dashboard: don't allow lease deletion when there are template still using it

circle/dashboard/templates/dashboard/confirm/ajax-delete.html

@@ -13,7 +13,9 @@
         <br />
         <div class="pull-right" style="margin-top: 15px;">
           <button type="button" class="btn btn-default" data-dismiss="modal">{% trans "Cancel" %}</button> 
-          <button id="confirmation-modal-button" type="button" class="btn btn-danger">{% trans "Delete" %}</button> 
+          <button disabled id="confirmation-modal-button" type="button" class="btn btn-danger"
+          {% if disable_submit %}disabled{% endif %}
+            >{% trans "Delete" %}</button> 
         </div>
         <div class="clearfix"></div>
       </div>

circle/dashboard/templates/dashboard/confirm/base-delete.html

@@ -26,7 +26,9 @@
             {% csrf_token %}
             <a class="btn btn-default">{% trans "Cancel" %}</a>
             <input type="hidden" name="next" value="{{ request.GET.next }}"/>
-            <button class="btn btn-danger">{% trans "Yes" %}</button>
+            <button class="btn btn-danger"
+              {% if disable_submit %}disabled{% endif %}
+              >{% trans "Yes" %}</button>
           </form>
         </div>
       </div>

circle/dashboard/views.py

@@ -1761,9 +1761,26 @@ class LeaseDelete(LoginRequiredMixin, SuperuserRequiredMixin, DeleteView):
         else:
             return ['dashboard/confirm/base-delete.html']
 
+    def get_context_data(self, *args, **kwargs):
+        c = super(LeaseDelete, self).get_context_data(*args, **kwargs)
+        lease = self.get_object()
+        templates = lease.instancetemplate_set
+        if templates.count() > 0:
+            text = _("You can't delete this lease because some templates "
+                     "are still using it, modify these to proceed: ")
+
+            c['text'] = text + ", ".join("<strong>%s (#%d)</strong>"
+                                         "" % (o.name, o.pk)
+                                         for o in templates.all())
+            c['disable_submit'] = True
+        return c
+
     def delete(self, request, *args, **kwargs):
         object = self.get_object()
 
+        if (object.instancetemplate_set.count() > 0):
+            raise SuspiciousOperation()
+
         object.delete()
         success_url = self.get_success_url()
         success_message = _("Lease successfully deleted!")