--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/logic/helper/timeline.py	Wed Feb 04 21:10:34 2009 +0000
@@ -0,0 +1,106 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2008 the Melange authors.
+#
+# 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.
+
+"""Functions that are useful when dealing with timelines.
+"""
+
+__authors__ = [
+  '"Lennard de Rijk" <ljvderijk@gmail.com>',
+  ]
+
+
+import datetime
+
+
+def isBeforePeriod(entity, period):
+  """Returns true iff the current DateTime is before the given period_start.
+
+  Args:
+    entity: Instance of a timeline model.
+    period: The name of a period (without start or end).
+  """
+
+  return isBeforeEvent(entity, '%s_start' % period)
+
+def isBeforeEvent(entity, event):
+  """Returns true iff the current DateTime is before the given event.
+
+  Args:
+    entity: Instance of a timeline model.
+    event: The name of property in the timeline model.
+  """
+  event_time = getDateTimeByName(entity, event)
+
+  if event_time:
+    return datetime.datetime.utcnow() < event_time
+  else:
+    return False
+
+def isActivePeriod(entity, period):
+  """Returns true iff the current DateTime is between period_start and period_end.
+
+  Args:
+    entity: Instance of a timeline model.
+    period: The name of a period (without start or end).
+  """
+
+  period_start = '%s_start' % period
+  period_end = '%s_end' % period
+
+  period_started = isAfterEvent(entity, period_start)
+  period_not_ended = isBeforeEvent(entity, period_end)
+
+  return period_started and period_not_ended
+
+def isAfterPeriod(entity, period):
+  """Returns true iff the current DateTime is after the given period_end.
+
+  Args:
+    entity: Instance of a timeline model.
+    period: The name of a period (without start or end).
+  """
+
+  return isAfterEvent(entity, '%s_end' % period)
+
+def isAfterEvent(entity, event):
+  """Returns true iff the current DateTime is after the given event.
+
+  Args:
+    entity: Instance of a timeline model.
+    event: The name of property in the timeline model.
+  """
+  event_time = getDateTimeByName(entity, event)
+
+  if event_time:
+    return event_time < datetime.datetime.utcnow()
+  else:
+    return False
+
+def getDateTimeByName(entity, name):
+  """Returns the DateTime property with the given name. 
+
+  Args:
+    entity: Instance of a timeline model.
+    name: The name of a specific property in the given timeline model.
+
+  Returns:
+    The requested DateTime property, or None if there is no such property set.
+  """
+
+  if hasattr(entity, name):
+    return getattr(entity, name)
+  else:
+    return None