CORD-1849 Split XOS code out of OLT and VTN repos

Change-Id: I307b2a9a54fdcdab14e6bf96d9a9b060ff421a77
diff --git a/xos/attic/volttenant_model.py b/xos/attic/volttenant_model.py
new file mode 100644
index 0000000..c7a3420
--- /dev/null
+++ b/xos/attic/volttenant_model.py
@@ -0,0 +1,69 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+def __init__(self, *args, **kwargs):
+    volt_services = VOLTService.objects.all()
+    if volt_services:
+        self._meta.get_field("owner").default = volt_services[0].id
+    super(VOLTTenant, self).__init__(*args, **kwargs)
+    self.cached_vcpe = None
+
+@property
+def vcpe(self):
+    # TODO: hardcoded service dependency
+    from services.vsg.models import VSGTenant
+
+    vsg = None
+    for link in self.subscribed_links:
+        # cast from base class to derived class
+        vsgs = VSGTenant.objects.filter(serviceinstance_ptr=link.provider_service_instance)
+        if vsgs:
+            vsg = vsgs[0]
+
+    if not vsg:
+        return None
+
+    # always return the same object when possible
+    if (self.cached_vcpe) and (self.cached_vcpe.id == vsg.id):
+        return self.cached_vcpe
+
+    vsg.caller = self.creator
+    self.cached_vcpe = vsg
+    return vsg
+
+@vcpe.setter
+def vcpe(self, value):
+    raise XOSConfigurationError("vOLT.vCPE cannot be set this way -- create a new vCPE object and set its subscriber_tenant instead")
+
+@property
+def subscriber(self):
+    for link in self.provided_links:
+        # cast from base class to derived class
+        roots = CordSubscriberRoot.objects.filter(serviceinstance_ptr=link.subscriber_service_instance)
+        if roots:
+            return roots[0]
+    return None
+
+def save(self, *args, **kwargs):
+    if not self.creator:
+        if not getattr(self, "caller", None):
+            # caller must be set when creating a vCPE since it creates a slice
+            raise XOSProgrammingError("VOLTTenant's self.caller was not set")
+        self.creator = self.caller
+        if not self.creator:
+            raise XOSProgrammingError("VOLTTenant's self.creator was not set")
+
+    super(VOLTTenant, self).save(*args, **kwargs)