--- date_api_ical.inc	2009-05-10 21:44:14.000000000 +0900
+++ date_api_ical-new.inc	2009-11-11 10:32:10.000000000 +0900
@@ -195,19 +195,30 @@ function date_ical_parse($icaldatafolded
             if (isset($subgroup['DURATION'])) {
               date_ical_parse_duration($subgroup, 'DURATION');
             }
+            // iCal spec states 'The "DTEND" property for a "VEVENT" calendar component specifies the
+            // non-inclusive end of the event'
+            // This is fine for hours such as 11:00~12:00 means one hour, not two but
+            // for whole days the current calendar code assumes the end date is inclusive so Oct 30 ~ Oct 31 is
+            // interpreted as two days, not one. So make an adjustment to account for this difference in logic
+            if (!empty($subgroup['DTEND']) && (!empty($subgroup['DTEND']['all_day']))) {
+              // make the end date one day earlier
+              $subgroup['DTEND']['datetime'] = date( 'Y-m-d', date_convert($subgroup['DTEND']['datetime'], DATE_DATETIME, DATE_UNIX) - 86400);
+            }
             // Add a top-level indication for the 'All day' condition.
             // Leave it in the individual date components, too, so it
             // is always available even when you are working with only
             // a portion of the VEVENT array, like in Feed API parsers.
             $subgroup['all_day'] = FALSE;
-            if (!empty($subgroup['DTSTART']) && (!empty($subgroup['DTSTART']['all_day']) || 
-            (empty($subgroup['DTEND']) && empty($subgroup['RRULE']) && empty($subgroup['RRULE']['COUNT'])))) {
-              // Many programs output DTEND for an all day event as the
-              // following day, reset this to the same day for internal use.
-              $subgroup['all_day'] = TRUE;
+            // if a start datetime is defined  AND  there is no definition for the end datetime
+            //  THEN make the end datetime equal the start datetime
+            //  and if it is an all day event define the entire event as a single all day event
+            if (!empty($subgroup['DTSTART']) &&
+               (empty($subgroup['DTEND']) && empty($subgroup['RRULE']) && empty($subgroup['RRULE']['COUNT']))) {
               $subgroup['DTEND'] = $subgroup['DTSTART'];
-            }
-          // Add this element to the parent as an array under the
+              if (!empty($subgroup['DTSTART']['all_day'])) {
+                $subgroup['all_day'] = TRUE;
+              }
+            }          // Add this element to the parent as an array under the
           // component name
           default:
             prev($subgroups);