# Immediately exit if any command has a non-zero exit.
# A reference to any variable you haven't previously defined - with the exceptions of $* and $@ - is an error.
# If any command in a pipeline fails, that return code will be used as the return code of the whole pipeline.
set -euo pipefail

# There are already cron scripts installed to automatically run rsnapshot in
# the background on a regular hourly/daily/weekly/monthly schedule.  If this
# is on a machine that is shutdown or goes to sleep often, then install
# anacron.
#
ENABLE_CRON=no

# Also run the hourly job in addition to the daily, weekly, and monthly
#ENABLE_HOURLY=yes

# Specify the disk where the backups are written to, this is the same place as
# is specified in /etc/rsnapshot.conf as 'snapshot_root'.  This is used to
# detect if the disk is mounted or not when rsnapshot runs in a cron job.
#
SNAPSHOT_ROOT="<NOT_DEFINED>"

RSNAPSHOT="/usr/bin/rsnapshot"

function backup()
{
    wait="$1" # in seconds
    freq="$2" # hourly, daily, weekly or monthly

    #retry every 10 minutes
    every=600

    if [[ "$ENABLE_CRON" == "yes" ]] ; then
        exit 1000
    fi

    until=$(( $(date +%s) + $wait))
    while [[ $(date +%s) < $until ]] ; do
        test -d "$SNAPSHOT_ROOT" && break
        sleep $every
    done

    # See ionice(1)
    if [ -x /usr/bin/ionice ] &&
        /usr/bin/ionice -c3 true 2>/dev/null; then
        IONICE="/usr/bin/ionice -c3"
    fi

    test -d "$SNAPSHOT_ROOT" && \
        nice -n 20 $IONICE $RSNAPSHOT $freq
}