added categories, import export, settings

lib/models/purchase.dart

@@ -0,0 +1,36 @@
+/// One time a product was bought, used for price and purchase history.
+library;
+
+class Purchase {
+  const Purchase({
+    required this.shopId,
+    required this.boughtAt,
+    required this.supermarket,
+    required this.price,
+    this.quantity,
+    this.unitPrice,
+    this.receiptImagePath,
+  });
+
+  final int shopId;
+  final DateTime boughtAt;
+  final String supermarket;
+  final double price;
+  final int? quantity;
+  final double? unitPrice;
+  final String? receiptImagePath;
+
+  double get unitOrLinePrice => unitPrice ?? price;
+
+  factory Purchase.fromMap(Map<String, Object?> map) {
+    return Purchase(
+      shopId: map['shop_id']! as int,
+      boughtAt: DateTime.parse(map['shopped_at']! as String),
+      supermarket: map['supermarket']! as String,
+      price: (map['price']! as num).toDouble(),
+      quantity: map['quantity'] as int?,
+      unitPrice: (map['unit_price'] as num?)?.toDouble(),
+      receiptImagePath: map['receipt_image_path'] as String?,
+    );
+  }
+}