Initial snapshot.

lib/session.py

@@ -0,0 +1,88 @@
+# Copyright 2014, Ian Gulliver
+#
+# 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.
+
+import functools
+
+from google.appengine.api import users
+
+from cosmopolite.lib import auth
+from cosmopolite.lib import models
+
+
+def _CheckClientAndGoogleUser(client, google_user):
+  if not google_user:
+    # Nothing to check. If there's a user on the profile, it can stay there.
+    return client
+
+  client_profile_google_user = client.parent().google_user
+  if client_profile_google_user:
+    if client_profile_google_user == google_user:
+      return client
+    else:
+      # Shared computer? Google account wins.
+      return models.Client.FromGoogleUser(google_user)
+
+  # User just signed in. Their anonymous profile gets permanently
+  # associated with this Google account.
+  profiles = (models.Profile.all()
+              .filter('google_user =', google_user)
+              .fetch(1))
+  if profiles:
+    # We can't convert the anonymous profile because there's already
+    # a profile for this Google user. Create a new client_id pointing to that
+    # profile.
+    # TODO(flamingcow): Fetch-then-store uniqueness is a race.
+    google_profile = profiles[0]
+    google_profile.MergeFrom(client.parent_key())
+    return models.Client.FromProfile(google_profile)
+
+  # First time signin.
+  client_profile = client.parent()
+  client_profile.google_user = google_user
+  client_profile.put()
+  return client
+
+
+def session_required(handler):
+  """Find or create a session for this user.
+
+  Find or create a Client and Profile for this user. Muck with the return value
+  to wrap it in an object that contains session info for the client.
+
+  Make sure to wrap this in google_user_xsrf_protection.
+  """
+
+  @functools.wraps(handler)
+  def FindOrCreateSession(self):
+    client_key = auth.ParseKey(self.request.get('client_id', None))
+
+    # The hunt for a Profile begins.
+    if client_key:
+      self.client = _CheckClientAndGoogleUser(
+          models.Client.get(client_key),
+          self.verified_google_user)
+    else:
+      self.client = models.Client.FromGoogleUser(self.verified_google_user)
+
+    ret = {
+        'status': 'ok',
+        'response': handler(self),
+    }
+    if client_key != self.client.key():
+      # Tell the client that this changed
+      ret['client_id'] = auth.Sign(self.client.key())
+
+    return ret
+
+  return FindOrCreateSession