[FIX] product_catalog_tree: improve order line quantity update logic

closes #858

Signed-off-by: matiasperalta1 <mnp@adhoc.com.ar>

Author: lef-adhoc

product_catalog_tree/models/product_product.py

@@ -58,9 +58,26 @@ def _inverse_catalog_values(self, product_catalog_qty):
 
         order = self.env[res_model].browse(order_id)
         for rec in self:
-            # Actualizar la información de la línea de orden
-            # Call the order method with a cleared context to avoid errors on creating move line
-            order.with_company(order.company_id).with_context(**{})._update_order_line_info(rec.id, product_catalog_qty)
+            existing_lines = order.order_line.filtered(lambda line: line.product_id.id == rec.id)
+            if len(existing_lines) > 1 and product_catalog_qty > 0:
+                total_current_qty = sum(existing_lines.mapped("product_uom_qty"))
+                qty_difference = product_catalog_qty - total_current_qty
+                if qty_difference >= 0:
+                    existing_lines[0].product_uom_qty += qty_difference
+                else:
+                    remaining_to_reduce = abs(qty_difference)
+                    for line in existing_lines:
+                        if remaining_to_reduce <= 0:
+                            break
+                        can_reduce = min(line.product_uom_qty, remaining_to_reduce)
+                        line.product_uom_qty -= can_reduce
+                        remaining_to_reduce -= can_reduce
+            else:
+                # Actualizar la información de la línea de orden
+                # Call the order method with a cleared context to avoid errors on creating move line
+                order.with_company(order.company_id).with_context(**{})._update_order_line_info(
+                    rec.id, product_catalog_qty
+                )
 
     def increase_quantity(self):
         for rec in self: