From 7ce7c3b60505a72a1d46343d6595e1176d107e84 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@hornquist.se>
Date: Sun, 6 Oct 2019 22:49:14 +0200
Subject: Identified timezone problem.

---
 module/vcomponent.scm                     |  2 +-
 module/vcomponent/recurrence/generate.scm |  2 ++
 module/vcomponent/timezone.scm            | 36 ++++++++++++++++++++++++++++++-
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/module/vcomponent.scm b/module/vcomponent.scm
index a65ef2d4..d8e6e61f 100644
--- a/module/vcomponent.scm
+++ b/module/vcomponent.scm
@@ -118,7 +118,7 @@
 
                 (unless (attr component "COLOR")
                   (set! (attr component "COLOR")
-                    (attr root      "COLOR")))
+                    (attr root "COLOR")))
 
                 ;; return
                 component))))
diff --git a/module/vcomponent/recurrence/generate.scm b/module/vcomponent/recurrence/generate.scm
index 3f4cb869..78a5e3d5 100644
--- a/module/vcomponent/recurrence/generate.scm
+++ b/module/vcomponent/recurrence/generate.scm
@@ -54,6 +54,8 @@
     (set! (attr ev 'DTSTART)
       (copy-time (attr ev 'DTSTART)))
 
+    (set! (attr ev 'date-obj) d)
+
     (let ((i (interval r)))
      (case (freq r)
        ((SECONDLY) (mod! (second d) = (+ i)))
diff --git a/module/vcomponent/timezone.scm b/module/vcomponent/timezone.scm
index f6112ebc..a89c8c5c 100644
--- a/module/vcomponent/timezone.scm
+++ b/module/vcomponent/timezone.scm
@@ -10,7 +10,7 @@
   :use-module ((vcomponent datetime) :select (ev-time<?))
   )
 
-;;@begin exampe
+;;@begin example
 ;; <VTIMEZONE> :: "#<vcomponent 558c5da80fc0>"
 ;;                  TZID: Europe/Stockholm
 ;;        X-LIC-LOCATION: Europe/Stockholm
@@ -28,10 +28,44 @@
 ;; :         TZOFFSETFROM: +0200
 ;; @end example
 
+;;; GENERAL INFINITE EXTRAPOLATION OF TIMEZONE DATA IS IMPOSSIBLE, SINCE TIMEZONES
+;;; DON'T CHANGE THAT PREDICTABLY
+
+;; @begin example
+;; BEGIN:VTIMEZONE
+;;  TZID:Europe/Stockholm
+;;  BEGIN:STANDARD
+;;   DTSTART;VALUE=DATE-TIME:20181028T020000
+;;   TZNAME:CET
+;;   TZOFFSETFROM:+0200
+;;   TZOFFSETTO:+0100
+;;  END:STANDARD
+;;  BEGIN:DAYLIGHT
+;;   DTSTART;VALUE=DATE-TIME:20190331T030000
+;;   TZNAME:CEST
+;;   TZOFFSETFROM:+0100
+;;   TZOFFSETTO:+0200
+;;  END:DAYLIGHT
+;; END:VTIMEZONE
+;; @end example
+;; This should really be parsed as:
+;; STANDARD : [2018-10-28 02:00, 2019-03-31 03:00)
+;; DAYLIGHT : [2019-03-21 03:00, ∞)
+
 ;; 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.
 (define (extrapolate-tz-stream strm)
+  (let ((nevent (copy-vcomponent (stream-car strm))))
+    (set! (attr nevent 'DTSTART)
+      ))
+
+
+  ;; old code fails since (length standard) ≠ (length summer)
+  ;; Also, it copies the summmer time, making the alternation
+  ;; break (but that wasn't the primary problem)
+
+  #;
   (let ((nevent (copy-vcomponent (stream-ref strm 1))))
     (mod! (attr nevent 'DTSTART)
           = (add-duration (time-difference
-- 
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