# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1424976060 -3600
# Node ID 7edd0d9f6f13ca3fcdf9ad62feecbf6e858b4518
# Parent  f24ecac37a457021c0324e922a854266f28b2a5c
Added initial support for RDATE and EXDATE properties.

diff -r f24ecac37a45 -r 7edd0d9f6f13 imiptools/data.py
--- a/imiptools/data.py	Thu Feb 26 19:38:14 2015 +0100
+++ b/imiptools/data.py	Thu Feb 26 19:41:00 2015 +0100
@@ -59,6 +59,13 @@
     def get_utc_datetime(self, name):
         return get_utc_datetime(self.details, name)
 
+    def get_item_datetimes(self, name):
+        items = get_item_datetime_items(self.details, name)
+        return items and [dt for dt, attr in items]
+
+    def get_item_datetime_items(self, name):
+        return get_item_datetime_items(self.details, name)
+
     def get_datetime(self, name):
         dt, attr = get_datetime_item(self.details, name)
         return dt
@@ -248,6 +255,23 @@
 def get_value(d, name):
     return get_values(d, name, False)
 
+def get_item_datetime_items(d, name):
+
+    """
+    Return datetime items from 'd' having the given 'name', where a single item
+    yields potentially many datetime values, each employing the attributes given
+    for the principal item.
+    """
+
+    item = get_item(d, name)
+    if item:
+        values, attr = item
+        if not isinstance(values, list):
+            values = [values]
+        return [(get_datetime(value, attr), attr) for value in values]
+    else:
+        return None
+
 def get_utc_datetime(d, name):
     t = get_datetime_item(d, name)
     if not t:
@@ -322,40 +346,60 @@
     to the given 'window_size' in days starting from the present moment.
     """
 
-    # NOTE: Need also RDATE and EXDATE support.
-
     rrule = obj.get_value("RRULE")
 
-    if not rrule:
-        return [(obj.get_datetime("DTSTART"), obj.get_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.
 
     duration = dtend - dtstart
 
-    # Recurrence rules create multiple instances to be checked.
-    # Conflicts may only be assessed within a period defined by policy
-    # for the agent, with instances outside that period being considered
-    # unchecked.
+    if not rrule:
+        periods = [(dtstart, dtend)]
+    else:
+        # Recurrence rules create multiple instances to be checked.
+        # Conflicts may only be assessed within a period defined by policy
+        # for the agent, with instances outside that period being considered
+        # unchecked.
+
+        window_end = to_timezone(datetime.now(), tzid) + timedelta(window_size)
 
-    window_end = to_timezone(datetime.now(), tzid) + timedelta(window_size)
+        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 = to_timezone(datetime(*start), tzid)
+            end = start + duration
+            periods.append((start, end))
+
+    # Add recurrence dates.
 
-    selector = get_rule(dtstart, rrule)
-    parameters = get_parameters(rrule)
-    periods = []
+    periods = set(periods)
+    rdates = obj.get_item_datetimes("RDATE")
+
+    if rdates:
+        for rdate in rdates:
+            periods.add((rdate, rdate + duration))
+
+    # Exclude exception dates.
+
+    exdates = obj.get_item_datetimes("EXDATE")
 
-    for start in selector.materialise(dtstart, window_end, parameters.get("COUNT"), parameters.get("BYSETPOS")):
-        start = to_timezone(datetime(*start), tzid)
-        end = start + duration
-        periods.append((start, end))
+    if exdates:
+        for exdate in exdates:
+            period = (exdate, exdate + duration)
+            if period in periods:
+                periods.remove(period)
 
+    # Return a sorted list of the periods.
+
+    periods = list(periods)
+    periods.sort()
     return periods
 
 def get_periods_for_freebusy(obj, periods, tzid):