From 8a1dbbb0b3158cdd8870e8abbbf485b8bf84c505 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Thu, 14 May 2020 17:44:39 +0200
Subject: Remove recurrence instances before our start date.

---
 module/vcomponent/recurrence/display/test.scm | 6 +++---
 module/vcomponent/recurrence/generate-alt.scm | 8 ++++++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/module/vcomponent/recurrence/display/test.scm b/module/vcomponent/recurrence/display/test.scm
index 2e04adf7..bcfbaafe 100644
--- a/module/vcomponent/recurrence/display/test.scm
+++ b/module/vcomponent/recurrence/display/test.scm
@@ -20,7 +20,7 @@
   (let ((count 0))
    (lambda (comp)
      (mod! count = (+ 1))
-     (format #t "~%~a > ~a~%" count (attr comp 'SUMMARY))
+     (format #t "~%~a > \x1b[1m~a\x1b[m~%" count (attr comp 'SUMMARY))
      (format #t "=> upprepas ~a.~%~{~a~^, ~}~%" (format-recurrence-rule
                                                  (attr comp 'RRULE))
              (map (lambda (d) (datetime->string d "~a ~1 ~3"))
@@ -52,6 +52,8 @@
 
   v)
 
+;; TODO bysetpos
+
 (map run-test
  (list
   (vevent
@@ -304,8 +306,6 @@ Thursday, for the next 3 months"
    rrule: "FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO")
   ;; => "varannan tisdag & söndag, 4 gånger."
 
-  ;; TODO this starts one to early (and by consequence ends one to early)
-  ;; first instance should be the 5th.
   (vevent
    summary: "changing only WKST from MO to SU, yields different results..."
    dtstart: "19970805T090000"
diff --git a/module/vcomponent/recurrence/generate-alt.scm b/module/vcomponent/recurrence/generate-alt.scm
index a98d10db..77304b55 100644
--- a/module/vcomponent/recurrence/generate-alt.scm
+++ b/module/vcomponent/recurrence/generate-alt.scm
@@ -71,7 +71,6 @@
 
 
 
-;; TODO compliacted fields
 ;; rrule → (list extension-rule)
 (define (all-extenders rrule)
   (make-extenders
@@ -345,7 +344,12 @@
                       (aif (attr* event 'EXDATE)
                            (cut member <> (map value it))
                            (const #f))
-                      (generate-posibilities rrule (attr event 'DTSTART))
+                      ;; Some expanders can produce dates before our start time.
+                      ;; For example FREQ=WEEKLY;BYDAY=MO where DTSTART is
+                      ;; anything after monday. This filters these out.
+                      (stream-drop-while
+                       (lambda (d) (date/-time< d (attr event 'DTSTART)))
+                       (generate-posibilities rrule (attr event 'DTSTART)))
                       ;; TODO ideally I should merge the limited recurrence set
                       ;; with the list of rdates here. However, I have never
                       ;; sen an event with an RDATE attribute, so I wont worry
-- 
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