#!/usr/bin/env bash

REALPATH="$(realpath $0)"
BASEDIR="${REALPATH%/*}"

mkdir -p "$BASEDIR/var"
mkdir -p "$BASEDIR/etc"
CONFFILE="$BASEDIR/etc/tunnels.conf"

if [[ ! -f "$CONFFILE" ]]; then
  echo "Config file \"$CONFFILE\" does not exist"
  exit 1
fi

function ruroot () {
  if [[ $UID -ne 0 ]]; then
    echo "You must be root to do this"
    exit
  fi
}

DEBUGLEVEL=$(cat "$CONFFILE" | grep -i "#: *debug" | grep -o [0-9])
case "$DEBUGLEVEL" in
  2) dbgopt='-v';;
  3) dbgopt='-vvv';;
  *) dbgopt='';;
esac

function dbg () {
  if [[ $DEBUGLEVEL != "0" ]]; then
    logger -t tunnelkeeper
  fi
}

case "$1" in
  FORKSTART )
    touch "$BASEDIR/var/${2}.connected"
    while [[ -e "$BASEDIR/var/${2}.connected" ]]; do
      ssh -F "${CONFFILE}" $dbgopt -N $2 2>&1 | dbg
      sleep 5
    done
  ;;
  FORKKILL ) kill $(sudo netstat -tnlp | grep "127.0.0.1:${2}" | grep -o '[0-9]*/ssh' | grep -o '[0-9]*') &>/dev/null ;;
  FORKDEL ) rm "$BASEDIR/var/${2}.connected" ;;
  start)
    if [[ -e "$BASEDIR/var/tunnelkeeper.pid" ]]; then
      exit
    fi
    echo $$ > "$BASEDIR/var/tunnelkeeper.pid"
    cat "$CONFFILE" | awk '/^Host / {print $2}' | xargs -I% -P0 $0 FORKSTART % &
  ;;
  stop)
    rm "$BASEDIR/var/tunnelkeeper.pid"
    cat "$CONFFILE" | awk '/^Host / {print $2}' | sed 's/^Host //' | xargs -I% -P0 $0 FORKDEL %
    cat "$CONFFILE" | grep -o 'LocalForward [0-9]* ' | grep -o '[0-9]*' | xargs -I% -P0 $0 FORKKILL %
  ;;
  restart) $0 stop; sleep 2; $0 start ;;
  install )
    ruroot
    mkdir -p /opt/tunnelkeeper/var
    mkdir -p /opt/tunnelkeeper/etc
    if [[ -f "$BASEDIR/etc/tunnels.conf" ]]; then
      cp "$BASEDIR/etc/tunnels.conf" /opt/tunnelkeeper/etc
    fi
    cp "$REALPATH" "/opt/tunnelkeeper/tunnelkeeper"
    ln -f -s /opt/tunnelkeeper/tunnelkeeper /usr/local/bin/tunnelkeeper
    echo "[Unit]
Description=TunnelKeeper keeps SSH tunnels open.
After=network.target
[Service]
User=root
Group=root
Type=forking
ExecStart=/opt/tunnelkeeper/tunnelkeeper start
ExecStop=/opt/tunnelkeeper/tunnelkeeper stop
RestartSec=15
Restart=always
[Install]
WantedBy=multi-user.target" > /lib/systemd/system/tunnelkeeper.service
    systemctl daemon-reload
    systemctl enable tunnelkeeper.service
    echo -e "\nTunnelKeeper service installed.\n"
  ;;
  uninstall )
    ruroot
    rm /usr/local/bin/tunnelkeeper
    rm /lib/systemd/system/tunnelkeeper.service
    systemctl enable tunnelkeeper.service
    systemctl daemon-reload
    rm -rf /opt/tunnelkeeper
    echo -e "\nTunnelKeeper service uninstalled.\n"
  ;;
  list )
    echo "---"
    find "$BASEDIR/var/" -name '*.connected' | sed 's/^.*\///g; s/\.connected//g'
    echo "---"
  ;;
  config )
    ruroot
    vi "$CONFFILE"
  ;;
   * )
    echo -e "\nUsage: $(basename $0) start|stop|restart|install|uninstall|config|list\n"
  ;;
esac