Sales order barcode (#466)

* Add barcode handler for allocating stock to sales order

* Refactor sales order allocation fields

* Improve barcode handling

* Handle barcode scan from sales order line detail view

* Remove debug statements

lib/barcode/sales_order.dart

@@ -1,4 +1,6 @@
 import "package:flutter/material.dart";
+import "package:font_awesome_flutter/font_awesome_flutter.dart";
+import "package:inventree/api_form.dart";
 
 import "package:inventree/inventree/part.dart";
 import "package:inventree/inventree/sales_order.dart";
@@ -77,5 +79,98 @@ class SOAddItemBarcodeHandler extends BarcodeHandler {
     }
 
   }
+}
 
+
+class SOAllocateStockHandler extends BarcodeHandler {
+
+  SOAllocateStockHandler({this.salesOrder, this.lineItem, this.shipment});
+
+  InvenTreeSalesOrder? salesOrder;
+  InvenTreeSOLineItem? lineItem;
+  InvenTreeSalesOrderShipment? shipment;
+
+  @override
+  String getOverlayText(BuildContext context) => L10().allocateStock;
+
+  @override
+  Future<void> processBarcode(String barcode,
+  {
+    String url = "barcode/so-allocate/",
+    Map<String, dynamic> extra_data = const {}}) {
+
+    final so_extra_data = {
+      "sales_order": salesOrder?.pk,
+      "shipment": shipment?.pk,
+      "line": lineItem?.pk,
+      ...extra_data
+    };
+
+    return super.processBarcode(barcode, url: url, extra_data: so_extra_data);
+  }
+
+  @override
+  Future<void> onBarcodeMatched(Map<String, dynamic> data) async {
+    if (!data.containsKey("line_item")) {
+      return onBarcodeUnknown(data);
+    }
+
+    barcodeSuccessTone();
+    showSnackIcon(L10().allocated, success: true);
+  }
+
+  @override
+  Future<void> onBarcodeUnhandled(Map<String, dynamic> data) async {
+
+    if (!data.containsKey("action_required") || !data.containsKey("line_item")) {
+      return super.onBarcodeUnhandled(data);
+    }
+
+    // Prompt user for extra information to create the allocation
+    var fields = InvenTreeSOLineItem().allocateFormFields();
+
+    // Update fields with data gathered from the API response
+    fields["line_item"]?["value"] = data["line_item"];
+
+    Map<String, dynamic> stock_filters = {
+      "in_stock": true,
+      "available": true,
+    };
+
+    if (data.containsKey("part")) {
+      stock_filters["part"] = data["part"];
+    }
+
+    fields["stock_item"]?["filters"] = stock_filters;
+    fields["stock_item"]?["value"] = data["stock_item"];
+
+    fields["quantity"]?["value"] = data["quantity"];
+
+    fields["shipment"]?["value"] = data["shipment"];
+    fields["shipment"]?["filters"] = {
+      "order": salesOrder!.pk.toString()
+    };
+
+    final context = OneContext().context!;
+
+    launchApiForm(
+      context,
+      L10().allocateStock,
+      salesOrder!.allocate_url,
+    fields,
+    method: "POST",
+    icon: FontAwesomeIcons.rightToBracket,
+    onSuccess: (data) async {
+        showSnackIcon(L10().allocated, success: true);
+    });
+  }
+
+  @override
+  Future<void> onBarcodeUnknown(Map<String, dynamic> data) async {
+    barcodeFailureTone();
+    showSnackIcon(
+        data["error"] as String? ?? L10().barcodeError,
+        success: false
+    );
+  }
 }