From 5a17028620ed7d940eb18ce7f4f552e12214ce12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Mon, 23 Mar 2020 01:04:37 +0100
Subject: Hopefully fixed events-between.

---
 module/output/html.scm       | 15 +++++++++------
 module/srfi/srfi-41/util.scm | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 6 deletions(-)

(limited to 'module')

diff --git a/module/output/html.scm b/module/output/html.scm
index d6a9e8fa..50203652 100644
--- a/module/output/html.scm
+++ b/module/output/html.scm
@@ -248,13 +248,16 @@
                 (iota 12 0 2)))))
 
 ;; date, date, [sorted-stream events] → [list events]
-;;; TODO
 (define (events-between start-date end-date events)
-  (filter-sorted-stream
-   (lambda (e)
-     (timespan-overlaps? start-date (date+ end-date (date day: 1))
-                         (attr e 'DTSTART) (attr e 'DTEND)))
-   events))
+  (define (overlaps e)
+    (timespan-overlaps? start-date (date+ end-date (date day: 1))
+                        (attr e 'DTSTART) (attr e 'DTEND)))
+
+  (stream-filter overlaps
+                 (get-stream-interval
+                  overlaps
+                  (lambda (e) (not (date< end-date (as-date (attr e 'DTSTART)))))
+                  events)))
 
 ;; Returns number of days in time interval.
 ;; @example
diff --git a/module/srfi/srfi-41/util.scm b/module/srfi/srfi-41/util.scm
index 3101bc85..dda0fcd0 100644
--- a/module/srfi/srfi-41/util.scm
+++ b/module/srfi/srfi-41/util.scm
@@ -28,6 +28,10 @@
 ;; on. From there it knows that once it has found the first element
 ;; that satisfies our predicate all remaining elements satisfying pred
 ;; will be in direct succession.
+;; Does have some drawbacks, concider an event between 2020-01-01 and 2020-12-31.
+;; The collection is sorted on start time, and we want all events overlapping the
+;; interval 2020-02-01 to 2020-02-29. We would get the long event, but then probably
+;; stop because all regular small events in january.
 (define-public (filter-sorted-stream pred stream)
   (stream-take-while
    pred (stream-drop-while
@@ -48,6 +52,16 @@
         [else (filter-sorted-stream* pred? keep-remaining?
                                      (stream-cdr stream))]))
 
+
+;; returns all object in stream from the first object satisfying
+;; start-pred, until the last object which sattisfies end-pred.
+(define-public (get-stream-interval start-pred end-pred stream)
+  (stream-take-while
+   end-pred (stream-drop-while
+             (negate start-pred)
+             stream)))
+
+
 ;; Finds the first element in stream satisfying pred.
 ;; Returns #f if nothing was found
 (define-public (stream-find pred stream)
-- 
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