vars/generate: improve output when vars are updated

fixes #2076

- print old and new value if possible
- also inform the user if something hasn't changed

pkgs/clan-cli/clan_cli/vars/set.py

@@ -7,23 +7,38 @@ from clan_cli.completions import add_dynamic_completer, complete_machines
 from clan_cli.machines.machines import Machine
 from clan_cli.vars.get import get_var
 
+from ._types import Var
 from .prompt import ask
 
 log = logging.getLogger(__name__)
 
 
-def set_command(machine: str, var_id: str, flake: FlakeId) -> None:
+def set_var(
+    machine: str | Machine, var: str | Var, value: bytes, flake: FlakeId
+) -> None:
+    if isinstance(machine, str):
+        _machine = Machine(name=machine, flake=flake)
+    else:
+        _machine = machine
+    if isinstance(var, str):
+        _var = get_var(_machine, var)
+    else:
+        _var = var
+    _var.set(value)
+
+
+def set_via_stdin(machine: str, var_id: str, flake: FlakeId) -> None:
     _machine = Machine(name=machine, flake=flake)
     var = get_var(_machine, var_id)
     if sys.stdin.isatty():
         new_value = ask(var.id, "hidden").encode("utf-8")
     else:
         new_value = sys.stdin.buffer.read()
-    var.set(new_value)
+    set_var(_machine, var, new_value, flake)
 
 
 def _set_command(args: argparse.Namespace) -> None:
-    set_command(args.machine, args.var_id, args.flake)
+    set_via_stdin(args.machine, args.var_id, args.flake)
 
 
 def register_set_parser(parser: argparse.ArgumentParser) -> None: