ccchh-website/fetch-calendar.sh

#!/bin/sh
set -eu

ICAL_URL=https://cloud.hamburg.ccc.de/remote.php/dav/public-calendars/QJAdExziSnNJEz5g
OUTFILE=data/calendar.json

# See here for uname -s outputs: https://en.wikipedia.org/wiki/Uname#Examples
OS_TYPE=$(uname -s)
if [ "$OS_TYPE" = "Linux" ]; then
    START_TIME=$(date --date="-6 hours" +%s) # now - 6 hours
    END_TIME=$(date --date="+1 month" +%s) # now + 1 month
elif [ "$OS_TYPE" = "Darwin" ] || [ "$OS_TYPE" = "FreeBSD" ]; then
    START_TIME=$(date -v-6H +%s) # now - 6 hours
    END_TIME=$(date -v+1m +%s) # now + 1 month
else
    echo "ERROR: Unsupported OS type"
    return 1
fi

mkdir -p $(dirname $OUTFILE)

echo "loading calendar file..."
curl -s $ICAL_URL\?export\&accept=jcal\&expand\=1\&start\=$START_TIME\&end\=$END_TIME | jq '.[2]|map({_type:.[0]}+(.[1]|map({key:.[0],value:.[3]})|from_entries))' > $OUTFILE
echo "...done"