import 'package:flutter/foundation.dart';
import 'package:hive_flutter/hive_flutter.dart';

import '../local/hive_boxes.dart';
import 'notification_analytics_service.dart';

class NotificationInboxItem {
  const NotificationInboxItem({
    required this.id,
    required this.title,
    required this.body,
    required this.type,
    required this.createdAt,
    required this.expiresAt,
    required this.readAt,
    required this.isPinned,
    required this.source,
    required this.deeplink,
    required this.meta,
  });

  final String id;
  final String title;
  final String body;
  final String type;
  final DateTime createdAt;
  final DateTime? expiresAt;
  final DateTime? readAt;
  final bool isPinned;
  final String source;
  final String? deeplink;
  final Map<String, dynamic> meta;

  bool get isRead => readAt != null;
  bool get isExpired => expiresAt != null && DateTime.now().isAfter(expiresAt!);

  Map<String, dynamic> toMap() => {
        'id': id,
        'title': title,
        'body': body,
        'type': type,
        'createdAt': createdAt.toIso8601String(),
        'expiresAt': expiresAt?.toIso8601String(),
        'readAt': readAt?.toIso8601String(),
        'isPinned': isPinned,
        'source': source,
        'deeplink': deeplink,
        'meta': meta,
      };

  static NotificationInboxItem fromMap(Map<dynamic, dynamic> map) {
    final createdRaw = (map['createdAt'] ?? '').toString();
    final expiresRaw = (map['expiresAt'] ?? '').toString();
    final readRaw = (map['readAt'] ?? '').toString();
    final rawMeta = map['meta'];

    return NotificationInboxItem(
      id: (map['id'] ?? '').toString(),
      title: (map['title'] ?? '').toString(),
      body: (map['body'] ?? '').toString(),
      type: (map['type'] ?? 'system').toString(),
      createdAt: DateTime.tryParse(createdRaw) ??
          DateTime.fromMillisecondsSinceEpoch(0),
      expiresAt: expiresRaw.isEmpty ? null : DateTime.tryParse(expiresRaw),
      readAt: readRaw.isEmpty ? null : DateTime.tryParse(readRaw),
      isPinned: map['isPinned'] == true,
      source: (map['source'] ?? 'local').toString(),
      deeplink: ((map['deeplink'] ?? '').toString().trim().isEmpty)
          ? null
          : (map['deeplink'] ?? '').toString(),
      meta: rawMeta is Map
          ? rawMeta.map((k, v) => MapEntry(k.toString(), v))
          : const <String, dynamic>{},
    );
  }
}

class NotificationInboxService {
  NotificationInboxService._();
  static final NotificationInboxService instance = NotificationInboxService._();

  Box get _box => Hive.box(HiveBoxes.notificationInbox);

  ValueListenable<Box> listenable() => _box.listenable();

  List<NotificationInboxItem> allItems({
    String filter = 'all',
  }) {
    final items = _box.values
        .whereType<Map>()
        .map((raw) => NotificationInboxItem.fromMap(raw))
        .where((item) => !item.isExpired)
        .where((item) {
      switch (filter) {
        case 'unread':
          return !item.isRead;
        case 'system':
          return item.type == 'system';
        default:
          return true;
      }
    }).toList()
      ..sort((a, b) {
        if (a.isPinned != b.isPinned) {
          return a.isPinned ? -1 : 1;
        }
        return b.createdAt.compareTo(a.createdAt);
      });
    return items;
  }

  int unreadCount() => allItems().where((e) => !e.isRead).length;

  Future<void> addItem({
    required String title,
    required String body,
    required String type,
    String source = 'local',
    String? deeplink,
    String? dedupeKey,
    DateTime? expiresAt,
    bool isPinned = false,
    Map<String, dynamic> meta = const <String, dynamic>{},
  }) async {
    final key = dedupeKey ?? _defaultKey(type, title, body);
    if (_box.containsKey(key)) {
      final existingRaw = _box.get(key);
      if (existingRaw is Map) {
        final existing = NotificationInboxItem.fromMap(existingRaw);
        await _box.put(
          key,
          existing
              .copyWith(
                title: title,
                body: body,
                type: type,
                source: source,
                deeplink: deeplink,
                expiresAt: expiresAt ?? existing.expiresAt,
                isPinned: isPinned || existing.isPinned,
                meta: meta.isEmpty ? existing.meta : meta,
              )
              .toMap(),
        );
      }
      return;
    }

    final item = NotificationInboxItem(
      id: key,
      title: title,
      body: body,
      type: type,
      createdAt: DateTime.now(),
      expiresAt: expiresAt,
      readAt: null,
      isPinned: isPinned,
      source: source,
      deeplink: deeplink,
      meta: meta,
    );
    await _box.put(key, item.toMap());
    await NotificationAnalyticsService.instance.track(
      'notif_inbox_created',
      dimensions: <String, dynamic>{
        'event_type': type,
        'source': source,
      },
    );
  }

