feat: make server owner of tabs

lib/services/product_service.dart

@@ -4,9 +4,9 @@ import 'package:uuid/uuid.dart';
 import '../database/app_database.dart';
 import '../database/stock_queries.dart';
 import '../models/product.dart';
+import '../models/tab_event.dart';
 
-export '../database/stock_queries.dart'
-    show InsufficientStockException, ProductNotFoundException;
+export '../database/stock_queries.dart' show ProductNotFoundException;
 
 abstract class ProductService {
   /// Active products, re-emitted whenever the products table changes.
@@ -37,9 +37,11 @@ abstract class ProductService {
 
 class DriftProductService implements ProductService {
   final AppDatabase database;
+  final TabEventFactory eventFactory;
   final _uuid = const Uuid();
 
-  DriftProductService({required this.database});
+  DriftProductService({required this.database, TabEventFactory? eventFactory})
+    : eventFactory = eventFactory ?? TabEventFactory();
 
   Product _mapRowToProduct(ProductRow row) {
     return Product(
@@ -95,39 +97,69 @@ class DriftProductService implements ProductService {
     required int priceInCents,
     required String? imagePath,
   }) async {
-    await database
-        .into(database.products)
-        .insert(
-          ProductsCompanion.insert(
-            id: _uuid.v4(),
-            name: name,
-            category: category,
-            stockQuantity: stockQuantity,
-            lowStockThreshold: lowStockThreshold,
-            infiniteStock: Value(infiniteStock),
-            priceInCents: priceInCents,
-            imagePath: Value(imagePath),
-          ),
+    final id = _uuid.v4();
+
+    await database.transaction(() async {
+      await database
+          .into(database.products)
+          .insert(
+            ProductsCompanion.insert(
+              id: id,
+              name: name,
+              category: category,
+              stockQuantity: stockQuantity,
+              lowStockThreshold: lowStockThreshold,
+              infiniteStock: Value(infiniteStock),
+              priceInCents: priceInCents,
+              imagePath: Value(imagePath),
+            ),
+          );
+      // The server starts a product it doesn't know as untracked
+      if (!infiniteStock) {
+        await database.queueStockSet(
+          eventFactory.stockSet(productId: id, quantity: stockQuantity),
         );
+      }
+    });
   }
 
+  /// A changed stock or tracking is queued for the server as a count.
   @override
   Future<void> updateProduct(Product product) async {
-    final query = database.update(database.products)
-      ..where((row) => row.id.equals(product.id));
+    await database.transaction(() async {
+      final current = await (database.select(
+        database.products,
+      )..where((row) => row.id.equals(product.id))).getSingleOrNull();
 
-    await query.write(
-      ProductsCompanion(
-        name: Value(product.name),
-        category: Value(product.category),
-        stockQuantity: Value(product.stockQuantity),
-        lowStockThreshold: Value(product.lowStockThreshold),
-        infiniteStock: Value(product.infiniteStock),
-        priceInCents: Value(product.priceInCents),
-        imagePath: Value(product.imagePath),
-        active: Value(product.active),
-      ),
-    );
+      await (database.update(
+        database.products,
+      )..where((row) => row.id.equals(product.id))).write(
+        ProductsCompanion(
+          name: Value(product.name),
+          category: Value(product.category),
+          stockQuantity: Value(product.stockQuantity),
+          lowStockThreshold: Value(product.lowStockThreshold),
+          infiniteStock: Value(product.infiniteStock),
+          priceInCents: Value(product.priceInCents),
+          imagePath: Value(product.imagePath),
+          active: Value(product.active),
+        ),
+      );
+
+      if (current == null) return;
+      final stockChanged = product.infiniteStock
+          ? !current.infiniteStock
+          : current.infiniteStock ||
+                current.stockQuantity != product.stockQuantity;
+      if (stockChanged) {
+        await database.queueStockSet(
+          eventFactory.stockSet(
+            productId: product.id,
+            quantity: product.infiniteStock ? null : product.stockQuantity,
+          ),
+        );
+      }
+    });
   }
 
   /// Only hidden, since open tabs and history still refer to it.