# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1427058290 -3600
# Node ID 65be38056560b4c1123304741be671551bb1ea7a
# Parent  f658ca7505b221ac83a6cb0cdab8c243af65bf9e
Added a convenience method for getting the assumed time regime for objects.

diff -r f658ca7505b2 -r 65be38056560 imiptools/data.py
--- a/imiptools/data.py	Sun Mar 22 21:38:04 2015 +0100
+++ b/imiptools/data.py	Sun Mar 22 22:04:50 2015 +0100
@@ -110,6 +110,11 @@
         periods = self.get_periods(tzid, end)
         return get_periods_for_freebusy(self, periods, tzid)
 
+    def get_tzid(self):
+        dtstart, dtstart_attr = self.get_datetime_item("DTSTART")
+        dtend, dtend_attr = self.get_datetime_item("DTEND")
+        return get_tzid(dtstart_attr, dtend_attr)
+
 # Construction and serialisation.
 
 def make_calendar(nodes, method=None):
@@ -359,6 +364,9 @@
 def get_window_end(tzid, window_size=100):
     return to_timezone(datetime.now(), tzid) + timedelta(window_size)
 
+def get_tzid(dtstart_attr, dtend_attr):
+    return dtstart_attr.get("TZID") or dtend_attr.get("TZID")
+
 def get_periods(obj, tzid, window_end, inclusive=False):
 
     """
@@ -383,7 +391,7 @@
     else:
         dtend, dtend_attr = dtstart, dtstart_attr
 
-    tzid = dtstart_attr.get("TZID") or dtend_attr.get("TZID") or tzid
+    tzid = get_tzid(dtstart_attr, dtend_attr) or tzid
 
     if not rrule:
         periods = [(dtstart, dtend)]
@@ -449,7 +457,7 @@
     else:
         end, end_attr = start, start_attr
 
-    tzid = start_attr.get("TZID") or end_attr.get("TZID") or tzid
+    tzid = get_tzid(start_attr, end_attr) or tzid
 
     l = []