import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:permission_handler/permission_handler.dart';

import '../../services/notification_service.dart';

import '../../providers/notifications_provider.dart';
import '../../providers/profile_provider.dart';
import '../../providers/tasks_provider.dart';
import '../../providers/tickets_provider.dart';
import '../../widgets/app_page_header.dart';
import '../../widgets/app_state_view.dart';
import '../../widgets/mono_text.dart';
import '../../widgets/responsive_body.dart';
import '../../theme/app_surfaces.dart';
import '../../theme/m3_motion.dart';

class NotificationsScreen extends ConsumerStatefulWidget {
  const NotificationsScreen({super.key});

  @override
  ConsumerState<NotificationsScreen> createState() =>
      _NotificationsScreenState();
}

class _NotificationsScreenState extends ConsumerState<NotificationsScreen> {
  bool _showBanner = false;
  bool _dismissed = false;

  @override
  void initState() {
    super.initState();
    _checkChannel();
  }

  Future<void> _checkChannel() async {
    final muted = await NotificationService.isHighPriorityChannelMuted();
    if (!mounted) return;
    if (muted) {
      setState(() => _showBanner = true);
    }
  }

  @override
  Widget build(BuildContext context) {
    final notificationsAsync = ref.watch(notificationsProvider);
    final profilesAsync = ref.watch(profilesProvider);
    final ticketsAsync = ref.watch(ticketsProvider);
    final tasksAsync = ref.watch(tasksProvider);

    final profileById = {
      for (final profile in profilesAsync.valueOrNull ?? [])
        profile.id: profile,
    };
    final ticketById = {
      for (final ticket in ticketsAsync.valueOrNull ?? []) ticket.id: ticket,
    };
    final taskById = {
      for (final task in tasksAsync.valueOrNull ?? []) task.id: task,
    };

    return ResponsiveBody(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          const AppPageHeader(
            title: 'Notifications',
            subtitle: 'Updates and mentions across tasks and tickets',
          ),
          if (_showBanner && !_dismissed)
            Padding(
              padding: const EdgeInsets.only(bottom: 12),
              child: MaterialBanner(
                content: const Text(
                  'Push notifications are currently silenced. Tap here to fix.',
                ),
                actions: [
                  TextButton(
                    onPressed: openAppSettings,
                    child: const Text('Open settings'),
                  ),
                  TextButton(
                    onPressed: () => setState(() => _dismissed = true),
                    child: const Text('Dismiss'),
                  ),
                ],
              ),
            ),
          Expanded(
            child: notificationsAsync.when(
              data: (items) {
                if (items.isEmpty) {
                  return const AppEmptyView(
                    icon: Icons.notifications_none_outlined,
                    title: 'No notifications yet',
                    subtitle:
                        "You'll see updates here when something needs your attention.",
                  );
                }
                return ListView.separated(
                  padding: const EdgeInsets.only(bottom: 24),
                  itemCount: items.length,
                  separatorBuilder: (context, index) =>
                      const SizedBox(height: 12),
                  itemBuilder: (context, index) {
                    final item = items[index];
                    final actorName = item.actorId == null
                        ? 'System'
                        : (profileById[item.actorId]?.fullName ??
                              item.actorId!);
                    final ticketSubject = item.ticketId == null
                        ? 'Ticket'
                        : (ticketById[item.ticketId]?.subject ??
                              item.ticketId!);
                    final taskTitle = item.taskId == null
                        ? 'Task'
                        : (taskById[item.taskId]?.title ?? item.taskId!);
                    final subtitle = item.announcementId != null
                        ? 'Announcement'
                        : item.taskId != null
                            ? taskTitle
                            : ticketSubject;

                    final title = _notificationTitle(item.type, actorName);
                    final icon = _notificationIcon(item.type);

                    Future<void> handleTap() async {
                      final ticketId = item.ticketId;
                      final taskId = item.taskId;
                      if (ticketId != null) {
                        await ref
                            .read(notificationsControllerProvider)
                            .markReadForTicket(ticketId);
                      } else if (taskId != null) {
                        await ref
                            .read(notificationsControllerProvider)
                            .markReadForTask(taskId);
                      } else if (item.isUnread) {
                        await ref
                            .read(notificationsControllerProvider)
                            .markRead(item.id);
                      }
                      if (!context.mounted) return;
                      if (item.announcementId != null) {
                        context.go('/announcements');
                      } else if (taskId != null) {
                        context.go('/tasks/$taskId');
                      } else if (ticketId != null) {
                        context.go('/tickets/$ticketId');
                      }
                    }

                    return M3FadeSlideIn(
                      delay: Duration(
                        milliseconds: index.clamp(0, 6) * 50,
                      ),
                      child: M3PressScale(
                        onTap: handleTap,
                        child: Card(
                          shape: AppSurfaces.of(context).compactShape,
                          child: ListTile(
                            leading: Icon(icon),
                            title: Text(title),
                            subtitle: Column(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Text(subtitle),
                                const SizedBox(height: 4),
                                if (item.ticketId != null)
                                  MonoText('Ticket ${item.ticketId}')
                                else if (item.taskId != null)
                                  MonoText('Task ${item.taskId}'),
                              ],
                            ),
                            trailing: item.isUnread
                                ? Icon(
                                    Icons.circle,
                                    size: 10,
                                    color:
                                        Theme.of(context).colorScheme.error,
                                  )
                                : null,
                          ),
                        ),
                      ),
                    );
                  },
                );
              },
              loading: () => const Center(child: CircularProgressIndicator()),
              error: (error, _) => AppErrorView(
                error: error,
                onRetry: () => ref.invalidate(notificationsProvider),
              ),
            ),
          ),
        ],
      ),
    );
  }

  String _notificationTitle(String type, String actorName) {
    switch (type) {
      case 'assignment':
        return '$actorName assigned you';
      case 'created':
        return '$actorName created a new item';
      case 'swap_request':
        return '$actorName requested a shift swap';
      case 'swap_update':
        return '$actorName updated a swap request';
      case 'announcement':
        return '$actorName posted an announcement';
      case 'announcement_comment':
        return '$actorName commented on an announcement';
      case 'it_job_reminder':
        return 'IT Job submission reminder';
      case 'mention':
      default:
        return '$actorName mentioned you';
    }
  }

  IconData _notificationIcon(String type) {
    switch (type) {
      case 'assignment':
        return Icons.assignment_ind_outlined;
      case 'created':
        return Icons.campaign_outlined;
      case 'swap_request':
        return Icons.swap_horiz;
      case 'swap_update':
        return Icons.update;
      case 'announcement':
        return Icons.campaign;
      case 'announcement_comment':
        return Icons.comment_outlined;
      case 'it_job_reminder':
        return Icons.print;
      case 'mention':
      default:
        return Icons.alternate_email;
    }
  }
}