# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1423606386 -3600
# Node ID f8538cef6ceda84fb6b9b1c9eab0fbb775df31da
# Parent  ba6f36a05ef5ca97cb5d9f84819517a6498bfcc7
Changed the get_periods function to use time regime information so that
recurring events function across time zone changes.

diff -r ba6f36a05ef5 -r f8538cef6ced imiptools/data.py
--- a/imiptools/data.py	Tue Feb 10 21:53:52 2015 +0100
+++ b/imiptools/data.py	Tue Feb 10 23:13:06 2015 +0100
@@ -22,7 +22,7 @@
 from datetime import datetime, timedelta
 from email.mime.text import MIMEText
 from imiptools.dates import format_datetime, get_datetime, get_freebusy_period, \
-                            to_utc_datetime
+                            to_timezone, to_utc_datetime
 from pytz import timezone
 from vCalendar import iterwrite, parse, ParseError, to_dict, to_node
 from vRecurrence import get_parameters, get_rule
@@ -58,6 +58,10 @@
     def get_utc_datetime(self, name):
         return get_utc_datetime(self.details, name)
 
+    def get_datetime(self, name):
+        dt, attr = get_datetime_item(self.details, name)
+        return dt
+
     def get_datetime_item(self, name):
         return get_datetime_item(self.details, name)
 
@@ -80,11 +84,11 @@
 
     # Computed results.
 
-    def get_periods(self, window_size=100):
-        return get_periods(self, window_size)
+    def get_periods(self, tzid, window_size=100):
+        return get_periods(self, tzid, window_size)
 
     def get_periods_for_freebusy(self, tzid, window_size=100):
-        periods = self.get_periods(window_size)
+        periods = self.get_periods(tzid, window_size)
         return get_periods_for_freebusy(self, periods, tzid)
 
 # Construction and serialisation.
@@ -287,15 +291,26 @@
 # NOTE: Need to expose the 100 day window for recurring events in the
 # NOTE: configuration.
 
-def get_periods(obj, window_size=100):
+def get_periods(obj, tzid, window_size=100):
 
     """
     Return periods for the given object 'obj', confining materialised periods
     to the given 'window_size' in days starting from the present moment.
     """
 
-    dtstart = obj.get_utc_datetime("DTSTART")
-    dtend = obj.get_utc_datetime("DTEND")
+    # NOTE: Need also RDATE and EXDATE support.
+
+    rrule = obj.get_value("RRULE")
+
+    if not rrule:
+        return [(obj.get_utc_datetime("DTSTART"), obj.get_utc_datetime("DTEND"))]
+
+    # Use localised datetimes.
+
+    dtstart, start_attr = obj.get_datetime_item("DTSTART")
+    dtend, end_attr = obj.get_datetime_item("DTEND")
+
+    tzid = start_attr.get("TZID") or end_attr.get("TZID") or tzid
 
     # NOTE: Need also DURATION support.
 
@@ -306,22 +321,17 @@
     # for the agent, with instances outside that period being considered
     # unchecked.
 
-    window_end = datetime.now() + timedelta(window_size)
+    window_end = to_timezone(datetime.now(), tzid) + timedelta(window_size)
 
-    # NOTE: Need also RDATE and EXDATE support.
-
-    rrule = obj.get_value("RRULE")
+    selector = get_rule(dtstart, rrule)
+    parameters = get_parameters(rrule)
+    periods = []
 
-    if rrule:
-        selector = get_rule(dtstart, rrule)
-        parameters = get_parameters(rrule)
-        periods = []
-        for start in selector.materialise(dtstart, window_end, parameters.get("COUNT"), parameters.get("BYSETPOS")):
-            start = datetime(*start, tzinfo=timezone("UTC"))
-            end = start + duration
-            periods.append((start, end))
-    else:
-        periods = [(dtstart, dtend)]
+    for start in selector.materialise(dtstart, window_end, parameters.get("COUNT"), parameters.get("BYSETPOS")):
+        start = to_timezone(datetime(*start), tzid)
+        start = to_timezone(start, "UTC")
+        end = start + duration
+        periods.append((start, end))
 
     return periods