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-rw-r--r--module/vcomponent/timezone.scm21
1 files changed, 13 insertions, 8 deletions
diff --git a/module/vcomponent/timezone.scm b/module/vcomponent/timezone.scm
index f6112ebc..ed3bef6b 100644
--- a/module/vcomponent/timezone.scm
+++ b/module/vcomponent/timezone.scm
@@ -28,15 +28,20 @@
;; : TZOFFSETFROM: +0200
;; @end example
-;; Given a tz stream of length 2, takes the time difference between the DTSTART
-;; of those two. And creates a new VTIMEZONE with that end time.
-;; TODO set remaining properties, and type of the newly created component.
+;; Given a tz stream of length 2, extrapolates when the next timezone
+;; change aught to be.
+;; Currently it does so by taking the first time zone, and adding one
+;; year. This kind of works.
+;; Previously it took the difference between element 2 and 1, and added
+;; that to the start of the secound time zone. This was even more wrong.
+;; TODO? set remaining properties, and type of the newly created component.
(define (extrapolate-tz-stream strm)
- (let ((nevent (copy-vcomponent (stream-ref strm 1))))
- (mod! (attr nevent 'DTSTART)
- = (add-duration (time-difference
- (attr (stream-ref strm 1) 'DTSTART)
- (attr (stream-ref strm 0) 'DTSTART))))
+ (let ((nevent (copy-vcomponent (stream-car strm))))
+ (set! (attr nevent 'DTSTART)
+ (date->time-utc
+ (set (date-year
+ (time-utc->date (attr nevent 'DTSTART)))
+ = (+ 1))))
(stream-append strm (stream nevent))))
;; The RFC requires that at least one DAYLIGHT or STANDARD component is present.