import 'package:flutter/foundation.dart';

import '../models/bar_tab.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<BarTab> _openTabs = [];
  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 {
    return _closedTabs
        .where((tab) => _matchesCustomer(tab.customerName))
        .toList();
  }

  List<BarTab> get openTabs {
    return _openTabs
        .where((tab) => _matchesCustomer(tab.customerName))
        .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(),
        barTabService.getOpenTabs(includeRemoved: true),
      ]);

      _closedTabs = (results[0] as List<ClosedTab>).toList()
        ..sort(_compareClosedTabs);
      _totalCount = results[1] as int;
      _openTabs = (results[3] as List<BarTab>).toList()..sort(_compareOpenTabs);
      _customerNames = {
        ...(results[2] as List<String>),
        ..._openTabs.map((tab) => tab.customerName),
      }.toList()..sort();
      _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]..sort(_compareClosedTabs);
      _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,
    );
  }

  int _compareClosedTabs(ClosedTab a, ClosedTab b) {
    final byClosedAt = b.closedAt.compareTo(a.closedAt);
    if (byClosedAt != 0) return byClosedAt;

    return b.id.compareTo(a.id);
  }

  int _compareOpenTabs(BarTab a, BarTab b) {
    final byOpenedAt = b.openedAt.compareTo(a.openedAt);
    if (byOpenedAt != 0) return byOpenedAt;

    return b.id.compareTo(a.id);
  }

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

  bool _matchesCustomer(String customerName) {
    if (_selectedCustomer != null && customerName != _selectedCustomer) {
      return false;
    }

    if (_searchQuery.isEmpty) return true;

    return customerName.toLowerCase().contains(_searchQuery.toLowerCase());
  }

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

    await load();
  }
}