feat: add equality operators, make history screen paginated, random performance updates

lib/services/bar_tab_service.dart

@@ -18,11 +18,13 @@ abstract class BarTabService {
   Future<void> addProductToTab({
     required String tabId,
     required Product product,
+    Future<void> Function()? stockAdjustment,
   });
 
   Future<void> updateTabItemQuantity({
     required String tabItemId,
     required int quantity,
+    Future<void> Function()? stockAdjustment,
   });
 
   /// Archives the tab's current items into history and clears them.
@@ -30,6 +32,16 @@ abstract class BarTabService {
   Future<void> closeTab(String tabId);
 
   Future<List<ClosedTab>> getClosedTabs();
+
+  Future<List<ClosedTab>> getClosedTabsPaginated({
+    int limit = 20,
+    int offset = 0,
+    String? customerName,
+  });
+
+  Future<int> getClosedTabCount({String? customerName});
+
+  Future<List<String>> getDistinctCustomerNames();
 }
 
 class DriftBarTabService implements BarTabService {
@@ -144,6 +156,7 @@ class DriftBarTabService implements BarTabService {
   Future<void> addProductToTab({
     required String tabId,
     required Product product,
+    Future<void> Function()? stockAdjustment,
   }) async {
     await database.transaction(() async {
       final existingItemQuery = database.select(database.tabItems)
@@ -162,6 +175,10 @@ class DriftBarTabService implements BarTabService {
           TabItemsCompanion(quantity: Value(existingItem.quantity + 1)),
         );
 
+        if (stockAdjustment != null) {
+          await stockAdjustment();
+        }
+
         return;
       }
 
@@ -178,6 +195,10 @@ class DriftBarTabService implements BarTabService {
               createdAt: DateTime.now(),
             ),
           );
+
+      if (stockAdjustment != null) {
+        await stockAdjustment();
+      }
     });
   }
 
@@ -185,19 +206,31 @@ class DriftBarTabService implements BarTabService {
   Future<void> updateTabItemQuantity({
     required String tabItemId,
     required int quantity,
+    Future<void> Function()? stockAdjustment,
   }) async {
-    if (quantity <= 0) {
-      final deleteQuery = database.delete(database.tabItems)
+    await database.transaction(() async {
+      if (quantity <= 0) {
+        final deleteQuery = database.delete(database.tabItems)
+          ..where((item) => item.id.equals(tabItemId));
+
+        await deleteQuery.go();
+
+        if (stockAdjustment != null) {
+          await stockAdjustment();
+        }
+
+        return;
+      }
+
+      final updateQuery = database.update(database.tabItems)
         ..where((item) => item.id.equals(tabItemId));
 
-      await deleteQuery.go();
-      return;
-    }
+      await updateQuery.write(TabItemsCompanion(quantity: Value(quantity)));
 
-    final updateQuery = database.update(database.tabItems)
-      ..where((item) => item.id.equals(tabItemId));
-
-    await updateQuery.write(TabItemsCompanion(quantity: Value(quantity)));
+      if (stockAdjustment != null) {
+        await stockAdjustment();
+      }
+    });
   }
 
   @override
@@ -255,8 +288,26 @@ class DriftBarTabService implements BarTabService {
 
   @override
   Future<List<ClosedTab>> getClosedTabs() async {
-    final query = database.select(database.closedTabs)
-      ..orderBy([(tab) => OrderingTerm.desc(tab.closedAt)]);
+    final count = await getClosedTabCount();
+    if (count == 0) return [];
+
+    return getClosedTabsPaginated(limit: count, offset: 0);
+  }
+
+  @override
+  Future<List<ClosedTab>> getClosedTabsPaginated({
+    int limit = 20,
+    int offset = 0,
+    String? customerName,
+  }) async {
+    var query = database.select(database.closedTabs)
+      ..orderBy([(tab) => OrderingTerm.desc(tab.closedAt)])
+      ..limit(limit, offset: offset);
+
+    if (customerName != null && customerName.isNotEmpty) {
+      query = query
+        ..where((tab) => tab.customerName.equals(customerName));
+    }
 
     final closedTabRows = await query.get();
 
@@ -281,4 +332,30 @@ class DriftBarTabService implements BarTabService {
 
     return closedTabs;
   }
+
+  @override
+  Future<int> getClosedTabCount({String? customerName}) async {
+    final countExpr = database.closedTabs.id.count();
+
+    var query = database.selectOnly(database.closedTabs)
+      ..addColumns([countExpr]);
+
+    if (customerName != null && customerName.isNotEmpty) {
+      query = query
+        ..where(database.closedTabs.customerName.equals(customerName));
+    }
+
+    final row = await query.getSingle();
+    return row.read(countExpr) ?? 0;
+  }
+
+  @override
+  Future<List<String>> getDistinctCustomerNames() async {
+    final rows = await database.select(database.closedTabs).get();
+    return rows
+        .map((row) => row.customerName)
+        .toSet()
+        .toList()
+      ..sort();
+  }
 }