#!/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

case "$1" in
  FORKSTART )
    touch "$BASEDIR/var/${2}.connected"
    while [[ -e "$BASEDIR/var/${2}.connected" ]]; do
      ssh -F $CONFFILE -N $2 &> /dev/null
      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 | grep '^Host ' | sed 's/^Host //' | xargs -I% -P0 $0 FORKSTART % &>/dev/null &
  ;;
  stop)
    rm "$BASEDIR/var/tunnelkeeper.pid"
    cat $CONFFILE | grep '^Host ' | sed 's/^Host //' | xargs -I% -P0 $0 FORKDEL %
    cat $CONFFILE | grep -o 'LocalForward [0-9]* ' | grep -o '[0-9]*' | xargs -I% -P0 $0 FORKKILL % &>/dev/null
  ;;
  install )
    if [[ $UID -ne 0 ]]; then
      echo "You must be root to do this"
      exit
    fi
    mkdir -p /opt/tunnelkeeper/var
    mkdir -p /opt/tunnelkeeper/etc
    if [[ -f "$BASEDIR/etc/tunnels.conf" ]]; then
      cp "$BASEDIR/etc/tunnels.conf" /opt/tunnelkeeper/etc
    fi
    cp "$REALPATH" "/opt/tunnelkeeper/tunnelkeeper.sh"
    echo "[Unit]
Description=TunnelKeeper keeps SSH tunnels open.
After=network.target
[Service]
User=root
Group=root
Type=forking
ExecStart=/opt/tunnelkeeper/tunnelkeeper.sh start
ExecStop=/opt/tunnelkeeper/tunnelkeeper.sh stop
RestartSec=15
Restart=always
[Install]
WantedBy=multi-user.target" >> /lib/systemd/system/tunnelkeeper.service
    systemctl daemon-reload
    systemctl enable tunnelkeeper.service
    echo "tunnelkeeper service installed"
  ;;
  * )
    echo -e "\nUsage: $(basename $0) [start|stop|install]\n"
  ;;
esac