calendar: hide empty attendee list

Include the ATTENDEE and DETAILED LIST section in the calendar filter's
output only if there are actually attendees to list.  I was especially
confused by the empty DETAILED LIST, as it wasn't clear which kind of
detail it was supposed to list (and it also looked a bit like a heading
for the description following immediately below), see e.g. the test
output in filters/vectors/calendar-invite.expected.

Fixes: 777bbb77e806 ("contrib: improve readability of meeting requests")
Changelog-fixed: Builtin `calendar` filter shows empty attendee list.
Signed-off-by: Timon Reinold <tirei+aerc@agon.one>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 30 insertions, 21 deletions

diff --git a/filters/calendar b/filters/calendar
index aeddeadf..a808a253 100755
--- a/filters/calendar
+++ b/filters/calendar
@@ -175,28 +175,30 @@ BEGIN {
 			printf fmt, "LOCATION",  location
 		if(organizer != "")
 			printf fmt, "ORGANIZER", organizer
-		printf "  %-14s", "ATTENDEES "
-		for (idx in people_attending) {
-			if (idx == 1){
-				printf "%s,\n", people_attending[idx]
+		if (notEmpty(people_attending)) {
+			printf "  %-14s", "ATTENDEES "
+			for (idx in people_attending) {
+				if (idx == 1){
+					printf "%s,\n", people_attending[idx]
+				}
+				else if (idx == length(people_attending)){
+					printf "  %-14s%s\n", "", people_attending[idx]
+				}
+				else{
+					printf "  %-14s%s,\n", "", people_attending[idx]
+				}
 			}
-			else if (idx == length(people_attending)){
-				printf "  %-14s%s\n", "", people_attending[idx]
-			}
-			else{
-				printf "  %-14s%s,\n", "", people_attending[idx]
-			}
-		}
-		printf "\n\n  %-14s\n", "DETAILED LIST:"
-		for (idx in people_attending) {
-			printf fmt, "ATTENDEE [" idx "]", people_attending[idx]
-			partstat = people_partstat[idx]
-			if (partstat != "") {
-				printf fmt, "", "STATUS\t" partstat
-			}
-			rsvp = people_rsvp[idx]
-			if (rsvp != "") {
-				printf fmt, "", "RSVP\t" rsvp
+			printf "\n\n  %-14s\n", "DETAILED LIST:"
+			for (idx in people_attending) {
+				printf fmt, "ATTENDEE [" idx "]", people_attending[idx]
+				partstat = people_partstat[idx]
+				if (partstat != "") {
+					printf fmt, "", "STATUS\t" partstat
+				}
+				rsvp = people_rsvp[idx]
+				if (rsvp != "") {
+					printf fmt, "", "RSVP\t" rsvp
+				}
 			}
 		}
 		if(entry != "")
@@ -205,6 +207,13 @@ BEGIN {
 	}
 }
 
+function notEmpty(array)
+{
+	# "length(array) > 0" isn't POSIX-comapoptible, length accepts only strings
+	for (idx in array) return 1;
+	return 0;
+}
+
 function prepare(line)
 {
 	gsub($1, "", line)