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(((srfi srfi-41 util) filter-sorted-stream)
((srfi srfi-41) stream stream->list stream-filter stream-take-while)
((vcomponent base) extract prop make-vcomponent)
((vcomponent datetime) event-overlaps?)
((datetime) date date+ date<)
((calp util) set!))
(define* (event key: summary dtstart dtend)
(define ev (make-vcomponent 'VEVENT))
(set! (prop ev 'SUMMARY) summary
(prop ev 'DTSTART) dtstart
(prop ev 'DTEND) dtend)
ev)
(define start #2021-11-01)
(define end (date+ start (date day: 8)))
(define ev-set
(stream
(event ; should be part of the result
summary: "A"
dtstart: #2021-10-01
dtend: #2021-12-01)
(event ; should NOT be part of the result
summary: "B"
dtstart: #2021-10-10
dtend: #2021-10-11)
(event ; should also be part of the result
summary: "C"
dtstart: #2021-11-02
dtend: #2021-11-03)))
;; (if (and (date< (prop ev 'DTSTART) start-date)
;; (date<= (prop ev 'DTEND) end-date))
;; ;; event will be picked, but next event might have
;; (and (date< start-date (prop ev 'DTSTART))
;; (date< end-date (prop ev 'DTEND)))
;; ;; meaning that it wont be added, stopping filter-sorted-stream
;; )
;; The naïve way to get all events in an interval. Misses C due to B being "in the way"
(test-equal "incorrect handling of non-contigious"
'("A" #; "C")
(map (extract 'SUMMARY)
(stream->list
(filter-sorted-stream
(lambda (ev) (event-overlaps? ev start (date+ start (date day: 8))))
ev-set))))
;; A correct way
(test-equal "correct handling of non-contigious"
'("A" "C")
(map (extract 'SUMMARY)
(stream->list
(stream-filter (lambda (ev) (event-overlaps? ev start end))
(stream-take-while (lambda (ev) (date< (prop ev 'DTSTART) end))
ev-set)))))
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