1 files changed, 39 insertions, 0 deletions
diff --git a/module/vcomponent/group.scm b/module/vcomponent/group.scm
new file mode 100644
index 00000000..c5b6948e
--- /dev/null
+++ b/module/vcomponent/group.scm
@@ -0,0 +1,39 @@
+(define-module (vcomponent group)
+  #:use-module (vcomponent)
+  #:use-module (vcomponent datetime)
+  #:use-module (srfi srfi-19)
+  #:use-module (srfi srfi-19 util)
+  #:use-module (srfi srfi-41)
+  #:use-module (srfi srfi-41 util)
+  #:export (group-stream))
+
+(define-stream (group-stream in-stream)
+  (define (ein? day) (lambda (e) (event-contains? e (date->time-utc day))))
+
+  (let loop ((days (day-stream (time-utc->date (attr (stream-car in-stream) 'DTSTART))))
+             (stream in-stream))
+    (if (stream-null? stream)
+        stream-null
+        (let* ((day (stream-car days))
+               (tomorow (add-day (date->time-utc (drop-time day)))))
+          (let ((head (stream-take-while (ein? day) stream))
+                (tail
+                 (filter-sorted-stream*
+                  (lambda (e) (time<? tomorow (attr e 'DTEND)))
+                  (lambda (e) (time<=? tomorow (attr e 'DTSTART)))
+                  stream)))
+
+            (stream-cons (cons day head)
+                         (loop (stream-cdr days)
+                               tail)))))))
+
+(define-public (get-groups-between groups start-date end-date)
+  (filter-sorted-stream
+   ;; TODO in-date-range? drops the first date
+   (compose (in-date-range? start-date end-date)
+            car)
+   groups))
+
+
+(define-public (group->event-list group)
+  (stream->list (cdr group)))