From cad1bb506aa7b2723cbeb5ba435b65868c10916a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@hornquist.se>
Date: Wed, 25 Dec 2019 19:20:18 +0100
Subject: HTML output only describe multi-day events once.

The HTML renderer mostly works in days. Events spanning over midnight
therefore appears multiple times in the layout. This lead to their
start-time + uid not to be unique any more, which was bad since I
assumed it to be unique.

This commit only describes a multi-day event on the day the event
starts, with a special case for events which start before a given time
span.

Repeating events aren't affected, and are still show once per instance.
---
 module/output/html.scm | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/module/output/html.scm b/module/output/html.scm
index 21713455..977c73b9 100644
--- a/module/output/html.scm
+++ b/module/output/html.scm
@@ -1,5 +1,6 @@
 (define-module (output html)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-41)
   #:use-module (srfi srfi-41 util)
   #:use-module (vcomponent)
@@ -149,7 +150,16 @@
               (header (h2 ,(let ((s (date->string date "~Y-~m-~d")))
                              `(a (@ (href "#" ,s)
                                     (class "hidelink")) ,s))))
-              ,@(map fmt-single-event (stream->list events)))))
+              ,@(stream->list
+                 (stream-map fmt-single-event
+                             (stream-filter
+                              (lambda (ev)
+                                ;; If start was an earlier day
+                                ;; This removes all descriptions from events for previous days,
+                                ;; solving duplicates.
+                                (time<? (date->time-utc date)
+                                        (attr ev 'DTSTART)))
+                              events))))))
 
 (define (days-in-month n)
   (cond ((memv n '(1 3 5 7 8 10 12)) 31)
@@ -226,6 +236,11 @@
 
 (define repo-url (make-parameter "https://git.hornquist.se"))
 
+;;; NOTE
+;;; The side bar filters all earlier events for each day to not create repeats,
+;;; and the html-generate procedure also filters, but instead to find earlier eventns.
+;;; All this filtering is probably slow, and should be looked into.
+
 (define-public (html-generate calendars events start end)
   (define evs (get-groups-between (group-stream events)
                                   start end))
@@ -293,6 +308,14 @@
 
                        ;; List of events
                        (div (@ (class "eventlist"))
+                            ;; Events which started before our start point, but "spill" into our time span.
+                            (section (@ (class "text-day"))
+                                     (header (h2 "Tidigare"))
+                                     ,@(stream->list
+                                        (stream-map fmt-single-event
+                                          (stream-take-while (compose (cut time<? <> (date->time-utc start))
+                                                                      (extract 'DTSTART))
+                                            (cdr (stream-car evs))))))
                             ,@(stream->list (stream-map fmt-day evs)))))))))
 
 
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