#!/bin/bash


set -eux


[ -n "${DOMAIN}" ] || {
    echo "Error: you must set \$DOMAIN prior to running this script." >&2
    exit 1
}

[ -n "${BACKUP_SERVER}" ] || {
    echo "Error: you must set \$BACKUP_SERVER prior to running this script." >&2
    exit 1
}

KEY_BACKUP_ID=${KEY_BACKUP_ID:-rsync}

KEY_COMMENTARY="$KEY_BACKUP_ID@$DOMAIN"

MIRROR_DIR_PATH="${MIRROR_DIR_PATH:-$PWD/resources/bin/mirror-dir}"
[ -e "$MIRROR_DIR_PATH" ] || {
    echo "Error: you must set \$MIRROR_DIR_PATH or be the root of the charm to run this script." >&2
    exit 1
}

## rsync
type -p rsync >/dev/null 2>&1 || apt-get install -y rsync </dev/null

## creating rsync user
mkdir -p /var/lib/rsync

getent group rsync >/dev/null ||
    groupadd -r rsync

getent passwd rsync >/dev/null ||
    useradd -r rsync -d /var/lib/rsync -g rsync

chown rsync:rsync /var/lib/rsync

## rsync ssh key creation
if [ -e /var/lib/rsync/.ssh/id_rsa.pub ]; then
    ## Mainly for update of old solution
    content=$(cat /var/lib/rsync/.ssh/id_rsa.pub)
    commentary=${content##* }
    if [ "${commentary}" != "$KEY_COMMENTARY" ]; then
        echo "Updating ssh key commentary from '${commentary}' to '$KEY_COMMENTARY'" >&2
        sed -ri "s/ [^ ]+\$/ $KEY_COMMENTARY/" /var/lib/rsync/.ssh/id_rsa.pub
    fi
else
    su -c 'ssh-keygen -t rsa -N "" -f ~/.ssh/id_rsa -q -C '"$KEY_COMMENTARY" - rsync
fi

dest="$BACKUP_SERVER"
if [[ "$dest" == *"/"* ]]; then
    dest="${dest%/*}"
fi

if [[ "$dest" == *":"* ]]; then
    ssh_options+=("-p" "${dest#*:}")
    dest="${dest%%:*}"
fi

ssh-keyscan "${ssh_options[@]}" -H "${dest}" > /var/lib/rsync/.ssh/known_hosts

apt-get install -y kal-shlib-{common,process,cmdline,array} </dev/null
case $(awk -Wversion 2>/dev/null || awk --version) in
    "mawk 1.3.3"*)
        ## Not good, it is from 1996, and we still find it on Debian 10
        apt-get install -y gawk </dev/null
        ;;
esac

ln -sf "$PWD/resources/bin/mirror-dir" /usr/local/sbin/mirror-dir


if ! [ -e /etc/mirror-dir/config.yml ]; then
    mkdir -p /etc/mirror-dir
    cat <<EOF > /etc/mirror-dir/config.yml
default:
  sources:
  - /etc
EOF
fi

cat <<EOF > /etc/cron.d/mirror-dir
SHELL=/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

$((RANDOM % 60)) $((RANDOM % 4))-23/4 * * *   root   mirror-dir backup -q -h "$DOMAIN" -d "$BACKUP_SERVER"

EOF