# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1431901597 -7200
# Node ID ade19f50b58e7a4b779bbb69f1803aaa1896baa1
# Parent  88cd1741a2a2b8d96c34cae23d4089cb1768ec57
Produce recurring periods employing dates if they are involved.
Handle missing DTSTART when encountering CANCEL messages.

diff -r 88cd1741a2a2 -r ade19f50b58e imiptools/data.py
--- a/imiptools/data.py	Sun May 17 22:57:31 2015 +0200
+++ b/imiptools/data.py	Mon May 18 00:26:37 2015 +0200
@@ -20,7 +20,7 @@
 """
 
 from bisect import bisect_left
-from datetime import datetime, timedelta
+from datetime import date, datetime, timedelta
 from email.mime.text import MIMEText
 from imiptools.dates import format_datetime, get_datetime, get_duration, \
                             get_freebusy_period, get_period, get_tzid, \
@@ -127,6 +127,8 @@
         return get_periods(self, tzid, end)
 
     def get_tzid(self):
+        if not self.has_key("DTSTART"):
+            return None
         dtstart, dtstart_attr = self.get_datetime_item("DTSTART")
         dtend, dtend_attr = self.get_datetime_item("DTEND")
         return get_tzid(dtstart_attr, dtend_attr)
@@ -439,7 +441,8 @@
             inclusive = True
 
         for start in selector.materialise(dtstart, window_end, parameters.get("COUNT"), parameters.get("BYSETPOS"), inclusive):
-            start = to_timezone(datetime(*start), tzid)
+            create = len(start) == 3 and date or datetime
+            start = to_timezone(create(*start), tzid)
             end = start + duration
             periods.append(RecurringPeriod(start, end, tzid, "RRULE"))