# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1414349021 -3600
# Node ID 5815cad7939619fe200b116fac6a2d75b810b712
# Parent  83c4cbfe4673beb4bb8effb9cb62333cc7eed166
Moved conflict detection into a separate function that can return the
conflicting periods.

diff -r 83c4cbfe4673 -r 5815cad79396 imiptools/handlers/resource.py
--- a/imiptools/handlers/resource.py	Sun Oct 26 19:42:40 2014 +0100
+++ b/imiptools/handlers/resource.py	Sun Oct 26 19:43:41 2014 +0100
@@ -6,7 +6,7 @@
 
 from datetime import date, datetime, timedelta
 from imiptools.content import Handler, format_datetime, to_part
-from imiptools.period import insert_period, period_overlaps, remove_period
+from imiptools.period import have_conflict, insert_period, remove_period
 from vCalendar import to_node
 from vRecurrence import get_parameters, get_rule
 
@@ -108,18 +108,11 @@
                 periods = [(format_datetime(dtstart), format_datetime(dtend))]
 
             conflict = False
-            freebusy = self.store.get_freebusy(attendee)
+            freebusy = self.store.get_freebusy(attendee) or []
 
             if freebusy:
                 remove_period(freebusy, self.uid)
-                conflict = True
-                for start, end in periods:
-                    if period_overlaps(freebusy, (start, end)):
-                        break
-                else:
-                    conflict = False
-            else:
-                freebusy = []
+                conflict = have_conflict(freebusy, periods)
 
             # If the event can be scheduled, it is registered and a reply sent
             # accepting the event. (The attendee has PARTSTAT=ACCEPTED as an
diff -r 83c4cbfe4673 -r 5815cad79396 imiptools/period.py
--- a/imiptools/period.py	Sun Oct 26 19:42:40 2014 +0100
+++ b/imiptools/period.py	Sun Oct 26 19:43:41 2014 +0100
@@ -4,6 +4,27 @@
 
 # Time management.
 
+def have_conflict(freebusy, periods, get_conflicts=False):
+
+    """
+    Return whether any period in 'freebusy' overlaps with the given 'periods',
+    returning a collection of such overlapping periods if 'get_conflicts' is
+    set to a true value.
+    """
+
+    conflicts = []
+    for start, end in periods:
+        period = period_overlaps(freebusy, (start, end))
+        if period:
+            if get_conflicts:
+                conflicts.append(period)
+            else:
+                return True
+    if get_conflicts:
+        return conflicts
+    else:
+        return False
+
 def insert_period(freebusy, period):
     insort_left(freebusy, period)
 
@@ -17,12 +38,20 @@
             i += 1
 
 def period_overlaps(freebusy, period):
+
+    """
+    Return from 'freebusy' any period overlapping with the given 'period', or
+    None if no overlap occurs.
+    """
+
     dtstart, dtend = period[:2]
     i = bisect_left(freebusy, (dtstart, dtend, None))
     return (
-        i < len(freebusy) and (dtend is None or freebusy[i][0] < dtend)
+        i < len(freebusy) and (dtend is None or freebusy[i][0] < dtend) and freebusy[i]
         or
-        i > 0 and freebusy[i - 1][1] > dtstart
+        i > 0 and freebusy[i - 1][1] > dtstart and freebusy[i - 1]
+        or
+        None
         )
 
 # vim: tabstop=4 expandtab shiftwidth=4