#!/bin/bash

rsyncOptions='-6vxcaHAXF'
rsync --help | \
  grep -q -- --may-modify-others && \
  rsyncOptions="${rsyncOptions} --may-modify-others"

[ -r "#ETCDIR#/backup.conf" ] && \
  . "#ETCDIR#/backup.conf"

usage()
{
  >&2 echo \
'Usage:  backup /tmp/pidFile /path/to/destination/ user@source:path [proxy_user@ssh_host]
Backup files from remote with rsync, possibly via SSH-tunnel.

With no arguments, information is expected to be in array $backups in #ETCDIR#/backup.conf with name of executable (e.g. a symlink) as key.

Options:
  /tmp/pidFile           location of file to store PID in
  /path/to/destination   location to store backups in
  user@source:path       remote data to back up
  proxy_user@ssh_host    ssh login to proxy node (optional)
#HELPTEXT#              #'
  [ -z "$1" ] && exit 1
  exit $1
}

if [ $# -eq 1 ]
then
  if [ "$1" == "--help" ]
  then
    usage 0
  elif [ "$1" == "--version" ]
  then
    echo '#VERSION#'
    exit
  fi
fi

if [ $# -eq 0 ]
then
  backupID="$(basename $0)"
  [ -z "${backups[${backupID}]}" ] && usage
  set /tmp/${backupID}.pid ${backups[${backupID}]}
fi

Basis="$2"
pidFile="$1"
QuellIP=$(echo "$3" | sed "s|^[a-zA-Z]*://||; s|^[a-zA-Z]*@||; s|:\?/.*$||")

if [ "$#" -eq 3 ]
then
  Quelle="$3"
elif [ "$#" -eq 4 ]
then
  sshHopp="$4"
  lokPort=$[$RANDOM/2+8000]
  rsyncShell="-e ssh -6 -p${lokPort} -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null"
  tunnelBefehl="ssh -6 -t -t -L[::1]:${lokPort}:${QuellIP}:22 ${sshHopp}"
  HoppIP="${sshHopp#*@}"
  Quelle="$(echo "$3" | sed "s|${QuellIP}|[::1]|")"
else
  usage
fi

if [ -n "${QuellIP}" ]
then
  ping -c1 ${QuellIP} > /dev/null || exit 11
fi
if [ -n "${HoppIP}" ]
then
  ping -c1 ${HoppIP} > /dev/null || exit 11
fi

if [ ! -d ${Basis} ]
then
  [ $(mount | grep -c "\S\+\s\+\S\+\s\+/var/ftp\s") -eq 0 ] && exit 11
  exit 2
fi

neues_Datum="${Basis}/$(date "+%Y_%m_%d")"
neues="${Basis}/aktuell"
linkdests=""
for s in $(ls -1 "${Basis}" | sort -r | grep -vxF -m 20 aktuell )
do
  linkdests="${linkdests} --link-dest ${Basis}/${s}"
done

if [ ! "$(whoami)" == "root" ]
then
  echo "I need to be root."
  exit 3
fi

[ -w "${Basis}" ] || exit 11
[ -e "${neues_Datum}" ] && exit 4
[ -e "${pidFile}" ] && exit 5

echo $$ > "${pidFile}"

if [ -n "${tunnelBefehl}" ]
then
  ${tunnelBefehl} &
  backgroundPid=$!
  sleep 4
fi

for toExclude in "${excludes[@]}"
do
  excludeArgs="${excludeArgs} --exclude ${toExclude}"
done

if [ ! -e "${neues}/wip" ]
then
  mkdir -p "${neues}/wip"
fi
chmod 750 "${neues}"{,/wip}
chown root:root "${neues}"{,/wip}
if [ -z "${rsyncShell}" ]
then
  rsync ${rsyncOptions} \
    ${linkdests} \
    ${excludeArgs} \
    ${Quelle} "${neues}/wip/"
  sleep 1
  rsync ${Quelle}
else
  rsync "${rsyncShell}" \
    ${rsyncOptions} \
    ${linkdests} \
    ${excludeArgs} \
    ${Quelle} "${neues}/wip/"
  sleep 1
  rsync "${rsyncShell}" ${Quelle}
fi
erg=$?

[ -n "${backgroundPid}" ] && kill "${backgroundPid}"

if [ ${erg} -eq 0 ] || [ ${erg} -eq 24 ]
then
  chmod o-rwx "${neues}/wip"
  neueres_Datum="${Basis}/$(date "+%Y_%m_%d")"
  if [ ! -e "${neueres_Datum}" ]; then
    neues_Datum="${neueres_Datum}"
  fi
  mv "${neues}/wip" "${neues_Datum}"
  rmdir "${neues}"
  rm "${pidFile}"
else
  rm "${pidFile}"
  exit 11
fi