import 'package:flutter/foundation.dart';

import '../models/closed_tab.dart';
import '../services/bar_tab_service.dart';

class HistoryViewModel extends ChangeNotifier {
  final BarTabService barTabService;

  HistoryViewModel({required this.barTabService});

  static const int _pageSize = 20;

  List<ClosedTab> _closedTabs = [];
  List<String> _customerNames = [];
  String? _selectedCustomer;
  int _offset = 0;
  int _totalCount = 0;
  bool _isLoading = false;
  bool _hasLoaded = false;
  bool _isLoadingMore = false;
  String? _errorMessage;
  String _searchQuery = '';

  List<ClosedTab> get closedTabs {
    if (_searchQuery.isEmpty) return _closedTabs;

    return _closedTabs
        .where(
          (tab) => tab.customerName.toLowerCase().contains(
            _searchQuery.toLowerCase(),
          ),
        )
        .toList();
  }

  List<String> get customerNames => _customerNames;

  String? get selectedCustomer => _selectedCustomer;

  bool get isLoading => _isLoading;

  bool get hasLoaded => _hasLoaded;

  bool get isLoadingMore => _isLoadingMore;

  bool get hasMore => _closedTabs.length < _totalCount;

  String? get errorMessage => _errorMessage;

  Future<void> ensureLoaded() async {
    if (_hasLoaded || _isLoading) return;

    await load();
  }

  Future<void> load() async {
    if (_isLoading) return;

    _isLoading = true;
    _errorMessage = null;
    notifyListeners();

    try {
      final results = await Future.wait([
        _fetchPage(offset: 0),
        barTabService.getClosedTabCount(
          customerName: _selectedCustomer,
        ),
        barTabService.getDistinctCustomerNames(),
      ]);

      _closedTabs = results[0] as List<ClosedTab>;
      _totalCount = results[1] as int;
      _customerNames = results[2] as List<String>;
      _offset = _closedTabs.length;
    } catch (e) {
      debugPrint('HistoryViewModel: load error: $e');
      _errorMessage = 'Could not load tab history.';
    } finally {
      _hasLoaded = true;
      _isLoading = false;
      notifyListeners();
    }
  }

  Future<void> loadMore() async {
    if (_isLoadingMore || !hasMore) return;

    _isLoadingMore = true;
    notifyListeners();

    try {
      final more = await _fetchPage(offset: _offset);
      _closedTabs = [..._closedTabs, ...more];
      _offset = _closedTabs.length;
    } catch (e) {
      debugPrint('HistoryViewModel: loadMore error: $e');
      _errorMessage = 'Could not load more tabs.';
    } finally {
      _isLoadingMore = false;
      notifyListeners();
    }
  }

  Future<List<ClosedTab>> _fetchPage({required int offset}) {
    return barTabService.getClosedTabsPaginated(
      limit: _pageSize,
      offset: offset,
      customerName: _selectedCustomer,
    );
  }

  void search(String query) {
    _searchQuery = query;
    notifyListeners();
  }

  Future<void> filterByCustomer(String? customerName) async {
    _selectedCustomer = customerName;
    _searchQuery = '';
    _offset = 0;
    _closedTabs = [];

    await load();
  }
}