feat: New Open Tab dialog with search and optional customer email. Drinks are now grouped per order. Payments trigger cha-ching and money rain.

lib/viewmodels/bar_screen_view_model.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
 import 'package:sentry_flutter/sentry_flutter.dart';
+import 'package:uuid/uuid.dart';
 
 import '../models/app_error.dart';
 import '../models/bar_tab.dart';
@@ -15,9 +16,20 @@ import '../services/bar_tab_service.dart';
 /// up without manual reloads. Actions report to Sentry and rethrow; the view
 /// decides how to tell the user.
 class BarScreenViewModel extends ChangeNotifier {
-  final BarTabService barTabService;
+  /// Drinks rung up on the same tab within this time of the previous one are
+  /// one order; a later drink starts a new order.
+  static const orderTimeout = Duration(minutes: 5);
 
-  BarScreenViewModel({required this.barTabService});
+  final BarTabService barTabService;
+  final DateTime Function() _now;
+  final _uuid = const Uuid();
+
+  BarScreenViewModel({required this.barTabService, DateTime Function()? now})
+    : _now = now ?? DateTime.now;
+
+  /// The order being rung up: selecting a tab (again) or a pause of
+  /// [orderTimeout] starts a new one.
+  ({String tabId, String orderId, DateTime lastAddedAt})? _order;
 
   StreamSubscription<List<BarTab>>? _subscription;
   List<BarTab> _tabs = [];
@@ -25,7 +37,30 @@ class BarScreenViewModel extends ChangeNotifier {
   bool _hasLoaded = false;
   AppError? _loadError;
 
-  List<BarTab> get tabs => _tabs;
+  /// Tabs opened on this tablet that have no drinks yet. Only kept in memory:
+  /// after a restart the list starts empty again.
+  final Set<String> _openedTabIds = {};
+
+  /// Every tab the venue knows, open or not.
+  List<BarTab> get allTabs => _tabs;
+
+  /// The tabs on the bar screen: opened here, with drinks on them, or
+  /// selected.
+  List<BarTab> get tabs => [
+    for (final tab in _tabs)
+      if (_isOpen(tab)) tab,
+  ];
+
+  /// The tabs that can be opened from the Open Tab dialog.
+  List<BarTab> get closedTabs => [
+    for (final tab in _tabs)
+      if (!_isOpen(tab)) tab,
+  ];
+
+  bool _isOpen(BarTab tab) =>
+      tab.itemCount > 0 ||
+      _openedTabIds.contains(tab.id) ||
+      tab.id == _selectedTabId;
 
   String? get selectedTabId => _selectedTabId;
 
@@ -55,11 +90,22 @@ class BarScreenViewModel extends ChangeNotifier {
   }
 
   void _onTabs(List<BarTab> tabs) {
+    // A tab whose drinks are all gone (settled elsewhere, or taken off) is
+    // closed again; while it is selected it stays on screen
+    final previousCounts = {for (final tab in _tabs) tab.id: tab.itemCount};
+    for (final tab in tabs) {
+      if ((previousCounts[tab.id] ?? 0) > 0 && tab.itemCount == 0) {
+        _openedTabIds.remove(tab.id);
+      }
+    }
+
     _tabs = tabs;
     _hasLoaded = true;
     _loadError = null;
 
-    if (selectedTab == null) _selectedTabId = tabs.firstOrNull?.id;
+    final ids = {for (final tab in tabs) tab.id};
+    _openedTabIds.retainAll(ids);
+    if (!ids.contains(_selectedTabId)) _selectedTabId = null;
 
     notifyListeners();
   }
@@ -75,13 +121,44 @@ class BarScreenViewModel extends ChangeNotifier {
 
   void selectTab(String tabId) {
     _selectedTabId = tabId;
+    _order = null;
     notifyListeners();
   }
 
-  Future<void> createTab(String customerName) {
+  /// Leaves no tab selected, so products can't be added by accident.
+  void deselectTab() {
+    _selectedTabId = null;
+    _order = null;
+    notifyListeners();
+  }
+
+  /// The order a drink rung up on [tabId] now is part of.
+  String _orderFor(String tabId) {
+    final now = _now();
+    final order = _order;
+    final orderId =
+        order != null &&
+            order.tabId == tabId &&
+            now.difference(order.lastAddedAt) < orderTimeout
+        ? order.orderId
+        : _uuid.v4();
+    _order = (tabId: tabId, orderId: orderId, lastAddedAt: now);
+    return orderId;
+  }
+
+  /// Puts [tabId] on the bar screen and selects it.
+  void openTab(String tabId) {
+    _openedTabIds.add(tabId);
+    selectTab(tabId);
+  }
+
+  Future<void> createTab(String customerName, {String? email}) {
     return _guard('createTab', () async {
-      final tab = await barTabService.createTab(customerName: customerName);
-      selectTab(tab.id);
+      final tab = await barTabService.createTab(
+        customerName: customerName,
+        email: email,
+      );
+      openTab(tab.id);
     });
   }
 
@@ -102,17 +179,30 @@ class BarScreenViewModel extends ChangeNotifier {
 
     await _guard(
       'addProductToSelectedTab',
-      () => barTabService.addProductToTab(tabId: tab.id, product: product),
+      () => barTabService.addProductToTab(
+        tabId: tab.id,
+        product: product,
+        orderId: _orderFor(tab.id),
+      ),
     );
   }
 
-  Future<void> changeItemQuantity(TabItem item, int delta) async {
+  /// More drinks go into the current order; taking drinks off takes them off
+  /// order [orderId], the one they are shown in.
+  Future<void> changeItemQuantity(
+    TabItem item,
+    int delta,
+    String? orderId,
+  ) async {
     if (delta == 0) return;
 
     await _guard(
       'changeItemQuantity',
-      () =>
-          barTabService.adjustTabItemQuantity(tabItemId: item.id, delta: delta),
+      () => barTabService.adjustTabItemQuantity(
+        tabItemId: item.id,
+        delta: delta,
+        order: (orderId: delta > 0 ? _orderFor(item.tabId) : orderId),
+      ),
     );
   }
 
@@ -126,6 +216,9 @@ class BarScreenViewModel extends ChangeNotifier {
       'closeSelectedTab',
       () => barTabService.closeTab(tab.id, paymentMethod: paymentMethod),
     );
+    // A paid tab goes back to the Open Tab dialog
+    _openedTabIds.remove(tab.id);
+    deselectTab();
   }
 
   Future<T> _guard<T>(String action, Future<T> Function() body) async {