# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1505255388 -7200
# Node ID caed4fe9512208b537c877fc30c285fdbdef4d4c
# Parent  3247e43c0af89512d200adcc4a7be0f7f4fd4df6# Parent  1aa985ba6e761305bf79d1e1cf23f0fd22133dbc
Merged changes from concurrent branch.

diff -r 3247e43c0af8 -r caed4fe95122 imipweb/data.py
--- a/imipweb/data.py	Wed Sep 13 00:11:22 2017 +0200
+++ b/imipweb/data.py	Wed Sep 13 00:29:48 2017 +0200
@@ -358,6 +358,34 @@
                 active_periods[p] += 1
     return active_periods
 
+def get_removed_periods(periods, still_to_remove):
+
+    """
+    From the recurrence 'periods', given details of those 'still_to_remove',
+    return the remaining active periods and the periods to unschedule or
+    exclude, using a tuple of the form (active, unscheduled, excluded).
+    """
+
+    to_remove = set()
+
+    # Get all periods that are not replaced.
+
+    active_periods = get_active_periods(periods)
+
+    for period in still_to_remove:
+        active_periods[period] -= 1
+        to_remove.add(period)
+
+    # Determine whether some periods are both removed and added.
+
+    remaining = []
+    for period, n in active_periods.items():
+        if n > 0:
+            remaining.append(period)
+
+    to_remove.difference_update(remaining)
+    return remaining, to_remove
+
 
 
 # Form field extraction and serialisation.
diff -r 3247e43c0af8 -r caed4fe95122 imipweb/event.py
--- a/imipweb/event.py	Wed Sep 13 00:11:22 2017 +0200
+++ b/imipweb/event.py	Wed Sep 13 00:29:48 2017 +0200
@@ -25,7 +25,7 @@
 from imiptools.mail import Messenger
 from imipweb.data import EventPeriod, event_period_from_period, \
                          filter_duplicates, get_active_periods, \
-                         remove_from_collection, \
+                         get_removed_periods, remove_from_collection, \
                          get_period_control_values, \
                          PeriodError
 from imipweb.resource import DateTimeFormUtilities, FormUtilities, ResourceClientForObject
@@ -1044,31 +1044,21 @@
         excluded).
         """
 
+        # Get remaining periods and those whose removal is deferred.
+
+        remaining, to_remove = get_removed_periods(periods,
+            self.get_state("recur-remove", list))
+
+        # Sort the deferred removal periods into categories.
+
         to_unschedule = set()
         to_exclude = set()
 
-        # Get all periods that are not replaced.
-
-        active_periods = get_active_periods(periods)
-
-        for period in self.get_state("recur-remove", list):
-            active_periods[period] -= 1
-
+        for period in to_remove:
             if not self.can_edit_recurrence(period) and self.is_organiser():
-                l = to_unschedule
+                to_unschedule.add(period)
             else:
-                l = to_exclude
-            l.add(period)
-
-        # Determine whether some periods are both removed and added.
-
-        remaining = []
-        for period, n in active_periods.items():
-            if n > 0:
-                remaining.append(period)
-
-        to_unschedule.difference_update(remaining)
-        to_exclude.difference_update(remaining)
+                to_exclude.add(period)
 
         return remaining, to_unschedule, to_exclude