  Future<void> markRead(String id) async {
    final raw = _box.get(id);
    if (raw is! Map) return;
    final item = NotificationInboxItem.fromMap(raw);
    if (item.isRead) return;
    await _box.put(
      id,
      item.copyWith(readAt: DateTime.now()).toMap(),
    );
    await NotificationAnalyticsService.instance.track(
      'notif_mark_read',
      dimensions: <String, dynamic>{'event_type': item.type},
    );
  }

  Future<void> markUnread(String id) async {
    final raw = _box.get(id);
    if (raw is! Map) return;
    final item = NotificationInboxItem.fromMap(raw);
    if (!item.isRead) return;
    await _box.put(
      id,
      item.copyWith(readAt: null).toMap(),
    );
    await NotificationAnalyticsService.instance.track(
      'notif_mark_unread',
      dimensions: <String, dynamic>{'event_type': item.type},
    );
  }

  Future<void> markAllRead() async {
    final updates = <dynamic, Map<String, dynamic>>{};
    for (final key in _box.keys) {
      final raw = _box.get(key);
      if (raw is! Map) continue;
      final item = NotificationInboxItem.fromMap(raw);
      if (item.isRead) continue;
      updates[key] = item.copyWith(readAt: DateTime.now()).toMap();
    }
    if (updates.isNotEmpty) {
      await _box.putAll(updates);
    }
  }

  Future<void> remove(String id) async {
    await _box.delete(id);
  }

  Future<void> removeByType(String type) async {
    final keys = <dynamic>[];
    for (final key in _box.keys) {
      final raw = _box.get(key);
      if (raw is! Map) continue;
      final item = NotificationInboxItem.fromMap(raw);
      if (item.type == type) {
        keys.add(key);
      }
    }
    if (keys.isNotEmpty) {
      await _box.deleteAll(keys);
    }
  }

  Future<void> togglePinned(String id) async {
    final raw = _box.get(id);
    if (raw is! Map) return;
    final item = NotificationInboxItem.fromMap(raw);
    await _box.put(
      id,
      item.copyWith(isPinned: !item.isPinned).toMap(),
    );
  }

  Future<void> removeExpired() async {
    final expiredKeys = <dynamic>[];
    for (final key in _box.keys) {
      final raw = _box.get(key);
      if (raw is! Map) continue;
      final item = NotificationInboxItem.fromMap(raw);
      if (item.isExpired) expiredKeys.add(key);
    }
    if (expiredKeys.isNotEmpty) {
      await _box.deleteAll(expiredKeys);
    }
  }

  String _defaultKey(String type, String title, String body) {
    final seed = '$type|$title|$body';
    var hash = 17;
    for (final rune in seed.runes) {
      hash = 31 * hash + rune;
    }
    return 'inbox_${hash.abs()}';
  }
}

extension on NotificationInboxItem {
  static const _readAtUnchanged = Object();

  NotificationInboxItem copyWith({
    String? title,
    String? body,
    String? type,
    DateTime? createdAt,
    DateTime? expiresAt,
    Object? readAt = _readAtUnchanged,
    bool? isPinned,
    String? source,
    String? deeplink,
    Map<String, dynamic>? meta,
  }) {
    return NotificationInboxItem(
      id: id,
      title: title ?? this.title,
      body: body ?? this.body,
      type: type ?? this.type,
      createdAt: createdAt ?? this.createdAt,
      expiresAt: expiresAt ?? this.expiresAt,
      readAt: identical(readAt, _readAtUnchanged)
          ? this.readAt
          : readAt as DateTime?,
      isPinned: isPinned ?? this.isPinned,
      source: source ?? this.source,
      deeplink: deeplink ?? this.deeplink,
      meta: meta ?? this.meta,
    );
  }
}