ubuntu-pro: use checkboxes to skip or enter token

Instead of relying on the contract token empty to skip Ubuntu Pro, we
now explicitly ask the user to decide if he wants to input a token or
not. This makes a small difference in that the user is now able to
supply an empty contract token. Our different implementations (i.e.,
mock & based on u-a-c) don't handle empty tokens properly, so we now
reject empty tokens.

Signed-off-by: Olivier Gayot <olivier.gayot@canonical.com>

subiquity/server/ubuntu_advantage.py

@@ -79,12 +79,16 @@ class MockedUAInterfaceStrategy(UAInterfaceStrategy):
         UA token. No actual query is done to the UA servers in this
         implementation. Instead, we create a response based on the following
         rules:
+        * Empty tokens are considered invalid.
         * Tokens starting with "x" will be considered expired.
         * Tokens starting with "i" will be considered invalid.
         * Tokens starting with "f" will generate an internal error.
         """
         await asyncio.sleep(1 / self.scale_factor)
 
+        if not token:
+            raise InvalidTokenError(token)
+
         if token[0] == "x":
             path = "examples/uaclient-status-expired.json"
         elif token[0] == "i":
@@ -118,6 +122,11 @@ class UAClientUAInterfaceStrategy(UAInterfaceStrategy):
         UA token. The information will be queried using the UA client
         executable passed to the initializer.
         """
+        if not token:
+            # u-a-c does not produce the expected output when the contract
+            # token is empty ; so let's not call it at all.
+            raise InvalidTokenError(token)
+
         command = tuple(self.executable) + (
             "status",
             "--format", "json",

subiquity/ui/views/ubuntu_pro.py

@@ -43,7 +43,11 @@ from subiquitycore.ui.container import (
     )
 from subiquitycore.ui.form import (
     Form,
+    SubForm,
+    SubFormField,
+    NO_HELP,
     simple_field,
+    RadioButtonField,
     WantsToKnowFormField,
     )
 from subiquitycore.ui.spinner import (
@@ -62,10 +66,6 @@ from subiquitycore.ui.interactive import StringEditor
 
 log = logging.getLogger('subiquity.ui.views.ubuntu_pro')
 
-ua_help = _("If you want to enroll this system using your Ubuntu Pro "
-            "subscription, enter your Ubuntu Pro token here. "
-            "Otherwise, leave this blank.")
-
 
 class UATokenEditor(StringEditor, WantsToKnowFormField):
     """ Represent a text-box editor for the Ubuntu Pro Token.  """
@@ -87,15 +87,56 @@ class UATokenEditor(StringEditor, WantsToKnowFormField):
         return super().valid_char(ch)
 
 
+class UbuntuProTokenForm(SubForm):
+    """ Represents a sub-form requesting Ubuntu Pro token.
+    +---------------------------------------------------------+
+    |      Contract token: C123456789ABCDEF                   |
+    +---------------------------------------------------------+
+    """
+    UATokenField = simple_field(UATokenEditor)
+
+    token = UATokenField(_("Contract token:"), help=NO_HELP)
+
+
 class UbuntuProForm(Form):
     """
     Represents a form requesting Ubuntu Pro information
+    +---------------------------------------------------------+
+    | (X)  Enable now with my contract token                  |
+    |                                                         |
+    |      Contract token: C123456789ABCDEF                   |
+    |                                                         |
+    | ( )  Skip Ubuntu Pro for now                            |
+    |                                                         |
+    |                         [ Done ]                        |
+    |                         [ Back ]                        |
+    +---------------------------------------------------------+
     """
     cancel_label = _("Back")
+    group = []
 
-    UATokenField = simple_field(UATokenEditor)
+    with_token = RadioButtonField(
+            group,
+            _("Enable now with my contract token"), help=NO_HELP)
+    token_form = SubFormField(UbuntuProTokenForm, "", help=NO_HELP)
+    skip_ua = RadioButtonField(
+            group,
+            _("Skip Ubuntu Pro for now"), help=NO_HELP)
 
