fix nxos_vlan mode idempotence bug (#55144)

* fix nxos_vlan mode idempotence bug

Signed-off-by: Trishna Guha <trishnaguha17@gmail.com>

* Fix CI failure

Signed-off-by: Trishna Guha <trishnaguha17@gmail.com>

lib/ansible/modules/network/nxos/nxos_vlan.py

@@ -75,6 +75,7 @@ options:
       - Set VLAN mode to classical ethernet or fabricpath.
         This is a valid option for Nexus 5000 and 7000 series.
     choices: ['ce','fabricpath']
+    default: 'ce'
     version_added: "2.4"
   aggregate:
     description: List of VLANs definitions.
@@ -154,6 +155,7 @@ import time
 
 from copy import deepcopy
 
+from ansible.module_utils.network.nxos.nxos import get_capabilities
 from ansible.module_utils.network.nxos.nxos import get_config, load_config, run_commands
 from ansible.module_utils.network.nxos.nxos import normalize_interface, nxos_argument_spec
 from ansible.module_utils.basic import AnsibleModule
@@ -196,6 +198,8 @@ def map_obj_to_commands(updates, module):
     commands = list()
     purge = module.params['purge']
     want, have = updates
+    info = get_capabilities(module).get('device_info')
+    os_platform = info.get('network_os_platform')
 
     for w in want:
         vlan_id = w['vlan_id']
@@ -208,13 +212,15 @@ def map_obj_to_commands(updates, module):
         state = w['state']
         del w['state']
 
-        obj_in_have = search_obj_in_list(vlan_id, have)
+        obj_in_have = search_obj_in_list(vlan_id, have) or {}
+        if not re.match('N[567]', os_platform) or (not obj_in_have.get('mode') and mode == 'ce'):
+            mode = w['mode'] = None
 
         if state == 'absent':
             if obj_in_have:
                 commands.append('no vlan {0}'.format(vlan_id))
 
-        elif state == 'present':
+        elif state == 'present' and not purge:
             if not obj_in_have:
                 commands.append('vlan {0}'.format(vlan_id))
 
@@ -627,7 +633,7 @@ def main():
         delay=dict(default=10, type='int'),
         state=dict(choices=['present', 'absent'], default='present', required=False),
         admin_state=dict(choices=['up', 'down'], required=False, default='up'),
-        mode=dict(choices=['ce', 'fabricpath'], required=False),
+        mode=dict(default='ce', choices=['ce', 'fabricpath']),
     )
 
     aggregate_spec = deepcopy(element_spec)