgeState extends ConsumerState<NotificationBridge>
    with WidgetsBindingObserver {
  // store previous notifications to diff
  List<NotificationItem> _prevList = [];

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _setupFcmHandlers();
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);
    if (state == AppLifecycleState.resumed) {
      try {
        // Trigger a best-effort realtime reconnection when the app resumes.
        ref.read(realtimeControllerProvider).recoverConnection();
      } catch (_) {}
    }
  }

  void _showBanner(String type, NotificationItem item) {
    final ctx = widget.navigatorKey.currentState?.overlay?.context;
    if (ctx == null) return;

    ScaffoldMessenger.of(ctx).showSnackBar(
      SnackBar(
        content: Text('New $type received!'),
        action: SnackBarAction(
          label: 'View',
          onPressed: () => _navigateToNotification(item),
        ),
      ),
    );
  }

  void _navigateToNotification(NotificationItem item) {
    widget.navigatorKey.currentState?.pushNamed(
      '/notification-detail',
      arguments: item,
    );
  }

  void _setupFcmHandlers() {
    // ignore foreground messages; realtime websocket will surface them
    FirebaseMessaging.onMessage.listen((_) {});

    // handle taps when the app is backgrounded
    FirebaseMessaging.onMessageOpenedApp.listen(_handleMessageTap);

    // handle a tap that launched the app from a terminated state
    FirebaseMessaging.instance.getInitialMessage().then((msg) {
      if (msg != null) _handleMessageTap(msg);
    });
  }

  void _handleMessageTap(RemoteMessage message) {
    final data = message.data.cast<String, dynamic>();
    final item = NotificationItem.fromMap(data);
    _navigateToNotification(item);
  }

  @override
  Widget build(BuildContext context) {
    // listen inside build; safe with ConsumerState
    ref.listen<AsyncValue<List<NotificationItem>>>(notificationsProvider, (
      previous,
      next,
    ) {
      final prevList = _prevList;
      final nextList = next.maybeWhen(
        data: (d) => d,
        orElse: () => <NotificationItem>[],
      );
      if (nextList.length > prevList.length) {
        final newItem = nextList.last;
        _showBanner(newItem.type, newItem);
      }
      _prevList = nextList;
    });
    return widget.child;
  }
}