names: Create a generic TLS domain selection form

Signed-off-by: Joseph Nuthalapati <njoseph@riseup.net>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/forms.py

@@ -39,6 +39,24 @@ class DomainSelectionForm(forms.Form):
             'changed later.'), choices=[])
 
 
+class TLSDomainForm(forms.Form):
+    """Form to select a TLS domain for an app."""
+
+    def get_domain_choices():
+        """Double domain entries for inclusion in the choice field."""
+        from plinth.modules.names import get_available_tls_domains
+        return ((domain, domain) for domain in get_available_tls_domains())
+
+    domain = forms.ChoiceField(
+        choices=get_domain_choices(),
+        label=_('TLS domain'),
+        help_text=_(
+            'Select a domain to use TLS with. If the list is empty, please '
+            'configure at least one domain with certificates.'),
+        required=False,
+    )
+
+
 class LanguageSelectionFormMixin:
     """Form mixin for selecting the user's preferred language."""
 

plinth/modules/names/__init__.py

@@ -93,3 +93,14 @@ def on_domain_removed(sender, domain_type, name='', **kwargs):
 
                 logger.info('Remove domain %s of type %s', domain_name.name,
                             domain_type)
+
+
+######################################################
+# Domain utilities meant to be used by other modules #
+######################################################
+
+
+def get_available_tls_domains():
+    """Return an iterator with all domains able to have a certificate."""
+    return (domain.name for domain in components.DomainName.list()
+            if domain.domain_type.can_have_certificate)

plinth/modules/quassel/__init__.py

@@ -114,12 +114,6 @@ def setup(helper, old_version=None):
     app.get_component('letsencrypt-quassel').setup_certificates()
 
 
-def get_available_domains():
-    """Return an iterator with all domains able to have a certificate."""
-    return (domain.name for domain in names.components.DomainName.list()
-            if domain.domain_type.can_have_certificate)
-
-
 def set_domain(domain):
     """Set the TLS domain by writing a file to data directory."""
     if domain:
@@ -136,7 +130,7 @@ def get_domain():
         pass
 
     if not domain:
-        domain = next(get_available_domains(), None)
+        domain = next(names.get_available_tls_domains(), None)
         set_domain(domain)
 
     return domain

plinth/modules/quassel/forms.py

@@ -1,27 +0,0 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
-"""
-Forms for Quassel app.
-"""
-
-from django import forms
-from django.utils.translation import gettext_lazy as _
-
-from plinth.modules import quassel
-
-
-def get_domain_choices():
-    """Double domain entries for inclusion in the choice field."""
-    return ((domain, domain) for domain in quassel.get_available_domains())
-
-
-class QuasselForm(forms.Form):
-    """Form to select a TLS domain for Quassel."""
-
-    domain = forms.ChoiceField(
-        choices=get_domain_choices,
-        label=_('TLS domain'),
-        help_text=_(
-            'Select a domain to use TLS with. If the list is empty, please '
-            'configure at least one domain with certificates.'),
-        required=False,
-    )

plinth/modules/quassel/views.py

@@ -3,15 +3,14 @@
 from django.contrib import messages
 from django.utils.translation import gettext_lazy as _
 
+from plinth.forms import TLSDomainForm
 from plinth.modules import quassel
 from plinth.views import AppView
 
-from .forms import QuasselForm
-
 
 class QuasselAppView(AppView):
     app_id = 'quassel'
-    form_class = QuasselForm
+    form_class = TLSDomainForm
 
     def get_initial(self):
         """Return the values to fill in the form."""