From 4a63bd27c432e5c9f04309219bad3ef83814c45a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Mon, 27 Apr 2020 03:02:00 +0200
Subject: Add final-event-occurence procedure.

---
 module/datetime/zic.scm                       |  2 +-
 module/vcomponent/recurrence/generate-alt.scm | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/module/datetime/zic.scm b/module/datetime/zic.scm
index e9be7701..52457ada 100644
--- a/module/datetime/zic.scm
+++ b/module/datetime/zic.scm
@@ -102,7 +102,7 @@
   (stdoff zone-entry-stdoff)                   ; <timespec>
   (rule zone-entry-rule)                       ; #f | symbol | <timespec>
   (format zone-entry-format)                   ; string
-  (until zone-entry-until))                    ; <datetime>
+  (until zone-entry-until))                    ; <datetime> | #f
 
 (export zone-entry? zone-entry-stdoff zone-entry-rule zone-entry-format zone-entry-until)
 
diff --git a/module/vcomponent/recurrence/generate-alt.scm b/module/vcomponent/recurrence/generate-alt.scm
index 7337ddaa..d48e471d 100644
--- a/module/vcomponent/recurrence/generate-alt.scm
+++ b/module/vcomponent/recurrence/generate-alt.scm
@@ -292,6 +292,19 @@
                                       date-stream))]
           [else date-stream])))
 
+
+(define-public (final-event-occurence event)
+  (define rrule  (parse-recurrence-rule
+                  (attr event 'RRULE)
+                  (if (date? (attr event 'DTSTART))
+                      parse-ics-date parse-ics-datetime)))
+
+  (if (or (count rrule) (until rrule))
+      (let ((instances (rrule-instances event)))
+        (stream-ref instances (1- (stream-length instances))))
+      #f))
+
+
 (define (generate-recurrence-set base-event)
 
 
-- 
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