show date diff on schedule command

bot.sh

@@ -182,7 +182,8 @@ do
                     json=$(curl -s "https://radio.tildeverse.org/api/station/1/schedule?rows=1" | jq ".[]")
                     nextdj=$(jq -r .name <<< "$json")
                     nexttime=$(LANG=C TZ=UTC date -d "$(jq -r .start <<< "$json")")
-                    msg "$from" "$schedule - $nextdj will be on at $nexttime"
+                    timediff=$(TZ=UTC awk -v d="$nexttime" 'BEGIN { then=mktime(d); now=systime(); print strftime("%Hh %Mm", then - now); }')
+                    msg "$from" "$schedule - $nextdj will be on at $nexttime (in $timediff)"
                     ;;
 
                 help)