[FIX] sale_ux: Ensure correct account on downpayment lines

sale_ux/models/sale_order_line.py

@@ -51,3 +51,27 @@ def create(self, vals_list):
 
     def _get_protected_fields(self):
         return super()._get_protected_fields() + ["discount"]
+
+    def _prepare_invoice_line(self, **optional_values):
+        res = super()._prepare_invoice_line(**optional_values)
+        # Fix multicompañía: si se cambia la compañía de una factura de anticipo con el wizard de change company,
+        # luego al facturar el resto se puede usar una cuenta contable de la compañía incorrecta.
+
+        downpayment_lines = self.invoice_lines.filtered("is_downpayment")
+        account_id = res.get("account_id") and self.env["account.account"].browse(res["account_id"]) or None
+
+        if (
+            self.is_downpayment
+            and downpayment_lines
+            and account_id
+            and self.company_id.id not in account_id.company_ids.ids
+        ):
+            invoiceable_products = self.order_id._get_invoiceable_lines().mapped("product_id")
+            product_accounts = invoiceable_products.product_tmpl_id.get_product_accounts(
+                fiscal_pos=self.order_id.fiscal_position_id
+            )
+            new_account = product_accounts.get("downpayment") or product_accounts.get("income")
+            if new_account:
+                res["account_id"] = new_account.id
+
+        return res