import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../services/odoo_service.dart';
import '../services/notification_service.dart';
import '../theme/app_theme.dart';
import 'notification_detail_screen.dart';
import '../utils/safe_cast.dart';

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

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

class _NotificationsScreenState extends State<NotificationsScreen> {
  List<dynamic> _notifications = [];
  List<String> _readIds = [];
  bool _isLoading = true;

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

  Future<void> _fetchNotifications() async {
    try {
      if (OdooService().client == null) throw Exception('Not connected');

      final response = await OdooService().callRPC(
        '/api/loyalty/fetch_notifications',
        'call',
        {'last_id': 0},
      );

      if (response != null && response['status'] == 'success') {
        final List<dynamic> fetched = response['data'] ?? [];
        final prefs = await SharedPreferences.getInstance();
        final partnerId = OdooService().client?.sessionId?.partnerId ?? 0;
        final keyReadNotificationIds = 'read_notification_ids_$partnerId';
        final readIds = prefs.getStringList(keyReadNotificationIds) ?? [];

        if (mounted) {
          setState(() {
            _notifications = fetched;
            _readIds = readIds;
            _isLoading = false;
          });
        }
      } else {
        throw Exception('Invalid response from server');
      }
    } catch (e) {
      if (mounted) {
        setState(() => _isLoading = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error loading notifications: $e')),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Notifications')),
      body: _isLoading
          ? const Center(child: CircularProgressIndicator())
          : RefreshIndicator(
              onRefresh: _fetchNotifications,
              child: _notifications.isEmpty
                  ? CustomScrollView(
                      physics: const AlwaysScrollableScrollPhysics(),
                      slivers: [
                        SliverFillRemaining(
                          hasScrollBody: false,
                          child: Center(
                            child: Column(
                              mainAxisSize: MainAxisSize.min,
                              children: [
                                Icon(
                                  Icons.notifications_none,
                                  size: 64,
                                  color: AppTheme.onSurfaceVariant.withValues(
                                    alpha: 0.4,
                                  ),
                                ),
                                const SizedBox(height: 16),
                                Text(
                                  'No notifications yet.',
                                  style: Theme.of(context).textTheme.bodyLarge
                                      ?.copyWith(
                                        color: AppTheme.onSurfaceVariant,
                                      ),
                                ),
                              ],
                            ),
                          ),
                        ),
                      ],
                    )
                  : ListView.separated(
                      padding: const EdgeInsets.symmetric(
                        horizontal: 16,
                        vertical: 20,
                      ),
                      itemCount: _notifications.length,
                      separatorBuilder: (_, _) => const SizedBox(height: 8),
                      itemBuilder: (context, index) {
                        final notif = _notifications[index];
                        final isUnread = !_readIds.contains(
                          (notif['id'] as int? ?? 0).toString(),
                        );
                        return _NotificationCard(
                          notif: notif,
                          isUnread: isUnread,
                          onTap: () async {
                            final prefs = await SharedPreferences.getInstance();
                            final partnerId =
                                OdooService().client?.sessionId?.partnerId ?? 0;
                            final keyReadNotificationIds =
                                'read_notification_ids_$partnerId';
                            final readIds =
                                prefs.getStringList(keyReadNotificationIds) ??
                                [];
                            final notifIdStr = (notif['id'] as int? ?? 0)
                                .toString();
                            if (!readIds.contains(notifIdStr)) {
                              readIds.add(notifIdStr);
                              await prefs.setStringList(
                                keyReadNotificationIds,
                                readIds,
                              );

                              // Recalculate and update system badge count
                              final unreadCount = _notifications
                                  .where(
                                    (n) => !readIds.contains(
                                      (n['id'] as int? ?? 0).toString(),
                                    ),
                                  )
                                  .length;
                              await NotificationService().setBadge(unreadCount);
                            }

                            if (!context.mounted) return;
                            await Navigator.push(
                              context,
                              MaterialPageRoute(
                                builder: (_) =>
                                    NotificationDetailScreen(notif: notif),
                              ),
                            );
                            if (!context.mounted) return;
                            _fetchNotifications();
                          },
                        );
                      },
                    ),
            ),
    );
  }
}

class _NotificationCard extends StatelessWidget {
  final dynamic notif;
  final bool isUnread;
  final VoidCallback onTap;

  const _NotificationCard({
    required this.notif,
    required this.isUnread,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    final title = safeString(notif['title']) ?? 'Notice';

    return Material(
      color: AppTheme.surfaceContainerLow,
      child: InkWell(
        onTap: onTap,
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 18),
          child: Row(
            children: [
              notif['has_image'] == true && notif['image_128'] != null
                  ? Container(
                      width: 42,
                      height: 42,
                      decoration: BoxDecoration(
                        shape: BoxShape.rectangle,
                        borderRadius: BorderRadius.circular(4),
                        image: DecorationImage(
                          image: MemoryImage(
                            base64Decode(notif['image_128'] as String),
                          ),
                          fit: BoxFit.cover,
                        ),
                      ),
                    )
                  : Container(
                      padding: const EdgeInsets.all(10),
                      decoration: BoxDecoration(
                        color: AppTheme.primary.withValues(alpha: 0.15),
                        shape: BoxShape.rectangle,
                      ),
                      child: const Icon(
                        Icons.campaign_outlined,
                        color: AppTheme.secondary,
                        size: 22,
                      ),
                    ),
              const SizedBox(width: 16),
              Expanded(
                child: Text(
                  title,
                  style: Theme.of(context).textTheme.titleSmall?.copyWith(
                    color: AppTheme.onSurface,
                    fontWeight: isUnread ? FontWeight.bold : FontWeight.normal,
                  ),
                  maxLines: 2,
                  overflow: TextOverflow.ellipsis,
                ),
              ),
              const SizedBox(width: 8),
              if (isUnread) ...[
                Container(
                  width: 8,
                  height: 8,
                  decoration: const BoxDecoration(
                    color: Colors.red,
                    shape: BoxShape.circle,
                  ),
                ),
                const SizedBox(width: 8),
              ],
              const Icon(
                Icons.chevron_right,
                color: AppTheme.onSurfaceVariant,
                size: 20,
              ),
            ],
          ),
        ),
      ),
    );
  }
}