79 lines
2.2 KiB
Dart
79 lines
2.2 KiB
Dart
import 'package:drift/drift.dart';
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import 'app_database.dart';
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class InsufficientStockException implements Exception {
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const InsufficientStockException();
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@override
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String toString() => 'Not enough stock';
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}
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class ProductNotFoundException implements Exception {
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final String productId;
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const ProductNotFoundException(this.productId);
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@override
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String toString() => 'Product not found: $productId';
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}
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/// Atomic stock updates shared by the product and tab services, so they can
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/// run inside either one's transaction.
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extension StockQueries on AppDatabase {
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/// Products with infinite stock are only checked for existence.
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Future<void> decreaseStock(String productId, int amount) async {
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_validateStockAmount(amount);
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final updatedRows =
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await (update(products)..where(
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(row) =>
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row.id.equals(productId) &
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row.infiniteStock.not() &
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row.stockQuantity.isBiggerOrEqualValue(amount),
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))
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.write(
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ProductsCompanion.custom(
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stockQuantity: products.stockQuantity - Variable(amount),
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),
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);
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if (updatedRows == 1) return;
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final product = await _findProduct(productId);
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if (!product.infiniteStock) throw const InsufficientStockException();
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}
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Future<void> increaseStock(String productId, int amount) async {
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_validateStockAmount(amount);
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final updatedRows =
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await (update(products)..where(
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(row) => row.id.equals(productId) & row.infiniteStock.not(),
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))
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.write(
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ProductsCompanion.custom(
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stockQuantity: products.stockQuantity + Variable(amount),
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),
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);
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if (updatedRows != 1) await _findProduct(productId);
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}
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Future<ProductRow> _findProduct(String productId) async {
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final product = await (select(
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products,
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)..where((row) => row.id.equals(productId))).getSingleOrNull();
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if (product == null) throw ProductNotFoundException(productId);
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return product;
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}
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void _validateStockAmount(int amount) {
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if (amount <= 0) {
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throw ArgumentError.value(amount, 'amount', 'Must be greater than zero');
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}
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}
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}
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