Fix the error on showing number of members in modify trunk interface workflow.

gso/utils/helpers.py

@@ -12,7 +12,7 @@ from pydantic_core.core_schema import ValidationInfo
 from pydantic_forms.validators import Choice
 
 from gso import settings
-from gso.products.product_blocks.iptrunk import IptrunkInterfaceBlock
+from gso.products.product_blocks.iptrunk import IptrunkInterfaceBlock, PhysicalPortCapacity
 from gso.products.product_blocks.router import RouterRole
 from gso.products.product_blocks.site import LatitudeCoordinate, LongitudeCoordinate, SiteTier
 from gso.products.product_types.router import Router
@@ -336,3 +336,18 @@ def generate_inventory_for_active_routers(
             }
         }
     }
+
+
+def calculate_recommended_minimum_links(iptrunk_number_of_members: int, iptrunk_speed: PhysicalPortCapacity) -> int:
+    """Calculate the recommended minimum number of links for an IP trunk based on the number of members and speed.
+
+    If the IP trunk speed is 400G, the recommended minimum number of links is the number of members minus 1.
+    Otherwise, the recommended minimum number of links is the number of members.
+
+    :param int iptrunk_number_of_members: The number of members in the IP trunk.
+    :param PhysicalPortCapacity iptrunk_speed: The speed of the IP trunk.
+    :return: The recommended minimum number of links for the IP trunk.
+    """
+    if iptrunk_speed == PhysicalPortCapacity.FOUR_HUNDRED_GIGABIT_PER_SECOND:
+        return iptrunk_number_of_members - 1
+    return iptrunk_number_of_members