+
+
+
+
+/*
+ * Check to see if two events overlap. Returns nonzero if they do.
+ * (This function is used in both Citadel and WebCit. If you change it in
+ * one place, change it in the other. Better yet, put it in a library.)
+ */
+int ical_ctdl_is_overlap(
+ struct icaltimetype t1start,
+ struct icaltimetype t1end,
+ struct icaltimetype t2start,
+ struct icaltimetype t2end
+) {
+
+ if (icaltime_is_null_time(t1start)) return(0);
+ if (icaltime_is_null_time(t2start)) return(0);
+
+ /* First, check for all-day events */
+ if (t1start.is_date) {
+ if (!icaltime_compare_date_only(t1start, t2start)) {
+ return(1);
+ }
+ if (!icaltime_is_null_time(t2end)) {
+ if (!icaltime_compare_date_only(t1start, t2end)) {
+ return(1);
+ }
+ }
+ }
+
+ if (t2start.is_date) {
+ if (!icaltime_compare_date_only(t2start, t1start)) {
+ return(1);
+ }
+ if (!icaltime_is_null_time(t1end)) {
+ if (!icaltime_compare_date_only(t2start, t1end)) {
+ return(1);
+ }
+ }
+ }
+
+ /* Now check for overlaps using date *and* time. */
+
+ /* First, bail out if either event 1 or event 2 is missing end time. */
+ if (icaltime_is_null_time(t1end)) return(0);
+ if (icaltime_is_null_time(t2end)) return(0);
+
+ /* If event 1 ends before event 2 starts, we're in the clear. */
+ if (icaltime_compare(t1end, t2start) <= 0) return(0);
+
+ /* If event 2 ends before event 1 starts, we're also ok. */
+ if (icaltime_compare(t2end, t1start) <= 0) return(0);
+
+ /* Otherwise, they overlap. */
+ return(1);
+}
+
+
+
+
+
+
+