-    token = UATokenField(_("Ubuntu Pro token:"), help=ua_help)
+    def __init__(self, initial):
+        super().__init__(initial)
+        connect_signal(self.with_token.widget,
+                       'change', self._toggle_token_input)
+
+        if not initial["token_form"]["token"]:
+            self.skip_ua.widget.state = True
+            self.with_token.widget.state = False
+        else:
+            self.skip_ua.widget.state = False
+            self.with_token.widget.state = True
+
+    def _toggle_token_input(self, sender, new_value):
+        self.token_form.enabled = new_value
 
 
 class CheckingUAToken(WidgetWrap):
@@ -124,17 +165,37 @@ class CheckingUAToken(WidgetWrap):
 
 
 class UbuntuProView(BaseView):
-    """ Represent the view of the Ubuntu Pro configuration. """
+    """ Represent the view of the Ubuntu Pro configuration.
+    +---------------------------------------------------------+
+    | Enable Ubuntu Pro                              [ Help ] |
+    +---------------------------------------------------------+
+    | If you want to enable Ubuntu Pro, you can do it now     |
+    | with your contract token. Otherwise, you can skip this  |
+    | step and enable Ubuntu Pro later using the command      |
+    | 'ua attach'.                                            |
+    |                                                         |
+    | (X)  Enable now with my contract token                  |
+    |                                                         |
+    |      Contract token: C123456789ABCDEF                   |
+    |                                                         |
+    | ( )  Skip Ubuntu Pro for now                            |
+    |                                                         |
+    |                         [ Done ]                        |
+    |                         [ Back ]                        |
+    +---------------------------------------------------------+
+    """
 
     title = _("Enable Ubuntu Pro")
-    excerpt = _("Enter your Ubuntu Pro token if you want to enroll "
+    excerpt = _("If you want to enable Ubuntu Pro, you can do it now with"
-                "this system.")
+                " your contract token. "
+                "Otherwise, you can skip this step and enable Ubuntu Pro"
+                " later using the command `ua attach`.")
 
     def __init__(self, controller, token: str):
         """ Initialize the view with the default value for the token. """
         self.controller = controller
 
-        self.form = UbuntuProForm(initial={"token": token})
+        self.form = UbuntuProForm(initial={"token_form": {"token": token}})
 
         def on_cancel(_: UbuntuProForm):
             self.cancel()
@@ -148,8 +209,8 @@ class UbuntuProView(BaseView):
         """ If no token was supplied, move on to the next screen.
         If a token was provided, open the loading dialog and
         asynchronously check if the token is valid. """
-        token: str = form.token.value
+        results = form.as_data()
-        if token:
+        if not results["skip_ua"]:
             def on_success(services: List[UbuntuProService]) -> None:
                 self.remove_overlay()
                 self.show_activable_services(services)
@@ -163,6 +224,7 @@ class UbuntuProView(BaseView):
                 elif status == UbuntuProCheckTokenStatus.UNKNOWN_ERROR:
                     self.show_unknown_error()
 
+            token: str = results["token_form"]["token"]
             checking_token_overlay = CheckingUAToken(self)
             self.show_overlay(checking_token_overlay,
                               width=checking_token_overlay.width,
@@ -172,7 +234,7 @@ class UbuntuProView(BaseView):
                                         on_success=on_success,
                                         on_failure=on_failure)
         else:
-            self.controller.done(token)
+            self.controller.done("")
 
     def cancel(self) -> None:
         """ Called when the user presses the Back button. """
@@ -326,7 +388,8 @@ class ShowServicesWidget(Stretchy):
 
     def ok(self, sender) -> None:
         """ Close the overlay and submit the token. """
-        self.parent.controller.done(self.parent.form.token.value)
+        token = self.parent.form.as_data()["token_form"]["token"]
+        self.parent.controller.done(token)
 
 
 class ContinueAnywayWidget(Stretchy):
@@ -361,4 +424,5 @@ class ContinueAnywayWidget(Stretchy):
 
     def cont(self, sender) -> None:
         """ Move on to the next screen. """
-        self.parent.controller.done(self.parent.form.token.value)
+        token = self.parent.form.as_data()["token_form"]["token"]
+        self.parent.controller.done(token)