Automatic update checks (#434)

* Basic update checks

* Fix issues pointed out by @rixx

* First test

* Add tests

* Even more tests

src/pretix/control/views/global_settings.py

@@ -1,9 +1,13 @@
 from django.contrib import messages
-from django.shortcuts import reverse
+from django.shortcuts import redirect, reverse
 from django.utils.translation import ugettext_lazy as _
 from django.views.generic import FormView
 
-from pretix.control.forms.global_settings import GlobalSettingsForm
+from pretix.base.services.update_check import check_result_table, update_check
+from pretix.base.settings import GlobalSettingsObject
+from pretix.control.forms.global_settings import (
+    GlobalSettingsForm, UpdateSettingsForm,
+)
 from pretix.control.permissions import AdministratorPermissionRequiredMixin
 
 
@@ -21,4 +25,34 @@ class GlobalSettingsView(AdministratorPermissionRequiredMixin, FormView):
         return super().form_invalid(form)
 
     def get_success_url(self):
-        return reverse('control:global-settings')
+        return reverse('control:global.settings')
+
+
+class UpdateCheckView(AdministratorPermissionRequiredMixin, FormView):
+    template_name = 'pretixcontrol/global_update.html'
+    form_class = UpdateSettingsForm
+
+    def post(self, request, *args, **kwargs):
+        if 'trigger' in request.POST:
+            update_check.apply()
+            return redirect(self.get_success_url())
+        return super().post(request, *args, **kwargs)
+
+    def form_valid(self, form):
+        form.save()
+        messages.success(self.request, _('Your changes have been saved.'))
+        return super().form_valid(form)
+
+    def form_invalid(self, form):
+        messages.error(self.request, _('Your changes have not been saved, see below for errors.'))
+        return super().form_invalid(form)
+
+    def get_context_data(self, **kwargs):
+        ctx = super().get_context_data()
+        ctx['gs'] = GlobalSettingsObject()
+        ctx['gs'].settings.set('update_check_ack', True)
+        ctx['tbl'] = check_result_table()
+        return ctx
+
+    def get_success_url(self):
+        return reverse('control:global.update')