Add unique id check in wiffi config flow (#60388)

Co-authored-by: Franck Nijhof <frenck@frenck.nl>

homeassistant/components/wiffi/config_flow.py

@@ -38,6 +38,8 @@ class WiffiFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
             return self._async_show_form()
 
         # received input from form or configuration.yaml
+        await self.async_set_unique_id(user_input[CONF_PORT])
+        self._abort_if_unique_id_configured()
 
         try:
             # try to start server to check whether port is in use

homeassistant/components/wiffi/strings.json

@@ -10,6 +10,7 @@
     },
     "abort": {
       "addr_in_use": "Server port already in use.",
+      "already_configured": "Server port is already configured.",
       "start_server_failed": "Start server failed."
     }
   },

homeassistant/components/wiffi/translations/en.json

@@ -2,6 +2,7 @@
     "config": {
         "abort": {
             "addr_in_use": "Server port already in use.",
+            "already_configured": "Server port is already configured.",
             "start_server_failed": "Start server failed."
         },
         "step": {